Endangered and Threatened Wildlife and Plants; 12-Month Finding for 7 Foreign Species of Elasmobranchs Under the Endangered Species Act, 76067-76115 [2015-30660]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 80, Number 234 (Monday, December 7, 2015)]
[Proposed Rules]
[Pages 76067-76115]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-30660]



[[Page 76067]]

Vol. 80

Monday,

No. 234

December 7, 2015

Part II





Department of Commerce





-----------------------------------------------------------------------





National Oceanic and Atmospheric Administration





-----------------------------------------------------------------------





50 CFR Parts 223 and 224





Endangered and Threatened Wildlife and Plants; 12-Month Finding for 7 
Foreign Species of Elasmobranchs Under the Endangered Species Act; 
Proposed Rule

Federal Register / Vol. 80 , No. 234 / Monday, December 7, 2015 / 
Proposed Rules

[[Page 76068]]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Parts 223 and 224

[Docket No. 150909839-5839-01]
RIN 0648-XE184


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
for 7 Foreign Species of Elasmobranchs Under the Endangered Species Act

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

ACTION: Proposed rule; 12-month petition finding; request for comments.

-----------------------------------------------------------------------

SUMMARY: We, NMFS, have completed comprehensive status reviews under 
the Endangered Species Act (ESA) for seven foreign marine elasmobranch 
species in response to a petition to list those species. These seven 
species are the daggernose shark (Isogomphodon oxyrhynchus), Brazilian 
guitarfish (Rhinobatos horkelii), striped smoothhound shark (Mustelus 
fasciatus), narrownose smoothhound shark (Mustelus schmitti), spiny 
angel shark (Squatina guggenheim), Argentine angel shark (Squatina 
argentina), and graytail skate (Bathyraja griseocauda). Based on the 
best scientific and commercial information available, and after taking 
into account efforts being made to protect these species, we have 
determined that the daggernose shark (I. oxyrhynchus), Brazilian 
guitarfish (R. horkelii), striped smoothhound shark (Mustelus 
fasciatus), and Argentine angel shark (S. argentina) meet the 
definition of an endangered species under the ESA. We have determined 
that the narrownose smoothhound shark (M. schmitti) and spiny angel 
shark (S. guggenheim) meet the definition of a threatened species under 
the ESA. Therefore, we propose to list these six species under the ESA. 
Additionally, we have determined that the graytail skate (B. 
griseocauda) does not warrant listing under the ESA at this time. We 
are not proposing to designate critical habitat for any of the species 
proposed for listing because the geographical areas occupied by these 
species are entirely outside U.S. jurisdiction, and we have not 
identified any unoccupied areas within U.S. jurisdiction that are 
currently essential to the conservation of any of these species. We are 
soliciting comments on our proposal to list these six foreign marine 
elasmobranch species.

DATES: Comments on this proposed rule must be received by February 5, 
2016. Public hearing requests must be made by January 21, 2016.

ADDRESSES: You may submit comments on this document, identified by 
NOAA-NMFS-2015-0161, by either of the following methods:
     Electronic Submissions: Submit all electronic public 
comments via the Federal eRulemaking Portal. Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2015-0161. Click the ``Comment Now'' icon, 
complete the required fields, and enter or attach your comments.
     Mail: Submit written comments to NMFS Office of Protected 
Resources (F/PR3), 1315 East West Highway, Silver Spring, MD 20910, 
USA.
    Instructions: Comments sent by any other method, to any other 
address or individual, or received after the end of the comment period, 
may not be considered by NMFS. All comments received are a part of the 
public record and will generally be posted for public viewing on 
www.regulations.gov without change. All personally identifying 
information (e.g., name, address, etc.), confidential business 
information, or otherwise sensitive information submitted voluntarily 
by the sender will be publicly accessible. NMFS will accept anonymous 
comments (enter ``N/A'' in the required fields if you wish to remain 
anonymous).

You can find the petition, status review report, Federal Register 
notices, and the list of references electronically on our Web site at 
https://www.nmfs.noaa.gov/pr/species/petition81.htm.

FOR FURTHER INFORMATION CONTACT: Maggie Miller, NMFS, Office of 
Protected Resources (OPR), (301) 427-8403 or Chelsey Young, NMFS, OPR, 
(301) 427-8491.

SUPPLEMENTARY INFORMATION:

Background

    On July 15, 2013, we received a petition from WildEarth Guardians 
to list 81 marine species as threatened or endangered under the 
Endangered Species Act (ESA). This petition included species from many 
different taxonomic groups, and we prepared our 90-day findings in 
batches by taxonomic group. We found that the petitioned actions may be 
warranted for 27 of the 81 species and announced the initiation of 
status reviews for each of the 27 species (78 FR 63941, October 25, 
2013; 78 FR 66675, November 6, 2013; 78 FR 69376, November 19, 2013; 79 
FR 9880, February 21, 2014; and 79 FR 10104, February 24, 2014). This 
document addresses the findings for 7 of those 27 species: daggernose 
shark (Isogomphodon oxyrhynchus), Brazilian guitarfish (Rhinobatos 
horkelii), striped smoothhound shark (Mustelus fasciatus), narrownose 
smoothhound shark (Mustelus schmitti), spiny angel shark (Squatina 
guggenheim), Argentine angel shark (Squatina argentina), and graytail 
skate (Bathyraja griseocauda). The status of, and relevant Federal 
Register notices for, the other 20 species can be found on our Web site 
at https://www.nmfs.noaa.gov/pr/species/petition81.htm.
    We are responsible for determining whether species are threatened 
or endangered under the ESA (16 U.S.C. 1531 et seq.). To make this 
determination, we consider first whether a group of organisms 
constitutes a ``species'' under the ESA, then whether the status of the 
species qualifies it for listing as either threatened or endangered. 
Section 3 of the ESA defines a ``species'' to include ``any subspecies 
of fish or wildlife or plants, and any distinct population segment of 
any species of vertebrate fish or wildlife which interbreeds when 
mature.'' On February 7, 1996, NMFS and the U.S. Fish and Wildlife 
Service (USFWS; together, the Services) adopted a policy describing 
what constitutes a distinct population segment (DPS) of a taxonomic 
species (the DPS Policy; 61 FR 4722). The DPS Policy identified two 
elements that must be considered when identifying a DPS: (1) The 
discreteness of the population segment in relation to the remainder of 
the species (or subspecies) to which it belongs; and (2) the 
significance of the population segment to the remainder of the species 
(or subspecies) to which it belongs. As stated in the DPS Policy, 
Congress expressed its expectation that the Services would exercise 
authority with regard to DPSs sparingly and only when the biological 
evidence indicates such action is warranted. Based on the scientific 
information available we determined that the daggernose shark (I. 
oxyrhynchus), Brazilian guitarfish (R. horkelii), striped smoothhound 
shark (M. fasciatus), narrownose smoothhound shark (M. schmitti), spiny 
angel shark (S. guggenheim), Argentine angel shark (S. argentina), and 
graytail skate (B. griseocauda) are ``species'' under the ESA. There is 
nothing in the scientific literature indicating that any of these 
species should be further divided into subspecies or DPSs.
    Section 3 of the ESA defines an endangered species as ``any species 
which is in danger of extinction throughout all or a significant 
portion of its range'' and a threatened species as

