Injurious Wildlife Species; Silver Carp (Hypophthalmichthys molitrix) and Largescale Silver Carp (Hypophthalmichthys harmandi), 52305-52316 [06-7416]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 71, Number 171 (Tuesday, September 5, 2006)]
[Proposed Rules]
[Pages 52305-52316]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-7416]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 16

RIN 1018-AT29


Injurious Wildlife Species; Silver Carp (Hypophthalmichthys 
molitrix) and Largescale Silver Carp (Hypophthalmichthys harmandi)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; notice of availability of environmental 
documents.

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SUMMARY: The U.S. Fish and Wildlife Service proposes to add all forms 
(diploid and triploid) of live silver carp (Hypophthalmichthys 
molitrix), gametes, eggs, and hybrids; and all forms (diploid and 
triploid) of live largescale silver carp (Hypophthalmichthys harmandi), 
gametes, eggs, and hybrids to the list of injurious fish, mollusks, and 
crustaceans under the Lacey Act. This listing would have the effect of 
prohibiting the importation and interstate transportation of any live 
animal, gamete, viable egg, or hybrid of the silver carp and largescale 
silver carp, without a permit in limited circumstances. The best 
available information indicates that this action is necessary to 
protect the interests of human beings, and wildlife and wildlife 
resources, from the purposeful or accidental introduction and 
subsequent establishment of silver carp and largescale silver carp 
populations in ecosystems of the United States.

DATES: Comments must be submitted on or before November 6, 2006.

ADDRESSES: You may submit comments, identified by RIN number 1018-AT29, 
by any of the following methods:
     E-mail: silvercarp@fws.gov. Include ``RIN number 1018-
AT29'' in the subject line of the message. See the Public Comments 
Solicited section below for file format and other information about 
electronic filing.
     Fax: (703) 358-1800.
     Mail/Hand Delivery/Courier: Chief, Branch of Invasive 
Species, U.S. Fish and Wildlife Service, 4401 North Fairfax Drive, 
Suite 322, Arlington, VA 22203.
     Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the instructions for submitting comments.
    Instructions: All submissions received must include the agency name 
and Regulatory Information Number (RIN) for this rulemaking. For 
detailed instructions on submitting comments and additional information 
on the rulemaking process, see the ``Public Participation'' heading of 
the SUPPLEMENTARY INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Erin Williams, Branch of Invasive 
Species, at erin_williams@fws.gov, or (703) 358-2034.

SUPPLEMENTARY INFORMATION:

Background

    In October 2002, the U.S. Fish and Wildlife Service (Service) 
received a petition signed by 25 members of Congress representing the 
Great Lakes region to add bighead, silver, and black carp to the list 
of injurious wildlife under the Lacey Act (18 U.S.C. 42). A follow-up 
letter to the original petition had seven additional Legislator 
signatures that support the petition. The Service published a Federal 
Register notice of inquiry on silver carp (68 FR 43482-43483, July 23, 
2003) and provided a 60-day public comment period. We received 31 
comments in total, but 12 of these did not address the issues raised in 
the notice of inquiry. We considered the information provided in the 19 
relevant comments. Most of the comments supported the addition of 
silver carp to the list of injurious wildlife. One commenter noted that 
silver carp have no commercial value, but was concerned that listing 
would hinder control and management. One commenter asked us to delay 
listing until a risk assessment could be completed. Biological synopses 
and risk assessments were compiled for silver and largescale silver 
carp.
    Under the terms of the injurious wildlife provisions of the Lacey 
Act, the Secretary of the Interior is authorized to prohibit the 
importation and interstate transportation of species designated by the 
Secretary as injurious. Injurious wildlife are defined as those species 
and offspring and eggs that are injurious to wildlife and wildlife 
resources, to human beings, and to the interests of forestry, 
horticulture, or agriculture of the United States. Wild mammals, wild 
birds, fish, mollusks, crustaceans, amphibians, and reptiles are the 
only organisms that can be added to the injurious wildlife list.
    Species listed as injurious (including their gametes or eggs) may 
not be imported into the United States or transported between States, 
the District of Columbia, the Commonwealth of Puerto Rico, or any 
territory or possession of the United States by any means without a 
permit issued by the Service. Permits may be granted for the 
importation or transportation of

[[Page 52306]]

injurious wildlife and their offspring or eggs for bona fide 
scientific, medical, educational, or zoological purposes. A listing 
would not prohibit intrastate transport or possession of species within 
States, where not prohibited by the State. Any regulation pertaining to 
the use of species within States would continue to be the 
responsibility of each State.

Public Participation

    Our practice is to make comments, including names and home 
addresses of respondents, available for public review during regular 
business hours. Individual respondents may request that we withhold 
their home address from the rulemaking record, which we will honor to 
the extent allowable by law. In some circumstances, we would withhold 
from the rulemaking record a respondent's identity, as allowable by 
law. If you wish us to withhold your name and/or address, you must 
state this prominently at the beginning of your comment. However, we 
will not consider anonymous comments. We will make all submissions from 
organizations or businesses and from individuals identifying themselves 
as representatives or officials of organizations or businesses 
available for public inspection in their entirety.
    This proposed rule solicits economic, biological, or other 
information on adding all forms of live silver and largescale silver 
carp, and hybrids, to the list of injurious wildlife. The data will be 
used to determine if these species are a threat, or potential threat, 
to those interests of the United States delineated above, and thus 
warrant addition to the list of injurious fish in 50 CFR 16.13.
    We are soliciting public comments and supporting data, to gain 
additional information, on this proposed rule to add all forms of live 
silver and largescale silver carp, gametes, eggs, and hybrids, to the 
list of injurious wildlife under the Lacey Act. We specifically seek 
comment on the following questions:
    (1) What regulations does your State have pertaining to the use, 
transport, and/or production of silver or largescale silver carp?
    (2) How many silver carp are currently in culture or used to 
control algae in ponds, in how many and which States? Please provide 
the number of silver carp, if any, permitted within each State.
    (3) What would it cost to eradicate silver carp or largescale 
silver carp individuals and/or populations, or similar nonnative 
populations, if found?
    (4) What are the costs of implementing propagation, recovery, and 
restoration programs for native fish or other native species? What 
State-listed species would be impacted by the introduction of silver or 
largescale silver carp?
    (5) What is the economic value of commercial fisheries that have 
been or could be impacted by silver or largescale silver carp?
    (6) How many fishermen sell live silver carp?
    (7) What are the annual sales and landings for live and/or dead 
silver carp? What is the magnitude of the commercial market for live 
silver carp, if any?
    (8) What is the consumer surplus generated from fishing for native 
fish or fishing-related expenditures such as food, lodging, and 
equipment? What is the ex-vessel revenue from fishing for native fish 
that are more valuable than silver carp?
    (9) What is the economic value of baitfish industries in each 
State? How would the presence of wild silver carp affect baitfish 
imports or exports within a State?

