Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Riverside Fairy Shrimp (Streptocephalus woottoni, 19154-19204 [05-6825]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 70, Number 69 (Tuesday, April 12, 2005)]
[Rules and Regulations]
[Pages 19154-19204]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-6825]



[[Page 19153]]

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Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Designation of Critical 
Habitat for the Riverside Fairy Shrimp (Streptocephalus woottoni); 
Final Rule

Federal Register / Vol. 70, No. 69 / Tuesday, April 12, 2005 / Rules 
and Regulations

[[Page 19154]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018--AT45


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for the Riverside Fairy Shrimp (Streptocephalus 
woottoni)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), designate 
critical habitat for the federally endangered Riverside fairy shrimp 
(Streptocephalus woottoni) pursuant to the Endangered Species Act of 
1973, as amended (Act). The critical habitat designation encompasses 
approximately 306 acres (ac) (124 hectares (ha)) of land within 
Ventura, Orange, and San Diego counties, California.

DATES: This rule becomes effective on May 12, 2005.

ADDRESSES: Comments and materials received, as well as supporting 
documentation used in the preparation of this final rule, are available 
for public inspection, by appointment, during normal business hours, at 
the Carlsbad Fish and Wildlife Office, U.S. Fish and Wildlife Service, 
6010 Hidden Valley Road, Carlsbad, California 92009 (telephone 760/431-
9440). The final rule, economic analysis, and maps of the designation 
are also available via the Internet at https://carlsbad.fws.gov.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad 
Fish and Wildlife Office, at the above address (telephone 760/431-9440; 
facsimile 760/431-9618).

SUPPLEMENTARY INFORMATION:

Designation of Critical Habitat Provides Little Additional Protection 
to Species

    In 30 years of implementing the Act, the Service has found that the 
designation of statutory critical habitat provides little additional 
protection to most listed species, while consuming significant amounts 
of available conservation resources. The Service's present system for 
designating critical habitat has evolved since its original statutory 
prescription into a process that provides little real conservation 
benefit, is driven by litigation and the courts rather than biology, 
limits our ability to fully evaluate the science involved, consumes 
enormous agency resources, and imposes huge social and economic costs. 
The Service believes that additional agency discretion would allow our 
focus to return to those actions that provide the greatest benefit to 
the species most in need of protection.

Role of Critical Habitat in Actual Practice of Administering and 
Implementing the Act

    While attention to and protection of habitat are paramount to 
successful conservation actions, we have consistently found that, in 
most circumstances, the designation of critical habitat is of little 
additional value for most listed species, yet it consumes large amounts 
of conservation resources. Sidle (1987) stated, ``Because the Act can 
protect species with and without critical habitat designation, critical 
habitat designation may be redundant to the other consultation 
requirements of section 7.'' Currently, of the 1,253 listed species in 
the U.S. under the jurisdiction of the Service, only 470 species (38 
percent) have designated critical habitat.
    We address the habitat needs of all 1,244 listed species through 
conservation mechanisms such as listing, section 7 consultations, the 
section 4 recovery planning process, the section 9 protective 
prohibitions of unauthorized take, section 6 funding to the States, and 
the section 10 incidental take permit process. The Service believes 
that it is these measures that may make the difference between 
extinction and survival for many species.
    We note, however, that the recent 9th Circuit judicial opinion in 
the case of Gifford Pinchot Task Force v. United States Fish and 
Wildlife Service has invalidated the Service's regulation defining 
destruction or adverse modification of critical habitat. We are 
currently reviewing the decision to determine what effect it may have 
on the outcome of consultations pursuant to section 7 of the Act.

Procedural and Resource Difficulties in Designating Critical Habitat

    We have been inundated with lawsuits for our failure to designate 
critical habitat, and we face a growing number of lawsuits challenging 
critical habitat determinations once they are made. These lawsuits have 
subjected the Service to an ever-increasing series of court orders and 
court-approved settlement agreements, compliance with which now 
consumes nearly the entire listing program budget. This leaves the 
Service with little ability to prioritize its activities to direct 
scarce listing resources to the listing program actions with the most 
biologically urgent species conservation needs.
    The consequence of the critical habitat litigation activity is that 
limited listing funds are used to defend active lawsuits, to respond to 
Notices of Intent (NOIs) to sue relative to critical habitat, and to 
comply with the growing number of adverse court orders. As a result, 
listing petition responses, the Service's own proposals to list 
critically imperiled species and final listing determinations on 
existing proposals are all significantly delayed.
    The accelerated schedules of court ordered designations have left 
the Service with almost no ability to provide for adequate public 
participation or to ensure a defect-free rulemaking process before 
making decisions on listing and critical habitat proposals due to the 
risks associated with noncompliance with judicially-imposed deadlines. 
This in turn fosters a second round of litigation in which those who 
fear adverse impacts from critical habitat designations challenge those 
designations. The cycle of litigation appears endless, is very 
expensive, and in the final analysis provides relatively little 
additional protection to listed species.
    The costs resulting from the designation include legal costs, the 
cost of preparation and publication of the designation, the analysis of 
the economic effects and the cost of requesting and responding to 
public comment, and in some cases the costs of compliance with the 
National Environmental Policy Act (NEPA). None of these costs result in 
any benefit to the species that is not already afforded by the 
protections of the Act enumerated earlier, and they directly reduce the 
funds available for direct and tangible conservation actions.

Background

    Among the rarest animal species endemic (native) to Southern 
California is a tiny freshwater crustacean known as the Riverside fairy 
shrimp (Streptocephalus woottoni). Its distribution is highly 
restricted, with most of the known populations of the endangered 
Riverside fairy shrimp observed in vernal pools located in portions of 
a few counties and 50 miles (mi) (24 kilometers (km)) or less from the 
California coast, and ranging only approximately 125 mi (200 km) from 
its known northern limit (Ventura and Los Angeles counties) to its 
southern limit (Mexico border, San Diego County) within the U.S. (Eng 
et al. 1990; Simovich and Fugate 1992; Eriksen and Belk 1999; Service 
2004 (69 FR 23024)). It does not occur in the nearby desert or

