MTN 9:1-2 Editorial

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Editorial

N. Mrosovsky

In a previous Newsletter (No. 8, July 1978) we reported continuing attempts to tag hatchling turtles. At least in the case of tagging hatchlings, we all know that failure to solve this problem is a serious impediment to devising rational management procedures. But we need constantly to remind ourselves of our ignorance of turtle biology because there are interventions in natural reproductive processes, taken by many people as self-evidently beneficial, that could, for all we know, have harmful long-term consequences.

Take, for example, the incubation of eggs in styrofoam boxes, a practice that is becoming increasingly embedded in established conservation procedures. What could possibly be wrong with this? Protection is afforded to eggs that might have been taken by predators or destroyed in some other way. The hatch rates are often excellent. The eggs can be cared for within a single hatchery area with minimal effort, and known numbers of hatchlings released. What could be more rewarding for a conservation officer or park warden than taking a mass of struggling hatchlings out of their boxes and letting them crawl into the sea ... hatchlings that he knows would have had much reduced chances of survival this long without his help.

The thought that this procedure may be causing imbalances in the sex ratio of the population is probably far from his mind. But studies on freshwater and terrestrial chelonians have shown that changes of only a few °C can switch sex ratios from almost 100% male to 100% female (e.g., Yntema, C.L., 1976, Journal of Morpholooy, 150, 453-462). Now incubation times for marine turtle eggs in styrofoam boxes tend to be longer, presumably reflecting lower average temperatures in above ground hatcheries. The eggs are not experiencing the same temperatures as they would naturally. For a recent example, see the report below by R. Márquez in this Newsletter.

Fortunately some biologists, notably Dr. D.W. Owens (Department of Zoology and Entomology, Colorado State University, Fort Collins, Colorado, 80523, U.S.A.) have alerted turtle conservationists to the possibility that sexual differentiation of sea turtle eggs might also be influenced by temperature. Fortunately also it has been possible to interest Dr. C.L. Yntema (Department of Anatomy, State University of New York, Syracuse, New York, 13210, U.S.A.), an expert on chelonian embryology, in working on this problem. Information about his results will be made available through this newsletter as soon as there is anything clear cut to report, but surprisingly, these endeavors have been impeded by the regrettable reluctance of certain authorities to help in providing a few clutches of turtle eggs.

Of course, whatever the outcome of these researches, styrofoam boxes will have their uses. But let us also remember that nearly all of chelonian evolution has taken place not only in the pre-styrofoam era but also in the pre-human era. There is much to be said for the conservative policy of keeping at least some stretches of any turtle beach as natural as possible as a comparison area for any attempts to improve on what the turtles are doing themselves, and as a protection against our own ignorance.