Description of the Proposed Rule

    The regulations contained in 50 CFR part 16 implement the Lacey Act 
as amended. Under the terms of that law, the Secretary of the Interior 
is authorized to prohibit by regulation certain activities involving 
wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, 
reptiles, and the offspring or eggs of any of the foregoing that are 
injurious to human beings, to the interests of agriculture, 
horticulture, or forestry, or to the wildlife or wildlife resources of 
the United States. The lists of injurious wildlife species are at 50 
CFR 16.11 to 16.15. By adding all forms of live silver carp and 
largescale silver carp, gametes, eggs and hybrids to the list of 
injurious wildlife, their importation into the United States, and 
transportation between States, the District of Columbia, the 
Commonwealth of Puerto Rico, or any territory or possession of the 
United States by any means whatsoever would be prohibited, except by 
permit for zoological, educational, medical, or scientific purposes (in 
accordance with permit regulations at 50 CFR 16.22), or by Federal 
agencies without a permit solely for their own use. Federal agencies 
who wish to import silver or largescale silver carp for their own use 
must file a written declaration with the District Director of Customs 
and the U.S. Fish and Wildlife Service Inspector at the port of entry. 
No live silver carp or largescale silver carp, progeny thereof, viable 
eggs or hybrids imported or transported under a permit could be sold, 
donated, traded, loaned, or transferred to any other person or 
institution unless such person or institution has a permit issued by 
the U.S. Fish and Wildlife Service. The interstate transportation of 
all forms of live silver carp or largescale silver carp, gametes, 
viable eggs or hybrids currently held in the United States for any 
purpose would be prohibited without a permit.
    This action is being considered in order to protect the welfare and 
survival of native wildlife and wildlife resources and the health and 
welfare of human beings from the potential negative impacts of silver 
carp and largescale silver carp by adding them to the list of injurious 
wildlife and preventing their importation and interstate movement.
    Each State can regulate the transportation and possession of silver 
carp and largescale silver carp within its State boundaries, but States 
are not able to prohibit the importation into the United States or the 
interstate transportation of these species. If one State allows the use 
of either species, and if either species is introduced to natural 
waters that are connected to other States' waterbodies, the silver or 
largescale silver carp could be introduced to a State that prohibits 
their use or possession, potentially impacting that State's natural 
resources. Many States are asking the Federal Government to prohibit 
the importation and interstate transportation of silver carp and have 
submitted letters of support for the addition of silver carp to the 
list of injurious wildlife. They are concerned that interstate 
transportation, through trucking accidents or exchange of hauling 
water, could result in the introduction of silver carp into State 
waters where they do not exist and are prohibited by State law. In 
addition, they are concerned that if their importation into the United 
States is still allowed, silver carp could become established in new 
waterways where they do not currently exist through human movement. The 
evaluation of injuriousness follows the biology and natural history 
summary sections for each species.

Silver Carp

Biology and Natural History

    The commonly named silver carp belongs to the family Cyprinidae, 
with the species name of Hypophthalmichthys molitrix. The silver carp 
is a deep-bodied fish with scale counts typically ranging from 85 to 
108. Adult coloration is typically gray-

[[Page 52307]]

black along its top with upper sides olive-green that grade to silver 
along its side and stomach. Fins are dark and without true spines. 
Large adults can reach over 1.2 meters (m) in length and 50 kilograms 
(kg) in weight. The gill rakers of silver carp are unique and form a 
highly specialized filtering apparatus.
    The silver carp is a freshwater species that can live in slightly 
brackish waters. Silver carp occur naturally in a variety of freshwater 
habitats including large rivers and warm water ponds, lakes, and 
backwaters that receive flooding or are otherwise connected to large 
rivers. They also have been introduced to ponds, lakes, reservoirs, and 
canals where they grow well, but may not spawn and recruit without 
access to an appropriate riverine habitat. Silver carp usually occupy 
the upper and middle layers of the water column and are quite tolerant 
of broad water temperatures: from 4 [deg]C to 40 [deg]C.
    Silver carp can be distinguished from all native North American 
cyprinids, except the golden shiner, by the presence of a well-
developed ventral keel. It can be distinguished from the golden shiner 
in having very small scales (lateral line scales 85-108) compared to 
the golden shiner (39-51). Silver carp have only four pharyngeal teeth 
per side in a single row while the golden shiner has five on each side 
in a single row.
    Small silver carp may resemble shad (Dorosoma species). Of the nine 
established nonindigenous cyprinids in the United States, the silver 
carp is most similar to bighead carp. The silver carp is also very 
similar to largescale silver carp, a species which is not known to be 
in the United States.
    Though they are considered a deep water, schooling species, in the 
Missouri River these fish generally stay between 1 and 5 m deep and are 
rarely observed on the surface until disturbed. Once disturbed, silver 
carp often swim rapidly near the surface creating a characteristic 
large wake and regularly jump out of the water, particularly in 
response to outboard motors.

Hybrids

    Hybridization between closely related species of cyprinids (e.g., 
species of the genus Hypophthalmichthys) is not unusual. Silver carp 
are known to hybridize and to produce viable offspring with both 
bighead (Hypophthalmichthys nobilis) and largescale silver carps. 
Hybrids of silver and bighead carps are often used in aquaculture in 
other countries. Both crosses (bighead carp x silver carp and the 
reciprocal cross) are fertile. Hybrids of bighead and silver carps 
often strongly resemble one or the other of the parent species.
    Bighead carp x silver carp are common in parts of the United States 
and are likely to be the result of wild spawning, not escapement of 
artificially induced hybrids because neither silver carp nor the 
hybrids are known to be in use in aquaculture in the United States. 
Five percent of the adult Hypophthalmichthys caught in the lower 
Missouri River in 2004 were hybrids. Hybridization between closely 
related cyprinid fishes occurs most commonly where a species has been 
introduced; hybridization between cyprinids typically occurs when 
members of related species share similar spawning habitat, behavior, 
and season because of the loss of environmental cues that inhibit 
hybridization behavior. The presence of large numbers of wild-spawned 
hybrids implies that bighead and silver carps often spawn in the same 
place at the same time in United States waters. Although there has been 
moderate success in artificially producing hybrids of 
Hypophthalmichthys spp. and common carp (Cyprinus carpio), the spawning 
locations and behaviors of the two genera are so different that 
production of wild hybrids would be unlikely.

