Final 2022 Marine Mammal Stock Assessment Reports, 54592-54605 [2023-17219]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 88, Number 154 (Friday, August 11, 2023)]
[Notices]
[Pages 54592-54605]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-17219]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC506]


Final 2022 Marine Mammal Stock Assessment Reports

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; response to comments.

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SUMMARY: As required by the Marine Mammal Protection Act (MMPA), NMFS 
has considered public comments for revisions of the 2022 marine mammal 
stock assessment reports (SARs). This notice announces the availability 
of 25 final 2022 SARs that were updated and finalized.

ADDRESSES: The 2022 Final SARs are available in electronic form via 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region.
    Copies of the Alaska Regional SARs may be requested from Nancy 
Young, Alaska Fisheries Science Center; copies of the Atlantic, Gulf of 
Mexico, and Caribbean Regional SARs may be requested from Sean Hayes, 
Northeast Fisheries Science Center; and copies of the Pacific Regional 
SARs may be requested from Jim Carretta, Southwest Fisheries Science 
Center (see FOR FURTHER INFORMATION CONTACT below).

FOR FURTHER INFORMATION CONTACT: Zachary Schakner, Office of Science 
and Technology, 301-427-8106, [email protected]; Nancy Young, 
206-526-4297, [email protected], regarding Alaska regional stock 
assessments; Sean Hayes, 508-495-2362, [email protected], regarding 
Atlantic, Gulf of Mexico, and Caribbean regional stock assessments; or 
Jim Carretta, 858-546-7171, [email protected], regarding Pacific 
regional stock assessments.

SUPPLEMENTARY INFORMATION:

Background

    Section 117 of the MMPA (16 U.S.C. 1361 et seq.) requires NMFS and 
the U.S. Fish and Wildlife Service (FWS) to prepare stock assessments 
for each stock of marine mammals occurring in waters under the 
jurisdiction of the United States, including the U.S. Exclusive 
Economic Zone (EEZ). These SARs must contain information regarding the 
distribution and abundance of the stock, population growth rates and 
trends, estimates of annual human-caused mortality and serious injury 
(M/SI) from all sources, descriptions of the fisheries with which the 
stock interacts, and the status of the stock. Initial SARs were 
completed in 1995.
    The MMPA requires NMFS and FWS to review the SARs at least annually 
for strategic stocks and stocks for which significant new information 
is available, and at least once every 3 years for non-strategic stocks. 
The term ``strategic stock'' means a marine mammal stock: (A) for which 
the level of direct human-caused mortality exceeds the potential 
biological removal level or PBR (defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population); (B) which, based on 
the best available scientific information, is declining and is likely 
to be listed as a threatened species under the Endangered Species Act 
(ESA) within the foreseeable future; or (C) which is listed as a 
threatened species or endangered species under the ESA or is designated 
as depleted under the MMPA. NMFS and FWS are required to revise a SAR 
if the status of the stock has changed or can be more accurately 
determined.
    In order to ensure that marine mammal SARs are based on the best 
scientific information available, the updated SARs under NMFS' 
jurisdiction are peer-reviewed within NOAA Fisheries Science Centers 
and by members of three regional independent Scientific Review Groups 
(SRGs) established under the MMPA to independently advise NMFS and FWS 
on marine mammal issues. Because of the time it takes to review, 
revise, and assess available data, the period covered by the 2022 Final 
SARs is 2016 through 2020. While this results in a time lag, the 
extensive peer review process ensures that the SARs are based on the 
best scientific information available.
    NMFS reviewed the status of all marine mammal strategic stocks and 
considered whether significant new information was available for all 
non-

[[Page 54593]]

strategic stocks under NMFS' jurisdiction. As a result of this review, 
NMFS revised reports for 25 stocks in the Alaska, Atlantic, and Pacific 
regions to incorporate new information. The 2022 revisions to the SARs 
include revisions to stock structures, updated or revised human-caused 
mortality/serious injury (M/SI) estimates, and updated abundance 
estimates. With the publication of these SARs, the revised stock 
structure for all North Pacific humpback whale stocks and Southeast 
Alaska harbor porpoises is finalized. The revisions to stock structure 
and the addition of new reports resulted in five newly designated 
strategic stocks and three newly designated non-strategic stocks. No 
stocks changed in status from ``non-strategic'' to ``strategic.'' One 
Western North Atlantic common bottlenose dolphin stock, the Northern 
South Carolina Estuarine System Stock, changed from ``strategic'' 
status to ``non-strategic.'' A technical update was made to the 
Northern Gulf of Mexico Bay, Sound, and Estuary stocks of common 
bottlenose dolphin SAR that covers 23 Northern Gulf of Mexico stocks to 
move Florida Bay from the Western North Atlantic to the Gulf of Mexico. 
Florida Bay is now included within Table 1 and Figure 1 of the SAR, and 
the number of stocks in the Gulf of Mexico has been updated 
accordingly. No other changes or updates were made to that SAR.
    NMFS received comments on the draft 2022 SARs from the Marine 
Mammal Commission (Commission); the Department of Fisheries and Oceans 
Canada (DFO); the Washington Department of Fish and Wildlife (WDFW); 
the Alaska Department of Fish and Game (ADFG); seven fishing industry 
associations (California Coast Crab Association (CCCA), West Coast 
Pelagic (WCP), Maine Lobstermen's Association (MLA), Washington 
Dungeness Crab Fishermen's Association (WDCFA, United Fishermen of 
Alaska (UFA), Southeast Alaska Fishermen's Alliance (SEAFA), and United 
Southeast Alaska Gillnetters (USAG)); a non-governmental organization 
(Natural Resources Defense Council (NRDC)); and two letters from the 
public. Responses to substantive comments are below. Responses to 
comments not related to the SARs are not included. Comments suggesting 
editorial or minor clarifying changes were incorporated in the reports, 
but they are not included in the summary of comments and responses. We 
did not reply to comments outside the scope of the SARs (e.g., 
regulating impacts of offshore wind). In some cases, NMFS' responses 
state that comments would be considered or incorporated in future 
revisions of the SARs rather than being incorporated into the final 
2022 SARs.

Comments on National Issues

    Comment 1: The Commission recommends that NMFS secures the 
resources necessary to conduct the surveys required to produce complete 
and up-to-date SARs and work with other agencies to collect the 
information needed. Additionally, the Commission recommends NMFS 
provide sufficient personnel and resources to maximize the value of 
surveys by allowing for photo-identification, biopsy sampling, 
satellite tagging, acoustic monitoring, and other efforts, which 
provide valuable information for understanding marine mammal 
distribution, habitat use, health, and behavior.
    Response: NMFS acknowledges the Commission's comment and will 
continue to prioritize our efforts to collect needed data, as resources 
allow.
    Comment 2: The Commission recommends that NMFS set a deadline to 
make draft SARs available for public review no later than the end of 
September each year and allow for more thoughtful review by interested 
parties.
    Response: NMFS thanks the Commission for the recommendation; we 
strive to keep the SARs on schedule and released to the public as 
quickly as possible.
    Comment 3: A member of the public comments that the SARs fail to 
provide information on whether dolphin populations are increasing, 
decreasing, or staying the same. They state that the lack of 
information on population trends in these reports makes them of little 
use to scientists trying to protect dolphins.
    Response: NMFS agrees that long-term time series trend analyses are 
useful while also acknowledging that it is difficult to achieve the 
appropriate precision and accuracy needed to detect trends (Authier et 
al. 2020). When sufficient information is available to evaluate trends, 
the information is included within the SAR. We will continue to 
prioritize our efforts to collect data to address abundance estimates 
and trends as resources allow.

Comments on Atlantic Issues

    Comment 4: The Commission comments that the change to the status of 
four bottlenose dolphin stocks from ``strategic'' to ``non-strategic'' 
lacks adequate justification. The Commission notes estimates of human-
caused M/SI are based on minimum counts and are likely to be higher in 
reality and is concerned about the proposed changes. Also, the 
Commission notes that Wells et al. (2015) estimated the proportion of 
carcasses recovered to be 0.33 for common bottlenose dolphins near 
Sarasota, Florida, but less populated areas and those with intricate 
networks of marsh habitat likely have substantially lower carcass 
detections. The Commissions recommends the following: reevaluate the 
strategic status of these four stocks, considering all available 
scientific information regarding plausible human-caused M/SI beyond the 
minimum count of detected strandings and at-sea observations; 
substantially increase efforts to investigate alternative strategies 
for collecting information on human-caused M/SI for bays, sounds, and 
estuaries (BSE) common bottlenose dolphin stocks for which 
entanglements are difficult to detect or quantify, and for which 
observer programs are lacking.
    Response: NMFS had proposed to change the status of four stocks of 
bottlenose dolphin (the Northern South Carolina Estuarine System, the 
Central Georgia Estuarine System, the Southern Georgia Estuarine 
System, and the Biscayne Bay--88 FR 4162 01-24-34). Based on the 
Commission's comment, NMFS reevaluated the strategic status of the four 
stocks. We revisited Wells et al. (2015) and implemented a lower 
stranded carcass recovery rate for some stocks as recommended by the 
Commission. We estimated M/SI (NMFS 2023) based on two carcass recovery 
rate estimates: 0.33 for Sarasota Bay (Wells et al. 2015) and 0.16 for 
Barataria Bay (DWH MMIQT 2015). Using the best available scientific 
information on the minimum abundance for each of these stocks, we 
concluded that annual human-caused M/SI for three stocks (Central 
Georgia Estuarine System, Southern Georgia Estuarine System, and 
Biscayne Bay) exceed PBR. Hence, these stocks' strategic status will 
remain unchanged. Regardless of the stranded carcass recovery rate, the 
Northern South Carolina Estuarine System Stock is non-strategic. An 
additional explanation for the rationale of each stock's status was 
provided within the Status of Stock sections.
    Comment 5: The DFO strongly disagrees with the gear origin country 
assignment given to North Atlantic right whale (NARW) #3920. The gear 
removed from #3920 was reviewed by the DFO and country/fishery of 
origin was found to be inconclusive. The cases which DFO disagrees with 
the country of origin assignment are as follows: Mortalities--right 
whale #3893, #3694, #3920 and Serious Injury--right whale #4094 and 
#3125.
    Response: NMFS responds to the specific cases below and looks 
forward

