59
5
Risk Assessment of a Proposed
Introduction of Pacific Salmon in the
Delaware River Basin
Paul T. Jacobson
Introduction
Culture and introduction of nonindigenous species have long played an important
role in fisheries management (Stroud 1986). Many fisheries biologists consider
fish culture and stocking synonymous with fisheries management, and fisheries
management has been a dominant consideration in management of the aquatic
environment (Radonski and Martin 1986). Many species of fishes are highly
fecund and experience high natural mortality in the wild during their early life
stages. These factors make artificial propagation a feasible and often appealing
way to ameliorate overharvesting and habitat degradation.
Hatchery rearing and stocking has also been used as a means of artificially
extending the range of many fishes. Numerous species native to parts of North
America have been widely introduced by resource management agencies and
private citizens to provide additional sport fishing opportunities. Many of these
species have become naturalized and are considered part of the native fish fauna
by many persons. Examples of North American species transplanted outside of
their native range include Smallmouth Bass (Micropterus dolomieui), Largemouth Bass (Micropterus salmoides), Walleye (Stitzostedion vitreum vitreum),
Rainbow Trout (Oncorynchus mykiss), Striped Bass (Morone saxatilis), and
American Shad (Alosa sapidissima). In many rivers of the east coast, nonindigenous species have replaced native anadromous species that were extirpated
following construction of dams and other blockages. Some interbasin transfers
were undertaken to provide forage for indigenous and nonindigenous game fish
(e.g., Rainbow Smelt [Osmerus mordax]); others have occurred inadvertently via
anglers’ bait buckets. Additional species were long ago introduced from Europe
and beyond. Examples of exotic introductions include Brown Trout (Salmo trutta)
and the Common Carp (Cyprinus carpio)
The aquarium trade has led to introductions of nonindigenous fish when such
fish were released into suitable habitat, especially in Florida. More than 27 species
of fish may have been introduced by that route (Courtenay and Williams 1992).
The aquarium trade has led to introduction of at least seven species since 1980
(OTA 1993). Aquaculture also has led to introduction of nonindigenous fish. The
5
Risk Assessment of a Proposed
Introduction of Pacific Salmon in the
Delaware River Basin
Paul T. Jacobson
Introduction
Culture and introduction of nonindigenous species have long played an important
role in fisheries management (Stroud 1986). Many fisheries biologists consider
fish culture and stocking synonymous with fisheries management, and fisheries
management has been a dominant consideration in management of the aquatic
environment (Radonski and Martin 1986). Many species of fishes are highly
fecund and experience high natural mortality in the wild during their early life
stages. These factors make artificial propagation a feasible and often appealing
way to ameliorate overharvesting and habitat degradation.
Hatchery rearing and stocking has also been used as a means of artificially
extending the range of many fishes. Numerous species native to parts of North
America have been widely introduced by resource management agencies and
private citizens to provide additional sport fishing opportunities. Many of these
species have become naturalized and are considered part of the native fish fauna
by many persons. Examples of North American species transplanted outside of
their native range include Smallmouth Bass (Micropterus dolomieui), Largemouth Bass (Micropterus salmoides), Walleye (Stitzostedion vitreum vitreum),
Rainbow Trout (Oncorynchus mykiss), Striped Bass (Morone saxatilis), and
American Shad (Alosa sapidissima). In many rivers of the east coast, nonindigenous species have replaced native anadromous species that were extirpated
following construction of dams and other blockages. Some interbasin transfers
were undertaken to provide forage for indigenous and nonindigenous game fish
(e.g., Rainbow Smelt [Osmerus mordax]); others have occurred inadvertently via
anglers’ bait buckets. Additional species were long ago introduced from Europe
and beyond. Examples of exotic introductions include Brown Trout (Salmo trutta)
and the Common Carp (Cyprinus carpio)
The aquarium trade has led to introductions of nonindigenous fish when such
fish were released into suitable habitat, especially in Florida. More than 27 species
of fish may have been introduced by that route (Courtenay and Williams 1992).
The aquarium trade has led to introduction of at least seven species since 1980
(OTA 1993). Aquaculture also has led to introduction of nonindigenous fish. The