Habitat Use

    Silver carp in the Missouri River occupy primarily low-velocity 
water 1 to 5 m deep in all months of the year and use low-velocity 
sections of Missouri River tributaries. Adult silver carp aggregate in 
pool habitats to overwinter. Preliminary research indicates that silver 
carp in the Missouri River are active in winter, with activity slowing 
at less than 4 [deg]C and little movement occurring at temperatures 
below 2 [deg]C. Silver carp used tributaries to larger rivers in the 
summer.
    Large lakes connected to rivers often serve as nursery areas for 
silver carp. Juvenile silver carp typically remain in backwater 
habitats whereas adults are typically found in main channels of rivers. 
There is limited data about the habitat use of juvenile silver carp in 
the United States because their introduction, spread and establishment 
is relatively recent and ongoing. Young-of-year silver carp were found 
in abundance in the backwaters of the middle Mississippi River, and 
juvenile silver carp were collected in low-velocity and off-channel 
habitats in the Missouri, Mississippi, Wabash, and lower Ohio rivers. 
Young-of-year (<100 millimeters (mm)) and juvenile (100-500 mm) silver 
carp collected for the Long Term Resource Monitoring Program (LTRMP), 
of the U.S. Army Corps of Engineers, were found in similar proportions 
between main channel borders, side channel borders, and contiguous 
backwaters.

Reproduction and Growth

    The reproductive potential of silver carp is high and increases 
with body size. Estimates range from 145,000-5,400,000 eggs for fish 
3.18-12.1 kg. Eggs must be incubated in waters with fairly high ionic 
concentrations. Silver carp mature anywhere from 3-8 years, and males 
usually mature one year earlier than females. Silver carp use discrete 
spawning sites repeatedly. Silver carp usually spawn in the spring and 
early summer after a rise in water levels with water temperatures 
ranging from 18-26 [deg]C, though larva has been collected from the 
lower Missouri River in late August to mid-September. Eggs are semi-
buoyant, so spawning typically occurs in water of sufficient flow to 
keep the eggs from sinking to the bottom and dying. The same female may 
spawn twice during one growing season. There are indications of a 
prolonged spawning period, into late summer or early fall, in the 
United States.
    Silver carp can grow quickly: 20 to 30 kg in 5 to 8 years, and 
survival of silver carp in some culture ponds was 91%. Water 
temperatures for maximum growth of silver carp are between 24-34 
[deg]C. Silver carp are difficult to age, but have been reported to 
live 15-20+ years.

Diet and Feeding Habits

    Silver carp are primarily phytoplanktivores, but are highly 
opportunistic, eating phytoplankton, zooplankton, bacteria and 
detritus. Silver carp will also bite on bread paste and dough balls 
used as bait. Silver carp can effectively filter and consume smaller 
particles than bighead carp. Their food consumption rate is high, but 
widely variable. Fry at the smallest size class consumed up to 140% of 
their body weight daily; 63 mg fingerlings consumed just more than 30% 
and 70-166 mg fingerlings consumed 63% of their body weight. Adult 
silver carp have been shown to consume 8.8 kg of food per year, with 
90% of the consumption occurring during the three warmest months of the 
year. In the Missouri River, silver carp sometimes had full guts at 
temperatures lower than 4 [deg]C. Studies consistently show that filter 
feeding by silver carp shifts the species composition of the 
phytoplankton community to smaller species. Silver carp consume 
zooplankton, especially when phytoplankton abundance is low. Studies 
also consistently show that the

[[Page 52308]]

presence of silver carp results in a zooplankton community dominated by 
smaller individuals.

History of Introduction

    There are conflicting reports about the first importation of silver 
carp into the United States. One report said that silver carp were 
introduced in 1971 from Taiwan for algae control in sewage lagoons. 
Another report stated that silver carp were introduced in 1972 under an 
agreement of maintenance with the Arkansas Game and Fish Commission. A 
third citation said silver carp were introduced into Arkansas in 1973 
as a potential addition to fish production ponds. Regardless of the 
specific date, the major pathway for introduction of silver carp in the 
United States was importation for biological control of plankton in 
sewage lagoons and culture ponds. The pathway that led to presence of 
this species in open waters probably was escape from facilities. There 
is little, if any, current use of silver carp for algae control.
    Soon after importation, silver carp were used in research projects 
and stocked into wastewater treatment lagoons and impoundments in 
several States. In 1974 or 1975, silver carp were collected from Bayou 
Meto and the White River, Arkansas County, Arkansas. In January 1980, 
several silver carp were collected from Crooked Creek, northeastern 
Arkansas County, which flowed through two private fish hatcheries 
possessing silver carp. By 1981, silver carp had been collected from 
the White, Arkansas, and Mississippi rivers in Arkansas. From there, 
they continued to spread through the Mississippi River Basin. Silver 
carp have been collected from the natural waters of 16 States and 
Puerto Rico. Silver carp are well established throughout much of the 
Mississippi River Basin, and its range appears to be expanding in that 
basin.

Pathways of Introduction

    There are several potential pathways for further introductions of 
silver carp into additional water bodies that may spread existing 
populations of silver carp in the United States. One pathway is through 
the release of baitfishes contaminated with silver carp. Other 
potential pathways that would likely spread silver carp to new 
waterbodies in the United States include intentional release, ballast 
water release, spread by commercial fishing activities, and release or 
escape from livehaulers that support commercial fishing or release 
associated with the sale of the species in live food fish markets, 
regardless of whether the fish were cultured in fish farms or were 
caught live in the wild. Silver carp may be introduced and become 
established in new waterways beyond their current ranges through human 
use and movement.

Uses

    Worldwide more silver carp are produced than any other species of 
freshwater fish; they are raised for food or stocked for fishing. 
Silver carp are not presently being cultured commercially for food in 
the United States and have been minimally cultured in the last 20 
years. The ability of silver carp to effectively filter particles and 
reliance on phytoplankton for much of its diet has led to the use of 
silver carp as a biological control agent for phytoplankton. Silver 
carp have been studied as a potential tool for controlling excess 
nutrients in wastewater ponds, with mixed results.

Native Range and Potential Range in the United States

    In Asia (China and Eastern Siberia), silver carp are native from 
about 54 [deg]N southward to 21 [deg]N. Most of North America falls 
within these latitudes. This fact, along with establishment of this 
species in countries with climates as tropical as Vietnam, as cold and 
arid as Afghanistan and Pakistan, and as temperate as Kyrgyzstan and 
Latvia, leads to the conclusion that climate alone in the United States 
should not limit distribution of silver carp.
    Silver carp are likely to become established in the Great Lakes, 
especially given their close proximity. There are 22 rivers flowing 
into Lakes Erie, Huron, Michigan, and Superior that are potential 
spawning sites for silver carp. The Genetic Algorithm for Rule-Set 
Prediction (GARP) niche modeling tool estimates that United States 
distribution of silver carp could highly likely include most of the 
Midwest and eastern U.S. waterways, including the Chesapeake Bay, and 
tributaries, and the Connecticut River system. Based on the GARP model, 
silver carp, if introduced, are likely to also establish in the 
Columbia River system in the Northwest and possibly in parts of the 
Colorado and Sacramento/San Joaquin systems.
    Because food availability, predation, and competition are not known 
to limit populations of this species elsewhere, access to habitats 
required for successful reproduction (i.e., substantial lengths of 
flowing water) will play a large role in determining potential range of 
silver carp in American waters. Another factor that may limit the 
distribution of silver carp in the United States is the requirement to 
incubate eggs in waters with fairly high ionic concentrations.

