Effects of Prolonged Retention in Hatcheries on Green Turtle (Chelonia mydas) Hatchling Swimming Speed and Survival

Many sea turtle conservation projects include hatcheries where eggs are incubated and cared for, until hatchlings emerge and are released to the sea. Unfortunately, hatchlings are often retained for prolonged periods in hatchery enclosures after emerging from the sand. During this time they continuously crawl around, burning limited energy reserves, and missing valuable hours of darkness during which they would normally distance themselves from shore. We hypothesized that these forms of interference impair hatchling swimming behavior and, in turn, reduce survival rates during offshore migrations. We used hatch- lings of Chelonia mydas in laboratory experiments to determine effects of retention in hatchery enclosures on hatchling swimming speed and behavior. Our results indicate that hatchery operations have a detri- mental effect on hatchling behavior. Swimming speed decreased by over 12% with six hours of retention in the hatchery. Swimming style also varied with prolonged retention. Hatchlings frequently used a dog- paddle swimming style (rather than the more efficient powerstroke) after several hours of retention. This deviation in normal swimming style, coupled with decreased swimming speeds, likely hinders hatchling offshore migrations and reduces survival rates.