October 16, 2023
Capelin fish are critically depleted. How does climate change fit in?
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The coasts of Newfoundland and Labrador are beautiful and teeming with life, but how will a changing climate impact the oceans and marine life that call them home? Understanding and managing wild fish populations and the larger ecosystems that rely on them also means understanding where they live and breed and how climate change might be affecting them.
How is climate change impacting habitats in the northwest Atlantic?
Climate change is causing the northwest Atlantic Ocean to heat up, influencing processes like the circulation of ocean currents and direct changes to the temperatures of coastal habitats across Atlantic Canada. These factors, combined with human activities can contribute to the vulnerability of coastal ecosystems and habitats.
So, what does that mean for coastal communities and fisheries in Canada? As ocean habitats face increasing pressures from human activities and climate change, their ability to support marine animals can be impacted. This is especially true for the habitat of some of the most important fish in our ocean, such as the tiny but mighty capelin.
Capelin: tiny but important
Capelin are small schooling fish found off the coast of Newfoundland and Labrador. They provide food for people to eat and are also the main food source for many marine species such as northern cod, humpback whales and seabirds, including puffins. They are considered a keystone species in the northwest Atlantic food web, supporting the marine ecosystem. Capelin, like other forage fish, can be sensitive to environmental changes such as fluctuations in water temperature, salinity and sea ice extent. They can be considered the ‘canary in the coalmine’ of the ocean ecosystem; when capelin are in trouble, the whole ecosystem is vulnerable.
The capelin population on the northeast coast of Newfoundland and Labrador has been considered collapsed for decades. Much research has investigated why, and what is taking them so long to recover. For instance, it is now understood that pressure from both commercial fishing and natural predators affect capelin from the top down, while environmental conditions such as the availability of food, quality of habitat and climate conditions affect them from the bottom up. Another important area of research is how capelin spawning behavior – specifically where and how they spawn – may change in a warming ocean.
Capelin spawning: Where and why?
Capelin are known throughout Newfoundland and Labrador for the annual Capelin Roll, which takes place each summer across the province. During this annual spectacle, these fish roll along the beaches, depositing their eggs which stick like magnets to sediments and algae along the coast. Capelin are ‘facultative’ spawners, which essentially means that they are picky about where they lay their eggs. Some factors that influence where capelin choose to spawn are temperature, water circulation and the type of sediment on the beach or seafloor.
At the beginning of summer when the roll occurs, capelin primarily spawn near and onshore. They are also known to spawn in deeper waters, sometimes as deep as 90 meters, especially later in the summer when the temperature near and onshore is too hot for their eggs to survive.
Where capelin spawn impacts how long it takes for their eggs to hatch into larvae. For example, when they spawn near shore, their larvae emerge more quickly but are more vulnerable to air temperature, turbulent waves and a high number of predators. When capelin spawn in deeper waters, their larvae emerge later and can have less time to develop before summer ends. Therefore, the timing of when and where they spawn may have a direct impact on their survivability. With more capelin spawning in deeper waters to avoid hotter beaches, more research is needed to understand exactly how this will impact capelin – a population that has already been severely depleted by government mismanagement and overfishing.
What’s next?
Capelin are a critically important species to the Newfoundland and Labrador ecosystem, community, culture and economy. Warming waters are changing the ocean as we know it and more research is needed to better understand the impacts of climate change on capelin habitat and spawning. In the meantime, we must do everything we can to keep as many of them in the water as possible, including by closing the commercial fishery to give the population a chance at recovery. More capelin in the water means more capelin in the mouths of northern cod, puffins and humpback whales. It also means a more resilient ecosystem, one that can weather the impacts of climate change and support vibrant coastal communities throughout Newfoundland and Labrador.