Largescale Silver Carp

Biology and Natural History

    The commonly named largescale silver carp (or southern silver carp, 
Vietnamese carp, or Harmandi silver carp) belongs to the family 
Cyprinidae, with the species name of Hypophthalmichthys harmandi.
    The largescale silver carp is physically most similar to the silver 
carp, but does resemble bighead carp as well. The relatively larger 
scale size of the largescale silver carp is the most reliable 
characteristic to distinguish it from silver carp. The number of scales 
along the lateral line of the largescale silver carp range from 77 to 
88 compared to the silver carp with 85 to 108. Scale rows above the 
lateral line in largescale silver carp range from 21 to 23 compared to 
29 to 30 in the silver carp.
    Because largescale silver carp remain deep in the water column 
during daylight hours and swim toward the surface at night to feed on 
plankton, they may be less prone to jumping than silver carp in 
response to sounds of boat engines during daytime.

Hybrids

    Largescale silver carp are known to hybridize and to produce viable 
offspring with silver carp. In northern Vietnam, native largescale 
silver carp, introduced silver carp, and their hybrids are cultured 
together. Largescale silver carp grow faster than silver carp but 
hybrids do not grow as quickly as pure largescale silver carp. No 
additional information on polyculture of largescale silver carp with 
other fish species was found. Largescale and silver carp hybrids are 
tolerant of a temperate climate (ca. 42-46 [deg]N).

Habitat Use

    Largescale silver carp prefer slow-moving, plankton-rich open 
waters. This species is a nocturnal feeder and remains in deeper waters 
during daylight hours. Largescale silver carp is most closely related 
to silver carp, with which it hybridizes, therefore its salinity 
tolerance is probably similar to that of silver carp, which is a 
freshwater species that can live in slightly brackish waters.

Reproduction and Growth

    The reproductive capability is expected to be similar to that of 
silver carp, though largescale silver carp reach sexual maturity at a 
younger age than silver carp. Females reach maturity in 2 years and 
males in 1 year. Spawning

[[Page 52309]]

typically occurs in rivers during rains or floods in May and June, 
although spawning may be postponed until mid-August. Because largescale 
silver carp and silver carp are closely related and hybridize, spawning 
requirements are likely similar.
    The mean growth rate is greater for largescale silver carp than for 
silver carp. No information was found on longevity of largescale silver 
carp, but silver carp can live 15-20+ years suggesting the possibility 
of a similar longevity in the closely related largescale silver carp. 
Some adults may weigh 20-30 kg.

Diet and Feeding Habits

    Largescale silver carp feed on phytoplankton and prefer slow-
moving, plankton-rich open waters. This species is a nocturnal feeder 
and remains in deeper waters during daylight hours. Because this 
species is most closely related to silver carp, their food and feeding 
habits are likely similar.

Uses

    There is no indication that the largescale silver carp have been 
imported into or introduced into the open waters of United States. 
Largescale silver carp are considered the most important species for 
culture in Vietnam; the rapid growth and high fat content of this fish 
has made it an economically important species for food. Because this 
species is most closely related to silver carp, its potential 
effectiveness in controlling algae and its effect on excess nutrients 
in closed systems is possibly similar to that of silver carp.

Native Range and Potential Range in the United States

    Largescale silver carp are native to fresh waters of northern 
Hainan Island, China, and the Red (Hong Ha) River of northern Vietnam. 
The native range of largescale silver carp is subtropical to tropical 
(21-22 [deg]N), making it the southernmost fish of the genus. The 
species does not occur naturally on the Chinese mainland.
    Within its native range, largescale silver carp occur in 
subtropical to tropical climates. Therefore, should pure stock be 
introduced to U.S. waters, its potential range would likely be limited 
to subtropical waters such as those present in southern Florida, 
southern Texas, and Hawaii. Lack of access to suitable rivers for 
spawning in these areas may preclude successful spawning. Hybrids of 
largescale silver and silver carps, however, would be expected to 
tolerate temperate waters as they do in Kazakhstan at about 42-46 
[deg]N.

Factors That Contribute to Injuriousness for Silver Carp

Introduction and Spread

    The major pathway for introduction of silver carp in the United 
States was importation for biological control of plankton in culture 
ponds and sewage lagoons. The pathway that led to the presence of this 
species in open waters of the United States was probably escape from 
these facilities. Subsequent escapes and the mixture of silver carp 
with other species that were stocked may have contributed to the 
expansion of the species' range.
    Silver carp are difficult to handle and transport because of their 
propensity to jump and avoid being taken by seines. These attributes 
have resulted in little silver carp culture in the United States since 
1985. Silver carp are not being cultured commercially at this time; 
however, should culture of silver carp resume, a potential pathway for 
introduction would be escape or release from a facility or during the 
transport and sale of live fish in retail markets.
    Other more likely pathways that may aid the spread of existing 
populations of silver carp include connected waterways, contamination 
of pond-grown baitfishes with silver carp, ballast water release, 
release or escape from livehaulers that support commercial fisheries, 
or spread by commercial fishers themselves.
    Wild silver carp are at risk of being spread when juveniles are 
collected by cast net for use as live baitfish. Silver carp juveniles 
are very similar in appearance to shad and anglers sometimes catch 
young silver carp and use them as live bait. Release of live bait has 
been identified as a source for more than 100 introductions of fishes 
beyond their natural range in the United States. Although adult and 
market-sized silver carp are fragile and do not survive collection and 
transport well, fingerling silver carp are less susceptible to 
mortality due to handling stress.
    Other potential pathways for further introductions of silver carp 
into the wild involve those associated with the sale of the species in 
live food fish markets. Silver carp, caught as bycatch, may be sold as 
fillets or to live fish markets. Another potential pathway is the 
intentional release of silver carp through prayer release (the 
ceremonial release of a fish in honor of the one that will be eaten).
    Silver carp have survived, become established in river systems, and 
have been reproducing in natural waters of the United States since at 
least 1995. Because silver carp can occupy lakes, there is serious 
concern that this species will further expand its range in the United 
States beyond riverine environments and into lake environments 
including the Great Lakes. In its native range, juveniles and adults 
are found in lakes and reservoirs. Silver carp may be capable of 
establishing reproducing populations in other major river systems, such 
as the Potomac/Chesapeake, Columbia, and Sacramento/San Joaquin Delta.

