International eel symposium, 2003 - Quebec August 11, 2003
Oral Presentation

American Eel Dynamics and Abundance: A Fish Resource in Unprecedented Decline

Casselman, J.M.* Ontario Ministry of Natural Resources, Applied Research and Development Branch, Glenora Fisheries Station, R.R. 4, Picton, Ontario K0K 2T0

Presenter email address: john.casselman AT mnr.gov.on.ca

Abstract Text: American eels were historically abundant and a valued resource that sustained aboriginal North Americans, particularly the St. Lawrence Iroquois and the Onondaga's Eel Clan. Over the past 50 years, commercial catch was approximately equal in Canada (52%) and U.S. (48%), with similar dynamics, reaching record highs in the 1970s-80s. Declines were unprecedented from the mid-1980s throughout the 1990s and a decade later in Canada, where catches were older. Declines throughout the 1990s were most severe at the extremity of the range in U.S. southern and northern coastal states and distant St. Lawrence River-Lake Ontario (SLR-LO) stock. Scientific indices confirm universal decline. Recruitment to the large-bodied, highly fecund upper SLR-LO stock decreased over the past three decades by three orders of magnitude, most dramatically from 1986 to 1991, and has essentially ceased. Oceanic climatic changes may be important, since recruitment to the upper SLR-LO stock correlates positively with European eel recruitment (r2 = 0.759) and negatively with the North Atlantic Oscillation Index (r2 = 0.585). Concerted management intervention is needed to reduce human-induced mortality because, assuming panmixia, declining reproductive capacity and recruitment predicts continued resource declines caused by heavy exploitation throughout the range: dam construction, negative food web and habitat