For State Wildlife Action Plans

Fishes

Human activities continue to impact aquatic systems across the Northeast, and fish populations face many threats. The recent American Fisheries Society and USGS analysis (http://www.actionbioscience.org/biodiversity/walsh.html) describes the most significant threats to freshwater fish. Destruction or modification of habitat, which can result in loss of populations and reductions in species range, includes dam construction, stream channelization, mining, conversion of forests to agriculture, and urban and suburban development. Pollution from point and non-point source contaminants in run-off reduces water quality to the point where only highly tolerant fish species survive. Sedimentation of fine particulates can also smother bottom substrates, causing declines in bottom-dwelling species that require clean substrates and good water quality.

Introduction of non-native species, which may result in hybridization, competition, and predation, has also impacted native species. Examples include the Northern snakehead (now established in the Potomac River), the rusty crayfish, fishhook water flea, and diatoms such as didymo, have the potential to alter freshwater aquatic systems for all species including fish RSGCN. Disease or parasitism such as whirling disease (introduced from Europe) has affected many wild and hatchery populations of trout and salmon species in the United States and Canada. Overharvesting for commercial, recreational, scientific, or educational purposes has also historically affected some species such as sturgeon.

Global climate change and associated changes in weather and rainfall patterns across the Northeast have the potential to alter water quality and quantity in many streams, lakes, and rivers, with resulting detrimental effects for many fish species. Climate change can also exacerbate the other threats listed above. Most of these threats apply to fresh, estuarine, and marine fish species in the Northeast.

From a taxonomic perspective, most of the fish RSGCN in the Northeast are small-bodied freshwater species in the families Percidae (darters and perches) and Cyprinidae (chubs and minnows), a pattern which holds true across North America (http://www.actionbioscience.org/biodiversity/walsh.html). These smaller fish are primarily threatened by habitat alteration, including sedimentation, construction of dams and other barriers, and other forms of aquatic habitat destruction and contamination.

The list also includes several of the more primitive living fishes, including six species of lamprey, three species of sturgeon, and the paddlefish. These fishes are truly ancient, with the first sturgeon fossils appearing in the Triassic and forms similar to modern sturgeon appearing by the Late Cretaceous, with little subsequent morphological change. Populations of these unusual and morphologically distinctive fish species have been greatly reduced through overharvest and habitat alteration. The paddlefish is only one of two species in its lineage to have survived until modern times, although the other recent species of paddlefish (found in China) is thought to now be extinct.

The list also includes 14 cartilaginous fishes, including seven sharks, six skates, and one stingray. These fish are all marine or estuarine in their habitat associations. The list of sharks includes two species which are considered regulated game species that may be harvested by saltwater anglers, the short-finned mako shark and the thresher shark. Global populations of sharks and many other cartilaginous fishes have been decimated in recent decades through over-harvest for the commercial market.

Several other fish species on the list are popular with recreational or commercial anglers. These include the Atlantic salmon, American and hickory shad, blueback and Atlantic herring, American eel, brook trout, lake trout, and Atlantic mackerel. Several of these species have been the subject of intensive conservation efforts, including habitat conservation work to benefit wild runs of Atlantic salmon in Maine, dam removal and fish passage work throughout the mid-Atlantic to benefit shad and herring species, and the Eastern Brook Trout Joint Venture which has been working to restore habitat and increase connectivity for brook trout across the eastern United States.

Of the species that are harvested for recreational and commercial purposes, most are imperiled for a variety of reasons beyond simple harvest management. In the case of Atlantic salmon, the shads and herrings, dams and habitat destruction have unquestionably played a significant role in their decline. Coordinated fisheries management efforts have not yet yielded recoveries of those stocks. Some genetic strains of Atlantic salmon in Maine have reached the point where they are now federally listed as endangered. Non-native species have also played a role in the decline of harvested fish species, most notably with the advent of non-native sea lampreys which played an important role in the decline of lake trout in the Great Lakes beginning in the 1950s. Climate change also has the potential to pose a significant threat to recreational fisheries. Brook trout are cold water species that are sensitive to warming temperatures and thus vulnerable under warmer climate regimes. Ongoing climate-driven changes to water temperature are exacerbated by the loss of shading vegetation in riparian zones surrounding the cold water streams that provide habitat for these fish.

In order to develop the marine component of Northeast Wildlife Action Plans, updated information sources exist that can be used in state revisions. NOAA’s National Marine Fisheries Service and the Atlantic States Marine Fisheries Commission maintain status information on species of conservation need. The Atlantic Coast Fish Habitat Partnership’s recent plan presents important overview information on many of the Northeast states SGCN and RSGCN species and can be found at http://fishhabitat.org/partnership/atlantic-coastal-fish-habitat-partnership. The plan summarizes key species, habitat, threat, and conservation action information that can be used to help inform Wildlife Action Plan revisions. Recent review articles by the American Fisheries Society and USGS provide additional information about fish declines in North America and can be found at http://www.actionbioscience.org/biodiversity/walsh.html.