Spatial and temporal variability in somatic growth of green sea turtles (Chelonia mydas) resident in the Hawaiian Archipelago
Balazs GH and Chaloupka M. 2004. Spatial and temporal variability in somatic growth of green sea turtles (Chelonia mydas) resident in the Hawaiian Archipelago. Marine Biology. 145(5):1043-1059
The somatic growth dynamics of green turtles (Chelonia mydas) resident in five separate foraging grounds within the Hawaiian Archipelago were assessed using a robust non-parametric regression modelling approach. The foraging grounds range from coral reef habitats at the north-western end of the archipelago, to coastal habitats around the main islands at the south-eastern end of the archipelago. The expected size-specific growth rate functions for four populations sampled in the south-eastern archipelago displayed a non-monotonic function, with an immature growth spurt at ca. 50-53 cm SCL (~18-23 kg) or ca. 13-19 years of age. The growth spurt for the Midway atoll population in the north-western archipelago occurs at a much larger size (ca. 65 cm SCL or 36 kg), because of slower immature growth rates that might be due to a limited food stock and cooler sea surface temperature. Expected age-at-maturity was estimated to be ca. 35--40 years for the four populations sampled at the south-eastern end of the archipelago, but it might well be >50 years for the Midway population. Significant temporal variability was also evident, with expected growth rates declining over the last 10-20 years, while green turtle abundance within the archipelago has increased significantly since the mid-1970s. This inverse relationship between somatic growth rates and population abundance suggests a density-dependent effect on somatic growth dynamics that has also been reported recently for a Caribbean green turtle stock. The Hawaiian green turtle stock is characterised by slow growth rates displaying significant spatial and temporal variation and an immature growth spurt.
- Type
- Journal Article
- Authors
- Balazs, George; Chaloupka, M.
- Units
- ALKA , KALA , PACN
- Keywords
- Chelonia mydas, green sea turtle, Growth, Hawaii, Kaneohe Bay Oahu, Kiholo Bay Hawaii, Midway Atoll, Observations, Palaau Molokai, Presence (Biodiversity), Punaluu Bay Hawaii, Reptiles, Spatial variability, Temporal variability, Threatened-Endangered-Sensitive Animals