[[Page 54594]]

to continuing work with Canada on transboundary gear analyses to 
further our understanding of incident origins. Right whale cases #3893, 
#3694, and #3125 would benefit from bilateral gear analysis; but 
without new incident documentation, under longstanding NMFS protocols 
(https://www.greateratlantic.fisheries.noaa.gov/policyseries/index.php/GARPS/article/view/30/26), NMFS would not change the current 
attribution. Regarding #3920 and the potential uncertainties described 
in the DFO report ``Recovered Gear Analysis of North Atlantic Right 
Whale Eg #3920 `Cottontail' ''--references multiple isolated gear 
elements. The collective evidence (see report here https://media.fisheries.noaa.gov/2022-10/E22-20Cottontail-gear-analysis-updated-draft-GARFO.pdf) supports the conclusion that the recovered 
gear is consistent with the 2018/2019 Canadian Snow Crab Fishery. 
Regarding #4094, NMFS would consider changing the status to XC if 
Canada revises the published incident report (of which DFO are 
contributing authors) that identified this as Canadian snow crab gear.
    Comment 6: MLA comments that the Pace model's initial estimated 
population decline from 2011-2015 occurred during a time when NARW 
geographic distribution shifted to areas lacking survey effort and may 
be an underestimate of the population. MLA requests NMFS discuss the 
model's limitations and ensure they are taken into account as new data 
from the realigned survey effort are incorporated into the model. The 
draft SAR underweights the existence of natural predation as 
demonstrated by Taylor (2013), Curtis (2014), and Sharp (2019). MLA 
comments that the SAR must cite relevant literature on natural 
mortality in both NARW and closely related species, and discuss how the 
treatment of this significant factor affects population models. 
Finally, MLA believes Pace (2021) incorrectly assumes an equal sex 
ratio and probability of mortality. Males are known to make up a larger 
portion of the population and are statistically more likely to 
encounter and become entangled in a vertical line.
    Response: The Pace et al. (2017) and slightly updated Pace (2021) 
Mark-Recapture-Resight (MRR) model have been reviewed by both a journal 
peer review process for publication as well as more than 6 years of 
Atlantic SRG meetings across 20 expert members. Its contents are 
publicly available to review as the documents are cited within the SAR.
    The MRR model published by Pace et al. (2017) uses the sighting 
histories of individuals (adults and subadults) to estimate interval 
(in this case, annual) capture probabilities, which are allowed to vary 
at each interval. Indeed, the estimated capture probabilities since 
2011 of NARW have shown considerable variation compared with the 
previous decade. The statistical methodology employed simultaneously 
estimates rates of survival and capture and estimates the number of 
whales still alive. Additionally, the MRR model allows individual 
animals to have unique catchability parameters, thus reducing biases in 
capture rates found in simpler MRR models. The model does not assume an 
equal sex ratio and allows survival and capture rates to differ between 
the sexes. Although there is no accommodation for permanent emigration, 
there is no evidence that even modest numbers of NARW have permanently 
left all the areas surveyed in the United States and Canada, and all 
individuals identified in extralimital sightings have been seen in U.S. 
waters again following their oceanic sojourns. Hence, NMFS concludes 
that the estimated survival rates presented in the SAR and reflected in 
the abundance estimates represent actual survival rates of the stock 
and not merely apparent survival rates. Finally, it is important to 
note that the Pace et al. (2017) model relies on individual animals 
being photographically identifiable from their callosity patterns in 
order for them to be recruited into the population. Since these 
patterns do not typically stabilize until animals are at least 1 year 
old, the resulting abundance estimates, as well as the associated 
estimated total mortality estimated sensu Pace et al. (2021), only 
represent adult and subadult animals.
    Regarding natural mortality, NMFS and the SAR acknowledge that some 
natural mortality of calves exists, which is not inconsistent with the 
documented shark predation on calves, as noted by the commenter (Taylor 
2013; Curtis 2014). However, we cannot speak to the comments related to 
a Sharp et al. (2019) reference. Our reading of Sharp et al. (2019) 
included a review of only 70 NARW incidents, and the paper does not 
support the cited incident designations. There are no observations that 
attribute adult or subadult mortality to natural causes and only these 
age classes are included in the Pace et al. (2021) model estimates of 
total mortality. NMFS reviewed relevant data, existing models, and the 
literature with the Atlantic SRG on September 2, 2021, and requested 
their expert guidance on how to attribute estimated total mortality 
(adults and sub adults) to cause. The Atlantic SRG recommended NMFS 
continue to assign 100 percent of the total estimated mortalities of 
non-calf NARW (i.e., adult and subadult) to anthropogenic origins 
(Atlantic SRG letter to NMFS September 16, 2021).
    Comment 7: MLA asserts that NMFS' determination that 87 percent of 
undetected, assumed carcasses represent whales killed by fishing 
entanglements is unsupported and arbitrary. The draft 2022 SAR includes 
new text that entanglement is more likely to be detected than vessel 
strikes, which raises concern with NMFS' method of apportioning unknown 
sources of human-caused mortality. MLA questions NMFS' conclusion that 
because 87 percent of the observed, seriously injured right whales are 
caused by an entanglement, then 87 percent of assumed, undetected 
carcasses are similarly killed by entanglements. MLA believes it is 
more likely that the observed data with respect to carcass status as 
discussed in Pace (2021) are correct--that entanglements and vessel 
strikes kill whales in roughly equal proportions as reported in Sharp 
(2019). MLA thinks it is also plausible that when a whale is struck by 
a vessel, it is more likely to be killed than it is to be seriously 
injured. In contrast, MLA notes a majority of entanglements are of 
minor severity, when an incident occurs it is less likely to result in 
death, and mortality as a result of entanglement would probably be 
detected due to the amount of time that elapses between when an animal 
is entangled and when the animal ultimately dies.
    Response: NMFS continues to agree that no empirical study supports 
that whale carcasses are more likely to be detected when caused by 
vessel strikes, as opposed to entanglement. However, SARs provide 
published information on our current understanding of the right whale 
population, including trends in strandings and sightings data and a 
published hypothesis suggesting a disparity between detected 
entanglement/vessel strike serious injuries. Moore et al.'s (2020) 
hypothesis is founded in the physics of buoyancy on marine mammal 
bodies under varying conditions. There may be factors that increase the 
likelihood of detection of entanglements due to serious injuries. 
Lacking sufficient evidence regarding the likelihood of detecting 
vessel strikes or entanglements to inform an understanding of the cause 
of unseen, estimated mortalities of adults and sub adults, NMFS 
proposed many alternative scenarios to the Atlantic SRG on how best to 
apportion cryptic

[[Page 54595]]

