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Port Moller test fishery looks back on predictions

August 18th | Nick Ciolino, KDLG news Print this article   Email this article  

The Port Moller test fishery is funded by a combined effort from the state and the Bristol Bay commercial fishing industry. The study is conducted by fishing a series of stations every day for 20 minutes each on a straight line from Port Moller out into the bay toward Cape Newenham.

The Port Moller test fishery has proven to be fairly accurate at predicting run timing. The schools of fish, represented by the catch at Port Moller, usually take six to nine days to swim from the test transect to the commercial fishing districts.

But this year, the data did not always accurately represent which district the fish were swimming to.

"I tried to translate the catches at Port Moller into what was going to show up in the coming days inshore, and that proved to be difficult — as it always is. We still have a lot work to do on making that particular utility accurate," said Scott Raborn, a fisheries biologist for the Bristol Bay Science Research Institute and manager of the Port Moller test fishery.

Raborn uses scale sampling to determine which district the fish caught in the test transect are heading to.

He says this season the data did not quite accurately represent the record-sized run to the Nushagak district.

"The stock compositions at Port Moller indicated certain proportions, and then once they manifested inshore, we saw that the Nushagak-Wood was underrepresented and those other stocks were over-represented. So if we can get a better handle on how many fish and which fish we're missing offshore of the transect, I think we'll be a lot better off."

When the genetics of the Port Moller catch do not reflect the genetics of the larger run, it means the sample is inaccurate and fish from different stocks are swimming around the testing stations in a pattern too random for the study.

Raborn said the patterns with which fish move in and out of the transect can change at different points in the season and skew the data.

"It's OK to miss fish off the end of the transect, as long as we are consistently missing them throughout the season, and we're missing the same proportion of each stock, but if that's fluctuating then that's causing a lot of the noise in our ability to translate what we're seeing at Port Moller to inshore."

Raborn said some years are more accurate than others ... but the unprecedented run to the Nushagak added to the challenge of this season's data collection.

He said ideal testing would require an additional boat to run the tests across the entire opening of Bristol Bay all the way from Port Moller to Cape Newenham.

Contact KDLG fisheries reporter Nick Ciolino at fish@KDLG.org or 907-842-5281.

 

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