[[Page 76069]]

one ``which is likely to become an endangered species within the 
foreseeable future throughout all or a significant portion of its 
range.'' We interpret an ``endangered species'' to be one that is 
presently in danger of extinction. A ``threatened species,'' on the 
other hand, is not presently in danger of extinction, but is likely to 
become so in the foreseeable future (that is, at a later time). In 
other words, the primary statutory difference between a threatened and 
endangered species is the timing of when a species may be in danger of 
extinction, either presently (endangered) or in the foreseeable future 
(threatened).
    When we consider whether a species might qualify as threatened 
under the ESA, we must consider the meaning of the term ``foreseeable 
future.'' It is appropriate to interpret ``foreseeable future'' as the 
horizon over which predictions about the conservation status of the 
species can be reasonably relied upon. The foreseeable future considers 
the life history of the species, habitat characteristics, availability 
of data, particular threats, ability to predict threats, and the 
reliability to forecast the effects of these threats and future events 
on the status of the species under consideration. Because a species may 
be susceptible to a variety of threats for which different data are 
available, or which operate across different time scales, the 
foreseeable future is not necessarily reducible to a particular number 
of years.
    Section 4(a)(1) of the ESA requires us to determine whether any 
species is endangered or threatened due to any of the following 
factors: the present or threatened destruction, modification, or 
curtailment of its habitat or range; overutilization for commercial, 
recreational, scientific, or educational purposes; disease or 
predation; the inadequacy of existing regulatory mechanisms; or other 
natural or manmade factors affecting its continued existence. Under 
section (4)(b)(1)(A), we are also required to make listing 
determinations based solely on the best scientific and commercial data 
available, after conducting a review of the species' status and after 
taking into account efforts being made by any state or foreign nation 
to protect the species.

Status Reviews

    Status reviews for the petitioned species addressed in this finding 
were conducted by a contractor for the NMFS Southeast Fisheries Science 
Center and are available at https://www.nmfs.noaa.gov/pr/species/petition81.htm or on the respective species pages found on the Office 
of Protected Resources Web site (https://www.nmfs.noaa.gov/pr/species/index.htm). These status reviews compiled information on each species' 
biology, ecology, life history, and threats from information contained 
in the petition, our files, a comprehensive literature search, and 
consultation with experts. The draft status review reports (Casselberry 
and Carlson 2015 a-g) were submitted to independent peer reviewers and 
comments and information received from peer reviewers were addressed 
and incorporated as appropriate before finalizing the draft report. The 
peer review report is available at https://www.cio.noaa.gov/services_programs/prplans/PRsummaries.html. These status reviews did 
not include extinction risk analyses for the species; thus, the 
extinction risk analyses for the seven species are included in this 12-
month finding. In addition to the status review reports, we considered 
information submitted by the public in response to our petition finding 
as well as information we compiled to assess the extinction risk of the 
species to make our determinations.

Extinction Risk Analyses

    We considered the best available information and applied 
professional judgment in evaluating the level of risk faced by each of 
the seven species. For each extinction risk analysis, we evaluated the 
species' demographic risks (demographic risk analysis), such as low 
abundance and productivity, and threats to the species including those 
related to the factors specified by the ESA section 4(a)(1)(A)-(E) 
(threats assessment), and then synthesized this information to estimate 
the extinction risk of the species (risk of extinction).
    The demographic risk analysis, mentioned above, is an assessment of 
the manifestation of past threats that have contributed to the species' 
current status and informs the consideration of the biological response 
of the species to present and future threats. For this analysis, we 
considered the demographic viability factors developed by McElhany et 
al. (2000). The approach of considering demographic risk factors to 
help frame the consideration of extinction risk has been used in many 
of our status reviews, including for Pacific salmonids, Pacific hake, 
walleye pollock, Pacific cod, Puget Sound rockfishes, Pacific herring, 
scalloped and great hammerhead sharks, and black abalone (see https://www.nmfs.noaa.gov/pr/species/ for links to these reviews). In this 
approach, the collective condition of individual populations is 
considered at the species level according to four demographic viability 
factors: Abundance, growth rate/productivity, spatial structure/
connectivity, and diversity. These viability factors reflect concepts 
that are well-founded in conservation biology and that individually and 
collectively provide strong indicators of extinction risk.
    In conducting the threats assessment, we identified and summarized 
the section 4(a)(1) factors that are currently operating on the species 
and their likely impact on the biological status of the species. We 
also looked for future threats (where the impact on the species has yet 
to be manifested) and considered the reliability to which we could 
forecast the effects of these threats and future events on the status 
of these species.
    Using the findings from the demographic risk analysis and threats 
assessment, we evaluated the overall extinction risk of the species. 
Because species-specific information (such as current abundance) is 
sparse, qualitative ``reference levels'' of risk were used to describe 
extinction risk. The definitions of the qualitative ``reference 
levels'' of extinction risk were as follows: ``Low Risk''--a species is 
at a low risk of extinction if it exhibits a trajectory indicating that 
it is unlikely to be at a moderate level of extinction risk in the 
foreseeable future (see description of ``Moderate Risk'' below). A 
species may be at low risk of extinction due to its present 
demographics (i.e., stable or increasing trends in abundance/population 
growth, spatial structure and connectivity, and/or diversity) with 
projected threats likely to have insignificant impacts on these 
demographic trends; ``Moderate Risk''--a species is at moderate risk of 
extinction if it exhibits a trajectory indicating that it will more 
likely than not be at a high level of extinction risk in the 
foreseeable future (see description of ``High Risk'' below). A species 
may be at moderate risk of extinction due to its present demographics 
(i.e., declining trends in abundance/population growth, spatial 
structure and connectivity, and/or diversity and resilience) and/or 
projected threats and its likely response to those threats; ``High 
Risk''--a species is at high risk of extinction when it is at or near a 
level of abundance, spatial structure and connectivity, and/or 
diversity that place its persistence in question. The demographics of 
the species may be strongly influenced by stochastic or depensatory 
processes. Similarly, a species may be at high risk of extinction if it 
faces clear and present threats (e.g., confinement to a small 
geographic area; imminent destruction,

[[Page 76070]]

modification, or curtailment of its habitat; or disease epidemic) that 
are likely to create such imminent demographic risks.
    Below we summarize information from the status review reports and 
information we compiled on the seven foreign marine elasmobranch 
species, analyze extinction risk of each species, assess protective 
efforts to determine if they are adequate to mitigate existing threats 
to each species, and propose determinations based on the status of each 
of the seven foreign marine elasmobranch species.

Daggernose Shark (Isogomphodon oxyrhynchus)

Species Description

    The daggernose shark (Isogomphodon oxyrhynchus) is the only species 
in the genus Isogomphodon, in the family Carcharhinidae (Compagno 
1988). It has a uniform gray or gray-brown color and white underside 
(Compagno 1984; Compagno 1988; Grace 2001), and is identified by its 
prominent, elongated snout. The pectoral fins of the species are very 
large and paddle-shaped (Compagno 1984; Compagno 1988; Grace 2001).

