Pacific Salmon: Responses to Changing Climate and Habitats

On August 22nd, the DFO released a new report examining broad scale trends in Pacific salmon. They found that species that spend more time in freshwater (chinook, coho, sockeye) are declining more than those that do not (chum, pink), in general.

Read the abstract below, or download the full article.

Report Abstract:

At DFO’s first State of the Salmon meeting in 2018, scientists concluded that Canadian Pacific salmon and their ecosystems are already responding to climate change. Northeast Pacific Ocean warming trends and marine heatwaves like “The Blob” are affecting ocean food webs. British Columbia and Yukon air and water temperatures are increasing and precipitation patterns are changing, altering freshwater habitats. The effects of climate change in freshwater are compounded by natural and human-caused landscape change, which can lead to differences in hydrology, and increases in sediment loads and frequencies of landslides. These marine and freshwater ecosystem changes are impacting Pacific salmon at every stage of their life-cycle.

Some general patterns in Canadian Pacific salmon abundances are emerging, concurrent with climate and habitat changes. Chinook numbers are declining throughout their B.C. and Yukon range, and Sockeye and Coho numbers are declining, most notably at southern latitudes. Salmon that spend less time in freshwater, like Pink, Chum, river-type Sockeye, and ocean-type Chinook, are generally not exhibiting declines. These recent observations suggest that not all salmon are equally vulnerable to climate and habitat change.

Improving information on salmon vulnerability to changing climate and habitats will help ensure our fisheries management, salmon recovery, and habitat restoration actions are aligned to future salmon production and biodiversity. To accomplish this, we must integrate and develop new research across disciplines and organizations. One mechanism to improve integration of salmon-ecosystem science across organizations is the formation of a Pacific Salmon-Ecosystem Climate Consortium, which has been recently initiated by DFO’s State of the Salmon Program.

Fraser River sockeye salmon populations recommended for listing under COSEWIC

(Globe and Mail, December 4th, 2017, by Ivan Semeniuk)

For centuries, sockeye salmon have raced up British Columbia’s Fraser River to spawn in the millions, completing an astonishing life cycle that spans four years and thousands of kilometres.

Now, scientists have determined that many populations of Fraser River sockeye are in such alarming decline that they should be listed under Canada’s Species at Risk Act.

The recommendation, announced Monday by the Committee on the Status of Endangered Wildlife in Canada, an independent scientific body that advises the federal government, is the most significant acknowledgment to date of the jeopardy facing the iconic red-bodied fish that was once the mainstay of British Columbia’s salmon industry.

For the full story visit the Globe and Mail here.

Species and population diversity in Pacific salmon fisheries underpin indigenous food security

A study just published by Holly Nesbit and Jonathon Moore at Simon Fraser University highlights the importance of population diversity in Pacific salmon fisheries.

Summary of the paper:

1. Indigenous people are considered to be among the most vulnerable to food insecurity and biodiversity loss. Biodiversity is cited as a key component of indigenous food security; however, quantitative examples of this linkage are limited.

2. We examined how species and population diversity influence the food security of indigenous fisheries for Pacific salmon (Oncorhynchus species). We compared two dimensions of food security – catch stability (interannual variability) and access (season length) – across a salmon diversity gradient for 21 fisheries on the Fraser River, Canada, over 30 years, using linear regression models. We used population diversity proxies derived from a range of existing measures because population-specific data were unavailable.

3. While both population and species diversity were generally associated with higher catch stability and temporal access, population diversity had a stronger signal. Fisheries with access to high species diversity had up to 14 times more stable catch than predicted by the portfolio effect and up to 12 times longer fishing seasons than fisheries with access to fewer species. Fisheries with access to high population diversity had up to 38 times more stable catch and three times longer seasons than fisheries with access to fewer populations.

4. Catch stability of Chinook Oncorhynchus tshawytscha and sockeye Oncorhynchus nerka fisheries was best explained by the number of populations and conservation units, respectively, that migrate past a fishery en route to spawning grounds. Similar population diversity metrics were important explanatory variables for season length of sockeye, pink Oncorhynchus gorbuscha, coho Oncorhynchus kisutch and chum Oncorhynchus keta fisheries.

5. Synthesis and applications. We show an empirical example of how multiple scales of biodiversity support food security across a large watershed and suggest that protecting fine-scale salmon diversity will help promote food security for indigenous people. The scales of environmental assessments need to match the scales of the socio-ecological processes that will be affected by development. We illustrate that upstream projects that damage salmon habitat could degrade the food security of downstream indigenous fisheries, with implications to Canadian indigenous people and to watersheds around the world where migratory fishes support local fisheries.

For the full paper, visit the Journal of Applied Ecology website.