mortality (NMFS intersessional September 21, 2021). The Atlantic SRG 
recommended that the ratio between entangled and vessel-struck NARW, 70 
percent (Table 2, NARW SAR), calculated from documented observations of 
Serious Injuries and Mortalities over the last 5 years, be used to 
apportion cause. NMFS scientists will continue to review published 
literature and work on improving methods of apportioning causes of 
estimated but unseen mortalities of adults and subadults. The Atlantic 
SRG will continue to consider the evidence presented as part of their 
responsibility in peer reviewing the SARs.
    Comment 8: MLA requests the draft SAR present the annual mortality 
and serious injury estimates by each fishery and describe area 
differences in such injuries. By lumping Canadian and U.S. fisheries 
together in the annual summaries presented in Table 2, MLA feels NMFS 
misleads the public with the implication that all of these injuries are 
attributable to U.S. fisheries. MLA requests that NMFS describe the 
observed M/SI by fishery for each year of the relevant 5-year reporting 
period. Specifically, MLA requests Table 2 to include summarized data 
concerning the country of origin of NARW entanglements during the 
relevant time period, taking into account scientific observations of 
entangling gear, the differentiating attributes of that gear, such as 
rope diameter and strength which influence comparative lethality, and 
describe the differences between the conservation programs and relative 
effectiveness of measures to protect NARW in each country.
    Response: NMFS continues to provide all available details on 
locations where right whale serious injury and mortality incidents are 
first observed and, when available, where the incidents originated (see 
Table 3, NARW SAR). Additionally, NMFS attempts to provide the maximum 
precision and resolution in apportioning all M/SI to fishery, vessel, 
or other causes following practices that have been peer-reviewed and 
recommended by the Atlantic SRG. However, sufficient evidence to assign 
entanglements to a specific country or fishery is usually lacking, 
given the rare instances of recovered gear with sufficient markings to 
distinguish initial entanglement location, gear type, or fishery. 
Because right whales are able to travel thousands of miles in short 
periods of time, even when trailing gear, it is very difficult to 
attribute entanglement based on the region of the initial sighting. 
Upon conferring with the Atlantic SRG, NMFS determined that there was 
insufficient information to provide guidance on the apportionment of 
estimated entanglements to a country of origin. We believe the 
expansion of gear marking and reporting requirements will assist us in 
this area moving forward.
    NMFS has invested considerable effort in developing better methods 
for apportioning M/SI to appropriate sources in light of increased 
mortality overall, including increasing observations determined to have 
occurred in Canadian fisheries. We are also working to improve our 
ability to quantify unseen (estimated) mortality of adults and 
subadults and to evaluate if and how to apportion natural versus 
anthropogenic mortality. As mentioned above, as part of this effort, 
the agency convened a special session of the Atlantic SRG in September 
2021 for scientific and technical input. The Atlantic SRG supported its 
prior position that 100 percent of the mortalities of non-calf NARW 
should be considered to be of anthropogenic origin. The Atlantic SRG 
also considered the various approaches provided by NMFS for 
apportioning M/SI between the United States and Canada but did not have 
enough information to provide a robust scientific alternative. 
Therefore, NMFS continues to use the best available information 
available to assign documented (and unobserved, estimated) mortalities 
and serious injuries (those identified as likely to result in 
mortality) to country and type of fishery. We continue to work with 
Canada on transboundary retrieved gear analyses and risk modeling. As 
science advances and more data become available, NMFS will consider 
assigning M/SI with greater resolution if scientifically appropriate, 
and if resources allow.
    Comment 9: MLA believes the NARW SAR should describe interactions 
between NARW and commercial fisheries, and this must include the 
information called for in section 117(a)(4) of the MMPA. MLA comments 
the SAR should also include data on the severity of entanglements, and 
MLA believes the SAR does not provide understanding of scarring data 
for the relevant time period.
    Response: The fisheries are summarized in ``Appendix 3--Fishery 
Descriptions'' because there are multiple species interactions with 
multiple fisheries. They are also available online at https://www.fisheries.noaa.gov/national/marine-mammal-protection/list-fisheries-summary-tables with table II category I and II fisheries 
referenced. NMFS cites our annual report that documents the details of 
our determination process for all reported injuries during the SAR time 
frame. Analyses of gear retrieved from large whales are also available 
online at https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-mammal-protection/atlantic-large-whale-take-reduction-plan. 
However, because only a small fraction of entanglements have gear 
recovered and a smaller fraction of that is traceable to the fishery, 
we have not been able to estimate the annual M/SI to the resolution of 
fishery and region of origin. Given new recommendations for the 
Atlantic SRG at the 2021 meeting and additional analysis from Pace et 
al. (2021), we are working to improve our understanding of this issue 
toward the resolution requested above for future SARs. We address this 
to the extent that data can support in Table 3. We discuss non-serious 
injuries in the third paragraph of the section titled ``Fishery-Related 
Mortality and Serious Injury.'' The report cites Knowlton et al. (2016) 
and, more recently, Hamilton et al. (2019), which indicate that the 
percentage of the population experiencing non-serious injuries is 
increasing (26 and 30 percent, respectively). Despite roughly 100 
injuries per annum in recent years, the incidents causing injuries are 
rarely observed. Wounds can persist for years, while animals may travel 
thousands of miles. Therefore, NMFS takes a conservative approach to 
not apportion injury by fishery or areas where data are unavailable. 
Additional language to address this concern has been added to the first 
paragraph of the ``Fishery-Related Mortality and Serious Injury'' 
section of the SAR.
    Comment 10: MLA asserts that the draft NARW SAR should include 
additional available scientific information about NARW behavior and 
associated risk of harm from fishing gear. MLA believes there are areas 
where NARW are rarely, if ever, observed and so NMFS' characterization 
of NARW year-round presence in the Gulf of Maine is misleading. These 
findings were most recently summarized and reported in Meyer-Gutbrod 
(2021); MLA requests this paper be referenced and discussed in the 
draft SAR. Additionally, Crowe (2021) determined that the Gulf of St. 
Lawrence is currently an important habitat for 40 percent of the right 
whale population.
    Response: The distribution changes and observations in the comment 
are correct. However, they are based on the assumption that NARW are 
only subject to mortality when they occur in dense aggregations and 
that those areas are the

[[Page 54596]]

only regions that should be managed for NARWs. In reality, dense 
aggregations in limited, small regions only occur during a portion of 
the year, and at no time of year are all right whales detected within 
known aggregations. NMFS recognizes that management measures must also 
reflect the documented acoustic presence of NARW during much of the 
year across their entire range, including areas of overlap with the 
Maine lobster fishery. There has been more recent acoustic monitoring, 
but these surveys cannot detect mortality/injury, determine the number 
of animals, or detect the presence of animals if they are not calling. 
Thus, gaps in visual survey data contribute to gaps in our 
understanding of NARW distribution and the locations of M/SI events. 
Recent congressional appropriations to increase surveillance in the 
Gulf of Maine may result in refining the identification of risk areas.
    Comment 11: MLA comments that the NARW SAR's reference to ``New 
England'' waters must specify that these important areas are located in 
southern New England. Also, MLA notes that the draft SAR under-reports 
recent calving data, stating that ``despite high survey effort, only 5 
and 0 calves were detected in 2017 and 2018, respectively,'' and adding 
that 7 were born in 2019 and 10 in 2020. The draft SAR omits the most 
recent calf detections from 2021, 2022, and 2023 (to date) with 20, 15 
and 12 calves detected, respectively. The section summarizing M/SI 
should be renamed ``Vessel Strike-Related Mortality and Serious 
Injury'' as is done for the section on M/SI from fishery-related M/SI. 
In the 2020 SAR, NMFS removed language stating that the majority of 
right whale sightings occur within 90 kilometers (km) of the shoreline 
of the southeastern United States. NMFS correspondingly added a 
sentence stating that ``telemetry data have shown rather lengthy 
excursions, including into deep water off the continental shelf (Mate 
et al. 1997; Baumgartner and Mate 2005).'' Both statements should be 
included and NMFS can simply add a sentence explaining the effort 
discrepancy. Finally, the SAR should report recent findings from the 
Canadian government that determined: ``[T]he movement behaviour of 
individual NARW [in the Gulf of St. Lawrence] was highly variable. Some 
individuals did not move far between successive days while others moved 
considerable distances. Some whales in the southwestern Gulf of St. 
Lawrence were estimated to move as much as 50 km in a single day.''
    Response: The description of NARW feeding grounds reflects NMFS' 
current understanding. Acoustic monitoring in the central Gulf of Maine 
indicates right whales are present in areas besides southern New 
England. The calves born during 2021-2023 fall outside of the reporting 
period for this report. The ``Other Mortality'' heading has been a 
standard heading for stock assessment reports for all species. The 
``vessel strike'' classification is accounted for in Table 3. NMFS 
believes our description of right whale sightings, distribution, and 
movement is as comprehensive and accurate as the data and available 
analyses currently allow.
    Comment 12: MLA states that the draft NARW SAR continues to cite 
Kenney (2018) and asserts that this reference is fundamentally flawed. 
Specifically, MLA believes the methods used in the study fail to 
account for basic biological processes--namely, natural death. Further, 
calves have natural mortality rates that are ignored during scenarios 
when they are included in this model.
    Response: As stated in previous responses to public comments, the 
Kenney (2018) reference is a relevant, peer-reviewed study that helps 
provide context to the impacts of fishery-related mortality on the NARW 
population. The study does account for non-fisheries mortality (e.g., 
vessel strikes, calving declines, resource limitation, etc.), removing 
only confirmed fishery-related deaths and serious injuries (likely to 
result in death). Several scenarios are provided with varying levels of 
hypothetically-reduced entanglement mortality rates corresponding to 
degrees of compliance with MMPA regulations. While the paper presents a 
simple representation of complex processes, the model parameters are 
reasonable, and the results are informative for the reader to 
appreciate the cumulative impact of entanglement on the population. Any 
element of natural mortality or other processes affecting the 
population other than documented entanglement mortality is accounted 
for by using the time series of abundance estimates as a baseline.
    The inclusion of the unrealized calves in the paper acknowledges 
basic population biology and the outsized effect of removing productive 
females on a population's trajectory cannot be ignored. Kenny (2018) 
treats this effect conservatively. Proven female calving intervals have 
varied between 3 and 10 years, but are primarily in the 3- to 7-year 
range, so the choice of a 5-year calving interval is well-founded. The 
paper's total of 26 calves lost due to the deaths of 15 females over 27 
years equals an unrealized population increase of much less than 0.01 
per year (1 divided by the average annual population size). This 
undoubtedly underrepresents the actual value, given that only known 
females documented as dead or seriously injured were used in the 
analysis.
    Comment 13: MLA notes that the draft NARW SAR includes recent 
research by Stewart et al. (2021) without stating that the NARW body 
size since 1981 does not correlate with calving rates. MLA believes 
there are limitations to the study's sample size of seven individuals 
with severe maternal entanglement injuries, particularly when these 
instances are conflated by the primary factor driving body size--birth 
year (i.e., oceanographic conditions). To this point, MLA comments that 
the draft SAR should not only cite Christiansen (2020) when drawing 
inferences from the southern population of right whales, but also 
Miller et al. (2011). Additionally, in the years following 1998-2002 
(the time period sampled by Miller et al. (2011)), there were 9 
consecutive above-average years in NARW calving rate.
    Response: NMFS agrees that prey availability is likely an important 
contributor to the observed decrease in right whales' size. Decreased 
size also appears to be related to reduced fecundity, with smaller and 
less robust females less likely to calve (Stewart et al. 2022). Miller 
et al. (2011) is a good addition to this section, along with Fortune et 
al. (2013). The impact of injury on the physiological state of females 
is also well documented (i.e., Rolland et al. 2016; Pettis et al. 2017; 
van der Hoop 2017), so it is likely the population's fecundity is being 
impacted by injury as well. Variation in birth rates should be expected 
for capital breeders in a variable environment, and the current 
downward trend in calving corresponds to documented shifts in right 
whale prey. However, the impacts of injury must be considered. 
Mortality rates have increased significantly during the same period, 
and sublethal injuries have likely increased as well.

