Global patterns of marine turtle bycatch

An 18 yr study (1990-2008) yielded new results on marine turtle bycatch in fishing gear. The research, led by Dr. Bryan Wallace of Duke University, is based on more than 85,000 records of snared turtles. Despite this high number, reports covered less than 1% of all fishing fleets, with little or no information from small-scale fisheries around the world.

Dr. Wallace said the conservative estimation they made is in the order of millions of sea turtles killed in the past two decades. Six of the seven sea turtle types are on the IUCN Red List of Threatened Species. Especially high rates of by-catch were found in the Mediterranean and eastern Pacific.

By-catch remains a main threat for many other marine species such as sharks, cetaceans, seabirds.

Elisa Remonato

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Photo: Marine turtles drown when trapped in fishing gear (by Projeto Tamar Brazil)

Wallace B.P., Lewison R.L., McDonald S.L., McDonald R.K., Kot C.Y., Kelez S., Bjorkland R.K., Finkbeiner E.M., Helmbrecht S., Crowder L.B. 2010. Global patterns of marine turtle bycatch. Conservation Letters.
ABSTRACT -- Fisheries bycatch is a primary driver of population declines in several species of marine megafauna (e.g., elasmobranchs, mammals, seabirds, turtles). Characterizing the global bycatch seascape using data on bycatch rates across fisheries is essential for highlighting conservation priorities. We compiled a comprehensive database of reported data on marine turtle bycatch in gillnet, longline, and trawl fisheries worldwide from 1990 to 2008. The total reported global marine turtle bycatch was ∼85,000 turtles, but due to the small percentage of fishing effort observed and reported (typically <1% of total fleets), and to a global lack of bycatch information from small-scale fisheries, this likely underestimates the true total by at least two orders of magnitude. Our synthesis also highlights an apparently universal pattern across fishing gears and regions where high bycatch rates were associated with low observed effort, which emphasizes the need for strategic bycatch data collection and reporting. This study provides the first global perspective of fisheries bycatch for marine turtles and highlights region–gear combinations that warrant urgent conservation action (e.g., gillnets, longlines, and trawls in the Mediterranean Sea and eastern Pacific Ocean) and region–gear combinations in need of enhanced observation and reporting efforts (e.g., eastern Indian Ocean gillnets, West African trawls).