Disappearing Southern New England River Herring, Data Gaps, and the Need to Reinstate Incidental Bycatch Sampling in Northwestern Atlantic Commercial Fisheries.

Job, Kevin¹, Ken Sprankle², ¹CT DEEP, ²USFWS, CT River Fish and Wildlife Conservation Office, Sunderland, MA

Decades of improved water quality, fish passage projects, harvest moratoriums, and a focus on run reintroductions have afforded River Herring (RH) populations ever more favorable breeding and rearing conditions. In 2022, however, exceptionally poor, and unexpected Alewife and Blueback Herring (BBH) runs across Southern New England suggest there may be more to the RH restoration puzzle. In response, an effort was undertaken by CT DEEP staff to investigate potential causes and resolutions. This effort identified above average BBH Juvenile Abundance Index observations during the 2018 Season. The USFWS annual adult assessment has shown a strong correlation with age-4 abundance, but 2022 demonstrated the lowest adult abundance in their data time-series. Similarly, above average 2019 adult Alewife passage, large scale stocking efforts, and exceptional YOY emigration observations, coupled with high flows during the YOY emigration period suggested a strong 2019 year class of Alewives. As expected, 2019 Alewives dominated returns at the Connecticut index site in 2022, suggesting that a year class failure across species was unlikely and that at-sea mortality was more likely to blame for the low returns in 2022. In September of 2022, a group of biologists from Rhode Island, Connecticut, Massachusetts, and USFWS met to discuss the poor 2022 runs and identify factors contributing to the poor returns observed throughout the region. The group identified several localized threats but identified the lack of observer coverage monitoring incidental bycatch in the mid-water trawl and nearshore fine mesh bottom trawl commercial fisheries since 2019 as a major data gap.