Anatomical evidence that arribada olive ridley sea turtles Lepidochelys olivacea feed at breeding and nesting grounds to maintain high reproductive output

Abstract

Several sea turtle life histories display a capital breeding pattern, in which females stockpile resources, like fat, during reproductive quiescence to fuel fasted egg production. The olive ridley Lepidochelys olivacea nests annually, restricting resource accumulation time, which may necessitate an income-like strategy. To evaluate the breeding strategy of olive ridleys nesting in Ostional, Costa Rica, 123 females were examined during mating or nesting from mid-June to early September in 2016 and 2017. We recaptured 9 females once and 2 females twice 2-6 wk apart, and 112 other females were sorted by behavior (mating/nesting) and ovarian state (non-atretic/atretic) to determine if body condition score (BCS) or subcutaneous fat layer thickness (SQFT) declined over the season, as expected in capital breeders. We calculated BCS and measured SQFT with ultrasound to quantify stored resources, and egg number, egg mass and ovarian follicle size for reproductive output. Two different BCS calculations did not correlate with SQFT. The 2016 female SQFTs showed a capital breeding pattern, with a significantly thicker initial SQFT, and a decline when recaptured that season; 2017 showed a more income-like pattern, with thinner initial SQFTs and no change at recapture. Intestinal contents (suggesting feeding) were found more frequently in 2017, while reproductive output showed no differences. The differences in SQFT and intestinal content frequency between years suggest olive ridleys may use an intermediate breeding strategy to facilitate resilience in fecundity when facing environmental fluctuations.