Fat fish, snapping shrimp, and the best books about the ocean: Thursday Afternoon Dredging, January 11, 2018

Cuttings (short and sweet): 

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Turtle excluder devices: analysis of resistance to a successful conservation policy

Conservation efforts often have an associated tradeoff, and many proposed solutions are shot down because the costs are perceived to be too high. A conservation policy that benefited a charismatic endangered species with very little cost should be popular and enthusiastically adopted. However, even though turtle excluder devices greatly reduce sea turtle mortality and have very low costs, they were vigorously opposed by shrimpers. Though many factors contributed to this opposition to turtle excluder devices, analysis of quotes from newspaper articles reveals that one of the major issues was a failure of the conservation community to educate and communicate with shrimpers.

The problem

Most species of sea turtles are either threatened or endangered. Although they face many threats, a 1990 National Academy of Sciences study reached the conclusion that “drowning in shrimp trawls kills more sea turtles than all other human activities combined”. Trawling consists of dragging a large net behind a boat to catch shrimp. This fishing method has one of the highest bycatch rates of any used today, resulting in over 11 million metric tons of bycatch a year. Sea turtles breathe at the surface, and being trapped underwater in a net can be fatal if they aren’t freed in time. Adult loggerhead turtles can hold their breath for up to 45 minutes, but trawlers often wait up to four hours before hauling in their nets. This resulted in an estimated 48,000 sea turtles caught in trawl nets each year from 1973-1984 in U.S. waters, of which 11,000 died . Gulf of Mexico shrimping was particularly hard on loggerhead and kemp’s ridley sea turtles.

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