Bryde's Whale, Gulf of Mexico Stock (Rice's Whale)

    Comment 14: Natural Resource Defense Council (NRDC) is concerned by 
the draft's assessment of scientific information on Rice's whale 
habitat use in the western Gulf of Mexico, and particularly by its 
suggestion that the whale's regularity of occurrence there is 
``unknown.'' The persistent occurrence of some Rice's whales in the 
northwestern Gulf of Mexico has recently been documented using passive 
acoustics. This evidence of regular use

[[Page 54597]]

of the continental shelf break by at least a portion of the Rice's 
whale population complements newly available habitat suitability 
predictions as well as forthcoming habitat suitability and prey 
condition analyses from NOAA, all of which indicate an extension of the 
whale's habitat between the 100 and 400 meter (m) isobaths across the 
northwestern Gulf. NRDC recommends that the draft be lightly edited to 
make this distinction clear, and also recommends that the present 
distribution map be replaced with one that displays the species' 
extended habitat, with the hydrophone locations from Soldevilla et al. 
(2022a, 2022b) and the 3 western Gulf sightings also indicated, if 
desired.
    Response: NMFS has slightly edited the ``Stock Definition and 
Geographic Range'' section per the suggestion to remove ``unknown'' and 
better clarify that there is some information regarding Rice's whale 
distribution in the northwestern Gulf. The distribution map includes 
the genetically confirmed sighting in the northwestern Gulf off Texas, 
and the core habitat is shaded. All information about known 
distribution, including the genetically confirmed sighting, is included 
within the text. We believe that including the locations of high-
frequency acoustic recording packages (HARP) on the map, which 
typically includes locations of visual sightings only, could confuse 
readers. We refer those interested in details of the calls detected 
from HARPs to see Soldevilla et al. (2022a), which we reference and 
summarize within the SAR.
    Comment 15: NRDC recommends that NMFS update the Rice's whale draft 
SAR to align with the 2023 revisions to the Guidelines for Preparing 
Stock Assessment Reports Pursuant to the MMPA and report PBR as 0.07.
    Response: NMFS has edited the SAR to report PBR as 0.07, per this 
public comment.
    Comment 16: NRDC recommends including information on the potential 
for disturbance from vessel noise and activity in the draft SAR for 
Rice's whale.
    Response: Per the comment, NMFS has edited the ``Habitat Issues'' 
text to include the anecdotal evidence from Soldevilla et al. (2022b) 
regarding Rice's whales that temporarily stopped calling when 
approached by the research vessel.

Comments on Pacific Issues

North Pacific Humpback Whale Stocks

    Comment 17: The Commission recommends using a maximum net 
productivity rate (Rmax) of 8.2 percent for the Mainland 
Mexico-CA/OR/WA stock and a default Rmax value of 4 percent for the 
Central America/Southern Mexico-CA/OR/WA stock.
    Response: Current estimated annual rates of increase for the 
Central America/Southern Mexico-CA/OR/WA stock (1.6 percent, 
incorrectly stated as 1.8 percent in the draft SAR) should not be 
confused with the Rmax. Where annual rates of increase have 
been estimated for different humpback populations, they have 
consistently been higher than the MMPA default of 4.0 percent (Zerbini 
et al. 2010 [7.3 percent and 8.6 percent annually, using 2 different 
approaches], Zerbini et al. 2006 [6.6 percent], Barlow and Clapham 1997 
[6.5 percent], Calambokidis and Barlow 2020 [8.2 percent]). Zerbini et 
al. (2010) proposed an upper 99th percentile of 11.8 percent annually. 
Still, this value has not been utilized in MMPA stock assessments due 
to the availability of region and/or stock-specific estimates for U.S. 
waters. Based on the best available data on estimated rates of increase 
for multiple humpback populations, use of the MMPA default of 4.0 
percent for the Central America/Southern Mexico-CA/OR/WA is 
unnecessarily conservative, given the spatial and temporal overlap with 
the larger Mainland Mexico-CA/OR/WA stock of humpbacks, both of which 
are exposed to the same types of anthropogenic threats along the U.S. 
West Coast. The mean estimate of annual growth rate of 8.2 percent 
reported by Calambokidis and Barlow (2020) for all humpbacks in U.S. 
West Coast waters also includes anthropogenic-related mortality; thus, 
the true Rmax is likely to be higher than that observed. 
Additionally, the PBR calculated for the Central America/Southern 
Mexico-CA/OR/WA stock is conservative, based on a recovery factor of 
0.1 to reflect its endangered status. Therefore, NMFS will continue to 
use an Rmax of 8.2 percent.
    Comment 18: The Commission notes that the PBR levels for the 
Mainland Mexico-CA/OR/WA and Central America/Southern Mexico-CA/OR/WA 
Stocks are divided by two to produce a ``U.S. PBR'' to assess the 
status of each stock. The Commission emphasizes there are no data, 
analyses, or references to support the conclusion that each stock 
spends approximately half its time outside the U.S. EEZ. The Commission 
recommends that NMFS use information on the timing of arrival to and 
departures from the U.S. EEZ by these two humpback whale stocks, as 
well as information on seasonal occupancy rates within the U.S. EEZ, to 
provide a more precise estimate of the ``proportion of time spent in 
U.S. waters'' for calculating the U.S. PBRs for these two humpback 
whale stocks. Response: NMFS agrees that a more refined estimate of 
humpback residency time in California, Oregon, and Washington, is 
required to prorate PBR for the Mainland Mexico-CA/OR/WA and Central 
America/Southern Mexico-CA/OR/WA Stocks. Ryan et al. (2019) provides 
both sighting and acoustic data suggesting that: (1) humpbacks are 
present in central California waters at least 8/12 months annually, and 
(2) December and April represent ``transition months,'' where whales 
are moving out of or into the central California region (see Figure 5d 
in Ryan et al. 2019). Counting December and April each as \1/2\ of a 
month of residency time during migration, plus the 7 months of May 
through November when sightings are abundant, yields 8/12 months of 
residency time, or \2/3\ of the year. This may be considered as a 
minimum residency time, as some whales are still present within the 
U.S. EEZ in waters north or south of the central California study area. 
NMFS has implemented this new PBR proration in the final SARs, which 
increased the calculated PBR for the Central America/Southern Mexico-
CA-OR-WA stock from 2.6 to 3.5, and for the Mainland Mexico-CA-OR-WA 
stock, from 32.5 to 43.
    Comment 19: The Commission comments that the Mainland Mexico-
California/Oregon/Washington and Central America/Southern Mexico-
California/Oregon/Washington SARs do not estimate or apply an 
appropriate correction factor to account for the undetected ``cryptic 
mortality'' of humpbacks due to fisheries interactions, and recommends 
that NMFS revise the SARs to provide estimates of total fisheries M/SI 
for these stocks using appropriate correction factors to account for 
undetected whale carcasses.
    Response: There are no published estimates of carcass detection 
rates for humpback whales in this region. Some range-wide estimates 
were made for gray whales (Punt and Wade 2012), including remote 
coastlines of Mexico, Canada, and Alaska that are not directly 
applicable to the U.S. West Coast. As such, these estimates are not 
applied to gray whale strandings involving anthropogenic sources in 
U.S. waters. Most cases of humpback whale injury and mortality due to 
fishery entanglements are based on opportunistic detection of injured 
whales at sea, stranded animals, and floating carcasses. This detection 
process does not include quantifiable ``search effort,'' which is 
needed to

[[Page 54598]]

