Unsustainable Salmon Populations: What are the issues?
Frequently, in the Pacific Northwest, there are media reports regarding the continued decline in the numbers of local salmon species. As an engineering company that pursues scientific validation of our processes and products, we can’t help but ask questions and look to what can be done to achieve a viable solution. Initial finger pointing typically focuses on global warming, commercial fishing, hatchery production, nuisance predators, fish passage at dams and the big blue (something(s) not altogether known impacting the ocean ecosystem). Salmon are a valued commodity and to some extent have been attributed a majestic quality. Driven by a primal, instinctive motivation to successfully reproduce, they migrate from rivers to oceans and back to complete their cycle of life. The images of their relentless efforts to forge their way upstream, launching themselves over obstacles, and shouldering their way step after step through the high velocity flows of fish ladders, embodies a strength and determination that is both admired and inspiring. Losing salmon to extinction is a discomforting thought. So, what is really going on? As might be expected, it’s a complex set of factors. Not all of the factors are within our control to impact, but for those that are, the single overarching element to embrace is the need to take action and change how and what we are doing now and into the future. What we are doing now is not good enough. Some of the factors include:
Temperature:Global warming is here and real.Temperatures have increased in the oceans and rivers relative to historical records, across all seasons. This has a multi-ecosystem impact changing the dynamic and shifting dominance to favor species most capable of adapting. Salmon like cool waters which they can find during migration if they have the opportunity to swim deep and reach cool mountain streams. Low flows, sedimentation and barriers together with global warming have reduced cool water access.Interestingly, while overall salmon numbers have shown decline, some subspecies are adjusting.Researchers studying the adaptation characteristics of sockeye salmon subspecies populations to increased water temperatures in the Fraser River, British Columbia, Canada have shown that there is hope. The most fit subspecies have broadened their ability to cope.They are finding ways to adapt.Still, it is unfortunate that they need to. We may be limited in our ability to restore water temperatures but providing access to cooler waters, that salmon have historically thrived in, is important to helping to reverse the overall decline in numbers. How can we increase access?
Fish Passage:The Columbia River and its major tributary, the Snake, move huge volumes of water down from the mountains of British Columbia, Washington, Oregon and Idaho out to the Pacific Ocean.There are fifteen major dams on these rivers and fish passage, primarily in the form of fish ladders, is present on the majority of the dams. Tens of thousands of fish pass through these fishways every year.Are they good enough? The fact that one or more subpopulation of almost every salmon species known to inhabit the Columbia River are now listed as threatened or endangered as part of the Endangered Species Act (ESA), the answer is no – not good enough. This brings us back to questions of what do we really know? How are current fishways evaluated? What is the cause of the decline in salmon population numbers?What factors can we influence?What can we do to achieve population sustainability?
Counting Methods: To ensure that commercial fishing is not a significant contributing factor to salmon population declines, the industry has become highly regulated with oversight becoming more and more prominent.This relies in part on annual assessments of fish numbers that are used to establish quotas.
These assessments are based in part on out-migrating smolt metrics of previous years, estimated species annual returns (wild and hatchery-origin), ESA status of potential bycatch, the number of commercial fishing fleet licenses anticipated, and the ecological projections of returns required for species population sustainability. Unfortunately, the accuracy of the estimates and reliability of the current count methods are subject to a substantial margin of error, which is significant in that not just the salmon, but an entire industry, is affected by metrics that lack validated precision. As the numbers of fish continue to decline, it begs the question, can we reliably evaluate salmon population sustainability?
Wild Verses Hatchery Salmon:Researchers have established that wild salmon population viability is impacted by hatchery-origin salmon competing for resources.Ironically, hatchery-origin salmon populations have been generated, in many cases, to mitigate wild salmon losses due to man-made obstacles such as dams, altered water flow, and environmental damage. Hatchery-origin fish are typically marked by clipping the adipose fin, the small fin on the top of the fish behind the large dorsal fin.Commercial and recreational fishing licenses sometimes specify hatchery-origin catch for specific salmonid species and catch-and-release for wild salmon. Unfortunately, identification of an adipose clipped fin requires visualization, which is a secondary action relative to the initial catch.The consequences of the initial catch can impact subsequent survival. Catch and release survival estimates vary greatly depending on method of capture and time-associated definition of survival (immediate verses survival to achieve reproduction).In 2009 the Washington Department of Fish and Wildlife (WDFW) initiated a Commercial Selective Gear Implementation Program to encourage better, sustainable, gear solutions for selective harvest of hatchery-origin fish . The technologies and techniques applied sought to limit handling, reduce gear-associated injury, stress and air exposure. Adopting different selective harvest gear such as these has the potential to improve fish welfare, revitalize fishing communities and facilitate more sustainable wild salmon populations and commercial fisheries. Actions worth taking.
Predators:Nuisance predators are a challenge to consider on many levels.Whether we are talking about sea lions, seals or orca in search of a dwindling food supply near dams, locks and fishing operations there is controversy and confusion.If we all agreed that ensuring sustainable salmon populations had priority, ranking first over all others, then the action plan would be clear.But, the public loves sea lions, seals and orca and they serve a vital role in the ecosystem.Salmon are their natural food source.Like many salmon, orca numbers are declining and are now listed as endangered in some locations.We created barriers, obstructions, and collectively guided fish for our own benefit. Now, these predators are simply using our ingenuity for their own benefit.These predators have adapted, going where the salmon, their food, is found. This raises a number of ethical questions. Do we have the right to remove these salmon predators? If we do or if we don’t, how can we ensure their safety? Where is the right place to move them and how might that impact them on a social, behavioral and at an intra-species community level? Restoration plans for salmon must take into account the complexity of the ecosystem in which they live including their prey and their predators.
