Executive Summary

In 2023, the Port Moller Test Fishery (PMTF) operated from June 11 to July 13 using two research vessels—the R/V Ocean Cat and the R/V Miss Leona. A total of 6,670 Sockeye were caught in 300 sets distributed across Stations 2-24 to provide the information used for inseason forecasting. An additional 12 sets made at and near Station 10 during June 19 and June 22 produced 414 Sockeye and helped to assess sampling error at a single station versus nearby patchiness in the passage rate. The coverage of stations and days during the 2023 test fishery was only surpassed by 2022, with only one day missed during mid-season due to weather.

The email distribution list ended the season with 1,228 email addresses, up about 11% over 2022. The median time between sample collection and stock composition release to the distribution list was a single day during the 2023 season (similar to 2022); the maximum lag time was only two days. The turnaround time for 2023 estimates was about two days faster than what has been observed since 2010. Over the entire season a total of 12 estimates were released (about three more than in previous years). The reduced turnaround time between genetic tissue collection at the PMTF and release of the stock composition estimates, as well as increased frequency and number of estimates for 2022 and 2023 was due entirely to the onboard genetics lab that allowed genotyping to be done at sea.

On June 20 and June 25, we estimated the weights of the average Sockeye passing the test fishing transect to be 5.6 lbs. These estimates agreed with the 5.5 lbs reported for inshore catch by ADF&G in their season summary. Likewise, the estimated age and stock compositions based on the PMTF reflected that of the inshore run very well.

The 2023 run was 54.5 million with 50% of C+E occurring by July 6 making it 2-days late if July 4 is the date we use to reference an “average” run timing. Run timings over the previous eight years (2015-2022) have been late (mean=3.8 days late; range=1-6). The seasonal pattern in the 2023 run was similar to 2017 and 2021 in that a dramatic increase in C+E occurred in early July following a drop off in late June mostly due to the Nushagak-Wood District. Dissimilar to any other run going back to 2011, was the subsequent multimodal pattern having substantial peaks on July 10 and 14. Unlike other years when the outer stations were fished (2018-2022) a strong second mode of catches did not occur beyond Station 12. Although, catches did increase offshore slightly compared to inshore after June 30.

Like 2022, the Daily Index was not indicative of the entry pattern for C+E during 2023. As such, we forewent publishing proximate forecasts of daily C+E during 2023. Seasonal shifts in the travel time (TT) between the test fishery and inshore likely caused fish to stack outside the districts before surging in causing the multimodal pattern in C+E that was not apparent in the Port Moller signal. Alternately, catchability unknowingly changed, which altered the return-per-index (RPI=the number of fish inshore that each catch index point at Port Moller represents). In other words, the passage rate increased more or less consistently and then subsided as the season progressed, but our ability to catch passing Sockeye likely fluctuated during the season.

Recommendations for project scope in 2024:

• Continue to sample stations across the entire fishing transect as time and effort allow using two vessels large enough to stay on the fishing transect.

• Use “smart buoys” fixed to both top ends and one bottom end of each gillnet. The surface buoys will be attached near the existing trailing floats and therefore cause no increase in the nets’ profiles. The bottom buoys can be covered with a bait bag to reduce visibility. These devices will provide:

Redundant sea surface temperatures to within 1/0th of a degree for each set.

Temperature and possibly salinity differences between the surface and bottom of the nets. Such differences may indicate the development of a thermocline.

Better estimates of sea state (wave height).

GPS coordinates that will inform us how much the net drifted in on itself (i.e., their distance apart at the beginning versus the end of each set), the direction and distance each set drifted, and how much net orientation shifted.

• Continue sampling at odd stations as time and energy allows. More samples from odd stations adjacent to an even station over consecutive days would help test the degree to which the run forms braids in the migration pattern across the transect consistent across several days. Such a phenomenon could bias the Daily Catch Index that is currently formed from a systematic sampling design at fixed stations across the transect.