Mortality Rate Estimates for Sea Turtles in Mid-Atlantic and Northeast Fishing Gear, 2012-2017

Abstract

The NMFS Northeast Sea Turtle Injury Workgroup reviewed all sea turtle interactions from 2012 to 2017 recorded by the Northeast Fisheries Observer Program (n = 157) and At-Sea Monitoring (n =15), and interactions reported to the Sea Turtle Disentanglement Network (n=217). The workgroup first determined if the interaction occurred while the turtle was alive (e.g., not a carcass from the seafloor) and whether any injuries or other apparent effects were attributable to the interaction. If so, interactions were assigned one of three injury categories with associated post-interaction mortality rates, or a determination of 100% mortality was applied according to the criteria in NMFS (2017). Sea turtle records are presented by major gear type for the fishery observer records (trawl, gillnet, dredge, pot/trap gear) and by vertical fishing line, fish trap, or aquaculture gear for the entanglement records. The results are delineated by rolling 5-year periods (2012-2016; 2013-2017) to retain consistency with how previous regional results were presented and for applicability in Section 7 consultations. For the most recent 5-year time period (2013-2017), the resulting estimated mortality rate for observable interactions in trawl gear is 48%, gillnet gear is 73%, dredge gear is 40%, vertical line gear is 55% (or 61% if we include turtles that were not disentangled that we assumed died), and fish trap gear is 57%. While NMFS calculated previous mortality rate estimates for trawl, gillnet, and dredge gear, this is the first estimate of post-interaction mortality rates in vertical fishing lines (using entanglement data).