estimate the undetected portion. Methods used to estimate carcass 
detection for more coastal species, such as bottlenose dolphins (Wells 
et al. 2015; Carretta et al. 2016), are also not applicable to humpback 
whales, given the differences in detection processes. With regard to 
vessel strikes, NMFS is already using the estimated vessel strike 
deaths reported by Rockwood et al. (2017) in the Central America/
Southern Mexico-CA-OR-WA and Mainland Mexico-CA-OR-WA SARs; thus, no 
correction is necessary for that source of anthropogenic mortality. We 
also compare reported numbers with estimates from Rockwood et al. 
(2017) to give the reader a sense of the detected fraction of vessel 
strikes. NMFS continues to work on the issue of undetected injury and 
mortality and states in SARs that reported entanglement cases represent 
a minimum accounting of total interactions.
    Comment 20: WDFW comments pertain to the Central America/Southern 
Mexico-CA-OR-WA, Mainland Mexico-CA-OR-WA and Hawaii stocks of humpback 
whales in the Pacific. WDFW is concerned about the exclusion of whales 
that summer in WA state waters from the Hawai'i distinct population 
segment (DPS), which affects estimates of M/SI for Washington 
fisheries. WDFW recommends that estimates of total mortality and 
proration to ESA-listed stocks include an estimate of non-listed stocks 
off Washington, and that more research is conducted on understanding 
the stock and DPS/Demographically Independent Population (DIP) 
composition of whales in Southern British Columbia (SBC), northern WA, 
and the Salish Sea.
    Response: NMFS agrees that more research will aid in determining 
the relative fractions of whales summering in WA State waters that 
winter in Hawai'i waters. In the final SAR, we revised the proration 
scheme to prorate WA State human-caused M/SI to all three stocks that 
occur in these waters (Central America/Southern Mexico-CA/OR/WA, 
Mainland Mexico-CA/OR/WA, and Hawai'i) based on summer to winter area 
movement probabilities in Wade (2021). Human-caused M/SI from CA/OR/WA 
waters for the Hawai`i stock (based on movement probabilities from WA/
SBC to Hawai'i) has now been added to the Hawai'i stock SAR published 
in the Alaska stock assessments (Young et al. 2023).
    Comment 21: WDCFA comments that the SARs contradict previous 
studies by Wade in 2016 and 2021 in relation to the composition of 
humpback populations that forage off the coast of Washington. WDCFA 
believes that Wade's analysis revealed that the humpback populations 
off Washington differ significantly from those in California and 
Oregon. Instead of two distinct populations (both ESA-listed), WDCFA 
comments that Washington's foraging humpbacks consist of three distinct 
population segments (two listed and one not). Also, WDCFA comments that 
the exclusion of the SBC/WA stock (estimated at 1,593 distinct animals) 
from the SARs' total estimated humpback whale abundance for the U.S. 
West Coast (4,973 humpback whales) is problematic. WDCFA believes a 
more accurate calculation for the minimum population estimate 
(Nmin) and PBR would benefit and be more reflective of 
population abundance from a proportional inclusion of SBC/WA 
populations.
    Response: The 1,593 whales noted by the commenters are partially 
included in the estimate of abundance for CA/OR/WA waters because three 
stocks (Central America/Southern Mexico-CA/OR/WA, Mainland Mexico-CA/
OR/WA, and Hawai'i) use CA/OR/WA waters during summer and autumn. 
Becker et al. (2020) estimated humpback abundance in 2018 for all CA/
OR/WA waters to be 4,784 whales. Becker et al.'s estimate is lower than 
that of Calambokidis and Barlow (2020) for CA/OR mark-recapture data 
(4,973), which lends support to Calambokidis and Barlow (2020) noting 
that their estimate likely represents whales in WA waters (representing 
multiple stocks), as there is interchange between CA/OR and WA. The 
fraction of SBC/WA whales attributable to the Hawai'i stock that occur 
north of the U.S. EEZ is unknown; thus, it is incorrect to imply that 
the 1,593 SBC/WA whales should be added to the estimates of either 
Becker et al. (2020) or Calambokidis and Barlow (2020). NMFS has 
changed the language in the SAR to reduce this confusion, now noting 
that some whales from the Hawai'i stock are present in U.S. west coast 
waters during the summer. We have also prorated CA/OR/WA human-caused 
M/SI for Hawai'i stock whales in addition to Central America/Southern 
Mexico-CA/OR/WA and Mainland Mexico-CA/OR/WA whales, based on movement 
probabilities in Wade (2021). The Hawai'i stock M/SI totals derived 
from the U.S. West Coast fisheries and vessel strikes in Washington 
State are summarized in the Hawai'i SAR, published with the Alaska 
marine mammal stock assessments (Young et al. 2023).
    Comment 22: CCCA notes that while the M/SI data are averaged over 
the period from 2016 to 2020, 22 humpback whale interactions occurred 
in 2016 out of the 34 reported in the SAR. CCCA requests NMFS to 
acknowledge in the final SAR that the interaction rates and M/SI rates 
for the fishery are skewed higher due to the spike in 2015-2016, and do 
not accurately reflect the current lower interaction rates based on the 
best available scientific information.
    Response: The entanglement data for 2016-2020 reported in the SAR 
are based on the number of reported cases, presumably related to 
fishing effort and the number of people on the water (or beaches) that 
detect entangled whales. In order to assess the ``rate of 
interactions'' (and any change thereof), both the number of 
entanglement cases and total fishing effort are required. Information 
on the total number of traps set annually is lacking; therefore, it is 
unclear if the decline in reported entanglement cases after 2016 is 
related to reduced fishing effort, a change in humpback distribution, 
or both. The 5-year total entanglement summary also includes the year 
2020, with the lowest number of pot-trap fishery entanglements recorded 
for the period. This is likely a reflection of reduced economic 
activity due to COVID-19 shutdowns. Thus, NMFS believes the additional 
text requested is not warranted.
    Comment 23: CCCA believes that the Mainland Mexico-CA/OR/WA 
humpback whale stock is too narrowly defined, and that the stock should 
include all animals that interbreed when mature. CCCA emphasizes that 
the draft SAR improperly skews the impact of fisheries that interact 
with the stock because it compares the M/SI from those fisheries 
against a PBR that is based only on a portion of the actual stock.
    Response: NMFS disagrees. Martien et al. (2021) note that humpback 
whale stocks in the North Pacific were previously designated at large 
geographically defined scales with names referring to feeding grounds 
(for example, the CA/OR/WA stock). However, these feeding ground 
aggregations do not represent DIPs. Rather, they comprise animals 
originating from multiple wintering grounds, which NMFS has recognized 
as different DPSs under the ESA. Martien et al. (2020) suggest that 
humpback research and management under the MMPA should focus on 
``migratory whale herds,'' defined as groups of animals that share the 
same feeding ground and wintering ground. Recruitment into a herd is 
almost entirely through maternally directed learning of the migratory 
destinations. Photographic and genetic data show

[[Page 54599]]

strong fidelity of animals to a given feeding and wintering area and, 
therefore, to a herd, suggesting very little dispersal (permanent 
movement of animals) between herds. If dispersal between herds is low 
enough to render them demographically independent, a migratory whale 
herd is a particular case of a DIP. Two strong lines of evidence 
(movements and genetics) support that the Mainland Mexico-CA/OR/WA unit 
of humpback whales meet the DIP definition, with levels of movement and 
genetic differentiation similar to those used to define DPSs.
    Comment 24: CCCA comments that the Central America Stock is not 
being prevented from reaching or maintaining its optimum sustainable 
population. Curtis et al. (2022) estimate that the ``Central America 
CA/OR/WA DIP'' (which corresponds to the Central America Stock) has 
been growing at an annual rate of 4.8 percent from the period of 2004-
2006 to the more recent period of 2019-2021. Although there is 
uncertainty with that estimated growth rate, the most recent population 
numbers indicate that there are approximately 1,494 whales that are 
part of the Central America Stock (Curtis et al. 2022), which is a 
significant increase of 1,083 whales since the Central America DPS 
(which also corresponds to the Central America Stock) was listed 7 
years ago. CCCA argues that NMFS should revisit the assumptions it has 
made for this stock because the low PBR proposed in the draft SAR does 
not reflect the fact that this population is growing significantly 
despite the M/SI rates reported in the draft SAR.
    Response: NMFS disagrees. The PBR reference point has several 
features that allow for a population to be increasing while human-
caused M/SI exceed PBR. The calculation of PBR involves using: (1) One-
half of the theoretical or estimated maximum net productivity level 
(instead of the point estimate); (2) The minimum population size 
estimate (or 20th percentile, rather than the point estimate); (3) A 
recovery factor below 1 for all stocks that are not at an optimum 
sustainable population (OSP) level. The goal of keeping M/SI below PBR 
is to ensure populations reach or maintain OSP. There is no evidence 
that the Central America/Southern Mexico-CA/OR/WA stock is at OSP. The 
depletion level of this population is unknown; if the population is 
well below OSP, it is possible for it to be increasing now, but may 
level off and not reach OSP if M/SI is too high. NMFS also notes that 
the estimated population growth rate for this population is lower than 
that of other humpback whale populations in the North Pacific (Curtis 
et al. 2022; Calambokidis and Barlow 2020; Mizroch et al. 2004; Zerbini 
et al. 2010).
    Comment 25: WCP comments that it is difficult to accurately compile 
population numbers for transboundary stocks, and that sampling a 
mixture of similar populations is challenging for assessments. WCP 
believes counting these animals when they return to their birth-origin 
habitat should predominate other methods for censuses.
    Response: Conducting wintering area surveys is not always feasible, 
but NMFS notes that estimates of wintering area abundance are available 
for multiple DPSs (e.g., Central America, Hawai'i). In cases where 
wintering area abundance is not available, it is necessary to assess 
human-caused M/SI against summering area abundance determined from U.S. 
waters, where anthropogenic threats from U.S. fisheries and vessel 
strikes are well-documented.

Comments on Alaska Issues

Eastern Bering Sea Beluga Whales

    Comment 26: The Commission recommends that NMFS use the default 
Rmax value of 4.0 percent for the Eastern Bering Sea (EBS) 
beluga whale stock until uncertainties are resolved or an 
Rmax value specific to the EBS stock is available. The draft 
2022 SAR for the EBS beluga whale stock suggests that the default 
Rmax value of 4.0 percent should be used for the stock, as 
an Rmax value specific to the EBS beluga whale is not 
available. Although an Rmax of 4.8 percent was calculated 
for the Bristol Bay beluga whale stock, the most recently published SAR 
for that stock rejected the 4.8 percent value in favor of the 4.0 
percent default due to the large coefficient of variation (CV) 
associated with the estimate.
    Response: NMFS has considered the concern raised in the comment and 
decided to continue to use 4.8 percent for Rmax for the EBS 
beluga stock for the following reasons. As stated in the draft SAR, 
NMFS' ``Guidelines for Preparing Stock Assessment Reports Pursuant to 
the MMPA'' (Guidelines) suggest that, in general, substitution of other 
values for the default Rmax value should be made with 
caution and when reliable stock-specific information is available on 
Rmax (NMFS 2023). However, the NMFS Guidelines also state 
that for stocks subject to subsistence harvests, NMFS will consult with 
appropriate Alaska Native co-management partners regarding scientific 
and other information relevant to preparing SARs, including information 
used to calculate PBR. Co-management of the EBS beluga whale stock is 
conducted by the Alaska Beluga Whale Committee (ABWC) and NMFS. Through 
the co-management process, NMFS, in consultation with ABWC, determined 
that the nearby Bristol Bay beluga whale stock has similar 
environmental conditions and habitat to the EBS beluga whale stock. 
Since the Bristol Bay beluga stock exhibited an estimated rate of 
increase of 4.8 percent per year (95 percent confidence interval (CI): 
= 2.1-7.5 percent), and despite the large CV associated with this 
estimate, NMFS determined that the actual realized value for the growth 
rate of the Bristol Bay beluga population is a more accurate value to 
use for the EBS beluga whale stock's Rmax than the default 
value. The Alaska SRG supported the use of 4.8 percent for 
Rmax for the EBS beluga whale stock.