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mountain areas (Hathaway and Simovich 1996). It is also among the most 
recently discovered freshwater crustacean species in California, first 
identified in 1985 as a unique species (Eng et al. 1990) in the genus 
Streptocephalus (Baird 1852). With 63 species that occur worldwide 
(retrieved February 22, 2005, from the Integrated Taxonomic Information 
System on-line database, https://www.itis.usda.gov), Streptocephalus is 
the most species-rich genus within the aquatic crustacean order 
Anostraca, which comprises over 258 fairy shrimp species and 7 
subspecies worldwide, organized into 21 genera (Belk et al. 1993). The 
fairy shrimp (Anostraca) are, except for one other group, the most 
primitive living crustaceans, or members of the sub-phylum Crustacea 
(Eriksen and Belk 1999). Among the 23 fairy shrimp (Anostracan) species 
that are found in California, 8 species are found only in this State, 
giving California the highest level of endemism for any comparable 
geographic region in North America (Eng et al. 1990), and resulting in 
the highest number of species occurring in a comparable land area in 
both North America and worldwide (Eriksen and Belk 1999). Despite this 
fact, the level of knowledge about many Anastrocans is relatively low 
due to the relative recentness of their discovery.
    The Riverside fairy shrimp and vernal pool crustaceans in general, 
occupy the first consumer level in the food chain, and thus constitute 
a cornerstone in the food web. Fairy shrimp form an important food 
source for an array of aquatic and terrestrial species, from diving 
beetles, backswimmers (Notonectids), vernal pool tadpole shrimp 
(Branchinecta species), predaceous aquatic insects and their larvae, to 
waterfowl and shorebirds, and occasionally even for frogs, toads, and 
tadpoles (Eriksen and Belk 1999). Humans have also been known to 
consume fairy shrimp; tribes in California have been known to 
extensively consume dried Artemia, and Tripos is said to be used as 
food by some natives in Mexico (Pennak 1989).
    The Riverside fairy shrimp, along with numerous sensitive and rare 
plant species, lives only in vernal pools, vernal ponds, swales, and 
ephemeral (short-lived) freshwater habitats. A vernal pool (including 
vernal pond and vernal lake) is defined as an area of shallow 
depression, usually underlain by some subsurface layer which prohibits 
drainage into the lower soil profile, thus causing water to collect 
during the rainy winter season (Holland 1976; Chetham 1976; Weitkamp et 
al. 1996), i.e., the depression is inundated for portions of the wet 
season, when temperatures are sufficient for plant growth (Keeley and 
Zedler 1998). Following a brief waterlogged period during the late wet 
season or early dry season, a vernal pool will eventually drain and dry 
out, followed by an extended period of extreme soil-drying conditions 
(Keeley and Zedler 1998; Rains et al. 2005). Swales are defined as 
shallow drainages that carry water seasonally. Central to the 
distinctive ecology of vernal pools is that they are vernal, or 
ephemeral, i.e., occurring only temporarily, during late winter and 
spring. The water in vernal pools stands sufficiently long to prohibit 
zonal vegetation growth (Holland 1976), yet not long enough to allow 
for colonization by fish species. Vernal pool habitat thus forms a 
unique type of ecosystem, different in character and species 
composition from the surrounding habitats (Service 2003; 68 FR46684), 
and being intermediate between marsh (nearly always wet) and most zonal 
vegetation communities (nearly always dry) (Holland 1976). In 
California, where extensive areas of vernal pool habitat have developed 
over long periods, unique species groups have evolved special 
adaptations to allow them to survive the unusual conditions of vernal 
pools. Vernal pools are often defined by their unique, often endemic, 
flora as well (Smith and Verrill 1998).
    The Riverside fairy shrimp occupies, and is thus completely 
dependent upon, vernal pools to survive. A combination of physical and 
environmental factors allows for the annual formation and maintenance 
of their vernal pool habitat. Vernal pools form generally where there 
is a Mediterranean climate, i.e., a wet season during fall and winter, 
when rainfall exceeds evaporation and fills the pools, followed by a 
spring and summer dry season, when evaporation exceeds rainfall and the 
pools dry up. A typical vernal pool season is characterized by an 
inundation phase, an aquatic phase, a water-logged drying phase, and a 
dried-out phase (Keeley and Zedler 1998). Thus, the water regime 
(hydrologic system) is crucial to the formation and functioning of a 
healthy vernal pool ecosystem. Some pools fill entirely from direct 
precipitation (Hanes and Stromberg 1998), while others have a 
substantial watershed, including both surface, subsurface, and 
groundwater, flowing through the surrounding bedrock and soils that 
contributes to their water inputs (Rains et al. 2005).
    Vernal pools can be a variety of shapes and sizes, from less than a 
square yard (0.8 square meters (m\2\), to 2.5 ac (1 ha) or more. They 
occur on gently sloping mesas above the primary drainages, or in 
valleys at the low end of a watershed (Bauder and McMillan 1998). 
Vernal pools may be fed or connected by low drainage pathways, or 
swales. The micro-relief of a vernal pool may be complex, and some are 
dotted with numerous rounded soil mounds (mima) (Scheffer 1947). Their 
typical patterning, visible from the air, has allowed a number of 
vernal pools to be mapped throughout California's Central Valley, on a 
10-40 ac unit scale (Holland 1998; 2003, Service 2003). The landscape 
in which they occur is typically grassland, but vernal pools also occur 
in a variety of other habitat types (Service 2003).
    A critical factor in the development of a vernal pool is the soil 
conditions of the landscape (an impermeable surface or subsurface 
layer) and a gently sloping topography (slope of 10 percent or less). 
Vernal pools form because the soil or sediment layer at or below the 
surface is nearly or completely impermeable to downward water seepage 
(Smith and Verrill 1998), and thus rainfall and water from the 
surrounding watershed becomes trapped above this layer. Soil types of 
the California vernal pools are volcanic flows, and hardpans and 
claypans, the latter of which have developed gradually over thousands 
of years, and can be a yard (1 m) or more thick. The unique assemblage 
of soils plays a critical role in nutrient cycling in vernal pool 
ecosystems. The soil types which underlie and surround the vernal pool 
therefore greatly influence the species composition of both plant and 
animals, as well as the hydrological functioning of the vernal pool 
(Hanes and Stromberg 1998; Hobson and Dahlgren 1998; Smith and Verrill 
1998). Because water and precipitation flow through the soil to the 
pool, the chemistry of the soils underlying a vernal pool, and in the 
surrounding upslope areas, is directly linked to the chemistry of the 
vernal pool's water, i.e., on its alkalinity, pH, oxidation and 
reduction processes, dissolved salts and gasses, ion concentrations, 
mineral richness, and organic material. Thus, soil chemistry likely has 
a tremendous impact on aquatic invertebrate endemism (cf. Hobson and 
Dahlgren 1998). The distinct seasonality of vernal pools results in 
alternating conditions of reduction and oxidation within the soil 
profile, creating edaphic (soil-influenced) controls that may provide a 
refuge for competition-sensitive plant and animal species (Hobson and 
Dahlgren 1998). The length of ponding may also be affected by variables 
like

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consistency of soil, depth of soil to impervious layer (e.g., duripan, 
claypan), type and thickness of the impervious layer, and local 
climatic factors (e.g., rainfall abundance and regularity, evaporation 
rates; Helm 1998).
    Because of the transportation of water, soil, minerals and 
nutrients over the landscape into vernal pools, the upland, or upslope 
areas associated with vernal pools are an important source of these for 
vernal pool organisms (Wetzel 1975). Since vernal pools are mostly 
rain-fed, they tend to have low nutrient levels (Keeley and Zedler 
1998). In fact, most of the nutrients that vernal pool crustaceans 
derive from their vernal pool habitat come from the detritus (decaying 
organic matter) that washes into pools from the adjacent upslope areas; 
these nutrients provide the foundation for the food chain in the vernal 
pool aquatic community (Eriksen and Belk 1999), of which the fairy 
shrimp fauna constitutes an important component.
    Typical to vernal pools are their dramatic fluctuations in local 
environmental conditions. The water, generally unbuffered, fluctuates 
greatly on a daily basis in pH, and concentrations of ions and 
dissolved gasses (oxygen and carbon dioxide), due to varying daily 
evaporation (Keeley and Zedler 1998). On a larger time-scale, there is 
extensive monthly and annual variation in the duration and extent of 
ponding of vernal pools, some pools not filling at all in some years, 
as the timing and amount of annual rainfall in California varies 
widely. Because of the unique and ephemeral nature of vernal pool 
habitat, and the adaptations of its plant and animal species, vernal 
pools are rich in species composition and contain a large number of 
highly specialized, native species that are found nowhere else in the 
region (endemic) (Holland and Jain 1978; Simovich 1998). Vernal pool 
habitats yield the highest number and species richness of endemics 
(native species) in comparison to other wetland types (Helm 1998).