Range and Habitat Use

    The daggernose shark occurs in the central western Atlantic Ocean 
and Caribbean Sea and has been reported along the coasts of Venezuela, 
Trinidad, Guyana, Suriname, French Guiana, and northern Brazil (Lessa 
et al. 2006a). The Brazilian range includes the states of Amap[aacute], 
Par[aacute], and Maranh[atilde]o, with Tubar[atilde]o Bay in 
Maranh[atilde]o as its easternmost limit (Silva 2004; Lessa et al. 
1999a). The daggernose shark has one of the smallest ranges of any 
elasmobranch species (Lessa et al. 2000). It is a coastal species that 
is commonly found in estuaries and river mouths in tropical climates 
and is most abundant in these areas during the Amazonian summer (i.e., 
the rainy season) (Compagno 1984; Compagno 1988; Lessa 1997; Lessa et 
al. 1999a; Lessa et al. 2006b; Grace 2001). These sharks are often 
found in association with mangrove coastlines, occur in highly turbid 
waters and in low lying and indented coastlines that can have tide 
changes that vary as much as 7 meters (m) (Martins-Juras et al. 1987; 
Lessa et al. 1999a). Daggernose sharks occur in water depths between 8 
m and 40 m, temperatures ranging from 21.5 [deg]C to 31.5 [deg]C and 
salinities between 13.96 and 33.60 ppt (Lessa 1997; Lessa et al. 1999a, 
b). Salinity is considered a determining factor for the distribution of 
the species, but does not prevent the capture of daggernose sharks in 
shallow waters during the rainy season when waters are less saline 
(Lessa 1997). Specific winter habitats of the daggernose shark are 
unknown.

Diet and Feeding

    Little is known about the diet and feeding of the daggernose shark. 
Bigelow and Schroeder (1948) and Compagno (1984) suggest that they feed 
on schooling fishes, such as clupeids, sciaenids, herring, anchovies, 
and croakers. It is speculated that their small eyes and elongated 
snout emphasize the use of their rostral sense organs over eyesight 
when hunting in turbid waters (Compagno 1984). In Maraj[oacute] Bay in 
Brazil, daggernose sharks were found eating catfish (Family Ariidae) 
(Barthem 1985).

Growth and Reproduction

    Growth rates of daggernose sharks are similar between males and 
females, with an estimated growth rate from birth to age 1 calculated 
to be approximately 14 cm/year (Lessa et al. 2000). This rate then 
slows to approximately 10 cm/year from age 1 to 5-6 for males and age 1 
to 6-7 for females (Lessa et al. 2000). Thus, estimated ages at 
maturity are 5-6 years for males and 6-7 years for females. In terms of 
size, male daggernose sharks begin maturing between 90 cm and 110 cm 
total length (TL), with fully adult males observed at sizes larger than 
119 cm TL in the field (Lessa et al. 1999a). According to von 
Bertalanffy growth parameters, size at maturity is 103 cm TL for males 
and about 115 cm TL for females (Lessa et al. 2000), although the 
smallest pregnant female recorded was 118 cm long (Lessa et al. 1999a). 
After maturity is reached, growth rates decrease to less than 10 cm/
year (Lessa et al. 2000). Maximum age is estimated to be approximately 
20 years based on converting the length of a 160 cm TL female with 
parameters from the von Bertalanffy growth equation, although the 
largest male caught was 144 cm TL, corresponding to an age of 13 years 
old, and the oldest aged individuals from vertebrae analyses were of a 
7 year old male and a 12 year old female (Lessa et al. 2000).
    The reproductive cycle of daggernose sharks in Brazil is 
synchronized with the rain cycle. The rainy season runs from January to 
June and the dry season runs from July to December. A study by Lessa et 
al. (1999a) found that 70 percent of the pregnant females collected 
during the study in the rainy season were carrying a recently 
fertilized egg or very small embryo, suggesting that the ovulation 
period takes place at the end of the dry season or at the beginning of 
the rainy season (Barthem 1985). The gestation period is approximately 
12 months, with a protracted birthing period throughout the 6-month 
rainy season (Lessa et al. 1999a; Lessa et al. 2006b). Mature females 
captured with flaccid uteri and white follicles indicate that there is 
a break in follicle development between two successive pregnancies, 
which indicates a 2-year reproductive cycle (Lessa et al. 1999a). 
Mating and gestation periods can also be postponed to compensate for 
climate variability and changing environmental conditions across years 
(Lessa et al. 1999a). Female fecundity is low, commonly ranging between 
3 to 7 embryos per female, with the largest litter observed containing 
7 embryos, and one report of a female with 8 embryos (Bigelow and 
Schroeder 1948; Barthem 1985; Lessa et al. 1999a). There is no 
significant relationship between female size and litter size in 
daggernose sharks (Lessa et al. 1999a).

Genetics and Population Structure

    Studies examining the genetics of the species or information on its 
population structure could not be found.

Demography

    Based on the above life history parameters, and following methods 
in Cort[eacute]s (2002) for estimating survivorship, Casselberry and 
Carlson (2015a) estimated productivity (as intrinsic rate of population 
increase, ``r'') at 0.004 year-\1\ (median) within a range 
of -0.040-0.038 (5 percent and 95 percent percentiles) (Carlson 
unpublished). Median generation time was estimated at 10.6 years, the 
mean age of parents of offspring of a cohort ([micro]1) was 
10.7 years and the expected number of replacements (R0) was 
1.05. Lessa et al. (2010) estimated annual population growth to be r = 
-0.048 under natural mortality rates (of 0.28 using the Hoenig (1984) 
method and 0.378 using the Pauly (1980) method), and a generation time 
of 9 years. If fishing mortality rates were incorporated, the annual 
population growth was estimated to be r = -0.074, with a generation 
time of 8.4 years (Lessa et al. 2010). These demographic parameters 
place daggernose sharks towards the slow growing end of the ``fast-
slow'' continuum of population parameters calculated for 38 species of 
sharks by Cort[eacute]s (2002), which means this species generally has 
a low potential to recover from exploitation.

[[Page 76071]]