Hybrids

    Hybridization of silver carp with native fishes is not possible, 
but hybridization has occurred between silver carp and bighead carp (H. 
nobilis), a nonnative species also present in the Mississippi River 
basin, and between silver carp and largescale silver carp (H. 
harmandi). Hybridization may also be possible with grass carp.

Potential Effects on Native Species

    Competition for food and habitat with other planktivorous fishes 
and with post-larvae and early juveniles of most native fishes is 
likely high. Since nearly all fishes are planktivorous as larvae and 
juveniles, it is highly likely that silver carp will adversely affect 
most native fishes in the Mississippi River and also the Great Lakes 
basins, if established. Silver carp will most likely affect native 
adults in the Mississippi River Basin, such as paddlefish (Polyodon 
spathula), bigmouth buffalo (Ictiobus cyprinellus), gizzard shad 
(Dorosoma cepedianum), the regionally abundant emerald shiner (Notropis 
atherinoides), and threadfin shad (Dorosoma petenens), particularly in 
waters where food may become limited.
    Paddlefish, native to the Mississippi River Basin and Gulf of 
Mexico river drainages from east Texas to Alabama, is a large river 
fish that has declined in abundance in recent years because of 
overharvest and habitat alteration. Like the silver carp, paddlefish 
use plankton as its primary food source, so silver carp or hybrids 
would directly compete with paddlefish for food throughout most of the 
paddlefish's range. Other fish, such as the buffalos or shads, use both 
plankton and aquatic invertebrates as food. While these fishes are 
currently more common than paddlefish, they may be at risk if silver 
carp or silver x largescale silver carp hybrids or silver x bighead 
hybrids are able to establish and reduce plankton. Gizzard shad are a 
primary forage base for predacious fishes and important to the ecology 
of Midwestern rivers; thus, the potential

[[Page 52310]]

competition with silver carp in these waters is cause for concern.
    If silver carp negatively affect important planktivorous forage 
fishes such as the gizzard shad and emerald shiner, fishes and birds 
that prey on these species would likely also be negatively affected. 
Adult silver carp are too large to be preyed on by almost any native 
predator. Young silver carp have likely been incorporated into the 
diets of piscivorous birds and fishes to some degree, but the extent of 
this predation is not known. Ecosystem balance is likely to be modified 
if silver carp populations become large enough to dominate other 
planktivorous fish species. Silver carp will likely have major effects 
on nutrient cycling and may have adverse effects on primary 
productivity, which could alter food webs and ultimately alter nutrient 
and energy cycling in aquatic communities. The most likely negative 
effect would be an alteration of fish community structure through 
competition for food. Fishes and mussels that are determined to be 
candidates for listing under the Endangered Species Act would be at 
risk.

Habitat Degradation

    There is low risk of silver carp causing direct habitat degradation 
and/or destruction, although the presence of silver carp is sometimes 
associated with decreased water clarity, which may also impact benthic 
chemistry and community structure. The effect of these fishes on 
nutrients, sediment re-suspension (which can stimulate plankton 
growth), and decreasing dissolved oxygen varies. Excrement from silver 
carp (which can equal their body weight in 10 days) has organically 
enriched lake bottoms and altered the benthic macroinvertebrate 
community structure. Once established, these fish are likely to cause 
shifts in the food web and compete with other zooplanktivorous fishes 
and fish larvae for food. Changes in the community structure towards 
smaller size plankton may have negative effects on fishes native to the 
United States that subsist on larger zooplankton.

Potential Pathogens

    Many species of parasites and bacterial diseases occur in silver 
carp. The only viral disease agent of silver carp found in the 
literature is Rhabdovirus carpio, the causative agent for spring 
viraemia of carp (SVC), a systemic, acute, and highly contagious 
infection commonly occurring in the spring when water temperatures are 
below 18 [deg]C. Silver carp are susceptible to many diseases caused by 
parasitic protozoans and trematodes and several crustaceans have also 
been reported from silver carp.
    Although there have been studies of disease-causing agents of 
silver carp, none have dealt with transfer of these pathogens to native 
fishes of the United States. Two parasites are a potential threat to 
native North American fishes, including cyprinids: Gill-damaging 
Lernaea cyprinacea, known as anchorworm (this parasite is also known to 
affect salmonids and eels), and Bothriocephalus acheilognathi, known as 
Asian carp tapeworm. The Asian carp tapeworm has infected native fishes 
of concern in five States: Arizona, Colorado, Nevada, New Mexico, and 
Utah. Silver carp are hosts of this parasite, but suffer minimal 
adverse effects from it. As hosts of this tapeworm, silver carp have 
the potential to spread it to native fishes beyond the five states 
listed above. This is a parasite that erodes mucus membranes and 
intestinal tissues, often leading to death of the host.
    Some disease-causing agents harbored by silver carp pose health 
risks to humans. The psychotropic pathogen Listeria monocytogenes has 
been found in market and fish farm samples of silver carp. Clostridium 
botulinum was found in 1.1% of fresh and smoked samples of silver carp 
from the Mazandaran Province in Iran. The toxigenic fungi Aspergillus 
flavus, Alternaria, Penicillium, and Fusarium were found from silver 
carp and from pond water in which they were raised at a fish farm in 
northern Iran. In addition, live Salmonella spp. can be found in silver 
carp for at least 14 days after transfer to clean water and silver 
carp, therefore, should be considered as a potential carrier for 
Salmonella (S. typhimumium).

