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Story by Mark Hume with Photography by Dr. John Volpe In 1997, Dr. John Volpe, an Associate Professor of fisheries ecology at the University of Alberta, began research into the spawning capabilities of Atlantic salmon in a typical Pacific river system.
The salmon farming industry was thriving in B.C., and the commercial fishery for wild coho, chinook, pinks, sockeye and chum was in trouble because of declining wild stocks. The government - and the salmon farming industry - wasn’t in the mood for any bad news. But with increasing reports of Atlantics showing up in commercial and sport catches, people were asking whether or not the introduced species could somehow take hold on the Pacific Coast, and start competing with wild stocks that were in low numbers. Dr. Volpe thought answering that question would fill a vital gap in scientific knowledge. But he soon found out that not everyone in government was enthusiastic about his research. “I enjoyed tremendous support from those within DFO who were ‘on the ground’, but at the bureaucratic level and beyond, reaction to my plans ranged from indifference to agitation,” he states in a report he wrote recently for the David Suzuki Foundation, a non-profit foundation based in Vancouver, B.C. “DFO. . .was not eager to ask questions they didn’t want the answers to.” His report, Super Un-Natural - Atlantic Salmon in BC Waters, was presented to a public inquiry into salmon farming.
The inquiry, headed by retired Supreme Court judge Stuart Leggatt, was funded by the Suzuki Foundation through public donations. DFO, the provincial fisheries branch and the salmon farming industry all refused to participate in the inquiry, which sought to provide the public with details about the possible environmental threats posed by salmon farming. Dr. Volpe has provided what is probably the most significant original research into the dangers Atlantic salmon pose in the Pacific. Following is a short extract from his presentation to the Leggatt Inquiry. “In summary, my findings indicate that commercially reared Atlantic salmon will sexually mature and successfully spawn to produce viable progeny in a simulated natural environment. However, per capita, reproductive success is low: most females sexually matured but did not spawn, and those females that did spawn exhibited considerable egg retention, poor next construction and limited egg viability. Nearly all males matured, but showed subdued breeding behavior relative to what would be expected of wild Atlantic salmon (Gibson 1993; Fleming 1996). These results correspond with other studies that have shown farm escapees to be less productive than their wild counterparts (Fleming et al. 1996; 2000). However, it is important to note that both Fleming and I are in agreement that our data paints a conservative picture of the spawning potential of escapees. Our studies used fish that were reared to maturity in a domestic environment, and we suspect a large portion of the observed inferior spawning performance is likely due to environmental effects of the domestic environment.
This scenario concurs with the often observed lag period of relatively low abundance soon after introduction of an exotic species and prior to populations growth. The fish in my BC study did not initiate spawning behavior until early winter 1998, which is considered quite late by BC standards but within the observed range of wild Atlantic salmon populations (Mills 1989; Fleming 1996). If these Atlantic salmon were in a BC river in late January, coho salmon would have largely completed spawning (Sandercock 1991) and steelhead would not likely have begun. Thus, they would face limited competitive interference from native salmonids and in fact might superimpose their eggs on top of those of the native fish. Superimposition has been demonstrated to be a significant factor in determining spawning success in space-limited systems (Hayes 1987). Nest destruction and superimposition by later-spawning steelhead may act to reduce this advantage, but the magnitude of the effect would be density dependent and steelhead are currently at all-time recorded lows in British Columbia (Slaney et al. 1996). . . These results set the stage for the second half of my experiment: evaluation of spawning performance in the presence of native salmon. Due to political sensibilities, the climate surrounding my research program was heating up. With, for the first time, empirical evidence that Atlantic salmon colonization in BC waters may be a possibility, the time and energy required to defend the program against those who would have it shut down became too great and it was decided that year-two experiments would not be possible and that the young salmon being reared in the channel would be transferred to the University of Victoria for observation. The impact of losing the second year of data - Atlantic salmon spawning performance in the company of Pacific Salmonids - was essentially rendered moot, however, the following summer with the discovery of the first population of wild-reared juvenile Atlantic salmon in the Tsitika River on Vancouver Island (Volpe et al. 2000). This discovery provided definitive proof that adult Atlantic salmon were capable of successful reproduction in B.C.” For more information, e-mail The David Suzuki Foundation at : solutions@davidsuzuki.org
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At the time Dr. Volpe was, by his own admission, a naive graduate student who assumed that the Canadian Department of Fisheries and Oceans would be interested in learning if Atlantic salmon that escaped from fish farms could spawn in local watersheds.
Thus, a critical hypothesis awaits testing: An individual’s performance in the wild is inversely associated with the age at which the fish escaped; the younger the fish at escape the better the performance as an adult. It is intuitive that an adult that has experienced life in the wild over the previous year is likely to outperform a sibling that escaped captivity the previous week. I extend this to suggest the performance of wild-spawned individuals will be demonstrably superior by virtue of not having spent any time in captivity. If this hypothesis is correct, the likelihood of widespread colonization increases with each natural spawning event that occurs.