Riverside Fairy Shrimp (Streptocephalus woottoni)

    The Riverside fairy shrimp is a small (0.56-0.92 inches (in) (14-23 
millimeters (mm))), slender Anostracan that has large stalked compound 
eyes and a delicate, elongate body with 11 pairs of phyllopods, or 
swimming appendages, which also function as gills (Eng et al. 1990; 
Eriksen and Belk 1999). Using their phyllopods in a complex, wavelike 
motion from front to back, they swim gracefully upside-down. As they 
swim about, fairy shrimp use these same appendages to filter-feed from 
the water column, allowing them to non-selectively consume algae, 
bacteria, protozoa, rotifers and bits of detritus (Eng et al. 1990; 
Eriksen and Belk 1999). Note that nothing is known specifically about 
the Riverside fairy shrimp's food resource requirements (Simovich and 
Ripley, pers. comm., May 25, 2004).
    Riverside fairy shrimp are distinguished from other fairy shrimp 
species primarily by the second pair of antennae on the adult male, 
which are enlarged for grasping the female during copulation (Pennak 
1989; Eriksen and Belk 1999; Service 2003). Both males and females are 
generally off-white in color, with orange pigment in their tail 
appendages (cercopods) and sometimes along the edges of the phyllopods 
(although some females have been observed to be entirely bright red-
orange) (Eriksen and Belk 1999). The females, when mature, can be 
identified by their brood pouch, the elongate, ventral protruding egg 
sac immediately behind the phyllopods (Eriksen and Belk 1999).
    Relative to most other fairy shrimp species, the Riverside fairy 
shrimp is a rare species with a highly restricted distribution 
(Hathaway and Simovich 1996). They are found only in a few pools at 
lower elevations in the Southern California coastal range that are 
inundated for a longer duration and generally deeper (greater than 12 
in or 30 centimeters (cm)) than pools that support San Diego fairy 
shrimp (Branchinecta sandiegonensis) (Hathaway and Simovich 1996). Some 
of these pools may have been artificially deepened with berms (i.e., 
cattle tanks and road embankments) (Hathaway and Simovich 1996). The 
two species are known to co-occur in a few deep pools; however they 
generally do not co-exist, as adults of the Riverside fairy shrimp 
emerge later in the season than San Diego fairy shrimp (Simovich and 
Fugate 1992; Hathaway and Simovich 1996).
    After copulation, the males of some fairy shrimp species die within 
a few hours (Pennak 1989). When the eggs are fertilized in the female's 
pouch, they become coated (encysted) with a protein layer that develops 
into a thick, usually multilayered shell (Eriksen and Belk 1999). When 
the egg enters the late stage of embryonic development, all growth then 
ceases, and the egg enters into a dormant stage, or diapause 
(Drinkwater and Clegg 1991; Eriksen and Belk 1999). The female then 
either ejects the cysts to fall to the pool bottom, or, if she survives 
for an extended period, continues to move successive clutches of eggs 
into her brood pouch. If the vernal pool persists for several weeks to 
a few months, fairy shrimp may have multiple hatches in a single season 
(Eriksen and Belk 1999). Cysts can also remain in the brood pouch until 
the female dies and sinks to the pool bottom (Eriksen and Belk 1999). 
However, females of some fairy shrimp species can, in the presence of 
male adults during the wet period, eject thin-shelled cysts that hatch 
immediately without becoming dormant (``summer eggs''), thus allowing 
for multiple generations during a single wet season, while the thick-
shelled, dormant (``winter'') eggs are deposited in the absence of 
males in the population (Pennak 1989). By the time the pool dries out, 
the numbers of dormant cysts within each pool basin can reach tens of 
thousands to millions, depending on pool size, volume, and depth (Belk 
1998).
    Mature cysts become fully desiccated (dried) after their pool has 
evaporated, and due to their protective coating, they can withstand 
extreme environmental conditions (Pennak 1989; Eriksen and Belk 1999). 
For example, they can survive subjection to physical extremes, such as 
near-boiling temperatures, months of freezing (Carlisle 1968), fire 
(Wells et al. 1997), or near-vacuum conditions for 10 years without 
damage to the embryo (Clegg 1967). These adaptations allow fairy shrimp 
cysts to survive extreme environmental fluctuations, and hatch only 
when conditions are favorable, after remaining dormant for as much as 
decades, possibly centuries (Belk 1998). In one closely related fairy 
shrimp, Streptocephalus sealii, cysts were brought to hatch after 25 
years of storage in the lab (Belk 1998). Further, because the wall of 
the cyst can even resist damage by stomach enzymes (Horne 1966), the 
cyst can pass through the digestive tract of animals without harm, thus 
allowing for one possible mechanism of cyst dispersal. There are 
several mechanisms for cyst dispersal, and thus fairy shrimp dispersal, 
to other habitats. Historically, large-scale flooding from heavy winter 
and spring rains has been a primary dispersal mechanism, but other 
major mechanisms include dispersal by migratory birds (i.e., wading 
birds, shorebirds, waterfowl), ungulates (i.e., cattle, buffalo, deer), 
and possibly amphibians (i.e., salamanders, frogs) and humans (Eriksen 
and Belk 1999). These animals either carry cyst-containing mud on their 
bodies incidentally from pool to pool, or the cysts are ingested and 
are passed through the gut at another location.

