Fish Radio

Excluders reduce trawler salmon bycatch
June 30, 2016                                 bycatch facts

This is Fish Radio. I’m Laine Welch – New excluders reduce salmon bycatch in trawl nets. More after this –

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When trawlers take too many salmon as bycatch when fishing for pollock, cod and other groundfish, those fisheries can shut down fast.  An example:  last year for the first time Chinook salmon caps were imposed on Gulf of Alaska trawlers in various fisheries. Boats targeting cod and flatfish tripped their cap 27-hundred Chinook cap in May, those fisheries were quickly closed by federal managers.  Kodiak and its resident processing workforce took a big hit from the early closure.

That represents, depending on how you want to calculate it, about $5 million in exvessel value and about $12 million in first wholesale value. Those numbers also don’t necessarily accommodate  the fact that there are downstream affects –  anytime you shut a fishery, in particular the trawl fisheries kind of serve as a supplement between the various salmon fisheries, state water fisheries that are also occurring, so there are other economic impacts  on processor workers, purchases in the community, utilities, other things like that were impacted by the closure. And that is definitely something the council considered when making the recommendation.  

Glenn Merrill is NOAA Fisheries Assistant Regional Administrator for the Alaska region in Juneau.

Now, a new excluder device in development for more than a decade allows Chinook and chum salmon to escape from trawl nets while keeping target species in.

 We do now have an excluder that is shown to reduce Chinook bycatch by 25-35 percent and  another design is coming on line where the Chinook bycatch is reduced by 40 percent. It reduces takes of chums as well.

John Gauvin of the Alaska Groundfish Forum presented the encouraging findings from the Bering Sea pollock fishery at the Marine Science Symposium in Anchorage.  The excluder  device is placed  near the end of the net and creates an eddy that salmon are strong enough to swim out through, but pollock are not.   For chum escapes, the key is  openings both  under and at the top of the  trawl net.

Over/under excluders allow escapement both out the top  and on the bottom. This is done by a weighted panel on the top and a floated panel on the bottom effectively allowing a double pathway. We’re thinking that Chinooks will go out thetop and chums will go out the bottom. We’ve got this thing. Our performance results so far have been 40 percent Chinook escapement and 20 percent chum escapement. For the Bering Sea the pollock loss rate has been a fraction on one percent.   

The Bering Sea pollock fleet has a bycatch cap of  60,000 Chinook salmon; for the Gulf the cap is 32,5000 Chinook for all groundfish fisheries. There are no hard caps for bycatch of chum salmon.

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Fish Radio is also brought to you by Ocean Beauty Seafoods, an Alaska corporation proudly supporting Alaska’s coastal communities and the Alaskans who depend on fishing for their livelihoods and culture.    In Kodiak, I’m Laine Welch.