Enrichment devices for green turtles (Chelonia mydas) reared in captivity programs

Abstract

Environmental enrichment supports the well‐being and welfare of captive animals. In the current study, the most suitable form of enrichment device for captive green turtles (Chelonia mydas) was investigated, to support head‐start programs rearing turtles for release into their natural habitat. Fifteen‐day‐old turtles (113–114 g initial weight, n = 75) were randomly distributed into 15 experimental plastic tanks, comprising 5 treatments across three pools of each condition. The turtles in the experimental groups were exposed to four forms of enrichment devices (RS, ring shape; HSQS, hollow square shape; SS, sphere shape; CS, cylinder shape), and their outcomes related to growth, feed utilization, behavior, reduction of injury from conspecifics, and several health parameters were compared to those of a control group. At the end of the 10‐week trial, the growth and feed utilization parameters did not differ across the five groups (p > .05). Of the turtles in the experimental treatments, those in the RS treatment spent more time interacting with the enrichment device, followed by the HSQS group. The percentage of wounds suffered through biting was significantly reduced in the groups exposed to enrichment devices, notably in the turtles exposed to the SS device, followed by the RS device. Significant differences between experimental groups in the specific activities of the major intestinal protein‐digesting enzymes (trypsin and chymotrypsin) were observed. There were no effects noted in the hematological parameters and the main carapace elemental profile as compared to the control treatment. These findings suggest that the RS device is most appropriate in enriching the environment of juvenile green turtles in captivity programs, as well as in zoos or aquaria.

Rehabilitation of Marine Turtles and Welfare Improvement by Application of Environmental Enrichment Strategies

“…More research needs to be conducted to determine the enrichment effect of EDs against aggressive biting behavior in flippers and tails by changing ED design, such as other shapes, sizes and colors. This study supports the notion that using EE programs contribute to the welfare and wellbeing of green turtles reared in head-start programs in Thailand [55].…”

“…The fourth case deals with the application of four EDs made of PVC to support a head-start program in the rearing of green turtle (Chelonia mydas) hatchlings before being released into their natural environment [55]. Hatchlings (15 d old) (n = 75) were distributed at random in 15 plastic tanks (3 tanks per treatment, 5 turtles per tank) and submitted to four different ED treatments and a control group (no exposure to any ED).…”

“…The outcome of each ED was compared to the control. Turtles were fed ad libitum twice daily with commercial pellets for carnivore fish, with 12:12 h light:darkness photoperiod and 100% water exchange daily before the first feeding [55].…”

Dietary protein requirement for captive juvenile green turtles (Chelonia mydas)

“…predators (Kanghae et al, 2016). This approach has been successfully applied in many regions of the word, such as Cayman Islands and wider Caribbean (Barbanti et al, 2019), China (Zhang et al, 2021), USA (Sizemore, 2002), and Thailand (Kanghae et al, 2021). However, since this species is not commercially cultivated, limited information is available regarding captive rearing conditions and feeding regimens.…”

“…For monitoring feed utilization in endangered species, specific activities of digestive enzymes extracted from feces have been assessed (Jualaong et al, 2020(Jualaong et al, , 2021Kanghae et al, 2021). The liberation of cleaved products after enzymatic reaction, relative to its standard, indicates physiological response of reared animals to dietary treatments.…”