Monthly Archives: November 2019

On Salmon Hatcheries as an Ecological Paradigm

The West Coast of North America hosts 5 species of Pacific salmon that are an invaluable fishery resource and at least in theory a resource that is completely sustainable. The management of these fisheries provides a useful case study in how humans currently approach major resources, the mistakes they make, and how attempts to fix mistakes can lead to even further mistakes.

Salmon have been a major resource utilized by the First Nations of the Pacific Coast after the glaciers melted some 10-12,000 years ago. Salmon are anadromous fish, living in the ocean and spawning in fresh water. Their populations fluctuate from year to year but until the 1900s they were essentially considered an inexhaustible resource and thus became a target for exploitation. The buildup of salmon fisheries during the last 100 years coincided with an increase in environmental damage to freshwater spawning grounds. Dams on rivers cut migration routes to spawning grounds, pollution arising from mining, and erosion from forestry and agriculture all began to cut into spawning habitat and subsequently the available catch for the fishery. Salmon catches began to decline and in the late 1800s hatcheries began to be built both to restore fish stocks that were threatened and to increase the abundance of desirable fish like salmon (Naish et al 2007).

The simple model of salmon hatcheries was that the abundance of juvenile fish was the main factor limiting the adult population, so that adding more juveniles to wild juveniles moving out into the ocean would be profitable. This view of the world I call the “Farmer Paradigm” and if you are a dairy farmer with 4 cows that produce X milk, if you add 4 more cows to your farm, you now get 2X milk and thus more profit. But it became apparent with fish hatcheries that adding more juvenile fish did not necessarily increase the resulting fish catch. Some simple reasons might be that more juveniles were eaten by the predators waiting at the mouth of the river or stream, so that predation on juvenile fish was limiting. Alternatively, perhaps the ocean only had a given amount of food for juvenile growth, so that adding too many juveniles induced starvation deaths. Other explanations involving disease transmission could also be invoked.

Whatever the mechanism, it became clear that hatcheries for salmon sometimes worked and sometimes did not work to increase the productivity of the fishery. The Farmer Paradigm had to add a footnote to say “its complicated”. One complication noted early on was the possibility that natural selection in hatcheries was not equivalent to natural selection in wild populations. If hatchery fish were replacing wild fish in any population, the genetic changes involved could work in two directions by either making the entire population more fit or less fit, more productive or less. Much depends on what traits are selected for in hatcheries. In one example for sockeye salmon in Washington State, hatcheries appear to have selected for earlier spawning, so that wild sockeye in one river system return to spawn later than hatchery raised sockeye raised in the same river (Tillotson et al. 2019). Since in general juveniles from early spawners have poorer survival, climate change could favour earlier breeding and thereby reduce the overall productivity of the sockeye population in the river system. We are far from knowing the long-term selection that is occurring in hatcheries, and what it means for future populations of salmon (Cline et al. 2019, Stevenson et al. 2019).

Hatcheries are popular with the public because they indicate the government is doing something to assist fishers and hatcheries should increase and maintain fisheries production for species we love to eat. Consequently, there is a social signal that might be suppressed in data that might suggest a particular hatchery was in fact harming the fishery for a particular river or lake system. If someone wishes to do an economic analysis of the costs and benefits of a hatchery, one runs up against the standard simple belief that more juvenile fish equals higher fishery production. When Amoroso et al. (2017) tried to evaluate for pink salmon in Alaska whether hatcheries were an economic benefit or a loss, their best analysis suggested that recent increases in pink salmon productivity were higher in areas of Alaska with no hatcheries, compared with those with hatcheries. Since different river populations of pink salmon mix in their oceanic phase, it is difficult to obtain a clear experimental signal of hatchery success or failure. The immediate and the longer-term unintended consequences of hatcheries require further study. The assumption that every hatchery is an ecological and social good cannot be presumed.  

Salmon hatcheries are for me an ecological paradigm because they illustrate the management sequence: unlimited abundance → overharvesting → collapse of resource → find a technological fix → misdiagnosed problem → failure of technological fix → better diagnosis of the problem → competing socio-economic objectives → failure to act → collapse of the resource. This need not be the case, and we need to do better (Bendriem et al. 2019).

Amoroso, R.O. et al. (2017). Measuring the net biological impact of fisheries enhancement: Pink salmon hatcheries can increase yield, but with apparent costs to wild populations. Canadian Journal of Fisheries and Aquatic Sciences 74, 1233-1242. doi: 10.1139/cjfas-2016-0334.

Bendriem, N. et al. (2019). A review of the fate of southern British Columbia coho salmon over time. Fisheries Research 218, 10-21. doi: 10.1016/j.fishres.2019.04.002.

Cline, T.J. et al. (2019). Effects of warming climate and competition in the ocean for life-histories of Pacific salmon. Nature Ecology & Evolution 3, 935-942. doi: 10.1038/s41559-019-0901-7.

Naish, K.A. et al. (2007). An evaluation of the effects of conservation and fishery enhancement hatcheries on wild populations of salmon. Advances in Marine Biology 53, 61-194. doi: 10.1016/S0065-2881(07)53002-6.