Southeast Alaska Harbor Porpoise

    Comment 27: ADFG, SEAFA, USAG, and two members of the public 
expressed concern regarding NMFS' genetic analyses of Southeast Alaska 
(SEAK) harbor porpoise. They assert that the genetic differences 
observed between stocks is, at least in part, an artifact of 
limitations in the spatial distribution of the collected environmental 
DNA (eDNA) samples (Parsons et al. in prep). In addition, they state 
that based on the methodology described in Zerbini et al. (2022b), the 
eDNA samples could not have resulted in independently identifiable 
individuals. Zerbini et al. (2022b) and the SAR treat the sampled 
haplotypes as independently sampled individuals for analysis when it is 
likely that a large portion of samples were pseudo-replicates. They 
assert that this makes it impossible to verify if the results presented 
reflect a genuine biological pattern, and said additional genetic 
analyses based on appropriate independent sampling are necessary to 
assess harbor porpoise stock structure in SEAK.
    Response: NMFS appreciates the concerns raised in the comment. 
Regarding the spatial distribution of the eDNA sample collection, we 
note that samples included in the analysis of population genetic 
structure included both tissue and eDNA samples (using the methods 
presented in Parsons et al. 2018). The eDNA samples were collected 
during several vessel surveys, between July 2016 and September 2019. 
eDNA samples were used to capture mitochondrial DNA (mtDNA) genetic 
diversity across geographic regions where harbor porpoise aggregations 
were detected. The data generated from eDNA included an informative 
section

[[Page 54600]]

of the mitochondrial control region that is comparable to that 
sequenced from tissue samples. eDNA samples were collected immediately 
after a porpoise sighting, directly in the fluke prints of individuals, 
or small groups of harbor porpoise. Individual genotypes were not 
generated from eDNA samples; however, both tissue and eDNA samples were 
collected over multiple days, months, and years in both Northern-SEAK 
(N-SEAK) and Southern-SEAK (S-SEAK) inland water stocks, minimizing the 
likelihood that the same individual would be sampled more than once. 
Surveys were conducted throughout inland waters of SEAK, whereby eDNA 
sampling reflects the locations of harbor porpoise aggregations at the 
time of the survey. Regarding the concerns of pseudo-replication, while 
the possibility of genetic recaptures (or pseudo-replicates) cannot be 
completely excluded, efforts were made to minimize possible pseudo-
replicates by moving away from small groups of porpoises between 
consecutive sample collections. In addition, the elusive or evasive 
nature of harbor porpoise behavior limits the likelihood of repeated 
close approaches by the sampling vessel of the sampled individuals. 
Samples of eDNA collected in the fluke prints of cetaceans often result 
in the discovery of multiple unique mtDNA haplotypes from a single 
sample. This highlights the likelihood of capturing eDNA from multiple 
individuals in a single sample, even when sample collections target the 
fluke prints of a single animal. This is not surprising given that shed 
cellular material can diffuse (and decay) in the marine environment in 
which it has been shed. Treating each sampled mtDNA haplotype as a 
single occurrence is a conservative approach adopted when samples 
represent an unknown number of unique individuals. This approach offers 
a valuable method for generating genetic haplotypes from eDNA samples, 
but likely results in an underestimate of the true haplotype frequency, 
particularly for common haplotypes.
    Comment 28: ADFG requests NMFS reevaluate the harbor porpoise 
population structure in N-SEAK and S-SEAK SARs, and reconsider the 
calculations for the PBR. Dahlheim et al. (2015) found differing trends 
in abundance between N-SEAK and S-SEAK harbor porpoise populations, 
with an unusually high growth rate of 25 percent in S-SEAK between 2006 
and 2007, and 2010 and 2012. The study acknowledged that such an 
increase is not biologically possible for a closed population, implying 
immigration into the area. However, the authors used this influx to 
hypothesize fine-scale population structure, which contradicts the 
evidence of significant immigration. This discrepancy necessitates a 
reevaluation of the population structure and PBR calculations.
    Response: NMFS appreciates this comment and the opportunity to 
provide more context. The increasing trend in abundance of 25 percent 
per year implied by the estimates of abundance of S-SEAK between 2006 
and 2007 and 2010 and 2012 presented in Dahlheim et al. (2015) applies 
only for the high density areas of harbor porpoise near Zarembo Island 
and the town of Wrangell, not the entire range of the S-SEAK DIP. It is 
conceivable that the unusual trend occurred because animals from areas 
within the range of the DIP that were not surveyed in 2006-2007 by 
Dahlheim et al. (2015) may have moved towards the region around Zarembo 
Island and Wrangell and may have been sampled in the early 2010s. 
Additionally, taking the CIs of the abundance estimate in Wrangell/
Zarembo in 2006-2007 and 2010-2012 into consideration, the trend 
implied by the data is still within biologically plausible values. For 
example, the trend between the upper CI for the 2006-2007 estimate (317 
individuals) and the lower CI of the 2010-2012 estimate (392 
individuals) is approximately 4.7 percent per year, which is 
biologically feasible given the reproductive potential for harbor 
porpoise and has been documented in other regions (e.g., California, 
Forney et al. 2021). Finally, the differential trend between N-SEAK and 
S-SEAK was used as supporting, not primary, evidence that harbor 
porpoise in these two areas should be considered two separate DIPs. 
Other lines of evidence (e.g., differences in mitochondrial DNA between 
the two regions and areas of low density/potential gaps in distribution 
between N-SEAK and S-SEAK) provide stronger support for the separation 
of the two regions into two DIPs. Given all this, NMFS has determined 
that a re-evaluation of the population structure in N-SEAK and S-SEAK 
is not warranted at this time.
    Comment 29: ADFG comments that NMFS should assess the degree of 
intermixing between harbor porpoise populations using a more rigorous 
sampling design and appropriate genetic methods and data. The 
distribution of harbor porpoise is not discontinuous, with high-density 
areas and regular observations outside these hotspots. Although no 
harbor porpoise were observed in Wrangell Narrows during aerial or 
boat-based surveys (Zerbini et al. 2022b), an eDNA sample was collected 
there (Parson et al., in prep). ADFG notes that a more comprehensive 
assessment using proper sampling design and genetic methods is needed 
to better understand their population structure.
    Response: NMFS agrees that additional genetic samples throughout 
the region would be helpful to better understand putative genetic 
boundaries and seasonal variances in porpoise density and distribution. 
However, existing information on the genetics of harbor porpoise in the 
inland waters of SEAK is currently sufficient to separate stocks 
following NMFS' process for reviewing and designating stocks (NMFS 
2019). NMFS acknowledges that harbor porpoise are notoriously difficult 
to study and approach for genetic sampling, requiring considerable 
resources and limiting the number of genetic samples available for 
analysis. Moreover, the movement of harbor porpoise can result in 
temporary spatial aggregations in response to tidal cycles and prey 
concentrations. As a result, the distribution of harbor porpoise is 
often patchy and variable on relatively small scales, which is 
reflected in the spatial distribution of samples and the large number 
of surveys conducted to collect the represented samples. Ideally, 
population genetic analyses would make use of tissue samples collected 
by remote biopsy sampling approaches; however, dedicated efforts to 
collect tissue samples from SEAK harbor porpoise demonstrated that this 
method is not efficient enough to be feasible. The tissue samples 
included in Zerbini et al. (2022b) were collected over multiple 
decades, highlighting the challenges of amassing a representative 
sample size for this species. Vessel-based surveys for eDNA samples 
were conducted throughout inshore waters of SEAK in 2016 (July and 
September) and 2019. Samples of eDNA collected during these surveys are 
representative of regions where harbor porpoise were encountered in 
those years. Rough boundaries between marine mammal stocks can be 
identified using known low-density areas or discontinuities. Of the 
boundaries identified using this approach, two boundaries between the 
northern and southern stocks were identified. These include the 
boundary at the north end of Wrangell Narrows and the boundary at Keku 
Strait. Low harbor porpoise density, not a lack of harbor porpoise, is 
implied. Known low-density areas or discontinuities in distribution 
have been used to identify boundaries for other harbor porpoise