Historical and Current Distribution and Population Abundance

    In Brazil, daggernose sharks were historically found in the states 
of Amap[aacute], Par[aacute], and Maranh[atilde]o, and were first 
formally recorded in surveys from the 1960s in the state of 
Maranh[atilde]o (Lessa 1986). In 1999, daggernose sharks were 
documented as occurring in two Marine Conservation Areas in northern 
Brazil, the Parque Nacional Cabo Orange in Amap[aacute], and the 
Reentr[acirc]ncias Maranhenses in Maranh[atilde]o (Lessa et al. 1999b). 
However, in recent years, the absence of daggernose sharks in areas 
where they were previously common has been noted. For example, in the 
Bragan[ccedil]a fish market in northern Brazil (State of Par[aacute]), 
daggernose sharks were once among the most common shark species sold in 
the market. However, a genetic analysis of shark carcasses collected 
from this fish market between 2005 and 2006 found no evidence of 
daggernose sharks being sold in the market (Rodrigues-Filho et al. 
2009). Although the species' absence in fish markets could indicate 
obeyance of Brazilian law, which prohibited the catch of daggernose 
sharks in 2004, it has been noted that these laws are poorly enforced 
and frequently ignored (see discussion of Inadequacy of Existing 
Regulatory Mechanisms below). Additionally, while daggernose sharks 
were once caught abundantly in Maranh[atilde]o prior to 1992, they were 
notably absent in research surveys conducted from November 2006 to 
December 2007 (Almeida et al. 2011). Based on the species' life history 
parameters and rates of fishing mortality, population abundance was 
estimated to have declined by 18.4 percent per year for 10 years from 
the mid-1990s to mid-2000, resulting in a total population decline of 
over 90 percent (Santana and Lessa 2002; Rosa and Lima 2005; Kyne et 
al. 2012).
    Very little information is available on the distribution and 
abundance of the daggernose shark outside of Brazil. While undated 
catch records exist across the entire coastline of French Guiana, 
records are scarce throughout Suriname, Guyana, and Trinidad and Tobago 
(Bigelow and Schroeder 1948; Springer 1950; Compagno 1988; Global 
Biodiversity Information Facility (GBIF) 2013). Additionally, although 
Lessa et al. (1999a) includes Venezuela as part of the daggernose shark 
range (citing Cervig[oacute]n 1968), no other information could be 
found regarding the present existence of the daggernose shark in 
Venezuela. Given the species' sensitive biological traits to 
exploitation and evidence of high artisanal fishing pressure, it is 
assumed that dramatic population declines have occurred in the last 
decade throughout this part of the species' range, similar to the 
levels documented in Brazil, but scientific data on population trends 
are severely lacking for this region (Kyne et al. 2012).

Summary of Factors Affecting the Daggernose Shark

    We reviewed the best available information regarding historical, 
current, and potential threats to the daggernose shark species. We find 
that the main threat to this species is overutilization for commercial 
purposes. We consider the severity of this threat to be exacerbated by 
the species' natural biological vulnerability to overexploitation, 
which has led to significant declines in abundance and subsequent 
extirpations from areas where the species was once commonly found. We 
find current regulatory measures inadequate to protect the species from 
further overutilization. Hence, we identify these factors as additional 
threats contributing to the species' risk of extinction. We summarize 
information regarding these threats and their interactions below 
according to the factors specified in section 4(a)(1) of the ESA. 
Available information does not indicate that habitat destruction or 
modification, disease, predation or other natural or manmade factors 
are operative threats on these species; therefore, we do not discuss 
these factors further in this finding. See Casselbury and Carlson 
(2015a) for discussion of these ESA section 4(a)(1) threat categories.

Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Based on historical catch data and trends, the primary threat to 
daggernose sharks is overutilization in artisanal fisheries. Given its 
rather shallow depth distribution, in Brazil, the species is bycaught 
in the artisanal gillnet fisheries for Spanish mackerel (Scomberomorus 
brasiliensis) and king weakfish (Cynoscion acoupa), which operate 
inside or near estuary mouths. Historically, the species was caught in 
large numbers along the northern Brazilian coastline and represented a 
significant component of the artisanal gillnet bycatch. For example, in 
the State of Par[aacute], daggernose sharks represented close to 70 
percent of the artisanal catch in the 1980s during the Amazonian summer 
(Lessa et al. 2010). Farther south, off the Maranh[atilde]o coast, 
harvest of daggernose sharks would begin in October and peak in 
January, with the catch per unit effort (CPUE) of these sharks in 
gillnets ranging from 6.04 kilogram (kg)/km/hour up to 71 kg/km/hour 
(during the peak in the rainy season) in the early 1990s. However, due 
to the species' sensitive life history traits, this high level of 
fishing mortality was found to be unsustainable, causing the daggernose 
shark population to decrease by 18.4 percent per year in the 1990s. By 
1999, the percentage of daggernose sharks in the artisanal gillnet 
bycatch along the Brazilian coast had significantly decreased, with 
daggernose sharks comprising only around 7-10 percent of the 
elasmobranch incidental catch (Lessa et al. 1999b; Lessa et al. 2000). 
By 2004 and 2006 the species was no longer observed or recorded in the 
states of Par[aacute] (Lessa et al. 2010) or Maranh[atilde]o (Almeida 
et al. 2011), respectively, based on data from research surveys 
conducted in these regions.
    Artisanal fisheries operating off Brazil continue to exert 
significant fishing pressure on the daggernose shark, which is likely 
contributing to fishing mortality rates that historically resulted in 
the substantial decline of the species. As such, overutilization 
continues to be a threat to the species as these fisheries are still 
highly active throughout its range. In fact, in the North region of 
Brazil (which includes the States of Amap[aacute] and Par[aacute]), the 
artisanal sector accounts for more than 80 percent of the total 
landings from this region and represents around 40 percent of the total 
artisanal landings for the entire country. These fisheries tend to be 
concentrated in areas where the daggernose shark would most likely 
occur, including the Amazon River estuary, small estuaries and bays, 
and shallow coastal waters within the extensive mangrove area that 
covers the northern coast of Brazil (Vasconcello et al. 2011). In the 
Northwest region of Brazil (which includes the States of 
Maranh[atilde]o south to Bahia), the artisanal sector is also the 
dominant fishing sector, accounting for more than 60 percent of the 
total landings from this region. The king weakfish fishery, which was 
noted as one of the main artisanal gillnet fisheries responsible for 
bycatching daggernose sharks, remains one of the most important 
fisheries in Brazil as evidenced by the fact that the species was the 
4th most landed marine fish in terms of volume in 2011 (21,074.2 t; 
Minist[eacute]rio da Pesca e Aquicultura (MPA) 2011). Together, the 
artisanal landings from these regions represent over 80 percent of the 
total artisanal landings for the entire country (Minist[eacute]rio do 
Meio Ambiente/Instituto Brasileiro do Meio Ambiente e dos

[[Page 76072]]

