Estimated 2007-2013 Survival and Detection Probabilities for Atlantic Sturgeon, Based on a Long-Term Telemetry Study

The New York Bight Distinct Population Segment of Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) was provided endangered status in 2012.  Although protected under a federal moratorium since 1998, lack of recovery coupled with mortality due to commercial bycatch were listed in the final ruling determination.   We implanted 351 VEMCO Ltd. acoustic transmitters in Atlantic Sturgeon (mean 158 cm FL (range 63-236 cm) off the Delaware coast.  Using data from our arrays and members of the ACT Network, we estimated apparent survival and detection probabilities for 2009-2013.  Median apparent annual survival (0.81) was lower than expected and ranged from 0.60 (2013) - 0.93 (2010).  Annual apparent survival rates were similar among adults (female median= 0.71; male= 0.73) but markedly higher for immature fish (0.81), suggesting that mortality risk may differ by life stage.   Median monthly detection probabilities were relatively high (0.35) and consistently followed a bi-modal distribution with a major peak in the spring, marked decrease in summer, a smaller fall peak, and approaching zero in the winter following seasonal migration patterns.  Our findings underline the value of long term collaborative studies to better inform the management of highly migratory and difficult to sample species including Atlantic sturgeon.