Program on the Environment

The Southern Distinct Population Segment (DPS) of green sturgeon (Acipenser medirostris) is protected under the Federal Endangered Species Act as a threatened species. This species is being caught as bycatch, however, in the California halibut bottom trawl fishery. Bycatch can be fatal to the green sturgeon and affect this species’ ability to recover a stable population size. I interned with NOAA Fisheries, where I conducted an in-depth video analysis of green sturgeon behavior when interacting with bottom trawl nets. The footage was taken from cameras attached to bottom trawl nets off boats, targeting California halibut (Paralichthys californicus) and fishing out of San Francisco and Half Moon Bay, California, USA. I reviewed 18 clips of interactions (ranging from one to ten seconds long) and identified variables, including behavioral descriptions, size estimations, and likely outcome of the interaction. Additionally, I conducted a literature review on potential gear modifications for bycatch reduction. The aim of my research was to identify solutions for reducing green sturgeon bycatch, which included gear modifications. I found that while off-bottom trawl nets and nets with windows allowing green sturgeon to escape may reduce bycatch, there are other important variables to consider. For instance, the depth of the trawl and seasonal variation impacts bycatch, with late spring to early winter accounting for the highest rates. I recommend that future research focuses on determining whether off-bottom gear is an effective way to mitigate green sturgeon bycatch.