Post by Ethan Seay, Fisheries and Aquatic Sciences undergraduate student

Fish are moving out

Warming waters in the tropics are causing commercially important fish stocks to pack up and head poleward. William Cheung from the University of British Columbia states that these mid-latitude regions, which are highly dependent on fish stocks, could see declines in catch as much as 30% by the mid 21st century. Fish will probably get smaller in these regions as well… So there goes your chance of catching a trophy tarpon on that fishing trip in Belize.

Key West trophy fish size in 1957 vs. 2007. From McClenachan 2009.

Besides seeing declines in fish size as documented by Loren McClenachan, we are experiencing a loss in a valuable food source. Many of the developing countries most impacted by fewer fish lack good fisheries management, representation and stock assessments; countries and communities that are already faced with difficult conditions may have rough times ahead. These vulnerable communities’ livelihoods depend on the presence of wild fish and something must be done to rebuild stocks. A recent paper depicts how loss in fish in these areas could present a real health problem for this globally important food source.

Where are the fish going?

Moving away from the warming tropic regions is a bit easier for a fish than it is for species found on land. There are fewer barriers in the oceans and for a fish, it makes sense to move where the water suits your thermal range. Ease of movement and limited barriers presents a problem in which we don’t know the rate they are moving and whether this varies between species. Research done by Malin Pinsky reveals that fish are not moving poleward at the same rates, which may cause changes in the species composition of marine communities. This rapid movement of fish away from traditional fishing grounds has already impacted the fisheries and makes typical management tactics more difficult.

Fisheries trying to keep up

When fish move, fisherman move. But it is becoming clear that we may not be able to keep up, and it is even trickier when fish move across management borders. Further work by Dr. Pinsky has revealed that while fish are moving northward, some fisheries only shifted 10-30% as much as the targeted fish stocks. By not keeping up with the moving fish, certain areas on the edges of the fisheries range could experience overfishing and further decline.

While the mid to low latitude regions are at greatest risk, we are seeing some of these effects here at home. Salmon fishing nets in Washington waters are coming up empty for the first time…ever. This incident was the result of a large mass of warm water off the Washington coast, bringing new species of fish into close quarters with salmon, resulting in competition for food and in some cases, predation.

What can we do?

While the obvious answer is to decrease carbon emissions and try to turn back time, it’s probably best to start small and look at these issues from a fisheries perspective.

Don’t wait until it’s too late. 

Discussing issues, conducting research, and providing multiple solutions for the uncertain future in fisheries may be the key to success. Institutions like the University of Washington have been participating in the Bevan Series seminars for the past 15 years, in which students and the public are educated and discuss the state of the environment from leading researchers in the field. Discussions such as these will need to become more common in the future to enact change and raise awareness. How are we to know there is a possibility of losing a global food source if we don’t talk about it?

© 2009 National Geographic

In addition to discussing the future, research in proactive management tactics and adaptive management strategies are promising when facing such a highly variable and changing system like the ocean. By getting ahead of possible food scarcities through implementation of aquaculture and diversifying target species in at-risk communities, we can limit the impacts of climate change. When dealing with the current issue of salmon in the Puget Sound, adaptive management allows for continuous planning, monitoring and evaluating of current stocks. Recent research highlights how this may be implemented by connecting science with the public to synthesize the various opinions on causes of salmon decline.

Connect Scientists with Politicians.

It is clear that the current state of opinion on climate change varies widely across the country. In order to tackle the issues of declining fish stocks, researchers pose the idea that we must improve the relationship between scientists and policy makers to enact change. Organizations such as the Ocean Lenfast Program funds scientific research and facilitates this communication in order to inform policy decisions for environmental reform. For more information on improving science and policy interactions, check out a recent blog post by UW undergrads.