Potential Impacts to Threatened and Endangered Wildlife

    Adverse effects of silver carp on selected threatened and 
endangered freshwater mussels and fishes is likely to be moderate to 
high. There are currently 116 fishes and 70 mussels on the Federal List 
of Endangered and Threatened Wildlife. Based on habitat requirements, 
it appears that 40 fishes and 25 mussels currently on the list would 
likely be impacted by the introduction and establishment of silver 
carp. Habitat requirements, springs and small streams, of the remaining 
listed fishes and mussels would probably preclude any detectable 
effects as it is unlikely that silver carp could survive in such small 
bodies of water.
    Adverse effects of established populations of silver carp on 
endangered and threatened fishes and mussels would vary between the two 
groups. Adverse effects to fishes would most likely be through direct 
competition for food resources, particularly phytoplankton and, to a 
lesser extent, zooplankton, in the water column during the larval 
stage. Potential for direct predation and injury of drifting fertilized 
eggs and larvae of native fishes also exists. Mussels are also filter 
feeders but live partly or totally buried in the substrate. Their 
association with the benthic environment means that they would be less 
likely to be affected by filter-feeding silver carp. Nevertheless, 
changes in the fish community structure caused by silver carp are 
likely to have adverse effects on abundance and availability of host 
fishes required for mussel reproduction. Nutrient levels are a concern 
because there is evidence of overloading of nutrients in waters where 
silver carp have been introduced. Silver carp may consume too much of 
the food in the water and compete with native species for food. 
Excrement from silver carp has been found to increase levels of certain 
nutrients, some which cannot be consumed by other animals in the 
digested form or may be harmful, which may lead to a net decrease in 
food resources available.
    The likelihood that silver carp would have adverse effects on 
designated critical habitats of threatened and endangered species is 
significant. There are currently 60 species of fishes and 18 mussels 
with designated critical habitat. Of the fishes and mussels with 
critical habitat, at least 26 inhabit lakes or reaches of streams large 
enough to support silver carp.
    In some habitats, silver carp can develop extremely large 
populations that would likely further imperil native fishes not 
currently on the Federal List of Endangered and Threatened Wildlife. 
Large populations of silver carp are likely to alter the native fish 
community structure, resulting in decline of native mussels since many 
rely on native host fishes for reproduction. The fact that silver carp 
can become extremely abundant and reach a very large size (> 1 m in 
length) in rivers, lakes, and reservoirs increases the probability of a 
negative impact on aquatic ecosystems they invade.

Potential Control

    Due to the extensive established range of silver carp in the 
Mississippi River Basin, conventional control methods are not feasible 
to reduce established populations. The damage to ancillary fisheries 
resources through control measures would be substantial. Netting

[[Page 52311]]

and electrofishing may be effective in reducing populations, but many 
non-target fish species would also be killed where such control 
measures are used. Selective removal of silver carp is possible given 
their location in the water column, but water trawling could also 
remove other non-target fish such as paddlefish.
    Use of chemical treatments, such as rotenone, would be expensive, 
only locally effective, and would negatively affect all fishes and 
invertebrates, not just the target carp. Chemical treatment of the 
Mississippi River and other large rivers in the United States to 
control silver carp is not feasible, either logistically or 
economically, and would have a low likelihood of success. Even most 
nonlethal methods to prevent the spread of silver carp, such as 
electrical barriers or acoustic, physical, or bubble barriers, would 
negatively affect migratory native fishes. This effect might be 
minimized, if somewhat species-specific sonic barriers were developed. 
Treatment of ballast water in vessels moving from waters containing 
reproductive populations of silver carp to waters devoid of these 
fishes may become necessary. At present, there is no method known to 
substantially reduce established populations of silver carp. On the 
basis of presently available technology, eradication is not possible.

Impacts to Humans

    Silver carp in the United States cause substantial impacts to the 
health and welfare of human beings that use waterways infested with 
silver carp. There are numerous reports of injuries to human beings and 
damage to boats and boating equipment because of the jumping habits of 
silver carp in the vicinity of moving motorized watercraft. Some 
reported injuries include cuts from fins, black eyes, broken bones, 
back injuries, and concussions. Silver carp also cause property damage 
including broken radios, depth finders, fishing equipment, and 
antennae. Some vessels have been fitted with a Plexiglas pilot's cab as 
protection against jumping silver carp.

Factors That Reduce or Remove Injuriousness for Silver Carp

Control

    The large and growing range of silver carp in U.S. waterways makes 
chemical control of established populations highly unlikely, both 
physically and fiscally. Some control might be possible with massive 
fishing efforts. Justifying the expense of such efforts would require a 
large commercial demand, which does not currently exist, nor is likely 
given the jumping behavior of silver carp which makes fishing 
difficult.
    The ability to control spread of established populations depends on 
their access to open waterways and riverine habitat to spawn. Barriers 
may help control the spread of silver carp from the Mississippi River 
basin into the Great Lakes or other waterbodies. However, there are 
still several pathways by which silver carp from established 
populations in the Mississippi River Basin might be moved to new 
waterbodies, such as the Potomac River or Columbia River, and have the 
potential to become established.

Recovery of Disturbed Sites

    Because the ability to eradicate this species is low, there is 
little likelihood for rehabilitation or recovery of ecosystems 
disturbed by this species. Additionally infested waterways allow 
connections to unpopulated sites. Utilizing sterile silver carp would 
do little to reduce or remove injuriousness as the present range of 
establishment in the Mississippi River Basin is too extensive for this 
option to reduce current silver carp populations in this area. The use 
of daughterless fish technology (introducing sterile males to produce 
unviable eggs) may reduce populations, but this would take many years 
before it would reduce numbers of fish where they currently exist. 
Research is being conducted on the use of pheromones to control carp, 
but it is years from demonstrating effectiveness in natural waters and 
mass production. These technologies might be useful to prevent 
establishment of silver carp in new areas.

Potential Pathogens

    The potential for silver carp to infect native fishes with 
pathogens is largely unknown. Should such transfers prove viable, the 
ability and effectiveness to control these transfers to native fishes 
would be low. The Asian carp tapeworm, for which silver carp is a known 
host, has demonstrated potential to jump to native species of several 
orders in other nations and within U.S. waters.

Potential Ecological Benefits for Introduction

    The ability of silver carp to effectively filter particles and 
reliance on phytoplankton for much of its diet led to research into 
their effectiveness as a biological control agent for phytoplankton in 
wastewater systems and other ponds. There is conflicting data 
concerning the benefit of using silver carp to control excess 
nutrients. Regardless of their effect on increasing or decreasing 
phytoplankton and zooplankton abundance, studies have consistently 
shown that filter feeding by silver carp shifts the species composition 
of these communities to smaller species. Silver carps' effectiveness 
has also been shown to be greatly influenced by the design of the 
facility.

Conclusion

    Because silver carp are likely to spread from their current 
established range to new waterbodies in the United States; are likely 
to compete with native species for food and habitat; are likely to have 
negative impacts on humans; are known to hybridize with bighead carp, a 
nonnative species also established in the United States; and because it 
would be difficult to eradicate, reduce large populations, or recover 
ecosystems disturbed by the species, the Service finds silver carp to 
be injurious to the interests of human beings and the wildlife and 
wildlife resources of the United States.

