**The title, authors, and abstract for this completion report are provided below.  For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**


Research into the relationship between abundance, harvest, and value by region for American eel


Casselman1, J.M. and L.A. Marcogliese2

1 Queen’s University, Department of Biology

  2406 Biosciences Complex, 116 Barrie Street

  Kingston, Ontario  K7L 3N6


2 30 Salem Road, R.R.1

  Ameliasburgh, Ontario  K0K 1A0



September 2007



Commercial harvest and price for the American eel (Anguilla rostrata) was analyzed using harvest and landed value from provincial and state jurisdictions across the North American range. Data were amalgamated for five Canadian and three United States regions for a 55-year period from 1950 to 2004. Price, deflated and standardized in terms of 1950 Canadian dollars, led to a better understanding of harvest and changing abundance. Standardized price of eels increased two-to-threefold over the period, but because of reduced harvest, value of the fishery is no greater now than in the 1950s. CUSUM and proportional residuals were used to analyze harvest and price. Significant deviations from synchronicity between harvest and price were first associated with high harvest at low price for silver eels in the Lower St. Lawrence River (SLR) in the 1950s, possibly related to lower turbine mortality prior to installation of the Moses Saunders hydroelectric dam (MSHD) in the Upper SLR. In the late 1960s and early 1970s, a disproportionately high harvest of eels initiated an unprecedented rate of regional harvest in the Gulf region of the SLR and to a lesser extent in Newfoundland and the sea fishery in Quebec. This harvest appeared to be related to increased abundance, possibly caused by reduced elver immigration up the SLR system and a backing-up downstream from MSHD, which created a partial obstruction (for 17 years, 1958-1973) before the ladder was installed to facilitate eel passage in 1974.


Harvest in the Gulf region of Canada initiated an important sequence of dynamics that was disproportionately higher than price beginning in 1969 to 1973 in Canada and, in 1974 to 1976, progressed to all regions in the United States. In 1978-79 in the United States, harvest was very much higher than price would have predicted, although price was increasing. In 1987-88, a distinctly different period began, with harvest lower than price would have predicted and a trend to decreasing harvest. In the United States from 1985 to 2004 and in Canada beginning in 1995, harvest was much lower than price would have predicted. From 1997 to 2001, there was a trend to lower price; indeed, in 2002 and 2004, harvest was lower than in the 1950s and 1960s, when eels were less valuable and more abundant. Regulations and management did not greatly curtail harvest until the mid-to-late 1990s, well after declines had begun, and contaminants and closures were generally short-term, local, and relatively minor. The combination of increasing and high price with decreasing and low harvest in the presence of minimal regulations indicates decreased abundance of eels, since price is inversely related to abundance, confirmed in Upper SLR and Lake Ontario, where price paid was inversely correlated with size of the harvestable stock (r = 0.716, P = <0.0001).


Commercial harvest was extremely high in the late 1960s to the early 1980s in both Canada and the United States and continued into the early 1990s in Canada. During the late 1970s and early 1980s, heavy exploitation in both countries resulted in declining catch and smaller eels, with a substantial increase in price near the end of the period, evidence that supply was not meeting demand and a concern about overexploitation in several regions. A disproportionate shift to high price and declining and lower harvest began in the United States in 1987 but not until 1995 in Canada, a difference explained by age of the catch (≈7 yr older in Canada). These sequential declines followed heavy exploitation (1970s) and subsequent declining recruitment (late 1970s). If harvest in some areas was previously underestimated by either underreporting or non-reporting, recent decreases in commercial harvest would be more severe than trends suggest. No doubt multiple factors, including oceanic effects, turbine mortality, habitat loss, and contaminants, were also involved in the declines in abundance and commercial harvest. However, when harvest was examined in relation to price, it was apparent that a combination of high early abundance, possibly accentuated by obstruction, heavy exploitation, expanded and integrated markets, created a demand. Along with increased value and price, these major factors worked in unison to increase harvest significantly, permanently reducing reproductive capacity of the species and subsequently creating declines in recruitment and population size, most apparent at the extremity of the range.