A slippery subject15 May 2001
Concern is growing about the fate of the American eel. It is still not clear what is causing the apparent decline of this species or what can be done to reverse the trend. Gemma Newman reports
The decline of the American eel (Anguilla rostrata) population is worrying fishery resource agencies and conservation organisations in the US, particularly as the characteristics and life history of this species are not well documented. As a result, the status of the American eel population along the Atlantic seaboard is poorly quantified and understood.
‘There is evidence of a coastwide population decline,’ says Doug Dixon of the electric-power-research-institute (EPRI), ‘but the complexity and plasticity of the eels’ life history precludes the application of standard fisheries assessment and management approaches.’
Since 1998, EPRI has been trying to determine why American eel populations have been declining. It published a literature review and report on American eels in 1999 but was unable to resolve the effects of hydro operations in relation to commercial harvest and other potential causes. But the study did raise awareness of the eels’ plight and pointed out where more research and information was needed to help improve the situation.
Dixon stresses the need for standardised long term monitoring programmes and information on downstream migratory behaviour for more effective design of downstream passage measures. He also recommends better characterisation of regional stocks to assess the cumulative impacts of hydro and research on basic life history, and potential new technologies to assist eel passage through hydro facilities.
At the request of many Atlantic coastal states, a fishery management plan is being prepared by the Atlantic States Marine Fisheries Commission (ASMFC). A draft plan has broad implications for the eastern hydro industry, such as habitat restoration, provisions for upstream passage and minimising turbine mortality.
More is needed
The national-hydropower-association (NHA) says that more is needed. ‘We need congressional action so that we may identify and evaluate all potential impacts on the American eel population, using the best scientific methods available to reverse its decline,’ said Linda Church Ciocci, NHA executive director.
NHA is proposing that US Congress provides US$1M per year (above the President’s budget) over the next five years for the US Fish and Wildlife Service (FWS) to carry out a comprehensive study on the status of the American eel (survival, metamorphosis and recruitment) and identify the causes of its decline so that it may be reversed.
NHA believes that the American eel is a classic example of a priority species for a federal agency such as the FWS because it has a life history that involves multiple jurisdictions over a broad geographic region. However existing FWS resources are committed to other inter-jurisdictional species such as Atlantic salmon, Atlantic sturgeon and American shad. In addition other species, such as the striped bass which has been successfully restored, require continued management to ensure that they do not decline to dangerously low levels in the future.
According to NHA, the US Fish and Wildlife Service is currently working with the Atlantic States Marine Fisheries Commission on an American eel fisheries management plan. A development team has been appointed to draft a public information document that has initiated public involvement in the fisheries management plan. But eels are indigenous to jurisdictions beyond the Atlantic coastal states, so the management and biological programmes of these areas will need to be integrated into the eel conservation programme as current information suggests that there is only one spawning population.
NHA suggests that the conservation programme should build on the lessons learned form the striped bass and its successful recovery, and that an oversight group similar to the striped bass study and planning co-ordination group should be established to address the eel issue. This group would have equal representation from the FWS, National Marine Fisheries Service, ASMFC, other interested management jurisdictions and representatives from other resource user groups.
The proposed American eel study and planning co-ordination group would be responsible for developing an initial study plan, reviewing annual progress and assisting the FWS in preparing an annual report to Congress. NHA proposes that the FWS would staff the group, provide the lead for the annual report to Congress and administer the appropriated funds. Most of the work will be performed through the states, ASMFC and other partners via co-operative agreements. The NMFS may also perform some additional work through an interagency agreement.
NHA suggests that at a minimum the five-year study would examine management information needs and issues that have been identified to date. It would assess American eel landing records for all life stages to determine their completeness and adequacy for evaluating the eel fishery; monitor population trends and commercial and recreational harvest; and monitor the effects of gear type on harvest rates. If necessary, the study would also determine what data are needed to improve landing records and monitoring programmes. Ideally, the study would also clamp down on illegal take; evaluate the impact of American eel aquaculture on fish health, eel culture/hatcheries and import and export concerns; and quantify and qualify the economic considerations of the domestic American eel bait fishery. Other considerations would be to:
• Quantify and qualify contaminant effects on survival, growth and reproductive success.
• Evaluate the impact, both upstream and downstream, of barriers on American eel with respect to passage and evaluate methods to reduce impacts if necessary.
• Stock assessment and determination of fishing mortality rates to develop a sustainable harvest rate.
• Determine the economic value of the fishery and the impact of regulatory management.
• Investigate, throughout their range, aspects of life history as identified by the co-ordinating group.