Establish temporary fishery closures

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Three studies evaluated the effects of establishing temporary fishery closures on reptile populations. Two studies were in the USA and one was in Brazil.



  • Abundance (1 study): One site comparison study in Brazil found that areas where a fishing agreement was implemented that involved seasonal fishing restrictions along with a wider set of measures had more river turtles than areas that did not implement the agreement. 
  • Survival (2 studies): One replicated, before-and-after study in the USA found that during seasonal closures of shrimp trawling there were fewer lethal strandings of loggerhead and Kemp’s ridley turtles. One study in the USA found that following the re-opening of a swordfish long-line fishery with turtle catch limits in place, loggerhead turtle bycatch reached the annual catch limit in two of three years, and when the limit was reached the fishery was closed for the rest of the year.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. 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.

    Study and other actions tested
  2. A study in 2005–2007 in pelagic waters north of Hawaii, USA (Howell et al. 2008) found that after annual catch limits were established for loggerhead turtles Caretta caretta in a swordfish Xiphias gladius shallow-set longline fishery, turtle catch reached the limit in the second year after the fishery re-opened with catch limits but was lower in the first and third year. Results were not statistically tested. In the first year after the fishery re-opened with a turtle catch limit, nine loggerhead turtles (0.004–0.049 turtles/1,000 hooks) were caught, but in the second year the catch limit of 17 turtles (0.013–0.044 turtles/1000 hooks) was reached and the fishery was closed for the rest of the year. In the third year, 12 turtles were caught (0.0–0.028 turtles/1,000 hooks). In late 2004, the fishery re-opened after a two-year shut down due the high number of loggerhead turtle catch levels. After re-opening, a catch limit of 17 turtles/year was established, after which the fishery would close for the rest of the year. In January–March 2005–2007, line deployments (2005: 520; 2006: 842; 2007: 797), hooks put out (2005: 429,580; 2006: 670,914; 2007: 689,486), and loggerhead turtle interactions were monitored. In January–March 2007, fishers were also provided daily information in electronic and paper format from a ‘TurtleWatch’ tool that recommended areas to avoid to reduce turtle interactions (see original paper).

    Study and other actions tested
  3. A site comparison study in 2009 on a flood plain with a variety of lakes and channels in Pará, Brazil (Miorando et al. 2013) found that areas that had community-based management (CBM) of fishing practices – including seasonal fishing restrictions, limiting use of gill-nets, protecting turtle nesting beaches and a ban on turtle trading – had more river turtles Podocnemis sextuberculata, Podocnemis unifilis and Podocnemis expansa than areas without CBM. The effect of different aspects of the management programme cannot be separated. Turtles were more abundant in areas with CBM (321 individuals) than in areas without CBM (33 individuals). For Podocnemis sextuberculata, abundance was higher in areas with CBM (14 individuals/1,000 m2 netting/12 hours) than in areas without (2 individuals/1,000 m2 netting/12 hours), and turtle biomass was also greater (with CBM: 20 kg/1,000 m2 netting/12 hours; no CBM: 3 kg/1,000 m2 netting/12 hours). The fishing agreement that formed the CBM programme had been in place for 20–30 years. While 13 communities in the area were a part of the fishing agreement, only two implemented the agreement. Turtle numbers were sampled at 14 sites (7 with CBM; 7 without CBM) in August–October 2009 using gill nets (15 nets/site; 215 m2 nets; 3 each of 5 mesh sizes) with help from local fishers.

    Study and other actions tested
Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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Reptile Conservation

This Action forms part of the Action Synopsis:

Reptile Conservation
Reptile Conservation

Reptile Conservation - Published 2021

Reptile synopsis

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