Recursos Naturais Renov[aacute]veis (MMA/IBAMA) 2007).
    These artisanal fishing practices and effort levels, which caused 
declines in daggernose shark populations off Brazil, are likely similar 
in Venezuela, Trinidad and Tobago, Guyana, Suriname, and French Guiana 
(which comprises the other half of the species' range). These countries 
have a substantial artisanal fishing sector presence, with catches from 
artisanal fishing comprising up to 80 percent of the total fish 
landings. In French Guiana, sharks alone comprised 40.4 percent of the 
annual artisanal landings for the local market (Harper et al. 2015). 
However, as noted in the Inadequacy of existing regulatory mechanisms 
section, due to minimal controls of these artisanal fisheries, 
including lack of enforcement capabilities of existing regulations, the 
available data indicate that many of these country's coastal marine 
resources are fully to overexploited (Food and Agriculture Organization 
of the United Nations (FAO) 2005a, 2005b, 2006, 2008). In Trinidad and 
Tobago, for example, it is estimated that the artisanal fleet catches 
between 75 and 80 percent of the total landings from these islands (FAO 
2006). Of concern, as it relates to overutilization of the daggernose 
shark, is the fact that Trinidad and Tobago have an open access fishery 
for the artisanal sector, which means there are no restrictions on the 
numbers and types of vessels, fishing gear, or trips (FAO 2006; 
Mohammed and Lindop 2015). In other words, any local vessel is allowed 
to enter the fishery and catch as much they can handle, with no 
restriction on fishing effort (FAO 2006). Similarly, Guyana also 
operates an open access fishery for its artisanal gillnet sector. Given 
that artisanal fishing for groundfish in Guyana, which comprises one of 
the country's two main fishing activities (the other being direct 
exploitation of shrimp by trawlers), is predominantly conducted using 
gillnets, open access fisheries cover a significant portion of the 
fishery sector for the country (FAO 2005a).
    As noted above, this essentially unregulated artisanal fishing 
throughout the Atlantic Caribbean, employing unselective net gear and 
concentrated in inshore coastal waters where daggernose sharks would 
primarily occur, has led to the overexploitation of many marine 
species, including sharks. However, there is virtually no information 
available on daggernose shark catches from the Caribbean countries in 
the daggernose shark range. These countries report general shark 
landings to the FAO but, in addition to these catches being 
significantly underestimated (on the order of 2.6 times for Trinidad 
and Tobago (Mohammed and Lindop 2015); 1.6 times for Guyana (Macdonald 
et al. 2015); 3.4 times for Suriname (Hornby et al. 2015); and 4 times 
for French Guiana (Harper et al. 2015)), daggernose sharks are not 
specifically identified in the catches (Shing 1999). However, 
historical and more recent information suggests daggernose sharks were 
and may still be utilized. Although the value of daggernose shark fins 
is low, its meat has been sold in markets from artisanal fisheries for 
decades (Lessa et al. 2006a), with Bigelow and Schroeder (1948) 
recording daggernose shark meat in markets in Trinidad and Tobago and 
noting its likelihood in markets in Guyana. Therefore, given the 
evidence of utilization of the species, as well as the significant 
fishing effort by artisanal fishing fleets throughout the daggernose 
shark range, including unregulated access to fishing grounds where the 
shark occurs, the observed absence of the daggernose shark in recent 
years can likely be attributed to overutilization of the species to the 
point where overutilization is significantly contributing to its risk 
of extinction.

Inadequacy of Existing Regulatory Mechanisms

    Throughout the species' range, species-specific protection for 
daggernose sharks is only found in Brazil. In 2004, the daggernose 
shark was first listed in Annex I of Brazil's endangered species list: 
``Lista Nacional Oficial de Esp[eacute]cies da Fauna Amea[ccedil]adas 
de Extin[ccedil][atilde]o--Peixes e Invertebrados Aqu[aacute]ticos'' 
(Silva 2004). An Annex I listing prohibits the catch of the species 
except for scientific purposes, which requires a special license from 
the Brazilian Institute of Environment and Renewable Resources (IBAMA) 
(Silva 2004). This protection was renewed in December 2014, when the 
daggernose shark was listed as ``critically endangered'' on the most 
recent version of the Brazilian endangered species list approved by the 
Ministry of the Environment (Directive No 445). ``Critically 
endangered'' on this list is defined as a species that presents an 
extremely high risk of extinction in the wild in the near future due to 
profound environmental changes or high reduction in population, or 
significant decrease in the taxon's range. In addition to the landing 
prohibition, daggernose sharks also receive protection when they occur 
within two of Brazil's marine protected areas (MPAs): The Parque 
Nacional Cabo Orange and the Reentr[acirc]ncias Maranhenses (Lessa et 
al. 1999b); however, the last time they were reported in these areas 
was in 1999.
    Although Brazil has a number of regulations in place to protect 
endangered or threatened species, like the ones described above for 
daggernose sharks, it is generally recognized that these regulations 
are poorly enforced, particularly within artisanal fisheries (Lessa et 
al. 1999b; Amaral and Jablonski 2005; Almeida et al. 2011; Rodrigues-
Filho et al. 2012). Poverty, lack of education within the artisanal 
fisheries sector, and increased artisanal fishing effort, especially in 
the State of Maranh[atilde]o, have already contributed to the decline 
of many elasmobranch populations, including the daggernose shark (Lessa 
et al. 1999b), despite the existence of protective legislation and 
marine protected areas. As such, effective conservation appears to be 
lacking in Brazil (Lessa et al. 1999b; Amaral and Jablonski 2005), with 
existing regulatory mechanisms likely inadequate to protect the 
daggernose shark from further fishery-related mortality.
    In December 2014, the Brazilian Government's Chico Mendes Institute 
for Biodiversity Conservation approved an FAO National Plan of Action 
(NPOA) for the conservation of sharks (hereafter referred to as FAO 
NPOA-sharks) for Brazil (No. 125). The plan considers the daggernose 
shark to be one of the country's 12 species of concern and recommends a 
moratorium on fishing with the prohibition of sales until there is 
scientific evidence in support of recovery (Lessa et al. 2005). 
Additionally, it proposes the expansion of the Reentr[acirc]ncias 
Maranhenses (where daggernose sharks were observed in 1999) to include 
the marine coastal zone and banks, providing additional protection to 
the sharks from potential fishery-related mortality. The plan 
recommends increased effort monitoring of vessels using nets in the 
area and increased education to encourage the release of live 
daggernose sharks and prevent the landing of the species. In general 
the plan sets short term goals for improved data collection on landings 
and discards, improved compliance and monitoring by the IBAMA, 
supervision of elasmobranch landings to ensure fins are landed with 
carcasses, the creation of a national port sampler program, and 
intensified on-board observer monitoring programs. Mid-term goals 
include increased monitoring and enforcement within protected areas as 
well as the creation of new protected areas based on essential fish 
habitat for the 12 species of concern. It also calls for improved 
monitoring of fishing from beaches in coastal and estuarine

[[Page 76073]]

environments. Long term goals call for improved ecological data and 
stock assessments for key species as well as mapping of elasmobranch 
spatiotemporal distributions. This data will be used to better inform 
the creation of protected areas and seasonal fishing closures. However, 
as stated above, the plan was only just approved as of December 2014, 
and will not be fully implemented for another 5 years. Even if the 
recommendations outlined in the plan are implemented in the future, it 
remains uncertain if they will be effective as the best available 
information suggests that current regulatory measures in Brazil to 
protect vulnerable species are poorly enforced, particularly within 
artisanal fisheries.
    Outside of Brazil, there is limited information on shark fishing 
regulations or their adequacy for protecting daggernose sharks from 
overutilization. In Guyana and Trinidad and Tobago, gillnet fisheries 
are restricted to using nets of 900 ft or less with no more than a 15-
foot depth; however, currently, there are no minimum size restrictions 
or catch quotas for sharks in either country (Shing 1999). As mentioned 
previously, both countries have open access fisheries (however, in 
Guyana the open access fishery only applies to the artisanal gillnet 
fishery) (FAO 2005a, 2006). In the late 1990s a fisheries management 
plan was drafted for Trinidad and Tobago, which prohibited the use of 
monofilament gillnets less than 4.75'' stretch mesh and developed a 
licensing system (Shing 1999); however, no further details about the 
plan, including effectiveness or enforcement of these regulations, 
could be found. According to Casselberry and Carlson (2015a), in the 
summer of 2013, Guyana's Fisheries Department within the Ministry of 
Agriculture passed a 5-year Fisheries Management Plan for Guyana to run 
from 2013 to 2018, with one aspect of this plan meant to address shark 
fishing, but no further details could be found at this time. 
Enforcement of existing fishery regulations is also lacking due to 
insufficient resources, with minimal control over the fisheries 
resulting in increasing competition and conflicts among fishermen and 
between fishing fleets and, consequently, overfishing of marine 
resources (FAO 2005a, 2005b, 2006, 2008). No other pertinent 
information could be found on shark fishing regulations or their 
adequacy in controlling the exploitation of sharks, and more 
specifically daggernose sharks.