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Wind, although less probable, may also be a dispersal agent (Eriksen 
and Belk 1999).
    Although cysts can remain dormant within the pool for decades, they 
can also hatch about a week after a rain-fill, due to their advanced 
stage of embryonic development (Pennak 1989; Hathaway and Simovich 
1996). However, when a dry vernal pool is once again inundated with 
water, only a fraction of the dormant cysts in the pool will hatch. 
Simovich and Hathaway (1997) found that when Riverside fairy shrimp 
cysts were hydrated once, only 0.18 percent hatched, and after three 
successive hydration periods, the cumulative total increased to only 
2.8 percent. This is among the lowest hatching rates, or prolonged 
diapause, yet recorded among fairy shrimp species (Simovich and 
Hathaway 1997). They suggested that the prolonged diapause of so many 
cysts was an adaptation to the variable nature of local rainfall 
patterns, as pools at times fill only partially and dry quickly--before 
the fairy shrimp are able to reach maturity and reproduce. Thus, in 
such an environment with unpredictable filling events, it benefits the 
individual to have offspring in prolonged diapause, such that not all 
hatch after just one hydration (Simovich and Hathaway 1997). In San 
Diego County, only approximately 28 percent of all filling events 
recorded over 13 years lasted at least a 17-day period, the minimum 
length of time needed by the San Diego fairy shrimp to develop to first 
reproduction (and insufficient time for the Riverside fairy shrimp); 
this period corresponded to the 28-percent hatching rate for their 
cysts found in the lab (Philippi 2001). This strategy of prolonged 
diapause is possibly a risk-spreading (``bet-hedging'') adaptation to 
the unpredictability of their environment (Simovich and Hathaway 1997; 
Philippi 2001).
    In addition to their low hatching percentage, the cysts of the 
Riverside fairy shrimp also take longer to hatch after inundation, 
relative to other species (Hathaway and Simovich 1996). The time from 
hydration to the hatching of Riverside fairy shrimp cysts took between 
12 to 25 days in the lab at varying temperatures, with the most rapid 
hatching occurring when temperatures were fluctuating at 41-59 degrees 
Fahrenheit ((F) 5-15 degrees Celsius (C)). San Diego fairy shrimp, in 
comparison, can hatch after only 3 days (Hathaway and Simovich 1996). 
The greatest number of Riverside fairy shrimp cysts hatching in the 
lab, however, was achieved at 50 degrees F (10 degrees C) (Hathaway and 
Simovich 1996). Their development or maturation rate is also slow, and 
individuals are relatively long-lived (Hathaway and Simovich 1996), as 
is typical of obligate deep pool species. The developmental time to 
maturity for the Riverside fairy shrimp was found to be 7-8 weeks, far 
longer than to the 7-10 day period of the San Diego fairy shrimp.
    It is not surprising, therefore, that the Riverside fairy shrimp 
also lives much longer (2.5 to over 4 months) than the San Diego fairy 
shrimp (4-6 weeks) (Hathaway and Simovich 1996). Thus, the minimum 
period of inundation, or pool duration, that the Riverside fairy shrimp 
need in order to hatch and reach maturity is 9 to 10 weeks (Gonzalez et 
al. 1996; Hathaway and Simovich 1996). Thus, the association of the 
Riverside fairy shrimp with large, deep vernal pools that pond 
continuously for many months may perhaps be explained by its long 
period of maturity and longevity (cf. Helm 1998). Because of their slow 
hatch and growth, the Riverside fairy shrimp occur therefore much later 
in the season than other fairy shrimp species (cf. Hathaway and 
Simovich 1996).
    The vernal pools that Riverside fairy shrimp are found in typically 
have water with a relatively neutral pH (approximately 7), low to 
moderate salinity, and low to moderate levels of total dissolved solids 
(Gonzalez et al. 1996; Eriksen and Belk 1999). One laboratory study 
conducted on the tolerance of Riverside fairy shrimp to variations in 
water chemistry found that they tolerate an 8-hour exposure to pH 
levels ranging from 8 to 10.5, with little effect (Gonzalez et al. 
1996). Generally, in vernal pools where Riverside fairy shrimp occur, 
the external ion concentrations (Na+) averaged 0.73 mmol/l\3\ (Gonzalez 
et al. 1996). Although the species was also able to maintain its 
internal levels of salt concentration fairly constantly over a wide 
range of external concentrations (0.5-60 mmol/l\3\), it was sensitive 
to the extremes, with 100-percent mortality occurring at 100 mmol/l\3\ 
(Gonzalez et al. 1996). Levels of alkalinity in the vernal pool are 
affected by the surrounding soil type and hydrological regime of the 
immediate adjacent upland watershed; in four vernal pools, alkalinity 
averaged 41 mg/l\3\ (Gonzalez et al. 1996). In the laboratory, 
Riverside fairy shrimp were found to tolerate a wide range of 
alkalinities (0-600 mg/l\3\), but none could survive levels above 800 
mg/l\3\ (Gonzalez et al. 1996). Importantly, studies show that the 
Riverside fairy shrimp is sensitive to water temperature; with their 
hatching occurring a longer time after inundation (25 days) and fewer 
hatching (1-3 percent) at steady higher temperature of 77 degrees F (25 
degrees C), than at cooler temperatures (i.e., 7 days hatching time at 
59-77 degrees F (15-25 degrees C); over 10 percent hatching at 50 
degrees F (10 degrees C) (Gonzalez et al. 1996).
    The upslope areas surrounding vernal pools are critical to the 
functioning of the vernal pool and thus to the survival of the 
Riverside fairy shrimp. The surrounding upslope areas provide the 
vernal pool with the appropriate annual and season temporality and 
volume of hydrological flow. With that flow follows the necessary 
nutrients, salts and minerals from the soil and bedrock that all 
influence the pool's water volume, the duration of ponding, and the 
complete chemistry, mineral and nutrient contents of the water itself. 
Therefore, Riverside fairy shrimp, together with its cohabitating 
vernal pool flora and fauna, is as dependent upon the upland areas for 
survival and reproduction as it is upon the pool it occupies.
    Urban and water development, flood control, and highway and utility 
projects, as well as conversion of wild lands to agricultural use, have 
eliminated or degraded vernal pools and/or their watersheds in southern 
California (Jones and Stokes Associates 1987). Changes in hydrologic 
patterns, certain military activities, unauthorized fills, overgrazing, 
and off-road vehicle use also may imperil this aquatic habitat and the 
Riverside fairy shrimp. The flora and fauna in vernal pools or swales 
can change if the hydrologic regime is altered (Bauder 1986). 
Anthropogenic (human-origin) activities that reduce the extent of the 
watershed or that alter runoff patterns (i.e., amounts and seasonal 
distribution of water) may eliminate the Riverside fairy shrimp, reduce 
population sizes or reproductive success, or shift the location of 
sites inhabited by this species. The introduction of non-native plant 
species, competition with invading species, trash dumping, fire, and 
fire suppression activities were some of the reasons for listing the 
Riverside fairy shrimp as endangered on August 3, 1993 (58 FR 41384). 
Because of these threats, we anticipate that intensive long-term 
monitoring and management will be needed to conserve this species. 
Historically, vernal pool soils covered approximately 500 km\2\ (200 
mi\2\ of San Diego County (Bauder and McMillan 1998). The greatest 
recent losses of vernal pool habitat in San Diego County have occurred 
in Mira Mesa, Rancho Pe[ntilde]asquitos, and Kearny Mesa, which 
together account for 73 percent of all the pools destroyed in the 
region during the