Assessment:Temperature, stress, predators, flow conditions, fish passage energy expenditures, and hatchery-origin competition for resources all impact wild salmon survival. Most would agree that all these factors are valid, however, the degree to which meaningful evaluations of survival are conducted relative to these factors is a question.At fishways, if survival is evaluated at all, most only look to see if the fish completed passage through the fishway, over the last step of the fish ladder. Longitudinal survival evaluations that consider the impact of fish passage relative to reproductive sustainability are rare. Our current monitoring methods provide only a key-hole view of survival. Fish counts are routinely achieved via visual monitoring through a fish window or via video of fish swimming up fishways. These counts are subject to human error, fallback, missed fish in night hours and count delays. When speaking about survival we must place context into the discussion. Survival through a fishway verse sustained migration survival to the spawning grounds is an important distinction when it comes to realizing sustainability goals.
Context: This lack of full-context, forward thinking has been a problem from the start.Over the course of nearly 50 years, only 96 peer-reviewed articles have been identified that focus on fishway evaluations, and as noted by the researchers who reviewed the scientific literature, very little has changed in that time-period .Fishway design was originally dominated by an engineering-focused approach with little consideration given to fish behavior, swim ability, fish motivation, habitat viability or sustainable ecology.If a fish reached the top of a fishway alive, fish passage was deemed “successful” and “sufficient”.Of the 96 publications, only seven examined the relationship between passage and fish physiology.Thankfully, this has begun to change.More recent studies have described biochemical markers and monitoring devices which may provide useful physiological evaluations of fish passage success linking passage to sustainable survival.Silva et al., state that “Designing efficient fishways, with minimal passage delay and post-passage impacts, requires adaptive management and continued innovation”.They stress the importance of looking beyond old ways of thinking, and pointing toward improved collaboration, information sharing, and method standardization as being needed to address the erroneous view that fish passage is largely a proven technology .
Process: Just because it is the way we have done things for 50 years doesn’t make it the best way for the fish.There are new, innovative fish passage technologies that can positively impact sustainable species survival.Traditional fish passage solutions have primarily been viewed as engineering challenges and endeavors in concrete. This we need to change.Fish passage is for fish; we need to look to the needs of the fish when considering design, development and fish passage installation. This requires we shift the paradigm in fishway engineering to embrace innovation and consider the fish first. Recent publications by a number of prominent fish biologists have lent voice to the fish perspective on designs for fish passage solutions .Given the lack of evaluations and standardization of fish passage assessment, the lack of precision in counting, and the repetition of use of outdated fishway designs, it is not surprising the erroneous view that traditional fishway design are effective persists.The monumental lack of evaluation means we cannot rely on fish passage data as justification for or against use of a fishway design. Once again, if we consider the fish perspective the picture becomes clearer. If the traditional fishways currently installed were doing their job well enough there would be no issues or questions about sustainable salmon populations.But there are issues and questions. The salmon populations are, in large part, declining. Fewer numbers of reproductively capable salmon are reaching the spawning grounds. Sustainability of salmon species populations is a very real and challenging concern.
Take-Action: Global warming, commercial fishing, hatchery production, nuisance predators, and fish passage at dams are important sustainability considerations.We can influence all of them if we are creative, innovative, and committed.First, however, we must be progressive and move beyond old ways of thinking.Henry Ford once said: “If you always do what you’ve always done, then you’ll always get what you’ve always got.” What we have got is not good enough. For salmon sustainability, changes are clearly needed.Changes are opportunities to improve, to do more better. Now is the time to take-action, to think creatively from unrestricted viewpoints, and embrace adaptive, innovative solutions that positively impact salmon population sustainability.If we adjust our mindset, acknowledge the factors we can impact and actively integrate science and new engineering technologies viable solutions will follow.
Janine Bryan, PhD
VP Biological and Environmental Sciences
1. Eliason, E.J., et al., Differnces in Thermal Tolerance Among Sockeye Salmon Populations. Science, 2011. 332: p. 109-112.
2. Wild fish conservancy, 2016 Washington Coastal Restoration Initiaitive Report Evaluation of Pound Nets as Stocl-Selective Fishing Tools- Year 1. 2016.
3. Wild fish conservancy, Commerical Fish Traps a Way Forward for Fish and Fishermen. 2017, Wild Fish Conservancy. p. 1-2.
4. Roscoe, D.W. and S.G. Hinch, Effectiveness monitoring of fish passage facilities: historical trends, geographic patterns and future directions.Fish and Fisheries, 2010. 11(1): p. 12-33.
5. Prystay, T.S., et al., The influence of water temperature on sockeye salmon heart rate recovery following simulated fisheries interactions.Conservation Physiology, 2017. 5: p. 1-12.
6. Raby, G.D., et al., Validation of reflex indicators for measuring vitality and predicting the delayed mortality of wild coho salmon bycatch released from fishing gear. Journal of Applied Ecology, 2012. 49: p. 90-98.
7. Burnett, N.J., et al., Burst Swimming in Areas of High Flow: Delayed Consequences of Anaerobiosis in Wild Adult Sockeye Salmon.Physiological and Biochemical Zoology, 2014. 87(5).
8. Silva, A.T., et al., The future of fish passage science, engineering and practice. Fish and Fisheries, 2017: p. 1-23.
9. Cooke, S.J. and S.G. Hinch, Improving the reliability of fishway attraction and passage efficiency etsimates to inform fishway engineering, science and practice. Ecological Engineering, 2013. 58: p. 123-132.
10. Williams, J.G., et al., Thinking Like a Fish: A Key Ingredient for Development of Effective Fish Passage Facilities at River Obstructions. River Research and Applications, 2012. 28(4): p. 407-417.