Fish & Wildlife | Ecotrope

What Happens To The Crab Fishermen Throw Back?

Ecotrope | Aug. 24, 2012 11:03 a.m. | Updated: Feb. 19, 2013 1:30 p.m.

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Remember when Oregon’s Dungeness crab fishery became certified sustainable?

The Marine Stewardship Council gave the fishery its stamp of approval in 2010. That means Oregon crab has more appeal among eco-conscious consumers and could sell for a higher price.

But that’s not the end of the story.

Thousands of Oregon Dungeness crab get caught and eaten every year, but the undersized males and female crab that come up in the pots get thrown back in the ocean. As part of the fishery's sustainable seafood label, the industry has hired a researcher to study whether crab being caught and thrown back suffer any stress or delayed mortality from being handled by fishermen.

Thousands of Oregon Dungeness crab get caught and eaten every year, but the undersized males and female crab that come up in the pots get thrown back in the ocean. As part of the fishery's sustainable seafood label, the industry has hired a researcher to study whether crab being caught and thrown back suffer any stress or delayed mortality from being handled by fishermen.

Altogether, Oregon crabbers are spending between $50,00 and $80,000 a year on studies that support MSC’s conclusion that the fishery is indeed sustainable.

In one study that caught my attention, Oregon State University Ph.D student Noelle Yochum is looking at how many crab die after being thrown overboard by fishermen.

Oregon crabbers can catch as many crab as their boats can carry – as long as the season is open and the crab are both male and larger than the legal size.

The “size, sex, season” management rule makes sure female and young crab aren’t caught so they can reproduce and provide crab for the next season’s fishery.

But what happens to the young crab and females that are caught in pots and tossed overboard? And what about crab that are inadvertently caught in trawl nets by groundfish boats? Yochum’s job is to find out how many of the crab that are caught and thrown back into the ocean are more likely to die afterwards. No one knows the number, she said. No one has ever studied it.

“Right now I think they’re trying to make sure it’s not some exorbitant amount,” said Yochum. “They want to make sure discard isn’t an issue.”

Furman said the study is part of proving that the crab fishery is sustainable.

“We don’t think that we’re going to find anything that’s going to create any real concern or alteration on how the fishery is done, but it will satisfy the reviewers’ curiosity and it will plug a data gap that was part of this fishery,” said Furman. “If there was mortality involved, we might want to rethink how we put crabs overboard.”

Yochum is using two primary methods to figure out whether handling crab causes harm. The first involves testing different reflexes in the crab after they’re caught to see if they’re healthy and then keeping the crab for up to a month to see if they die. By combining the two data sets, she can calculate the probability that the crab will die after being caught.

The reflexes she’s testing are interesting. She described one reflex she calls “mouth defense.” A healthy crab will defend its mouth if you try to manipulate it. A stressed and unhealthy crab will be slow to defend its mouth. Other reflexes should kick in if you tap on the crab’s eye or pull on its abdominal flap, she said.

But the reflex testing and holding method is really only designed to test for short-term impacts to crab, she said. The second method she’s using to see if the crab die later involves tagging the crab that are caught and keeping a record of how many are still alive after a year. For that study, Yochum is going to work with crabbers up and down the coast and offer a reward to fishermen who return the tags.

The first part of her study should be complete by the end of 2013, and the results of the tagging study should be in by 2014.

 

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