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7-year period between 1979 and 1986 (Keeler-Wolf et al. 1995). Other 
substantial losses have occurred in the Otay Mesa area, where over 40 
percent of the vernal pools were destroyed between 1979 and 1990. 
Similar to San Diego County, vernal pool habitat was once extensive on 
the coastal plain of Los Angeles and Orange counties. Unfortunately, 
there has been a near-total loss of vernal pool habitat in these areas 
(Ferren and Pritchett 1988; Keeler-Wolf et al. 1995; Mattoni and 
Longcore 1997; Service 1998). Significant losses of vernal pools 
supporting this species have also occurred in Riverside County.
    Adequately quantifying occurrence and distribution of the Riverside 
fairy shrimp can be difficult due to a number of factors. Firstly, 
Riverside fairy shrimp are restricted to a narrow geographic region, to 
certain pool types, and also temporally, as they emerge later in the 
season than other fairy shrimp species (Hathaway and Simovich 1996). 
Thus, surveys conducted to also encounter earlier-occurring species may 
actually miss the Riverside fairy shrimp as they may still be so small 
(in the juvenile stage) that they pass through the mesh of the 
collecting nets (Eriksen and Belk 1999). Secondly, surveys may also 
miss collecting adults simply due to their low hatching percent (as few 
as 0.18 percent; Simovich and Hathaway 1997), which may result in 
either a very low population level, or to none being detected in a 
particular year, when viable cysts are actually present. Further, only 
males can be identified to the species level with certainty (Eriksen 
and Belk 1999), and cysts can only be identified to the genus level. To 
add to the difficulty, vernal pools are generally too small to appear 
on topographic maps (Holland 1976), not all vernal pools fill each 
year, or fill long enough for hatching (i.e., discovery) of the 
Riverside fairy shrimp. Some estimates for San Diego County show that 
over a period of 13 years, only about 28 percent of the pool-filling 
events lasted 17 days or longer (Philippi 2001).
    For a more detailed discussion about the Riverside fairy shrimp's 
physical description, ecology, range, status and distribution, and a 
discussion of factors affecting this species, please refer to the 
following documents from the Federal Register: The final rule listing 
the species as threatened (58 FR 41384), published on August 3, 1993, 
the previous final rule to designate critical habitat (66 FR 29384), 
published on May 30, 2001, and our latest proposed rule to designate 
critical habitat (69 FR 23024), published on April 27, 2004.

Previous Federal Actions

    For more information on previous Federal actions concerning the 
Riverside fairy shrimp, please refer to the proposed rule to designate 
critical habitat for the Riverside fairy shrimp (69 FR 23024) and the 
notice of availability for the draft economic analysis (DEA) and 
reopening of the public comment period for the proposed designation of 
critical habitat for the Riverside fairy shrimp published in the 
Federal Register (October 19, 2004, 69 FR 61461).

Summary of Comments and Recommendations

    We requested written comments from the public on the proposed 
designation of critical habitat for the Riverside fairy shrimp in the 
proposed rule (69 FR 23024). We also contacted and invited the 
appropriate Federal, State, and local agencies, as well as scientific 
organizations and other interested parties to comment on the proposed 
rule. In the notice of availability of the draft economic analysis for 
the proposed designation of critical habitat (69 FR 61461), we again 
solicited comments from the public on both the draft economic analysis 
and the proposed rule. All comments and new information received during 
the two comment periods were incorporated into the final rule as 
appropriate.
    During the first comment period, open from April 27, 2004, to May 
27, 2004, we received 21 letters containing 143 comments directly 
addressing the proposed critical habitat designation from 6 peer 
reviewers, 5 Federal agencies, 2 county and local agencies, 1 group, 4 
businesses, 1 city, 1 water district, 1 individual, and 1 law firm 
writing on behalf of 2 groups and 2 transportation agencies.
    During the second comment period, open from October 19, 2004, to 
November 18, 2004, we received 11 letters containing 148 comments 
directly addressing the proposed critical habitat designation and the 
draft economic analysis. The letters came from 4 Federal agencies, 3 
groups, 2 businesses, 1 law firm on behalf of 2 businesses, and 1 law 
firm on behalf of 2 groups and 2 transportation agencies.
    Of a total 32 letters received, 4 supported the designation of 
critical habitat for the Riverside fairy shrimp, 2 opposed the 
designation, 18 letters suggested reducing the area of designation, and 
4 letters suggested expanding the area. Two letters were requests for 
an extension of the comment submission period, but did not express 
support or opposition to the proposed critical habitat designation. 
Comments received were grouped into six general issues specifically 
relating to the proposed critical habitat designation for the Riverside 
fairy shrimp, and are addressed in the following summary and 
incorporated into the final rule as appropriate. We did not receive any 
requests for a public hearing. We have reviewed all comments received 
from the peer reviewers and the public for substantive issues and new 
information regarding critical habitat for the Riverside fairy shrimp, 
and have incorporated them into the final rule as appropriate. These 
are addressed below in the following summary.

Peer Review

    In accordance with our policy published on July 1, 1994 (59 FR 
34270), to solicit opinions from at least three experts, we solicited 
the expert opinions of 7 knowledgeable individuals with significant 
scientific expertise that included familiarity with the Riverside fairy 
shrimp, the geographic region in which the species occurs, and 
conservation biology principles. We received responses from six of the 
peer reviewers. The peer reviewers were generally supportive of the 
designation of critical habitat, but strongly endorsed the approach 
that the appropriate management unit was the vernal pool complex (not 
single pools) together with their immediately surrounding upland 
watershed. They emphasized the importance of providing conservation 
protection of pool complexes to ensure the survival of the Riverside 
fairy shrimp in perpetuity, and of identifying and preserving all 
remaining populations of Riverside fairy shrimp, including those within 
conservation-managed areas. Three peer reviewers also gave specific 
comments on our decision to exclude certain lands from critical habitat 
based on Habitat Conservation Plans (HCPs) and Integrated Natural 
Resources Management Plans (INRMPs).

Comments From Peer Reviewers

    1. Peer Reviewer Comment: Most of the reviewers stressed the 
importance of providing or increasing Federal protection to the 
Riverside fairy shrimp and their vernal pool habitat, since 
conservation measures are needed to protect them. Over 95 percent of 
vernal pools in Southern California have been extirpated (destroyed), 
and the remaining vernal pools and the species that inhabit them are 
currently under threat of elimination from both private and public 
organizations. Additionally, vernal pools are valuable in that they are 
ecologically unique, while also

[[Page 19159]]

