The full ladder was installed in 1974 and was an immediate success; more than 4.3 million young eels ascended over the next six years. In 1981, Ontario Hydro replaced the wooden structure with a more permanent aluminum ladder. Another 2.6 million eels moved through in 1983 and 1984. The MNR dutifully kept track of the numbers and posted them in an internal fisheries report. “When you spend all that money on a ladder, you want to know that it’s working,” explains Mike Eckersley, the MNR biologist in charge of the ladder at the time. “But after a few years, we realized that we had the most extensive and most reliable index of eel recruitment in the world.”
One of the interested biologists who followed the annual eel census was Peter Hodson, by this time a toxicologist at the Maurice Lamontagne Institute, a marine research centre operated by the federal Department of Fisheries and Oceans near Mont-Joli, Quebec. He was studying beluga whales in the Lower St. Lawrence River and the Gulf of St. Lawrence, whose body fat carried an astonishingly high level of chemical contaminants, hypothetically because they were feeding heavily on the silvers coming out of Lake Ontario. (Hodson admits that he would have preferred to study eels directly, but in Ontario and Quebec they are considered a freshwater fish and fall under provincial rather than federal management; in the Maritimes, they are a marine fish, so their harvest is supervised by the DFO.)
However, the days of eels as an abundant, albeit obscure, species were about to end. The count was still high in 1985, when 935,320 juvenile eels ascended the ladder, but over the next four years, like a sputtering investment, it began to fall, hitting 258,622 in 1989. Then it crashed: 121,907 in 1990, 40,241 in 1991, and 11,534 in 1992.
“We were quite upset,” says Hodson. “It looked like a catastrophe. It wasn’t just that 1992 was a bad year; it was the overall trend. We were seeing a 99 percent decline, which is exponential, and there was no sign it was going to let up.”
Hodson was already slated to present a paper on contaminants in eels at a 1992 conference of the International Council for the Exploration of the Sea in Poland, convened as the stock of European elvers was crashing. Needless to say, the relationship of European and American eels is complex. The two species derive from the same ancestor but are genetically distinct, so they have somehow avoided each other’s annual party in the Sargasso. At the conference, Christopher Moriarty, an Irish researcher, put up a graph showing the decline of elver harvests in European rivers from 1980 to 1992. The shape of Moriarty’s diagram, Hodson realized, was virtually identical to the graph he had made of the Saunders numbers. The only difference was that the European crash preceded the collapse at Saunders by four years. And that was easily explained by the fact that the dam is 1,600 kilometres from the ocean — a four-to-seven-year swim for an eel.
Back in Canada, Hodson worked with biologist Martin Castonguay and pathologist Catherine Couillard, also of the Lamontagne Institute, on the first peer-reviewed paper to report the collapse of the juvenile American eel in the St. Lawrence River. The data from the Moses-Saunders dam was supported by eel surveys showing sharp drops at Quebec rivers feeding into the St. Lawrence. The article examined four possible causes for the decline: pollution in Lake Ontario, construction of the dam and the St. Lawrence Seaway, overfishing, and a weaker Gulf Stream. Lake Ontario was grossly contaminated, but it had been much worse in the 1960s, so if chemicals were to blame the effect should have shown up sooner.
Moses-Saunders and the seaway destroyed the habitats of many fish when they were constructed in the 1950s, but again the time lag was too great to explain the current decline. Quebec fishermen were continuing to take silver eels out of the St. Lawrence, and since 1975 had captured about 400 tonnes a year, but the comparative stability of that harvest ruled it out. Finally, it seemed possible the Gulf Stream had weakened, but this had happened in the early 1970s with no notable reduction in eels at the ladder. “By and large,” their paper concluded, “we do not really know what caused the pronounced recruitment decline in this species.”
In August 2003, eel experts on a field trip from an international symposium in Quebec City compared notes on the dramatic drop in juvenile populations among the Atlantic and Pacific branches of the Anguillidae family of eels. Among the scientists were MNR biologist John Casselman and David Cairns, a DFO fisheries manager from Prince Edward Island. “We sat there,” Casselman recalls, “saying we really need to do something here and this is the chance to do it.”
The upshot was the Quebec Declaration of Concern, endorsed by virtually all the symposium delegates from eighteen countries. Its wording, subsequently worked out in telephone calls and emails, departed sharply from the usual calm detachment of scientific papers: “With less than 1 percent of juvenile resources remaining for major populations, time is running out. Precautionary action (e.g., curtailing exploitation, safeguarding migration routes and wetlands, improving access to lost habitats) can and must be taken immediately by all parties involved and, if necessary, independently of each other.”
Meanwhile, back at the eel ladder the numbers had improved slightly: after hitting an all-time low of 944 in 2001, they were up to 2,876 in 2003. The MNR had twice cut fishing quotas for yellows by 50 percent — not that this was a problem for fishermen, since the actual catch was even lower. Rob MacGregor, the manager in charge of the Lake Ontario fishery, wrote a briefing note recommending the complete elimination of the eel quota. He explained the crisis and dutifully pointed out that given the panmictic, catadromous nature of eels, closing the Lake Ontario eel fishery would not necessarily bring them back. Since population pressure drives eels upstream, the collapse in Lake Ontario, at the extremity of the range, was a strong indicator that the entire species was in decline, notwithstanding the fact that harvests in the Maritimes remained high. Conversely, MacGregor and others thought, even if the species as a whole was not threatened, the past abundance of the Lake Ontario cohort, and its known fecundity, meant it soon would be. The zero quota took effect in the spring of 2004.