Extinction Risk

    Although accurate and precise population abundance and trend data 
for the daggernose shark are lacking, best available information 
provides multiple lines of evidence indicating that this species 
currently faces a high risk of extinction. Below, we present the 
demographic risk analysis, threats assessment, and overall risk of 
extinction for the daggernose shark.

Demographic Risk Analysis

Abundance
    There is a significant lack of abundance information for I. 
oxyrhynchus throughout its range. In northern Brazil, the relatively 
recent (2004-2009) absence of the species in fish markets where they 
were once abundantly sold, in addition to their absence in fishery-
independent research surveys in areas where they were commonly caught 
prior to 1992, suggests the species has suffered significant declines 
in population abundance. Based on the daggernose shark's life history 
parameters and rates of fishing mortality, the population abundance in 
northern Brazil is estimated to have declined by 18.4 percent per year 
from the mid-1990s to mid-2000, resulting in a total population decline 
of at least 90 percent in approximately half of the species' known 
range. Although abundance information from the other parts of the 
species' range, including off Venezuela, Trinidad, Guyana, Suriname and 
French Guiana, is presently unavailable, it is thought that these 
populations have suffered similar declines based on the species' 
biological vulnerability and susceptibility to artisanal fisheries 
operating in these areas. Given the continued artisanal fishing 
pressure throughout the species' range, coupled with the species' 
present rarity and its potential extirpation in areas where it was 
previously abundant, it is likely that the species is still in decline, 
with current abundance trends and levels contributing significantly to 
its risk of extinction.
Growth Rate/Productivity
    The daggernose shark has extremely low productivity. Litter sizes 
range from 2-8 pups, with a 1-year gestation period and a year of 
resting between pregnancies. In other words, annual fecundity averages 
only 1-4 pups because of the species' biennial reproductive 
periodicity. Using these life history parameters, Casselberry and 
Carlson (2015a) estimated a productivity (as the intrinsic rate of 
population increase) of r = 0.004 year-\1\ (median) within a 
range of -0.040-0.038 (Carlson unpublished). Under natural mortality 
rates, Lessa et al. (2010) estimated annual population growth to be 
negative, with an r = -0.048 and a generation time of 9 years. When 
fishing mortality was considered, the estimate of r decreased even 
further, to -0.074, with a generation time of 8.4 years. Considering 
the daggernose shark has already undergone substantial population 
declines, and is still susceptible to fishing mortality in the active 
artisanal fisheries throughout its range, the species' extremely low 
productivity (with estimates of negative annual population growth 
rates) is likely significantly contributing to its risk of extinction.
Spatial Structure/Connectivity
    Very limited information is available regarding spatial structure 
and connectivity of the daggernose shark populations. The best 
available information suggests the daggernose shark has a very 
restricted range, one of the smallest of any elasmobranch species, and, 
as such, an increased vulnerability to extinction from environmental or 
anthropogenic perturbations. In addition, the substantial declines in 
the Brazilian population and subsequent absence of the species in areas 
it was previously known to occur, as well as its rarity throughout the 
rest of its range, suggest the species likely exists as patchy and 
small populations, which may limit connectivity. However, there is not 
enough information to identify critically important populations to the 
taxon as a whole, or determine whether the rates of dispersal among 
populations, metapopulations, or habitat patches are presently posing a 
risk of extinction.
Diversity
    The loss of diversity can increase a species' extinction risk 
through decreasing a species' capability of responding to episodic or 
changing environmental conditions. This can occur through a significant 
change or loss of variation in life history characteristics (such as 
reproductive fitness and fecundity), morphology, behavior, or other 
genetic characteristics. Although it is unknown if I. oxyrhynchus has 
experienced a loss of diversity, the significant decline estimated for 
the population in northern Brazil (comprising approximately half of its 
known range), as well as the likely small populations elsewhere 
throughout its range, suggest the species may be at an increased risk 
of random genetic drift and could experience the fixing of

[[Page 76074]]

recessive detrimental genes, reducing the overall fitness of the 
species.

Threats Assessment

    The primary threat to the daggernose shark is overutilization in 
artisanal fisheries. In Brazil, the species is bycaught in the 
artisanal gillnet fisheries for Spanish mackerel and king weakfish. 
Historically, the species comprised up to around 70 percent of the 
artisanal catch during the Amazonian summer in the State of 
Par[aacute], and was caught in large numbers by the artisanal gillnet 
fisheries operating on the Maranh[atilde]o coast in Brazil. However, 
given the extremely low productivity of the species and vulnerability 
to depletion, this level of exploitation resulted in substantial 
declines (estimated at over 90 percent) to the point where the species 
is no longer found in fish markets or observed in trawl and research 
survey data. The artisanal gillnet fisheries that were responsible for 
this decline are still active throughout the species' range and likely 
exerting similar fishing pressure that historically resulted in the 
substantial decline of the daggernose shark populations. In fact, 
together, the artisanal landings from the North region of Brazil (which 
includes the States of Amap[aacute] and Par[aacute]) and Northwest 
region (which includes the States of Maranh[atilde]o south to Bahia), 
the areas where daggernose sharks were once historically abundant, 
represent over 80 percent of the total artisanal landings for the 
entire country, indicating the importance and, hence, likely 
continuation of this type of fishing in these regions. Notably, the 
king weakfish fishery, which was reported as one of the two main 
artisanal gillnet fisheries responsible for bycatching daggernose 
sharks, remains one of the most important fisheries in Brazil.
    Artisanal gillnet fisheries are also active in the other parts of 
the species' range, including Venezuela, Trinidad and Tobago, Guyana, 
Suriname, and French Guiana, with likely similar fishing practices. 
Although landings data from these countries are unknown, the available 
information suggests that artisanal fishing pressure is high and that 
the species has been taken in small numbers by local fishermen in these 
countries, with daggernose sharks historically sold in markets in 
Trinidad and likely Guyana. Given the species' susceptibility to 
depletion from even low levels of fishing mortality, it is highly 
likely that overutilization by artisanal fisheries operating throughout 
the species' range is a threat that is significantly contributing to 
its risk of extinction.
    In 2004, the daggernose shark was listed on Brazil's endangered 
species list, and as of 2014, was classified as ``critically 
endangered.'' Additionally, it is listed as one of 12 species of 
concern under Brazil's FAO NPOA-sharks. However, the implementation and 
effectiveness of the recommendations outlined in this plan remain 
uncertain, with the best available information indicating that current 
regulatory measures in Brazil to protect vulnerable species are poorly 
enforced, particularly in artisanal fisheries (the fishery sector that 
poses the biggest threat of overutilization of the species). In 
addition, there appears to be a lack of adequate fishing regulations to 
control the exploitation of the daggernose shark in the other parts of 
its range, and, as such, the inadequacy of existing regulatory measures 
is a threat that further contributes to the extinction risk of the 
species.