providing valuable ecosystem functions. Vernal pool complexes act as 
hydrologic ``sponges,'' buffering against drought and flooding. Large-
scale alterations or developments within the local watershed of vernal 
pool complexes would affect the local hydrology dramatically and, from 
an engineering and public works perspective, can lead to increases in 
the need for management of unnaturally large amounts of runoff 
following a rainstorm. Thus, vernal pools have not received adequate 
recognition in the rule for the benefits (ecological services) they 
provide. For their long-term survival, vernal pools must be adequately 
protected; the designation of critical habitat does not seem to provide 
adequate conservation measures to serve this purpose.
    Our Response: Section 4 of the Act requires us to designate 
critical habitat to the maximum extent prudent and determinable, which 
we have done, based upon the best data available to us at this time. We 
concur that additional, long-term conservation measures are needed to 
protect the Riverside fairy shrimp and its habitat, and additional data 
is needed on locations of their occurrence.
    In developing our final designation of critical habitat for the 
Riverside fairy shrimp, we used the best scientific and commercial data 
available to identify those areas that contain essential occurrences of 
Riverside fairy shrimp and/or are defined by the physical and 
biological features essential to their conservation. We used a number 
of criteria in defining critical habitat, including but not limited to 
the known species occurrence (known at the time of listing, as well as 
discovered subsequently) and distribution data, habitat types, presence 
of PCE's, degree of habitat fragmentation, soil and landform 
relationships, connectivity and dispersal factors, and conservation 
biology principles. We did not include all vernal pool landscapes 
within the Riverside fairy shrimp's range although surveys in these 
areas may result in the detection of other occurrences in the future. 
If significant information becomes available indicating that areas 
outside of our designation are essential to the conservation of the 
Riverside fairy shrimp, we can, under the Act, revise critical habitat 
in the future.
    2. Peer Reviewer Comment: While the Service's proposed designation 
of critical habitat for the Riverside fairy shrimp in southern 
California was supported, reviewers stated it is questionable whether 
5,795 acres in the proposed rule is ``enough'' critical habitat for the 
conservation of the remaining Riverside fairy shrimp populations. 
Firstly, reviewers strongly emphasized the importance of considering 
the vernal pool complex and the surrounding watershed as the management 
unit for this species. The unique physiochemical requirements of the 
Riverside fairy shrimp make it particularly vulnerable to changes in 
hydrology. Further, other vernal pool species have their own unique 
ecological requirements in terms of soil, hydrology, etc. Protecting 
and maintaining entire vernal pool complexes and their surrounding 
watershed as a functioning unit will benefit the Riverside fairy shrimp 
and the other endangered species that live in these habitats. If the 
landscape at a site is changed sufficiently to alter the hydrology of 
individual vernal pools, then the species in them will eventually go 
extinct, regardless of whether the pools are disturbed or not. 
Secondly, some vernal pools excluded from the designation, but set 
aside for conservation or mitigation, do not have sufficient protection 
in the surrounding watershed, and thus become ecologically useless. The 
exclusion of military lands from the final designation is particularly 
troubling in this regard, because there are no guarantees that the 
watershed, let alone pools with Riverside fairy shrimp in them, will be 
adequately protected.
    Our Response: Firstly, we note the support of our critical habitat 
designation, and concur with the reviewers on the importance of 
considering the vernal pool complexes together with their immediately 
surrounding upslope areas as the management unit (see Background and 
Primary Constituent Elements sections below). We have used this 
approach in our analyses when finalizing our critical habitat 
designation for the Riverside fairy shrimp, and have, wherever 
possible, included the upslope areas surrounding the pools. Secondly, 
for approved, legally operative HCPs that include areas eligible for 
designation as critical habitat and that specifically address the 
Riverside fairy shrimp and provide for its long-term conservation, we 
believe that the benefits of excluding those HCPs will outweigh the 
benefits of including them. Thirdly, we received requests from three 
military bases to exclude lands owned or managed by the Department of 
Defense for military purposes because the designation would increase 
the costs and regulatory requirements, hamper the military's ability to 
carry out their national security objectives, or because there is an 
INRMP in place that provides a benefit to the Riverside fairy shrimp. 
These installations have either been excluded from final designated 
critical habitat pursuant to section 4(b)(2) of the Act, or exempted 
according to section 4(a)(3) of the Act. Please refer to the sections 
Relationship of Critical Habitat to Approved Habitat Conservation Plans 
and Relationship of Critical Habitat to Department of Defense Lands 
below in this final rule for detailed discussions of our rationale for 
exclusions and exemptions.
    3. Peer Reviewer Comment: Any consideration of whether the 
Riverside fairy shrimp will persist indefinitely (i.e., avoid 
extinction due to anthropogenic causes) would require a quantification 
of the Riverside fairy shrimp's (a) dispersal biology, (b) adaptation 
to local physiochemical conditions, and (c) adaptation to hydrologic 
uncertainties (via reliance on an egg bank). In terms of the hydrology 
of the vernal pool habitat, quantifiable data is needed on (d) the 
historic environmental variation and (e) the predicted future 
environmental variation. However, only rudimentary data are available 
on any of these topics, with the possible exception of (d). Therefore, 
it would be wise to err on the side of caution and offer maximal 
protection to all remaining populations of this species.
    Our Response: We concur that more detailed studies are needed on 
most aspects of the Riverside fairy shrimp's biology. In this rule, we 
address the issue of designating critical habitat areas, areas 
containing the necessary primary constituent elements (PCEs) that are 
essential to the conservation of the Riverside fairy shrimp. For this 
purpose, we used the best scientific and commercial information that 
were available to us and based our analyses upon areas either 
containing with existing populations of Riverside fairy shrimp or 
containing features essential for the conservation of the species using 
the vernal pool complex together with the immediately surrounding 
upslope areas as our management unit. To assist us in developing this 
final rule, we also opened two comment periods to obtain as much 
additional, currently available information as possible.
    4. Peer Reviewer Comment: One reviewer suggested that the 
designation of critical habitat is no longer effective as a means to 
protect the species and its habitat, as funds that are needed to 
achieve that goal are spent instead on litigation. Rather, a new method 
is needed to accomplish this goal, such that the Riverside fairy shrimp 
and its habitat are actually preserved (rather than designated, then 
litigated).

[[Page 19160]]

