Port Moller test fishery season recap

Aug 9, 2017

The Port Moller test fishery is meant to help fisherman and processors in Bristol Bay to predict the timing, composition and size of the sockeye run. This season the study did well to predict run timing, but was not as accurate sampling the run's composition.

The figure above depicts mean stock composition estimate (%) for the 9 major stocks within Bristol Bay for each spatiotemporal stratum of the Port Moller Test Fishery in 2017. Time periods are along the horizontal axis while stations are along the vertical axis. The darker the red the higher the estimate, with completely red equal to 32% and white equal to 0%
Credit Alaska Department of Fish and Game, Division of Commercial Fisheries, Gene Conservation Laboratory

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 twenty minutes each on a straight line from Port Moller out into the bay toward Cape Newenham.

KDLG’s Nick Ciolino has a recap of this year’s Port Moller test fishery and its accuracy during the 2017 Bristol Bay sockeye season.


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.”

That’s Dr. Scott Raborn. He’s a fisheries biologist for the Bristol Bay Science Research Institute and manages 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 says 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 says 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 says 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