Rehabilitate and release injured or accidentally caught individuals: Sea turtles

Overall effectiveness category Awaiting assessment
Number of studies: 4
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Background information and definitions

Reptiles that are injured, sick or found in a weak condition are sometimes taken in by wildlife rehabilitators, to be treated and released back into the wild. Animals may be injured or weakened due to direct interactions with human threats, for example entanglement in fishing gear, or due to natural threats such as extremes of weather caused by climate change (for example sea turtles may become ‘cold-shocked’ due to sudden severe cold weather). Often rehabilitation is carried out more for animal welfare reasons than for species conservation. However, for rare species it may be essential to preserve populations and release of such animals may provide opportunities for choosing where to augment populations. The success of such programmes can be difficult to judge without benchmark data for survival of wild-reared reptiles. It is also important to note that some of the studies summarized below have small sample sizes, and that unsuccessful attempts are less likely to have been reported.

Due to the number of studies found, this action has been split by species group, though no studies were found for amphisbaenians. See here for: Tortoises, terrapins, side-necked & softshell turtles; Snakes & lizards; Crocodilians or Tuatara.

For studies evaluating the effect of releasing reptiles that were accidentally caught in fishing gear, see Threat: Biological resource use – Establish handling and release procedures for accidentally captured or entangled (‘bycatch’) reptiles and Release accidentally caught (‘bycatch’) reptiles.

Study locations

Key messages

Four studies evaluated the effects of rehabilitating and releasing injured or accidentally caught sea turtles on their populations. Two studies were in the USA and one was in each of the Philippines and the western Mediterranean.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (4 STUDIES)

Survival (4 studies): One study in the Philippines and one controlled study in the western Mediterranean found that of 79 rehabilitated sea turtles two were found dead and two alive within 1–5 months of release, and six rehabilitated loggerhead turtles survived for at least five months following release. Two studies in the USA found that around one third of stranded sea turtles and 96% of sea turtles caught in fishing gear could be rehabilitated and released. One study also found that the chance of surviving the rehabilitation process varied with species.

BEHAVIOUR (1 STUDY)

Behaviour change (1 study): One replicated, controlled study in the western Mediterranean found that six rehabilitated loggerhead turtles showed similar behaviour to wild caught turtles across 46 of 54 comparisons.