    Our Response: We concur that the Service's present system for 
designating critical habitat has evolved into a process that is often 
driven by litigation and the courts, and thus consumes enormous agency 
resources. The Service believes that additional agency discretion would 
allow our focus to return to those actions that provide the greatest 
benefit to the species most in need of protection. Pursuant to section 
4 of the Act, however, the Secretary shall, to the maximum extent 
prudent and determinable, designate any habitat which is then 
considered to be critical habitat for listed endangered or threatened 
species. Alternative or additional methods for accomplishing more 
effective conservation of the Riverside fairy shrimp are discussed in 
the Recovery Plan, Multiple Species Habitat Conservation Plans 
(MSHCPs), Natural Community Conservation Programs (NCCPs), and other 
conservation plans. These plans address the survival and recovery of 
this species, and we expect they will be in a continual process of 
improvement and increased efficiency with time.
    5. Peer Reviewer Comment: Several reviewers disagreed with the 
Service's statement in the rule (see SUPPLEMENTARY INFORMATION above) 
that designation of critical habitat provides little additional 
protection to species, and believed this should be amended or omitted 
from the rule, as it is self-contradictory. Although designating 
critical habitat does not in itself protect any habitat, the biggest 
advantage of critical habitat designation is the ability to address the 
``cumulative effects'' of many small impacts to the habitat. Impacts to 
a single location are not likely to drive the species to extinction, 
but the effects of impacts at many individual locations may, in total, 
create a substantial risk for species extinction. Designating critical 
habitat establishes a core, reducing the potential for individual small 
impacts to be allowed to drive the species to extinction.
    Our Response: While we concur that critical habitat designation can 
provide some level of species protection by addressing cumulative 
effects of numerous impacts to the habitat in certain circumstances, 
this can only be provided if there is Federal nexus for those agencies 
planning actions that may impact the designated habitat.
    6. Peer Reviewer Comment: The Service's statement in the rule, that 
the exclusion of HCPs offers ``unhindered, continued ability to seek 
new partnerships with future HCP participants'' (see Relationship of 
Critical Habitat to Approved Habitat Conservation Plans) should be 
amended in the rule as it is illogical and self-contradictory. Not 
designating critical habitat within HCPs in order to allow seeking new 
partnerships implies that the new partnerships would be compromised if 
they were actually forced to protect Riverside fairy shrimp habitat, 
which should be one goal of any ``partnership.''
    Our Response: Both HCPs and critical habitat designations are 
designed to provide conservation measures to protect the Riverside 
fairy shrimp. The advantage of seeking new conservation partnerships, 
through HCPs or other means, is that they can offer active management 
and other conservation measures for the habitat on a full-time and 
predictable basis, while a critical habitat designation only prevents 
adverse modification of the habitat where there is a Federal nexus to 
the modifying activity, a far lesser level of protection. It is our 
experience that landowners generally react very negatively to having 
their property designated as critical habitat, and that this is then a 
strong disincentive for them to cooperate in conservation of the 
species in question. HCPs offer conservation of covered species whether 
or not the area is designated as critical habitat (for details see the 
section Relationship of Critical Habitat to Approved Habitat 
Conservation Plans).
    7. Peer Reviewer Comment: The proposed rule appears to find ways to 
exclude most of the ``potential'' critical habitat in Riverside and San 
Diego counties. Except for areas on March Air Reserve Base, the 
proposed Map Unit 3 for Riverside County excludes all critical habitat, 
and specifically that on the Santa Rosa Plateau, based on the 
speculative assertion that the proposed Western Riverside County 
Multiple Species Habitat Conservation Plan (MSHCP) will adequately 
protect the Riverside fairy shrimp. What is the benefit of excluding 
critical habitat for the Riverside fairy shrimp on the Santa Rosa 
Plateau? Any scientifically defensible HCP must protect nearly all of 
the Santa Rosa Plateau.
    Our Response: HCPs and their Implementing Agreements include 
management measures and protections designed to protect, restore, 
monitor, manage, and enhance the habitat to benefit the conservation of 
the species covered in the plans. The Western Riverside County MSHCP, 
which has now been finalized, seeks to accomplish these goals for the 
Riverside fairy shrimp through the implementation of species-specific 
conservation objectives.
    In our analyses, the benefits of excluding critical habitat areas 
covered by the Western Riverside County MSHCP outweigh the benefits of 
inclusion. Of the conservation measures this plan identifies for the 
Riverside fairy shrimp, the first objective is to include within its 
Conservation Area at least five Core Areas of vernal pools (or vernal 
pool complexes) and their watersheds; these areas contain five known 
key Riverside fairy shrimp populations. Core Areas include the Santa 
Rosa Plateau Ecological Reserve (17,188 acres), Skunk Hollow (156 
acres), Murrieta (1,292 acres) and Lake Elsinore back basin (3,180 
acres). Within the key population areas, approximately 5,868 acres (33 
percent) of potential vernal pool and playa habitat and suitable soils 
habitat land coverages would be located outside the MSHCP Conservation 
Area. Any Riverside fairy shrimp present within this area would be 
subject to incidental take under the guidelines implemented as part of 
this Plan. Each Reserve Manager responsible for a Core Area containing 
soils identified as supporting the Riverside fairy shrimp (e.g., the 
Santa Rosa Plateau Ecological Reserve) shall evaluate their Core Area 
for the presence of historic or vestigial vernal pools. A program to 
enhance these areas will be undertaken. Within the MSHCP Conservation 
Area, that pond water seasonally will be identified and monitored for 
the presence of fairy shrimp. Reserve managers will ensure habitat 
support functions within the MSHCP Conservation Area by maintaining 
and/or preserving watersheds of conserved known or future vernal pools 
or depressions. Particular management emphasis will be given to 
disking, illegal dumping and maintaining hydrology (MSHCP Final 
Documents, Vol. 1--The Plan, June 17, 2003). See Western Riverside 
County Multiple Species Habitat Conservation Plan in the section 
Relationship of Critical Habitat to Approved Habitat Conservation Plans 
below for more details.
    8. Peer Reviewer Comment: The Service's assumption that the 
existence of an HCP automatically affords protection to the Riverside 
fairy shrimp within the covered area is questionable. In the 
development of the San Diego Multiple Species Conservation Plan (MSCP)/
HCP, vernal pools were explicitly excluded from its intended coverage, 
because at the time, those areas covered by the conservation plans were 
regulated as wetlands by the Environmental Protection Agency. As San 
Diego County does not have a good record of enduring protection of 
vernal pools, it is important, from a scientific and land-management 
perspective, to

[[Page 19161]]