Stevenson, C.F. et al. (2019). The influence of smolt age on freshwater and early marine behavior and survival of migrating juvenile sockeye salmon. Transactions of the American Fisheries Society 148, 636-651. doi: 10.1002/tafs.10156.

Tillotson, M.D. et al. (2019). Artificial selection on reproductive timing in hatchery salmon drives a phenological shift and potential maladaptation to climate change. Evolutionary Applications 12, 1344-1359. doi: 10.1111/eva.12730.

Do We Need Commissioners for the Environment?

Canada has just gone through an election, the USA will next year, and elections are a recurring news item everywhere. In our Canadian election we were spared any news on the state of the environment, and the dominant theme of the election was jobs, the economy, oil, gas, and a bit on climate change. The simplest theme was climate change, and yes, we are all in favour of stopping it so long as we do not need to do anything about it that would cost money or change our lifestyles. Meanwhile the fires of California and Australia and elsewhere carry on, generating another news cycle of crazy comments about the state of the environment.

Is there a better way? How can we get governments of the world to consider that the environment is worthy of some discussion? There is, and New Zealand has led the way in one direction. New Zealand has a Parliamentary Commissioner for the Environment, an independent Officer of Parliament, whose job it is to provide Members of Parliament with independent advice on matters that may have impacts on the environment. The Office is independent of the government of the day and the Prime Minister, and consequently can “tell it like it is”. A few quotations for the 2019 report give the flavour of this recent New Zealand report:

“If there is one thing that stands out from [our] reports, it is the extent of what we don’t know about what’s going on with our environment.  

“…the blind spots in our environmental reporting system don’t represent conscious choices to collect data or undertake research in some fields rather than others. Rather, they represent the unplanned consequences of a myriad choices over decades. Ours has been a passive system that has harvested whatever data is there and done the best it can to navigate what’s missing.

“In some ways, the most important recommendations in this report are those that relate to the prioritising and gathering of data in a consistent way. Despite attempts over more than two decades, no agreement has ever been reached on a set of core environmental indicators. This has to happen. Consistent and authoritative time series coupled with improved spatial coverage are essential if we are to detect trends. Only then will we be able to judge confidently whether we are making progress or going backwards – and get a handle on whether costly interventions are having an effect.

This report is full of ecological wisdom and would be a useful starting point for many countries. Canada has (to my knowledge) no Environmental Commissioner and although various provinces and cities provide State of the Environment Reports, they are largely based on inadequate data. In some cases, like commercial fisheries, Parliaments or Congress have mandated annual reports, provided the secure funding, and retained independence of the relevant director and staff. In many cases there is far too much bickering between jurisdictions, use of inadequate methods of data collecting, long time periods between sampling, and no indication that the national interest has been taken into account.

Most Western countries have National Academies or Royal Societies which provide some scientific advice, sometimes requested, sometimes not. But these scientific publications are typically on very specific topics like smoking and lung cancer, vaccine protection, or automobile safety requirements. We can see this problem most clearly in the current climate emergency. The Intergovernmental Panel on Climate Change (IPCC) of the United Nations provides excellent reports on the climate emergency but no government is required to listen to their recommendations or to implement them. So, we have local problems, regional problems and global problems, and we need the political structures to address environmental problems at all these levels. New Zealand has provided a way forward, and here is another quote from the 2019 report that ecologists should echo:

Given that many of the environmental problems we face have been decades in the making and that for nearly 30 years we have [made] specific reference to cumulative effects that arise over time…it is astonishing that we have so little data on trends over time.

….it takes time to assemble time series. If we start collecting data today, it may be a decade or more before we can confidently judge whether the issue being monitored is getting better or worse. Every year that we delay the collection of data in an area identified as a significant gap, we commit New Zealand to flying blind in that area. …..A lack of time series in respect of some environmental pressure points could be costing us dearly in terms of poorly designed policies or irreversible damage.

One example may be enough. Caribou herds in southern Canada are threatened with extinction (Hebblewhite 2017, DeMars et al. 2019). Here is one example of counts on one caribou herd in southern Canada:

2009 = 2093 caribou
2012 = 1003
2019 = 185

It would be difficult to manage the conservation of any species of animal or plant that has such limited monitoring data. We can and must do better. We can start by dragging state of the environment reports out of the control of political parties by demanding to have in every country Commissioners of the Environment that are fully funded but independent of political influence. As long as the vision of elected governments is limited to 3 years, environmental decay will continue, out of sight, out of mind.

There is of course no reason that elected governments need follow the advice of any independent commission, so this recommendation is not a panacea for environmental issues. If citizens have independent information however, they can choose to use it and demand action.

DeMars, al. (2019). Moose, caribou, and fire: have we got it right yet? Canadian Journal of Zoology 97, 866-879. doi: 10.1139/cjz-2018-0319.

Hebblewhite, M. (2017). Billion dollar boreal woodland caribou and the biodiversity impacts of the global oil and gas industry. Biological Conservation 206, 102-111. doi: 10.1016/j.biocon.2016.12.014.