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

A study in 2001–2011 in coastal fishing waters in the northeastern Sulu sea, the Philippines (Bagarinao 2011) reported that at least one of 79 rehabilitated sea turtles survived a minimum of four months after being released. Of 79 rehabilitated sea turtles, two were recaptured alive and two were found dead. One green turtle Chelonia mydas was recaptured alive in a fish corral an unspecified period after release. One hawksbill turtle Eretmochelys imbricata was recaptured alive in a fish corral 100 km from the release site 4–5 months later. One green turtle was found dead 1 km from the release site 4 months later. One olive ridley turtle Lepidochelys olivacea was found dead 32 km away from the release site 18 days later. In total, 79 sea turtles (green, olive ridley, leatherback Dermochelys coriacea, loggerhead Caretta caretta and hawksbill) were caught alive in fishing gear and released after a period of rehabilitation (see original paper for details). Most turtles were tagged prior to release. Turtle survival information was collected opportunistically when tagged turtles were recaptured.
Study and other actions tested
Referenced paper
Bagarinao T.U. (2011) The sea turtles captured by coastal fisheries in the northeastern Sulu sea, Philippines: documentation, care, and release. Herpetological Conservation and Biology, 6, 353-363.
A controlled study in 2003–2007 in the Balearic Islands, western Mediterranean Sea (Cardona et al. 2012) found that six rehabilitated loggerhead turtles Caretta caretta survived for several months after return to the wild, and had largely similar behaviour to 12 wild turtles. Six rehabilitated turtles were tracked for an average of 156 days following release, and half were followed for longer than wild turtles. Rehabilitated turtles showed similar behaviour to wild turtles in 46 of 54 comparisons, with four of six rehabilitated turtles showing 1–3 behavioural differences each (see paper for details). Six injured turtles were brought to a rescue centre in 2004, 2006 and 2007 due to injuries sustained from boat strikes (2 turtles, 330–332 days in captivity), deeply embedded fishing hooks (2 turtles, 137–150 days in captivity), and injured flippers from net entanglement (2 turtles, 41 days in captivity). They were released between November 2004–March 2007. Twelve wild turtles were captured by a diver in 2003–2004 while basking. All turtles had a satellite tag attached and location data was received and processed by the Argos satellite system
Study and other actions tested
Referenced paper
Cardona L., Fernández G., Revelles M. & Aguilar A. (2012) Readaptation to the wild of rehabilitated loggerhead sea turtles (Caretta caretta) assessed by satellite telemetry. Aquatic Conservation: Marine and Freshwater Ecosystems, 22, 104-112.
A study in 1986–2004 along the coast in Florida, USA (Baker et al. 2015) found that of sea turtles found live-stranded and taken for rehabilitation, just over one third survived and were released back into the wild, and more time in rehabilitation improved the chances of turtles surviving to be released. In total, 626 (37%) sea turtles survived rehabilitation and were released back into the wild, 1,047 (62%) died in rehabilitation and 27 (2%) survived but were kept in captivity. More time spent in rehabilitation increased the likelihood of turtles surviving and being released (data presented as statistical model outputs). Most deaths occurred within a few weeks of rehabilitation and successful rehabilitation took from several months to >3 years. Loggerhead turtles Caretta caretta were most likely to survive rehabilitation, followed by kemp’s ridley turtles Lepidochelys kempii, and green turtles Chelonia mydas had the lowest chance of survival (data presented as statistical model outputs). In 1986–2004, a total of 2,462 live-stranded sea turtles were taken into rehabilitation, of which 1,700 individuals had known outcomes and statistical modelling could be carried out using data from 392 individuals. Rehabilitated species included green, loggerhead, kemp’s ridley, hawksbill Eretmochelys imbricata, leatherback Dermochelys coriacea and olive ridley Lepidochelys olivacea sea turtles. Turtles were all found live-stranded along the Florida coast.
Study and other actions tested
Referenced paper
Baker L., Edwards W. & Pike D.A. (2015) Sea turtle rehabilitation success increases with body size and differs among species. Endangered Species Research, 29, 13-21.
A study in 2010–2014 in a coastal reef estuary in Mississippi, USA (Coleman et al. 2016) found that most sea turtles accidentally caught in fishing gear were able to be released after rehabilitation, but a fifth of those animals were recaptured in fishing gear. In total, 96% of rescued sea turtles were rehabilitated and released (744 of 775 individuals). However, in the third and fourth years after the release programme began, 161 turtles were recaptured incidentally in a recreational fishery. Twenty-nine turtles were recaptured three times and two turtles were recaptured six times. Time between original release and recapture ranged from 12–1,121 days and 71% of recaptures occurred within the vicinity of the release location. In total, 775 rescued live sea turtles were brought to a rehabilitation facility in 2010–2014. The majority were incidentally caught in a recreational hook and line fishery (732 individuals) and the remainder were either caught in trawl or dredge equipment or suffering from boat strikes or live strandings. Rehabilitated turtles were released after medical clearance. Turtles were individually marked, which allowed recaptures to be monitored opportunistically as they occurred. Sea turtles caught were kemp’s ridley Lepidochelys kempii (98%), loggerhead Caretta caretta (1%) or green sea turtles Chelonia mydas (1%).
Study and other actions tested
Referenced paper
Coleman A.T., Pulis E.E., Pitchford J.L., Crocker K., Heaton A.J., Carron A.M., Hatchett W., Shannon D., Austin F., Dalton M., Clemons-Chevis C.L. & Solangi M. (2016) Population ecology and rehabilitation of incidentally captured kemp’s ridley sea turtles (Lepidochelys kempii) in the Mississippi sound, USA. Herpetological Conservation and Biology, 11, 253-264.

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?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Reptile Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Breed reptiles in captivity: Tuatara Action Link	Awaiting assessment	1	Synopsis Link
Rehabilitate and release injured or accidentally caught individuals: Sea turtles Action Link	Awaiting assessment	4	Synopsis Link
Breed reptiles in captivity: Tortoises, terrapins, side-necked & softshell turtles Action Link	Awaiting assessment	28	Synopsis Link