Risk of Extinction

    Although there is significant uncertainty regarding the current 
abundance of the species, the species' population growth rate and 
productivity estimates indicate that the species has likely suffered 
significant population declines (of up to 90 percent) throughout its 
range and will continue to decrease without adequate protection from 
overutilization. The species' restricted coastal range, combined with 
its recent (2004-2009) absence in areas where it was once commonly 
found, as well as its present rarity throughout the rest of its range 
(with the last record of the species from 1999) indicate potential 
local extirpations and suggest an increased likelihood that the species 
is strongly influenced by stochastic or depensatory processes. This 
vulnerability is further exacerbated by the present threats of 
overutilization and inadequacy of existing regulatory measures that 
will significantly contribute to the decline of the existing 
populations (based on its demographic risks) into the future, 
compromising the species' long-term viability. Therefore, based on the 
best available information and the above analysis, we conclude that I. 
oxyrhynchus is presently at a high risk of extinction throughout its 
range.

Protective Efforts

    With the exception of the recommendations within Brazil's FAO NPOA-
sharks (discussed above), we were unable to find any other information 
on protective efforts for the conservation of daggernose sharks in 
Brazil, Venezuela, Trinidad and Tobago, Guyana, Suriname, or French 
Guiana that would potentially alter the extinction risk for the 
species. We seek additional information on other conservation efforts 
in our public comment process (see below).

Proposed Determination

    Based on the best available scientific and commercial information 
as presented in the status review report and this finding, we find that 
the daggernose shark is presently in danger of extinction throughout 
its range. We assessed the ESA section 4(a)(1) factors and conclude 
that that the species faces ongoing threats from overutilization and 
inadequacy of existing regulatory mechanisms throughout its range. The 
species' natural biological vulnerability to overexploitation and 
present demographic risks (e.g., low and declining abundance, negative 
population growth rates, small, fragmented and likely isolated 
populations, extremely restricted distribution, and very low 
productivity) are currently exacerbating the negative effects of the 
aforementioned threats, placing this species in danger of extinction. 
We also found no evidence of protective efforts for the conservation of 
daggernose shark that would reduce the level of extinction risk faced 
by the species. We therefore propose to list the daggernose shark as an 
endangered species.

Brazilian Guitarfish (Rhinobatos horkelii)

Species Description

    The Brazilian guitarfish (Rhinobatos horkelii) is a member of the 
order Rajiformes and the family Rhinobatidae (Lessa and Vooren 2007). 
The species within the family Rhinobatidae are very similar 
morphologically, which can make them difficult to distinguish from each 
other (De-Franco et al. 2010). The Brazilian guitarfish has long 
nostrils with transversely flat or a slightly convex crown and has a 
median row of tubercles (nodules) on its dorsal surface that are large 
and thorn-like (Lessa and Vooren 2005). The disc width is about 5/6 of 
the body length, with dorsal fins that are triangular and similar in 
size (Bigelow and Schroeder 1953). The dorsal side of the Brazilian 
guitarfish is olive grey or chocolate brown in color and lacks light or 
dark markings. Additionally, its snout has a ``sooty'' oval patch 
(Lessa and Vooren 2005).

Range and Habitat Use

    The Brazilian guitarfish is found along the coast of South America 
in the southwestern Atlantic from Bahia, Brazil to Mar del Plata, 
Argentina (Figueiredo 1977; Lessa and Vooren 2005, 2007; GBIF 2013). 
Newborns and

[[Page 76075]]

juveniles live year round in coastal waters less than 20 m deep. Adults 
coexist with immature individuals in shallow waters between November 
and March, when pupping and mating occur, but spend the rest of the 
year offshore in waters greater than 40 m depth. In the winter, 
individuals can be found in water temperatures as low as 9 [deg]C, 
while in the summer, individuals are found in average water 
temperatures of 26 [deg]C (Lessa and Vooren 2005). Brazilian guitarfish 
are commonly found in salinities ranging from 24-28 ppt in northern 
Argentina (Jaureguizar et al. 2006).

Diet and Feeding

    There is very little information on the diet or feeding behavior of 
Brazilian guitarfish. Refi (1973) recorded the stomach contents of six 
individuals caught in Mar del Plata, Argentina and found that stomachs 
contained the Patagonian octopus (Octopus tehuelchus), shrimp 
(Hymenopeneus muelleri), decapods, isopods, and polychaetes. No other 
information on diet or feeding could be found.

Growth and Reproduction

    Based on a yearly vertebral annulus formation in September, Vooren 
et al. (2005a; citing Lessa (1982)) report the von Bertalanffy growth 
rate (k) for Brazilian guitarfish to be 0.0194, with a theoretical 
maximum size of 135.5 cm TL and age at maturity between 7 and 9 years 
for females and 5 and 6 years for males. Similar results were estimated 
by Caltabellota (2014), with a theoretical maximum size of 121.71 cm TL 
and k = 0.21. No significant differences were found in growth between 
the sexes. Using two different methods, Caltabellota (2014) also 
estimated theoretical longevity of 18.24 and 14.17 years for females, 
and 13.86 and 10.90 years for males. Vooren et al. (2005a) found 
longevity to be longer for both females and males, with estimates of 28 
years and 15 years, respectively.
    Size at maturity for Brazilian guitarfish is between 90 cm and 120 
cm TL for both sexes; the smallest pregnant females recorded were 
between 91-92 cm TL, and all captured females larger than 119 cm TL 
were pregnant (Lessa et al. 2005a; Lessa and Vooren 2005). The 
Brazilian guitarfish has an annual reproductive cycle, with 
lecithotrophic development (i.e., larva depend on the egg's yolk 
reserve supplied by the mother), and a gestation period lasting 
approximately 11-12 months (Lessa et al. 2005a; Lessa and Vooren 2005). 
Gravid females live at depths greater than 20 m for most of the year, 
but migrate into the shallows in the spring and summer to give birth. 
Litter sizes range from 4-12 pups and increase with female size (Lessa 
and Vooren 2005).

Genetics and Population Structure

    Studies examining the genetics of the species or information on its 
population structure could not be found.

Demography

    Total natural mortality for Brazilian guitarfish was estimated by 
Caltabellota (2014) using an age at maturity of 5 years (i.e., an 
earlier age of maturity than what was reported by Vooren et al. 
(2005a)), and found the estimated total natural mortality from catch 
curves to be 0.692 for males and 0.751 for females. Modeling of various 
exploitation scenarios found that under natural conditions, with no 
fishing mortality, the population would increase by 9 percent each 
year, with a population doubling time of 7.41 years (Caltabellota 
2014). In the presence of fishing mortality and an age at first capture 
of 2 years, the Brazilian guitarfish population would decline by 25 
percent every 2.73 years; however, if the age at first capture was 
after the age at first maturity (assumed to be 5 years for these 
models), the population would increase by 4 percent each year 
(Catabellota 2014). Based on the life history parameters discussed 
previously, these demographic parameters indicate that the Brazilian 
guitarfish generally has a low potential to recover from exploitation, 
particularly if the species is experiencing fishing pressure on 
neonates and juveniles.