[[Page 54601]]

stocks (Carretta et al. 2002). Therefore, NMFS continues to rely on the 
original methodology and resulting stock structure at this time.
    Comment 30: ADFG, SEAFA, UFA, USAG, and two members of the public 
request that NMFS reevaluate the bycatch estimation methods for harbor 
porpoise in the SEAK salmon drift gillnet fishery, taking into account 
interannual variability and adequacy of survey effort, and reassess 
whether the PBR level is being exceeded for the proposed S-SEAK stock. 
The current bycatch estimation is based on the 2012-2013 Alaska Marine 
Mammal Observer Program (AMMOP), which only observed 6-7 percent of the 
drift gillnet fishery. The large CVs for serious injury and mortality 
indicate a lack of precision in the estimate. The draft SAR does not 
account for interannual variability, with no observed bycatch in 2012 
but documented interactions in 2013. The low survey coverage and 
potential for Type I or Type II errors make it difficult to determine 
if the PBR level is being exceeded or if the documented interactions 
were merely a fluke. A member of the public commented that the fishery 
had changed significantly since it was observed, thus invalidating the 
estimates, and a new observer program to monitor fishery takes should 
be undertaken.
    Response: NMFS acknowledges the concerns raised in the comment. 
Analyses predicting the expected precision of the SEAK AMMOP for given 
levels of effort were conducted prior to the implementation of the 
observer program. The achieved effort level (~6.5 percent observer 
coverage for the three observed fishing districts) was considered 
sufficient to detect harbor porpoise bycatch if it was occurring at a 
level greater than the PBR level. For example, if the true bycatch 
level was 1.5 times PBR, there is a very low (2 percent) probability 
that no harbor porpoise bycatch would be observed. The estimated 
bycatch does take into account the lack of observations of bycatch in 
2012; the estimate from 2013 is averaged with the zero from 2012 to 
estimate an annual bycatch. The effect of averaging with the zero in 
2012 is included in the estimated CVs for the annual average, which are 
still 0.7 and 1.0 for the two stocks. Although the CVs of the estimated 
bycatch are high, this is well within the range of CVs tested in the 
development of the PBR framework (i.e., a robustness trial was run with 
CV of bycatch estimate equal to 1.2). Therefore, it is still 
appropriate to use these estimates in the SAR. The Guidelines specify 
that the recovery factor should be lowered to a value less than 0.5 in 
situations such as these, where the CV of bycatch is relatively high. 
This adjustment will be evaluated for incorporation in the next SAR 
revision.
    The bycatch estimate presented in the SAR should be considered a 
minimum. AMMOP only operated in fishing districts six, seven, and 
eight, representing only a fraction (i.e., 16 percent of fish landed, 
the metric used to represent effort in the fishery) of the SEAK salmon 
drift gillnet fishery. The other fishing districts represent 84 percent 
of the landings, and bycatch estimates from districts six, seven, and 
eight were not extrapolated to those other areas. In other words, 
bycatch has not been estimated for the other districts. If one were to 
extrapolate the observed bycatch estimates in districts six, seven, and 
eight to the effort in the other districts, the estimated bycatch for 
the entire fishery would be six times higher, indicating that the 
current estimate of bycatch could be substantially underestimated. 
Another reason why the estimated bycatch should be considered a minimum 
estimate, with the potential for substantial negative bias, is that the 
observers were on a separate boat from the fishing vessel and their 
view of the gear during hauls was usually poor. In more than 90 percent 
of the hauls: (1) the observer's view of the portion of the net being 
pulled was obstructed for 25-50 percent of the time and (2) the 
observer could not see the net underwater. This means that the 
detection rate may not have been 100 percent in observed hauls and that 
the observations should be considered minimums. Less than a 100 percent 
detection would lead to a negative bias in the bycatch estimates.
    It is worthwhile to consider Type I and II error rates in planning 
survey effort levels. To evaluate whether the estimated M/SI level 
would cause a fishery to be considered Category I in the List of 
Fisheries, the most important metric to measure accurately is whether 
the number of M/SI harbor porpoise per year is below 50 percent of the 
PBR level for S-SEAK harbor porpoise. Using binomial probabilities, the 
false positive rate (incorrectly estimating M/SI to be above PBR) for 
this situation would be 0.236. Similarly, it is important to measure 
accurately when M/SI is well above PBR (e.g., 150 percent of PBR), and 
the false negative rate for that situation (incorrectly estimating M/SI 
to be below PBR) would be 0.298. These error rates are similar and not 
exceptionally high, and could be improved by increasing observer 
coverage relative to what was conducted previously. NMFS acknowledges 
the age of available data; regardless, without additional data, it 
remains the best available data on bycatch in the fishery. Planning 
efforts are underway for the AMMOP to consider new observer effort in 
the SEAK salmon drift gillnet fishery to gather more recent bycatch 
information for the fishery, as resources allow.
    Comment 31: ADFG, SEAFA, UFA, USAG, and two members of the public 
request that NMFS reevaluate the most recent boat-based survey estimate 
for harbor porpoise in SEAK, considering potential biases such as the 
species' elusive nature, avoidance of approaching boats, and inadequate 
sampling in nearshore shallow waters and known concentration areas, and 
one member of the public recommended that a new aerial-based survey be 
completed. Harbor porpoise are known to be shy, elusive, and difficult 
to detect, which may lead to underestimation in boat-based surveys. The 
assumption of perfect detection at a Beaufort wind scale of 0 is 
unrealistic for such an elusive species. The survey's effective strip 
width does not appear to account for the effects of the sun's position 
on the detection probability. The vessel size used in the survey may 
have limited sampling in shallow waters where harbor porpoise are known 
to frequent. Furthermore, the survey did not include Duncan Canal, a 
known concentration area in S-SEAK (Parsons et al. in prep), because it 
was assumed to have no harbor porpoise based on results from other S-
SEAK inlets.
    Response: NMFS acknowledges the concerns raised in the comment and 
agrees that harbor porpoise is an elusive species that tends to avoid 
vessels. We considered this in the 2019 survey sampling design. Highly 
experienced observers participated in the 2019 survey in SEAK with the 
goal of minimizing the negative effect of animal behavior during data 
collection. Search effort for porpoise during the survey was performed 
in a manner that maximized detection before the porpoise responded to 
the vessel. Search effort was focused several hundred meters ahead of 
the vessel. Vessel avoidance can typically be detected in line transect 
surveys when examining histograms of perpendicular distance data (e.g., 
Buckland et al. 2001). In such circumstances (presence of negative 
responsive movement by the porpoise), the number of sightings is 
expected to be greater farther away from the survey line than on or 
very near the survey line. Inspection of the perpendicular distance 
data in the 2019

[[Page 54602]]

survey in SEAK did not provide any evidence of responsive movement. On 
the contrary, it suggested porpoise groups were detected prior to 
showing any response to the presence of the vessel (see Zerbini et al. 
2022a, detection function in the Supplemental Material: https://www.frontiersin.org/articles/10.3389/fmars.2022.966489/full).
    NMFS disagrees that sampling was inadequate. The survey was 
designed using advanced, well-established, and robust statistical 
methods to minimize bias in survey coverage. Sampling transects 
followed a systematic ``zig-zag'' design that covered most known 
habitats of harbor porpoise within SEAK inland waters, either near the 
shore or in the center of channels and inlets. In the past, NMFS was 
criticized for not sampling small bays and narrow inlets, and time was 
allocated in the 2019 survey to sample and estimate abundance within 
these areas. Given the resources available at the time, it was not 
practical to sample the large number of small bays and inlets (~170) in 
SEAK. Therefore, an algorithm was implemented to randomly select inlets 
and bays for sampling, allowing for nearly 40 percent survey coverage 
in the area of all inlets and bays combined. The proportion of bays and 
inlets sampled in the N-SEAK and S-SEAK areas was approximately the 
same.
    The estimated average effective search width of harbor porpoise in 
SEAK (700-900 m) is substantially greater than that of open ocean 
surveys (130-375 m) (see detailed discussion and relevant literature in 
Zerbini et al. 2022a), suggesting that it is much easier to see harbor 
porpoise in enclosed environments such as inland waters of SEAK. 
Greater detectability of harbor porpoise in SEAK likely occurs because 
survey conditions in inland waters improve visibility of this species. 
For example, the presence of land in most of the region allows 
observers to focus on a smaller search area ahead of the vessel, likely 
increasing their detectability. Perhaps more importantly, sea 
conditions provided confidence in detectability during the 2019 surveys 
(92 percent of the sampling effort occurred in Beaufort state 
conditions varying between 0 and 3) and a rigorous protocol was 
implemented to stop sampling in poor visibility conditions to ensure 
the quality of the data were appropriate to develop density estimates 
of harbor porpoise. In addition, large swells, which greatly affect 
detection of cetaceans at sea, were extremely rare within most of SEAK 
inland waters where harbor porpoise were documented in the 2019 survey. 
Because detection of harbor porpoise is imperfect, a method was used to 
estimate the proportion of animals missed on the survey line--a 
quantity known as g(0)--under the assumption that observers will detect 
all porpoise in flat, calm conditions (Beaufort 0). NMFS determined 
this approach is appropriate, especially in a region where the 
environmental conditions favor the detectability of harbor porpoise.
    The effect of many covariates in the probability of detecting 
harbor porpoise were considered as described in Zerbini et al. (2022a). 
The effect of the sun's position can affect the detectability of 
cetaceans, but other covariates considered in that study are typically 
more important (e.g., sea state, group size, observer, swell height, 
cue; Barlow et al. 2001). In addition, most of the survey was conducted 
under cloudy or partially cloudy conditions, when the effect of glare 
is substantially reduced or is non-existent given the sun is not 
visible. The vessel used was small (~27.4 m long) compared to the size 
of other vessels used in similar surveys in SEAK in the past and 
allowed for sampling most of the habitats identified prior to 
completing the 2019 survey. Note that nearly all regions proposed for 
sampling were surveyed (Fig. 1 in Zerbini et al. 2022a). In addition, 
the vessel used in the 2019 survey towed a small rigid hull inflatable 
boat (RHIB) for collecting eDNA samples. This RHIB was launched to 
visit certain areas where depth was such that the larger survey vessel 
was unable to survey. One of these areas was Duncan Canal, where 
aggregations of harbor porpoise had been previously documented. No 
porpoise were seen in Duncan Canal during the small boat survey. It is 
important to note that Duncan Canal is adjacent to eastern Sumner 
Strait, an area of high density of harbor porpoise. It is possible that 
animals move in and out of the canal and were sampled by the survey 
vessel in Sumner Strait, even if they regularly occur in Duncan Canal. 
Therefore, the fact that the primary survey vessel did not visit Duncan 
Canal (and potentially other areas) does not mean that porpoise that 
visit the canal were not seen and are not accounted for in the 
estimates of abundance.
    Finally, NMFS agrees that additional surveys are important to 
improve our knowledge of abundance and stock structure of harbor 
porpoise in SEAK; study platform and survey design depends on many 
factors, including the purpose of the project, the desired level of 
precision, and need for consistency with previous surveys. Studies to 
better understand the population identity of porpoise along the outer 
coast are also extremely useful to assess whether animals in inland 
waters are separate from those in more offshore habitats.
    Comment 32: ADFG and UFA request that NMFS assess trends in harbor 
porpoise abundance in SEAK stocks, comparing historical and recent 
data, and evaluate the impact of drift gillnet fishery bycatch on the 
population. Despite differences in survey and analytical methods, the 
uncorrected abundance estimates from Zerbini et al. (2022a) can be 
compared with earlier surveys to analyze trends in abundance. The 
comparison suggests that harbor porpoise abundance increased in N-SEAK 
and remained constant in S-SEAK between 2013 and 2019. Historical 
abundance trends can inform assessments of stock status, potential 
threats, and the impact of bycatch. Considering the drift gillnet 
fishery occurred across the time series of harbor porpoise surveys, and 
the most recent abundance estimates for the Wrangell and Zarembo Island 
area are comparable to early 1990s estimates, bycatch in the drift 
gillnet fishery does not seem to be a driving factor affecting 
abundance. The rapid increase in abundance between 2006 and 2007, and 
2010 and 2012, indicates that the drift gillnet fishery may not hinder 
harbor porpoise population growth in the area, suggesting that the 
stock may be able to reach its optimum sustainable population.
    Response: NMFS recognizes the need to assess trends in abundance 
and to evaluate the impact of the drift gillnet fishery on harbor 
porpoise. The latter requires calculating new estimates of mortality 
through a fisheries monitoring program (e.g., to place the estimates of 
mortality in perspective with more recent abundance estimates). The 
uncorrected abundance from Zerbini et al. (2022a) cannot be directly 
compared to those from previous surveys because the area covered in 
2019 differs from the area covered in previous years. For example, by 
comparing the trackline design and area coverage in Fig. 1 in Zerbini 
et al. (2022a) and those in Figs. 2, 3, and 4 in Dahlheim et al. 
(2015), one can see the differences in the spatial coverage between the 
two surveys, which demonstrate the potential comparability issues 
between estimates from the two studies. For example, note that Chatham 
Strait, Lynn Canal, and lower Clarence Strait were not surveyed in 
2006, 2007, and 2010, whereas high coverage was achieved in these areas 
in 2019. The most accurate way to assess the current trend would be to 
conduct a survey comparable to that done in

