Research Document - 2012/083

2010 status of American eel (Anguilla rostrata) in Maritimes Region

By R.G. Bradford

Abstract

American eel (Anguilla rostrata) occur in numerous estuaries, streams, rivers, and lakes within the Maritimes Region. The fisheries for large eel and elvers in Maritimes Region were last assessed in 1996. The present assessment was conducted 1) in support of the national re-assessment of the status of American eel by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), and 2) to provide science advice on progress towards the 2006 (Draft) National Eel Management Plan objective of reducing human-induced mortality by 50 percent. Fisheries dependent data sources include commercial logbook returns from both the large eel and elver fisheries. Fisheries independent data sources include elver counts at an index site located on the East River-Chester, southwest Nova Scotia, bycatch of eels in juvenile salmonids electrofishing surveys of selected Maritimes Region Atlantic salmon rivers and May-June captures of eels in Rotary Screw Traps installed in two New Brunswick rivers. The increase in commercial landings of large eel between 1985 (80 mt) and 1996 (230 mt), and the decline to ≤ 100 mt in 2007, reflect change in number of participants in the fishery. Accurate estimates of fishing effort for large eels are not available for this time period. Elver landings exhibit no trend with time. Catch rates for eels in the 2009 juvenile salmonids electrofishing surveys on the Big Salmon and Nashwaak rivers, New Brunswick were not appreciably different from either the mean catch for the time series or the previous five year mean catch. Catch rates for eels in 2009 electrofishing surveys of St. Mary’s and LaHave river, Nova Scotia  were below the mean catch for the time series but near the mean of the previous five years. Elver abundance on the East River-Chester has varied interannually without trend since the inception of the index in 1996. The exotic swim bladder nematode, Anguillicoloides crassus, which may potentially reduce the likelihood that adults can successfully complete the spawning migration to the Sargasso Sea, was detected in eels collected from 8 of the 100 discrete river drainages surveyed during 2008 and 2009. Prevalence of infection (when detected) was estimated to be ≤ 27.3 percent and intensity of infection was ≤ 2.6 nematodes per eel. Compilation of all reported records of occurrence of the parasite is generally low and patchy but extending over a large range that includes the Bay of Fundy, Atlantic coastal Nova Scotia, and Cape Breton Island.

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