Fish Radio

Fish stomachs wanted for science

July 22, 2016

Arrowtooth flounder

This is Fish Radio. I’m Laine Welch – Fish stomachs are wanted for science. More after this –

 

Did you know that the Alaska seafood brand tops all others on menus across the nation? Learn more about the Alaska Seafood Marketing Institute at www.alaskaseafood.org.

 

Fish stomachs could help solve the mystery of why Alaska halibut are so small for their age.  One cause could be arrowtooth flounders, which are blanketing the bottom of the Gulf and out-competing halibut for food. A study in Southeast aims to find out –

The reason we’re interested in this question is that, as many people around the Gulf of Alaska know, we’ve seen reduced sizes at age of Pacific halibut. Nowadays an average size fish of the same age is about a third of the weight it once was about 30 years ago. 

Cheryl Barnes is a PhD student at the University of Alaska Fairbanks.

During the same time, there’s been a rapid increase in the abundance of arrowtooth flounder.   

People think that potentially arrowtooth is competing with halibut for space and/or prey which is limiting the growth of Pacific halibut. 

Working from NOAA’s Auke Bay Lab in Juneau, Barnes and adviser Anne Beaudreau are studying spatial and dietary overlaps between the two species. The team is analyzing Gulf bottom trawl data, and doing field studies in fishing areas around Juneau where no trawling occurs.

W’re trying to look at these two things: the space use and their prey composition from these stomachs to try and get at that.

If halibut and arrowtooth are sharing the same space, they may be eating different things to reduce competition. If the two species are in areas with little overlap, they may eat similar prey that are optimal for growth. It’s a concept called ‘resource partitioning.’

Barnes is studying the contents of over 1,000 halibut and arrowtooth stomachs collected last year from sport anglers and hopes to collect at least that many through September. Her diet study dovetails with other others that focus on environmental factors and impacts of fishing.

Size selective fishing – this idea that we have been removing the larger, faster growing individuals, it just kind of brings that average size at age down. 

If the project proves the two species are competing for food, it will fall to managers to find creative solutions. Meanwhile, Barnes wants more stomachs, either fresh or frozen, along with fish length, body weight, and where it was caught. And while the project now centers on fishing areas around Juneau, it could expand to other regions of the Gulf.

Funding comers from the Pollock Conservation Cooperative Research Center. Find links at www.alaskafishradio.com

Fish Radio is also brought to you by Ocean Beauty Seafoods – who salutes and says thanks to the men and women fishing across Alaska for their hard work and dedication. (www.oceanbeauty.com) In Kodiak, I’m Laine Welch.

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