[[Page 54603]]

2019 and evaluate the trend based on two recent, comparable surveys; 
resources to do this are currently unavailable. Nonetheless, the 
depletion level of this population is unknown; if it is well below OSP, 
it is possible for the population to be increasing now, but may level 
off and not reach OSP if M/SI is too high.
    Comment 33: ADFG emphasizes that the timeliness and transparency of 
data availability should be improved to ensure that stakeholders have 
adequate time to review and comment on proposed changes to the SARs. A 
member of the public commented that the State of Alaska should be 
provided with all data to peer review. ADFG commented that despite a 
data availability statement in Zerbini et al. (2022a), the data were 
provided late in the comment period, leaving insufficient time for 
thorough review. Similarly, the data from Parsons et al. (in prep) and 
the associated eDNA genetic sampling and analysis methods were provided 
with less than 10 working days left in the comment period. ADFG stated 
that the lack of timely data and methods sharing hinders transparency 
and the ability to properly assess the potential impacts of proposed 
changes to the SAR, particularly in relation to the small exceedance of 
PBR estimated for the proposed S-SEAK stock.
    Response: Data availability is important and NMFS strives to make 
data available in a timely manner. We experienced significant set-backs 
and limitations in the years between tissue and eDNA sample collection 
and publication of genetics results due to restrictions imposed during 
the global pandemic. These delays impacted progress on the publication 
of the genetics results, which in turn impacted the release of the 
data. Summary genetic data were provided to the requestor to the best 
of the agency's ability; raw genetic data will be made available after 
the results are published in a peer-reviewed journal. We note that key 
information used in the draft harbor porpoise SAR was included in a 
peer-reviewed scientific paper (Zerbini et al. 2022a) and a NOAA 
technical memorandum (Zerbini et al. 2022b), and those documents were 
also made available to the public and to the Alaska SRG during their 
review of the draft SARs. In addition, Alaska SRG meetings held in 
2018-2022 involved discussions about new studies on abundance and 
genetics of harbor porpoise, and the results of those studies. Minutes 
from the Alaska SRG meetings include considerable detail and are 
available to the public at https://www.fisheries.noaa.gov/national/marine-mammal-protection/scientific-review-groups#alaska-scientific-review-group.
    Comment 34: ADFG, UFA, and SEAFA request that NOAA carefully 
consider the potential economic impacts of proposed changes to the SEAK 
harbor porpoise SAR on the salmon gillnet fishery and coastal 
communities before implementing any changes. The proposed changes in 
the draft SAR would split the SEAK harbor porpoise stock into three 
separate stocks and categorize the proposed S-SEAK stock as a strategic 
stock under the MMPA. This categorization would require the 
establishment of a take reduction plan, leading to changes in 
regulation and operation of the salmon gillnet fishery. These changes 
could result in significant economic costs for the fishery and the 
coastal communities that rely on it, and should only be pursued if 
deemed necessary.
    Response: NMFS' policies for delineating demographically 
independent populations and designating stocks under the MMPA section 
117 is made on the basis of the best available science and is 
independent of any future agency actions under MMPA section 118 for 
establishing a take reduction plan that may or may not occur in the 
future. If a take reduction plan were implemented, NMFS recognizes that 
there may be economic implications for the fishery and the coastal 
communities that rely on the relevant stocks. Those implications would 
be considered as appropriate in other processes that flow from these 
determinations.
    Comment 35: A member of the public commented that NMFS' proposal to 
split harbor porpoise stocks with lines of demarcation at Dry 
Straights, Rocky Pass, Cape Decision, and Wrangell Narrows is arbitrary 
and unproven, lacking in robust genetic data to support it clearly. The 
commenter asserted that additional sampling from multiple areas is 
needed to better establish a delineation between stocks.
    Response: NMFS has concluded that the available evidence supports 
placing the boundaries between the N-SEAK and the S-SEAK stocks in Dry 
Straight, Wrangell Narrows, Keku Strait (Rocky Pass), and Cape 
Decision. These are areas with extremely low density or no recent 
records of harbor porpoise in the last 20 years as summarized in 
Zerbini et al. (2022b) and likely represent natural geographic/
ecological boundaries supporting demographic independence of harbor 
porpoise between Frederick Sound and Sumner Strait. Despite being 
relatively wide (1.2 km), Dry Strait is shallow (~0.4-0.5 m) and 
strongly influenced by the shoaling waters of the Stikine River Delta. 
The Stikine River Delta is continually expanding and depositing 
sediment on the ocean floor, creating tidal flats throughout the 
strait. It is unclear whether harbor porpoise use Dry Strait; the area 
has not been surveyed by vessel because of navigational constraints, 
but no harbor porpoise were there during aerial surveys in 1997 (Hobbs 
and Waite 2010). Harbor porpoise were documented in the Wrangell 
Narrows in the early 1990s, but infrequently since then (only one 
sighting in the lower portion of the Narrows in 2011) (Hobbs and Waite 
2010; Dahlheim et al. 2015; Zerbini et al. 2022). Keku Strait is a 
narrow channel with complex bathymetry and shallow areas in its 
narrowest portion. The northern end of Keku Strait (near the town of 
Kake) was surveyed in 2019 and data generated from eDNA samples 
collected there suggest that harbor porpoise in that area are 
genetically more similar to harbor porpoise in Glacier Bay and Icy 
Strait (Parsons et al. in prep., Zerbini et al. 2022b) than those in 
Sumner Strait. It is unclear whether harbor porpoise cross the narrow 
parts of Keku Strait (Rocky Pass) towards Sumner Strait. No porpoise 
were seen there during aerial surveys in 1997 (Hobbs and Waite 2010). 
The geography and the bathymetry in the narrow reaches could represent 
a geographic barrier, separating animals from the northern and southern 
inland water DIPs. The passage between Cape Decision and Coronation 
Island separates two relatively large straits in SEAK: lower Chatham 
and lower Sumner straits. Harbor porpoise have been documented in lower 
Sumner Strait, to the east of Cape Decision (Dahlheim et al. 2015; 
Zerbini et al. 2022a) and occasionally in lower Chatham Strait (Hobbs 
and Waite 2010), but occurrence in these regions is uncommon. Whether 
harbor porpoise move between the two straits (or whether animals from 
offshore areas move into the straits) is presently unknown. It is 
important to note that demographic independence does not require a 
complete lack of interchange of animals between two or more DIPs. NMFS 
(2023) defines the term ``demographic independence'' to mean that ``the 
population dynamics of the affected group is more a consequence of 
births and deaths within the group (internal dynamics) rather than 
immigration or emigration (external dynamics). Thus, the exchange of 
individuals between population stocks is not great enough to prevent 
the depletion of one of the populations as

[[Page 54604]]

a result of increased mortality or lower birth rates.''

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1403-y.


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    Dated: August 7, 2023.
Karl Ibrahim Moline,
Acting Director, Office of Science and Technology, National Marine 
Fisheries Service.
[FR Doc. 2023-17219 Filed 8-10-23; 8:45 am]
BILLING CODE 3510-22-P