Study

The impact of turtle excluder devices and fisheries closures on loggerhead and Kemp's ridley strandings in the Western Gulf of Mexico

  • Published source details Lewison R.L., Crowder L.B. & Shaver D.J. (2003) The impact of turtle excluder devices and fisheries closures on loggerhead and Kemp's ridley strandings in the Western Gulf of Mexico. Conservation Biology, 17, 1089-1097.

Actions

This study is summarised as evidence for the following.

Action Category

Establish temporary fishery closures

Action Link
Reptile Conservation

Install exclusion devices on fishing gear: Sea turtles

Action Link
Reptile Conservation
  1. Establish temporary fishery closures

    A replicated, before-and-after study in 1980–2000 in two coastal areas in the Gulf of Mexico, Texas, USA (Lewison et al. 2003) found that seasonal area closures to shrimp trawling in nearshore waters reduced lethal strandings of loggerhead Caretta caretta and Kemp’s ridley Lepidochelys kempii turtles. One statutory closure reduced lethal strandings of both loggerhead and Kemp’s ridley turtles for the 6–8-week duration of the closure compared to when it is not in effect (data reported as model outputs). When the second statutory closure was in effect, 6–8 Kemp’s ridley turtles were stranded inside the closed area, compared to the 13 turtles in the year prior to the closure taking effect (results were not statistically tested). Two statutory closures were implemented to restrict shrimp trawling within designated distances of Texas shores. The first excluded shrimping from all Texan Gulf of Mexico shores to 200 nm in 15 May–15 July each year (dates variable based on shrimp stocks; effective from 1981, updated in 1990). The second prohibited shrimp fishing within five miles of Padre Island on the south Texas coast from 1 December–15 July, effective from December 2000. Data from the Sea Turtle Stranding and Salvage Network (1980–2000) were used to analyse the effect of closures. Incidental turtle catch, captive-reared/head-started turtles and turtles below <10 cm were excluded from analysis.

    (Summarised by: Katie Sainsbury)

  2. Install exclusion devices on fishing gear: Sea turtles

    A replicated, before-and-after study in 1980–2000 on beaches in the Gulf of Mexico, Texas, USA (Lewison et al. 2003) found that mandating use of exclusionary grids with escape holes (‘turtle excluder device’) in a shrimp trawl fishery reduced lethal strandings of loggerhead turtles Caretta caretta. Lethal strandings of loggerhead turtles reduced by 7% after turtle excluder device use was mandated in the fishery compared to beforehand (results reported as model outputs). There was not enough data to assess the effect on Kemp’s ridley Lepidochelys kempii turtles. Data from the Sea Turtle Stranding and Salvage Network was used to analyse changes in the size and number of stranded turtles before excluder devices were mandated in the shrimp trawl fishery (1986–1990) and afterwards (1995–1999).

    (Summarised by: Katie Sainsbury)

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