Factors That Contribute to Injuriousness for Largescale Silver Carp

Potential Introduction and Spread

    To our knowledge, the largescale silver carp has not been imported 
into the United States. Its growth rate is greater than that of silver 
carp, and the species reaches sexual maturity sooner than silver carp. 
In culture situations, introduced silver carp hybridized with 
largescale silver carp. The hybrids did not grow as quickly as 
largescale silver carp but exceeded the growth rate of silver carp. 
Largescale silver carp x silver carp hybrids were introduced in 
Kazakhstan where they became established. The climate of Kazakhstan is 
temperate; thus, largescale silver carp x silver carp hybrids are more 
cold-tolerant than pure largescale silver carp. The faster growth rate 
of these hybrids than pure silver carp and the increased palatability 
of largescale silver carp compared to silver carp may conceivably 
stimulate interest in culturing either the hybrids or pure largescale 
silver carp in the United States. Because hybrids can tolerate 
temperate climates, they have the potential to be cultured in many 
southern States. Culture of pure largescale silver carp would probably 
require subtropical/tropical conditions.
    Escape from containment, as has happened with silver carp, would 
provide a pathway for release of largescale silver carp into natural

[[Page 52312]]

waters. Should this fish or its hybrids be released into natural 
waters, connected waterways would become a secondary pathway for 
spread. Because of the morphological similarity between this species 
and silver carp, stock contamination of silver carp by largescale 
silver carp is possible if imported from regions with populations of H. 
harmandi. Another possible introduction pathway, should largescale 
silver carp or their hybrids be imported for culture, would be sale of 
live individuals in food fish markets.
    Likelihood of spread of largescale silver carp, should they be 
introduced, would be high in subtropical/tropical waters of the United 
States, but only where river flows are sufficient to support spawning. 
Hybrid largescale silver carp x silver carp, however, would have high 
potential to live in much of the temperate United States. Because 
largescale silver carp can occupy reservoirs, they could also live in 
lakes. The same is likely true for hybrids. Young largescale silver 
carp or any hybrids captured by anglers for use as live bait would be a 
pathway that could lead to numerous future introductions of these 
species.

Hybrids

    Hybridization with native fishes is not believed to be possible. 
Largescale silver carp can hybridize with silver carp and possibly 
bighead carp, both of which are present in U.S. waters. Hybrids of 
largescale silver carp are known to have survived and became 
established in Kazakhstan at a latitude of approximately 45 [deg]N, a 
latitude that parallels the border between New York State and Ontario, 
Canada. Therefore, it can be assumed that these hybrids would be 
capable of surviving and probably establishing throughout much of the 
United States where suitable waters exist.

Potential Effects on Native Species

    Largescale silver carp consume primarily planktonic food sources. 
It is unknown if largescale silver carp feed more heavily on 
phytoplankton than zooplankton, but their hybrids with silver carp 
would likely show a preference for phytoplankton. Largescale silver 
carp and hybrids are highly likely to compete for food with other 
planktivorous native fishes and with post-larvae and early juveniles of 
most native fishes should they become established in the United States.
    Fishes most likely to be affected are those species whose diet is 
predominantly plankton including paddlefish (Polyodon spathula), native 
to the Mississippi River Basin and Gulf of Mexico river drainages from 
east Texas to Alabama, buffalos (Ictiobus spp.), or shads (Dorosoma 
spp.). Given that these fish may already be competing with bighead and 
silver carps in some areas, the presence of largescale silver carp 
would increase food competition and increase the threat of negative 
impacts to native species.
    Potential for direct predation and injury of drifting fertilized 
eggs and larvae of fishes exists. Mussels are also filter feeders but 
live partly or totally buried in the substrate; they would be less 
likely to be affected by filter-feeding largescale silver carp or their 
hybrids. Largescale silver carp feed in the water column at night. 
Nevertheless, changes in the fish community structure caused by 
largescale silver carp or hybrids would likely have adverse effects on 
abundance and availability of host fishes required for mussel 
reproduction.
    There are other possible, but less likely, effects that will 
cascade through any aquatic ecosystem with an established population of 
largescale silver carp or their hybrids. Nutrient levels are a concern 
because there is evidence of overloading of nutrients in waters into 
which silver carp have been introduced, and the same may apply to 
largescale silver carp or their hybrids.
    Habitat competition would likely be low unless populations become 
significantly large. The potential of largescale silver and any hybrids 
to cause habitat degradation and/or destruction is low as is possible 
predation on native wildlife.
    Additional adverse impacts on native wildlife, wildlife resources, 
and ecosystem balance are likely few, except for fishes. Ecosystem 
balance would likely be modified if populations of largescale silver 
carp or their hybrids with silver carp become large enough to dominate 
planktivorous fish species.
    Because largescale silver carp may survive and become established 
and compete with native fishes, there is no acceptable escape or 
release threshold for largescale silver carp or their hybrids.

Potential Pathogens

    The potential for largescale silver carp to transfer pathogens is 
largely unknown. No detailed studies of disease-causing agents of 
largescale silver carp have been found, but at least three trematode 
parasites (Dactylogyrus harmandi, D. hypophthalmichthys, D. 
chenthushenae) are known to infect largescale silver carp. Bighead, 
silver, grass, and black carps are known to host the Asian carp 
tapeworm (Bothriocephalus acheilognathi), but it is unknown whether 
largescale silver carp host this species. Since largescale silver carp 
are very similar to silver carp, they likely can host the Asian carp 
tapeworm.

Potential Impacts to Threatened and Endangered Wildlife

    Adverse effects of largescale silver carp on selected threatened 
and endangered freshwater mussels and fishes would be expected to be 
moderate to high. There are currently 116 fishes and 70 mussels on the 
Federal List of Endangered and Threatened Wildlife. Based on habitat 
requirements, it appears that 40 fishes and 25 mussels currently on the 
endangered or threatened species list would likely be impacted by the 
introduction and establishment of largescale silver carp. However, the 
habitat requirements, springs and small streams, of the remaining 
listed fishes and mussels would probably preclude any detectable 
effects as it is unlikely that largescale silver carp or their hybrids 
would survive in such small bodies of water.
    It is highly likely that largescale silver carp and particularly 
their hybrids with silver carp would have adverse effects on designated 
critical habitats of threatened and endangered species. There are 
currently 60 species of fishes and 18 mussels with designated critical 
habitat. At least 26 fishes and mussels with critical habitat inhabit 
lakes or reaches of streams large enough to support hybrids of 
largescale silver carp and silver carp. Largescale silver carp and 
their hybrids have the potential to alter food webs and ultimately 
alter nutrient and energy cycling in aquatic communities. The most 
likely effect would be an alteration of fish community structure 
through competition for food. Fishes and mussels that are determined to 
be candidates for listing under the Endangered Species Act would 
likewise be at risk.
    There is low likelihood that species may be placed in danger of 
extinction as a result of the introduction or establishment of 
largescale silver carp if only pure stock escaped and became 
established in subtropical/tropical waters in the United States. Yet, 
the potential exists for hybrids with silver carp to develop large 
populations that could further imperil native fishes not currently on 
the Federal List of Endangered and Threatened Wildlife. Large 
populations of hybrids with silver carp would likely alter native fish 
community structures, ultimately resulting in decline of native mussels 
since many rely on native host fishes for reproduction. The fact that 
hybrids have the potential to become abundant and

[[Page 52313]]

reach a very large size, > 1 m in length, in rivers, lakes, and 
reservoirs, increases the probability of a negative impact on aquatic 
ecosystems should largescale silver carp be introduced and become 
established.

