Guest Authors: Dr. Kathryn Peiman, Brian Morrison
Atlantic Salmon were once one of the most abundant and prominent predators in Lake Ontario, yet they were extirpated from the lake in 1896, a loss that happened in less than 100 years.
The usual litany of causes was partially responsible for their decline, including overfishing, construction of dams, and pollution. Yet, one cause has never before been suggested as also contributing to the extirpation of this once thriving population of fish.
During the mid 1800s, as the Atlantic Salmon population declined, hatchery efforts were established to rebuild the population. To this day, these hatchery efforts are heralded as a success, but upon closer inspection, these efforts were most likely just another nail in the coffin that led to the extirpation of Atlantic Salmon from this Great Lake.
The story goes: hatcheries are a good tool to mitigate against population declines by increasing abundance. The simple and logically appealing premise is that hatcheries result in higher juvenile survival than the wild, and therefore, by removing high natural mortality, more fish will be released into the system and therefore more adults will return.
However, scientific literature demonstrates that hatchery efforts can harm the very wild populations they are supposed to support. Yet, in many cases, hatcheries continue to be seen as an acceptable solution when wild populations are failing.
The first hatchery in Ontario was built in Newcastle by Samuel Wilmot in 1866 on his namesake creek. For 18 years, until 1883, Wilmot cultured and stocked more than 5.5 million Atlantic Salmon fry with the stated intention of restoring their numbers in Lake Ontario. Because of these efforts, Samuel Wilmot is known as the “Father of Fish Culture” in Canada.
Yet, upon reviewing old reports from that era, we found that Wilmot’s basic biological assumptions about Atlantic Salmon were flawed, leading to incorrect claims.
After hatching, Atlantic Salmon need 1-3 stream years and 1-2 lake years before returning as adults to their spawning grounds, yet Wilmot claimed that adult returns were from his previous year’s juvenile stockings, which is biologically impossible.
An additional issue was that no distinguishing mark was made to hatchery fish, and therefore, there was no way to differentiate hatchery raised fish from wild fish. Yet Wilmot claimed all adult returns were due to his hatchery efforts, while ignoring concurrent increases in abundance in non-stocked watersheds indicating that wild returns had a brief resurgence.
Adult returns also didn’t correspond with high stocking rates. 1.5 million eggs were collected for hatchery use in 1876, the highest number ever, yet subsequent adult returns from that year class were exceptionally low.
Yet none of these inconsistencies phased him. To the contrary, he was arrogant (referring to Atlantic Salmon by his name, Salmo wilmoti) and replied with rhetoric to suggestions that his activities were not working.
Whether or not he knew or admitted it, his hatchery resulted in multiple forms of harm: gametes collected from wild reproducing fish reduced natural reproduction; eggs transferred out of the basin to other regions reduced total young available for the next generation; populations were mixed across streams which ignored the local adaption of runs; and the release of millions of hatchery-reared fish likely resulted in negative genetic effects.
Considering the environmental degradation of the land and water of Lake Ontario over this time period, it is most likely that the Atlantic Salmon would still have been extirpated without these hatchery effects. But, in contrast to what was claimed by Samuel Wilmot, the loss was most likely sped up by his hatchery practices, and so this case of fisheries management for Atlantic Salmon in Lake Ontario is not as great a success story as it is commonly claimed to be.
There are some cases where the use of hatcheries is appropriate – creating fishable urban ponds, specific enhancement for cultural, ceremonial, or subsistence mitigation fisheries, or reintroducing species to areas where they have already been lost (as is the current case with Atlantic Salmon in Lake Ontario) – but many stocking programs are not achieving the end goal of more robust fish populations.
Management agencies often do not like narratives that challenge institutional beliefs or ingrained behaviours. Hatcheries are an excellent example of a deep-seated belief that ignores the science that clearly shows their harm when these fish are stocked on top of an existing strained wild populations. This is why, in a recent paper, we also talk about “the strong personalities of managers and entrenched agency practices that prioritize economic goals” when it comes to hatcheries.
For publishing this article that had statements our employer objected to (this manuscript was not written during work hours nor a product of our employment), we were professionally reprimanded. Our employer feared that these ideas would jeopardize the success of the Lake Ontario Atlantic Salmon program because sponsors and partners would withdraw their support of the program, yet we were forbidden from discussing the paper that we wrote with workplace partners and sponsors to alleviate any concerns that may arise.
Unsurprisingly to us, to the best of our knowledge, the partners and sponsors continue to support the program, and we hope as we always have, that the program will succeed with a self-sustaining population of Atlantic Salmon in Lake Ontario.
The choice we faced is one many of us will have in our careers when we realize that a practice or policy is not as helpful, appropriate, or grand as it is presented. At that point, we must ask ourselves: are we willing to facilitate open discussions, either in the workplace or on our free time, about those policies, ideas, and dogmas, knowing that we may face professional repercussions as a result?
For us, the answer was that it was worth it.
(As always, articles are reflective of the thoughts and opinions of Authors of that particular article. Please refer to the scientific paper written on this topic for further support, thoughts, tables, and figures.)
About the Guest Authors
Kathryn earned a BSc and a MSc from the University of Guelph and a PhD from UCLA. Kathyrn feels fortunate to have traveled to many cool places during academic work, from Hawaii to British Columbia, Alaska to Mexico, the Bahamas to Puerto Rico, and Australia to Denmark and Iceland, studying many aspects of behavioural ecology in fishes and birds. Kathryn is currently free-lancing in photography, videography, and science communication (https://www.youtube.com/c/NatureTidbits/videos).