Where did all the river herring go?
Over the past two centuries, river herring (blueback herring and alewife) populations have drastically decreased. While limited data make determining the status of the Atlantic coast populations difficult as a whole, river herring spawning runs in New Brunswick, Maine, and Virginia have been assessed as severely overfished, and runs in North Carolina have been assessed as overfished (2). Total commercial landings of river herring decreased drastically from 1950-2007 (Figure 1). Population decline occurred as river herring stocks encountered a variety of anthropogenic threats: commercial and recreational fishing, habitat loss, dam construction, siltation, and pollution (2).
Commercial and Recreational River Herring Fisheries
Commercial and recreational harvests have intensely exploited stocks over the past two centuries. The river herring fishery is one of the oldest documented fisheries in North America (3). Overfishing was a major problem by 1790, when the state of Massachusetts was forced to instate river herring fishing regulations. The use of harvested herring has changed from a primary food source for colonists, as smoked and pickled fish, to predominantly being used for fishmeal, pet food, and bait for commercial and sport fishing (4). Today, river herring are the most desirable bait source for the commercial American lobster (Homarus americanus) fishery (2).
Physical Impediments
While commercial and recreational fishing of river herring have had a profound effect on their population dynamics, so have physical barriers to upstream and downstream migrations such as dams and hydropower facilities (2). Permanent man-made structures are an ongoing barrier to upstream fish passage that can stop spawning outright. They can also limit downstream migration, as young fish passing through spillways are frequently killed due to turbulence, rapid pressure changes, rapid deceleration, and impact (5,6).
Water Pollution and Runoff
Water pollution has also contributed to the decline in river herring. Pollutants such as insecticides, herbicides, and heavy metals can impair reproductive abilities of fish (1,7,8). Additionally, high concentrations of nitrogen and phophorus from agricultural runoff frequently lead to accelerated algal production and consequently large fish kills (2).
Managing the Fishery
Proper management of the fishery will help to restore populations of alewife and blueback herring, as will installing and mainlining fish ladders around dams, and limiting water pollution. Effective management involves setting informed harvest limits by accurately assessing the population. This requires monitoring of forage fish populations, primarily during their spawning runs in the spring. Volunteers are essential to making accurate population estimates! They contributing to the monitoring process by making visual assessments in person or by analyzing video online from our fish ladder video monitoring system. Click the button below to learn more about volunteering!
References:
1. ASMFC. 1999. Amendment 1 to the Interstate Fishery Management Plan for Shad and River Herring. Fishery Management Report No. 35 Washington, D.C.
2. ASMFC. 2009. Amendment 2 to the Interstate Fishery Management Plan for Shad and River Herring. Fishery Management Report No. 35 Washington, D.C.
3. CRASC (Connecticut River Atlantic Salmon Commission). 2004. Management plan for river herring in the Connecticut River basin (Amended October 5, 2004). Connecticut River Atlantic Salmon Commission, Sunderland, Massachusetts.
4. Fay, C. W., R. J. Neves, and G. B. Pardue. 1983. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (mid-Atlantic) – alewife/blueback herring. United States Fish and Wildlife Service, Division of Biological Services Report No. FWS/OBS-82/11.9, and United States Army Corps of Engineers Report No. TR EL-82-4, Washington, D.C.
5. Ferguson, J. W. 1992. Analyzing turbine bypass systems at hydro facilities. Hydro Review 1992:46-56.
6. Heisey, P. G., D. Mathur, and E. T. Euston. 1996. Passing fish safely: A closer look at turbine vs. spillway survival. Hydro Review 15: 42-50.
7. Longwell, A. C., S. Chang, A. Herbert, J. Hughes, and D. Perry. 1992. Pollution and developmental abnormalities of Atlantic fishes. Environmental Biology of Fishes 35: 1-21.
8. Mac, M. J., and C. C. Edsall. 1991. Environmental contaminants and the reproductive success of lake trout in the Great Lakes: An epidemiological approach. Journal of Toxicology and Environmental Health 33: 375-394.
2. ASMFC. 2009. Amendment 2 to the Interstate Fishery Management Plan for Shad and River Herring. Fishery Management Report No. 35 Washington, D.C.
3. CRASC (Connecticut River Atlantic Salmon Commission). 2004. Management plan for river herring in the Connecticut River basin (Amended October 5, 2004). Connecticut River Atlantic Salmon Commission, Sunderland, Massachusetts.
4. Fay, C. W., R. J. Neves, and G. B. Pardue. 1983. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (mid-Atlantic) – alewife/blueback herring. United States Fish and Wildlife Service, Division of Biological Services Report No. FWS/OBS-82/11.9, and United States Army Corps of Engineers Report No. TR EL-82-4, Washington, D.C.
5. Ferguson, J. W. 1992. Analyzing turbine bypass systems at hydro facilities. Hydro Review 1992:46-56.
6. Heisey, P. G., D. Mathur, and E. T. Euston. 1996. Passing fish safely: A closer look at turbine vs. spillway survival. Hydro Review 15: 42-50.
7. Longwell, A. C., S. Chang, A. Herbert, J. Hughes, and D. Perry. 1992. Pollution and developmental abnormalities of Atlantic fishes. Environmental Biology of Fishes 35: 1-21.
8. Mac, M. J., and C. C. Edsall. 1991. Environmental contaminants and the reproductive success of lake trout in the Great Lakes: An epidemiological approach. Journal of Toxicology and Environmental Health 33: 375-394.