have an explicit analysis of what (if any) Riverside fairy shrimp 
populations and their habitats are actually covered in the designated 
protected areas of the HCP, before exclusion of any areas are made.
    Our Response: Vernal pool habitats that support the Riverside fairy 
shrimp that were considered essential but excluded from critical 
habitat were included on our website for public review and comment. Of 
the 1,183 ac (479 ha) of mapped vernal pool habitat within the MSCP 
planning area, over 847 ac (343 ha) occur within the planning area. The 
Service has completed a Biological Opinion (June 1997) on the San Diego 
MSCP, and found that the Plan meets the standards set forth in 50 CFR 
17.32(b)(2), and has issued an incidental take permit to the City of 
San Diego for the 85 species covered in the plan, including the 
Riverside fairy shrimp. The permit action does not, however, authorize 
impacts to wetlands or wetland communities; the MSCP assumes a policy 
of ``no net loss'' of vernal pools. The permit requires that impacts to 
vernal pools be avoided; unavoidable impacts will be minimized to the 
maximum extent practicable and mitigated at a 2:1 or 4:1 ratio to 
prevent any net loss of vernal pool function and value. In addition to 
conserving existing vernal pool habitat, the Multiple Habitat Planning 
Area is expected to conserve 7,745 ac (3,134 ha) of undeveloped areas 
with clay soils and clay hardpan, and implement management and 
monitoring measures for vernal pools within the area. In the Biological 
Opinion issues, the Service has specifically addressed the Riverside 
fairy shrimp, and emphasized the conservation of the hydrological 
processes needed for vernal pool functioning. Pursuant to section 
4(b)(2), we have excluded lands within legally operative HCPs, 
including the San Diego MSCP, that address the conservation needs of 
the Riverside fairy shrimp, if the plans provide assurances that the 
conservation measures outlined will be implemented and effective. 
Please see Relationship of Critical Habitat to Approved Habitat 
Conservation Plans section of the rule below.
    9. Peer Reviewer Comment: Several reviewers stated that the 
proposed critical habitat designation does not go far enough to provide 
for the protection of the Riverside fairy shrimp, because significant 
portions of the species' range were excluded from critical habitat 
protection. These areas include Department of Defense lands and MSCP/
HCP lands. The Riverside fairy shrimp populations in these areas, 
particularly those on Department of Defense land, are not protected and 
are either being lost at present, or vulnerable to loss due to a number 
of sources and activities, including military maneuvers, crushing by 
vehicles and toxic poisoning from vehicles or ordnances. In fact, lands 
under the jurisdiction of HCPs, MSCPs, and the Department of Defense 
have continued to lose populations of San Diego fairy shrimp (e.g., 
Cousin's pool, Marine Corps Air Station Miramar) and restoration/
creation efforts have thus far not succeeded, and this will likely 
happen with the Riverside fairy shrimp unless adequate protection is 
provided for the existing populations. For example, in San Diego 
County, 66 of 67 vernal pools occupied by the federally endangered San 
Diego fairy shrimp (Branchinecta sandiegonensis) have been recently 
lost in Mira Mesa, an area covered by the San Diego County MSCP. Thus, 
the benefits of exclusion do not outweigh the benefits of inclusion due 
to the significantly increased threat to the species survival that 
exclusion of critical habitat poses to the species.
    Our Response: We do not agree with the peer reviewer that excluding 
critical habitat on lands covered by an HCP or INRMP poses a 
``significantly increased threat to the species survival.'' Please 
refer to the responses to Peer Reviewer Comments 7 and 8 above, and the 
sections Relationship of Critical Habitat to Department of Defense 
Lands and Relationship of Critical Habitat to Approved Habitat 
Conservation Plans below.
    10. Peer Reviewer Comment: The small amounts of habitat designated 
as critical habitat may be questionable. The strip along the 
international border in the proposed rule (Map Sub-unit 5B, 
southwestern Otay Mesa) appears to be mitigation or restoration from 
the Border Infrastructure System. It is not clear that the current 
hydroperiods are comparable to the pre-impact hydroperiods. Further, it 
appears that the Department of Homeland Defense drives vehicles through 
the pools with impunity, without the need for permitted take from the 
Service. Habitat of such dubious condition is not a suitable substitute 
for the excluded (but intact) habitat surrounding the proposed areas on 
western Otay Mesa (critical habitat Map Sub-units 5A, 5B).
    Our Response: Please refer to the response to Comment 4-1 below.
    11. Peer Reviewer Comment: Areas of critical habitat that have been 
excluded in the proposed rule are under a high level of threat, and 
local populations of Riverside fairy shrimp in those areas thus face 
considerable risk of being extirpated, as has happened with populations 
of the San Diego fairy shrimp. Currently, there is not enough 
scientific information on the population genetic structure or life 
history of the Riverside fairy shrimp to be able to predict the 
consequences of population losses. Without such data, it is not 
possible to identify the areas of highest genetic variability, 
population sources and sinks, levels of gene flow, gene flow distances, 
evolutionarily significant units or population viability requirements. 
Loss of critical populations or connections between populations could 
increase the probability of extinction and put the species as a whole 
in jeopardy. Thus, it is important that all populations of the 
Riverside fairy shrimp be included in the critical habitat designation 
to provide adequate protection of the species as required by the Act.
    Our Response: We recognize the current threats facing the Riverside 
fairy shrimp, the need to minimize fragmentation effects, and to 
provide adequate conservation protection. However, we did not designate 
critical habitat for all populations of the Riverside fairy shrimp. 
Some areas in our proposed designation were not designated as critical 
habitat for the following reasons: (1) The area did not meet the 
definition of critical habitat under section 3(5)(A) of the Act, (2) 
the area is now included within legally operative HCPs, (3) the area 
was necessary for national security measures, or (4) economic impact 
costs. However, for some areas which were excluded from critical 
habitat under section 4(b)(2) of the Act, or exempted under section 
4(a)(3) of the Act, the Riverside fairy shrimp still receives 
protection under conservation plans such as HCPs or INRMPs.
    12. Peer Reviewer Comment: According to the proposed rule, critical 
habitat is identified for the Riverside fairy shrimp in six separate 
units, each of which correspond to the larger Management Areas that 
support Riverside fairy shrimp occurrences as outlined in the Recovery 
Plan (Service 1998; 2004). However, the management areas specified in 
the Recovery Plan for Vernal Pools of Southern California are based on 
simple geographical locations, not the biology of the species 
considered, and the Recovery Plan does not include a population 
viability analysis. Genetic information on the San Diego fairy shrimp 
has shown that these management areas do not coincide with the species' 
evolutionarily significant units based on the population genetic 
structure of the species. The identification of populations essential 
to the species requires genetic analysis and

[[Page 19162]]

life history analysis to determine ``source/sink'' status and to 
evaluation the viability of the population and probability of 
persistence. Simple geographic location is not sufficient, especially 
considering the amount of loss of intervening habitat. The management 
areas are therefore not relevant to the species' conservation, a fact 
which likely also applies for the Riverside fairy shrimp (Bohonak et 
al. 2003).
    Our Response: We agree that no scientific information is available 
on the genetic diversity of the Riverside fairy shrimp, as is the case 
for the San Diego fairy shrimp. Thus, we used geographical descriptions 
to identify critical habitat units. These geographical descriptions are 
not meant to suggest any evolutionary divergence or population genetic 
structure. At the same time, we also based our analyses on what areas 
constituted critical habitat upon the best available scientific and 
commercial data available to us at the time, and made available public 
comment periods to allow for submission of any new information.
    13. Peer Reviewer Comment: The proposed rule stated that an 
artificial vernal pool complex had been created to offset the impacts 
to a population of Riverside fairy shrimp by the Redhawk Development, 
and that another artificial vernal pool creation was planned in order 
to offset the taking of Riverside fairy shrimp at the Clayton Ranch 
Pool. Two reviewers questioned whether these artificial pools have 
produced viable, reproducing populations with positive rates of 
increase, rather than simply hatching shrimp from the transplanted 
cysts. To the reviewers' knowledge, no such successes have been 
recorded in the primary literature; i.e., see Ripley et al. (2004). 
Furthermore, the proposed rule stated that on Otay Mesa in San Diego 
County, significant work had been done to restore and enhance vernal 
pools for listed species, including the Riverside fairy shrimp. 
However, the reviewers noted that due to failure to check the 
transplanted cysts, the Otay pools have become ``infected'' with a 
``weedy'' species, the winter fairy shrimp (Branchinecta lindahli), 
which can hybridize with the San Diego fairy shrimp (Fugate 1998); its 
effect on the Riverside fairy shrimp is yet unknown. Thus, the 
restoration or creation efforts have not been verified as successful 
(producing viable populations and a growing cyst bank) for either San 
Diego fairy shrimp or Riverside fairy shrimp, and have in fact, 
introduced new potential threats.
    Our Response: We did not designate any artificial vernal pools as 
critical habitat for the Riverside fairy shrimp.

Public Comments

Issue 1: Policy and Regulations
    1-1. Comment: It was suggested that all essential Riverside fairy 
shrimp habitat areas within the boundaries covered by the Western 
Riverside County Habitat Conservation Plan (HCP), Central/Coastal 
Orange County Natural Community Conservation Program (NCCP), and San 
Diego Multiple Species Conservation Plan (MSCP) should be included in 
the final critical habitat designation because (a) areas within those 
plans meet the definition of critical habitat; the Service has 
identi