Potential Control

    Due to the potential range of establishment of hybrid largescale 
silver carp x silver carp in the United States, conventional control 
methods would not be feasible. The damage to ancillary fisheries 
resources through control measures would be substantial. Netting and 
electrofishing might be effective in reducing local populations of 
largescale silver carp, but they would also affect native fishes 
present in the area where such control measures are used. Similarly, 
use of chemical treatments would be expensive, only locally effective, 
and would negatively affect all fishes and invertebrates. Even most 
nonlethal methods to prevent the spread of largescale silver carp, such 
as electrical barriers or bubble curtains, would negatively affect 
migratory native fishes. At present, there is no method known to 
substantially reduce populations of established fishes in U.S. 
waterways. On the basis of presently available technology, eradication 
would not be possible.

Potential Impacts to Humans

    The potential impact on the health and welfare of humans from 
largescale silver carp or any hybrids is unknown. If largescale silver 
x silver hybrids display the jumping behavior of pure silver carp, 
their potential to injure humans could be considerable. Impacts to 
agriculture, horticulture or forestry from largescale silver carp or 
hybrids are highly unlikely.

Factors That Reduce or Remove Injuriousness for Largescale Silver Carp

Detection and Response

    If largescale silver carp were introduced into U.S. waters, it is 
unlikely that the introduction would be discovered until the numbers 
were high enough to impact wildlife and wildlife resources. Widespread 
surveys of waterways are not conducted to establish species' presence 
lists. Delay in discovery would limit the ability and effectiveness to 
rapidly respond to the introduction and prevent establishment. It is 
unlikely that hybrid largescale silver x silver carp could be 
eradicated from U.S. waterways, should they be introduced, unless they 
are found in unconnected waterbodies.

Control

    If hybrid largescale silver x silver carp were to escape and become 
established in natural waters, management of established populations 
would be nearly impossible both physically and fiscally. Some control 
might be possible with massive fishing efforts using nets, but this 
would unlikely stem range expansion. There would have to be substantial 
commercial demand to justify the expense of such efforts.
    Chemicals or selective removal may be used to manage populations in 
localized areas. However, selective removal of largescale silver carp 
would be difficult because they remain in deeper waters during daylight 
hours when such removal efforts would probably occur. If largescale 
hybrids lack this behavior, then selective removal may be feasible in 
specific situations. Pheromones may be a viable option to limit spread; 
this possibility is under investigation for silver carp, and may have 
applicability to largescale silver carp and any hybrids. However, 
research into this control method is in early stages.
    It would be difficult to control the spread of largescale silver 
carp or any hybrids to new locations except, perhaps, by use of 
electric, acoustic, physical and other types of barriers. At present, 
there is no method known to substantially reduce populations of 
introduced fishes in U.S. waterways. On the basis of presently 
available technology, eradication would not be possible.
    Although there is no evidence that this species has been introduced 
or targeted for introduction into the United States, its affinities 
with silver carp indicate that should it or its hybrids with silver 
carp be introduced, abilities to eradicate, manage or control spread to 
new locations would likely be low. Therefore, rehabilitation or 
recovery of ecosystems disturbed by this species or its hybrids is 
unlikely. Introduction of largescale silver carp or its hybrids has no 
known potential ecological benefits.
    Because no evidence exists that largescale silver carp have been 
imported or released into U.S. waters, triploidy or induced sterility 
could potentially reduce or eliminate injuriousness. Nevertheless, 
these processes are likely to be costly, time-consuming, and not 100% 
effective. Should this species be imported, it is likely that it would 
be placed in culture with other Asian carps including silver carp, a 
species with which the largescale silver carp can hybridize. Although 
the largescale silver carp is not known to hybridize with bighead carp, 
it is feasible because hybrids between silver and bighead carps are 
known.

Recovery of Disturbed Sites

    Although there is no evidence that this species has been introduced 
or targeted for introduction into the U.S., its similarities with 
silver carp indicate that should it or its hybrids with silver carp be 
introduced, abilities to eradicate, manage or control spread to new 
locations would likely be low. Therefore, there would be little 
likelihood for rehabilitation or recovery of ecosystems disturbed by 
this species or its hybrids.

Potential Pathogens

    The potential for largescale silver carp or largescale silver x 
silver carp hybrids to infect native fishes with pathogens is largely 
unknown. Should such transfers prove viable, ability and effectiveness 
to control the spread to native fishes would be low.

Potential Ecological Benefits for Introduction

    There are no potential ecological benefits for introduction of 
largescale silver carp or its hybrids.

Conclusion

    Because largescale silver carp are likely to escape or be released 
into the wild if imported to the United States; are likely to survive, 
become established and spread if escaped or released; are likely to 
compete with native species for food and habitat; have been shown to 
hybridize with silver carp, a nonnative species already established in 
the United States; hybrids with silver carp may display jumping 
behavior that could injure humans; and because it would be difficult to 
prevent, eradicate, reduce large populations, control spread to new 
locations or recover ecosystems disturbed by the species, the Service 
finds largescale silver carp to be injurious to the interests of human 
beings and the wildlife and wildlife resources of the United States.

Required Determinations

Paperwork Reduction Act (44 U.S.C. 3501 et seq.)

    This rule contains information collection activity for special use 
permits. The Fish and Wildlife Service has approval from the Office of 
Management and Budget (OMB) to collect information under OMB control 
number 1018-0093. This approval expires June 30, 2007. The Service may 
not conduct or sponsor, and a person is not required to respond to, a 
collection

[[Page 52314]]

of information unless it displays a currently valid OMB control number.

Regulatory Planning and Review

    (a) In accordance with the criteria in Executive Order 12866, OMB 
has designated this rule as a significant regulatory action.
    This rule would not have an annual economic effect of $100 million 
or more or adversely affect an economic sector, productivity, jobs, the 
environment, or other units of government.
Costs Incurred

Silver Carp

    We expect this proposed rule to have minimal costs. Silver carp are 
not cultured in the United States, nor do we believe that they are 
imported or exported. Currently, there are some commercial fisheries 
for silver carp in the Mississippi, Missouri, and Illinois rivers. 
Usually, commercial fishermen are catching silver carp as bycatch, 
which can account for up to 50 percent of the catch. Silver carp are 
not favorable because of their jumping habits and because they are less 
desirable by the consumer. In Missouri, many of the fishermen do not 
primarily target Asian carp (bighead and silver carp) because the price 
received is low ($0.10-$0.15 per pound). Instead, they fish for bighead 
and silver carp when other species or opportunities ar