Historical and Current Distribution and Population Abundance

    The Brazilian guitarfish is distributed along the coast of South 
America, from Bahia, Brazil to Mar del Plata, Argentina. The species' 
center of distribution lies between 28[deg] and 34[deg] S. and also 
corresponds to the area where it is most abundant. This area is known 
as the Plataforma Sul, which includes the continental shelf of southern 
Brazil and extends from Cabo de Santa Marta Grande (28[deg]36' S.) to 
Arroio Chu[iacute] (33[deg]45' S.). In historical bottom trawl surveys 
between latitudes 28[deg]00' S. and 34[deg]30' S., R. horkelii was 
common across the Plataforma Sul south of latitude 29[deg]40' S. 
(Vooren et al. 2005a). Annual catch of Brazilian guitarfish in this 
area was approximately 636 t-1803 t from 1975-1987 (Miranda and Vooren 
2003). Research surveys conducted between Chu[iacute] and 
Solid[atilde]o (Rio Grande do Sul, Brazil) in February 2005 found an 
average CPUE of 1.68 kg/hr (Vooren et al. 2005b), but no follow-up 
surveys were conducted after 2005.
    Throughout the rest of its range, there is little information on 
the abundance of R. horkelli, with the species considered to be a rare 
occurrance. In northern Argentina (34[deg] S.-43[deg] S.), estimated 
mean biomass of Brazilian guitarfish was 0.1240 t/nm\2\ between 1981 
and 1999, with R. horkelli comprising only 0.44 percent of the biomass 
of demersal fish on the northern Argentine continental shelf 
(Jaureguizar et al. 2006). In 1981, biomass of Brazilian guitarfish was 
calculated to be 0.010 t/nm\2\ in 1981. Estimated biomass then peaked 
at 0.441 t/nm\2\ in 1994 before falling steadily to 0.007 t/nm\2\ in 
1999 (Jaureguizar et al. 2006). Biomass estimates reported in 
Argentina's FAO NPOA-sharks for the coast of Buenos Aires province and 
Uruguay were 2,597 t in 1994, 661 t in 1998, and 91 t in 1999 
(Argentina FAO NPOA-sharks 2009). Along the oceanic coast of Uruguay, 
R. horkelii occurs with low density, with annual catches around 3 t in 
2000 and 2001 (Meneses 1999; Paesch and Sunday 2003).

Summary of Factors Affecting the Brazilian Guitarfish (Rhinobatos 
horkelii)

    We reviewed the best available information regarding historical, 
current, and potential threats to the Brazilian guitarfish species. We 
find that the main threat to this species is overutilization for 
commercial purposes. We consider the severity of this threat to be 
exacerbated by the species' natural biological vulnerability to 
overexploitation, which has led to significant declines in abundance of 
all life stages, particularly neonates. We find current regulatory 
measures inadequate to protect the species from further 
overutilization. Hence, we identify these factors as additional threats 
contributing to the species' risk of extinction. We summarize 
information regarding these threats and their interactions below 
according to the factors specified in section 4(a)(1) of the ESA. 
Available information does not indicate that habitat destruction or 
curtailment, disease, predation or other natural or manmade factors are 
operative threats on these species; therefore, we do not discuss these 
factors further in this finding. See Casselbury and Carlson (2015b) for 
discussion of these ESA section 4(a)(1) threat categories.

[[Page 76076]]

Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Based on historical catch data and trends, the primary threat to 
Brazilian guitarfish is overutilization in industrial and artisanal 
fisheries. Before landings were prohibited in Brazil in 2004, the 
Brazilian guitarfish was considered to be the only economically 
important species of the order Rajiformes in southern Brazil, where 
they were fished and caught in otter trawls, pair trawls, shrimp 
trawls, beach seines, and bottom gillnets (Haimovici 1997; Mazzoleni 
and Schwingel 1999; Martins and Schwingel 2003; Lessa and Vooren 2005). 
Commercial catches of the Brazilian guitarfish primarily occurred 
between 28[deg] S.-34[deg] S. in Brazil, where the species is most 
heavily concentrated (Martins and Schwingel 2003; Lessa and Vooren 
2005). The pair and simple trawl fleets, which operate on the inner 
continental shelf and outer shelf, respectively, were responsible for 
the majority of the commercial R. horkelli catch in the 1970s and 1980s 
(Vooren et al. 2005a). Based on historical data, CPUE for the pair 
trawling fleet was highest from December to March, when adults of the 
species would concentrate in coastal waters during the summer for 
birthing and reproduction purposes (making them, as well as their 
young, more susceptible to being caught in large numbers by the 
trawlers) (Miranda and Vooren 2003; Vooren et al. 2005a). In the winter 
(April to September), the simple trawl fleet saw an increase in CPUE as 
both juvenile and adult Brazilian guitarfish migrated to the outer 
shelf; however, as the species was able to spread out more on the outer 
shelf, the CPUE of the simple trawl fleet tended to be half of what the 
pair trawling fleet experienced (Miranda and Vooren 2003; Vooren et al. 
2005a). Regardless, given the effort and complementary spatial and 
temporal operations of these fleets, the adult population of Brazilian 
guitarfish was under high fishing pressure year-round. Consequently, 
this level of exploitation led to significant decreases in the 
abundance of the species, as evidenced by the substantial declines in 
landings and CPUE from both of these fleets. From 1975 to 1986, 
Brazilian guitarfish were common in the landings of these two fleets 
that were operating from Rio Grande do Sul, averaging more than 100 t 
annually in the simple trawl fleet and more than 200 t annually in the 
pair trawl fleet (Klippel et al. 2005). The simple trawl fleet saw 
maximum landings of Brazilian guitarfish in the years 1976 (228 t) and 
1984 (219 t) and the pair trawl fleet landed a Brazilian industrial 
fishing record amount of 1,014 t of R. horkelli in 1984 (Klippel et al. 
2005). However, both fleets saw a significant drop in landings and CPUE 
after 1986. After 1987, landings oscillated between 50 t and 200 t 
annually for the pair trawl fleet, and from 1991-2000, annual landings 
did not exceed 10 t for the single trawl fleet (Klippel et al. 2005). 
In terms of CPUE, the simple trawl fleet saw an 84 percent decline 
between 1975-1986 and 1993-1999, with CPUE decreasing from 0.55 t/trip 
(range: 0.41-0.94) to 0.09 t/trip (range: 0.04-0.15) for the respective 
time periods (Vooren et al. 2005a). Similarly, the pair trawl fleet 
CPUE decreased from 1.07 t/trip (range: 0.43-2.38) to 0.18 t/trip 
(range: 0.09-0.30), an 83 percent decline between the two time periods 
(Vooren et al. 2005a). Based on these landings and CPUE data, the 
Brazilian guitarfish population on the Plataforma Sul is thought to 
have collapsed after 1986, with the abundance of the species after 1993 
estimated to be around 16 percent of its 1986 level (Vooren et al. 
2005a).
    From 2000 to 2002, increases in CPUE of R. horkelli were recorded 
off Santa Catarina, Brazil, in both pair trawls (from 0.11 t/trip in 
2000 to 0.15 t/trip in 2002) and single trawls (from 0.63 t/trip in