Researchers tackle unseen crab mortality in Alaskan groundfish fisheries, win best paper award.

“The only way to have a substantial harvest of flatfish species is with a trawl. The question is how to make trawl fishing as sustainable as possible,” said Craig Rose, a biologist with NOAA’s Alaska Fisheries Science Center and the lead author of the study. “Some people think that’s not a tractable question. I believe it is.” This research would not have been possible without the participation of fishermen. Read more here 14:57


    Like many studies of this type the research methods have some pretty obvious flaws. It would be difficult to discern if the underbags were causing mortality in the more compressed condition of the lower trawl as opposed to the raised trawl. (I have participated in this type of research for NOAA’s “Fish Behavior in Trawls.” study.) Since crab have an injury defense that reqhires burying themselves in the mud on the sea floor, retaining them in tanks would inhibit some of their ability to survive.

    I wonder if raised bottom sweeps will be as effective as avoiding areas with dense populations of crab. The study I participated in lead to wide spread bottom trawl closure areas that assured the continued health of the crab stock.
    Ironically the flat fish trawlers cleaned up all of the old crab gear that was “ghost fishing,” helping the crab survive the early pot fisheries that did not have degradable escape panels.