On June 10, LMC had our first off-shore hatchling release of the season. After posting photos of the off-shore release on our Facebook page, we received a few questions from a supporter. We felt our entire fan base could benefit from the answers to the questions our fan asked. LMC Board Member, Dr. Jeanette Wyneken, answered these questions for us. Along with being an avid supporter, Dr. Wyneken is an Associate Professor at Florida Atlantic University in Boca Raton, Florida, who specializes in sea turtle research.
Will the hatchlings know what beach is home? Has there been new research that decided that beach imprinting is unnecessary?
First, hatchlings are imprinting (a kind of learning) on a region, not a specific beach. The evidence for this comes from measures of the DNA of a particular kind of organelle, the mitochondria. Those organelles are fully derived from the mother and none from the father (at least in vertebrates). So, what we see from mitochondrial DNA is that turtles nesting on the peninsula of Florida are related; those from Georgia to Virginia turtles are related; those from the panhandle are related, etc.. So turtles return to regions not specific beaches.
Second, the specific cue or experiences the turtles need to imprint is/are unknown. It may be they smell sand they hatch from, it may be they taste the water they experience, and/or it may be the specific earth’s magnetic field is important. There are lines of evidence that suggest turtles might use one or more of these. Third, turtles moving (by boat) from shore to offshore are still going from beach to what we know is an inevitable part of their nursery habitat, the Gulf Stream (– or as some term this southern part of it, the Florida Current). There is no evidence that they actually have to swim there. Whether they swim or are taken by boat, they are still move from the right shore region to the right Gulf Stream region. That may be enough.
So, why don’t we give all the turtles a lift offshore?
First, it’s important to realize that hatchlings that emerging naturally from the nest undergo a period of hyperactive swimming that distances them quickly from nearshore predators. Trapped hatchlings or those that are disoriented, or those that washback do not have such energy reserves and often are not able to distance themselves from predator rich nearshore waters.
Second, if we took all the turtles out, that assumes we know everything that is important to the turtle. We clearly don’t. When I explain this I often use a short quote that I stole from the old Chiffon margarine commercials (“It’s not nice to fool mother nature.”) and adapted to explain the issue for the nonscientist. “It’s not nice to screw with mother nature.” If the turtles are physically and behaviorally able to get offshore, that’s the best. But not all turtles are in any condition to do so. They would be dead turtles and have no chance of contributing to the future reproductive population of turtles.
By giving them a little chance to hydrate, recover and, sometimes feed, they at least have a chance when released at one of the known destinations, to become part of the future. That would not be the case if we tried to let them swim when exhausted or sick. Screwing with mother nature a little bit probably is not so bad when the other alternative is death.
Finally, there have been a few turtles that were captive for a while (years) that never allowed to crawl then swim as hatchlings. They were released as 40-60 cm turtles. Some of these turtles retained their tags (remarkably) for a decade or more and have been seen nesting in the correct regions.
Special thanks to Dr. Wyneken for answering these questions. It’s great information to have! To read more about do’s and don’ts of sea turtle nesting season, click here.