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Marine Turtle Newsletter 10:1, © 1979

Editorial

N. Mrosovsky

Editorials in the last two Newsletters have discussed our ignorance of turtle biology. We return to this theme again. Working independently in different parts of the world, George Balazs and Colin Limpus have been studying the growth rates of immature green turtles in natural conditions in the sea. Preliminary accounts of their findings suggest that green turtles, and some other species, may often take more than 30 years to mature: On the other hand George Hughes has suggested, on the basis of marking hatchlings with notches, that loggerhead turtles may mature in 4-6 years (Marine Turtle Newsletter No. 8, July 1978, p. 2). A difference between 4 and more than 30 years has enormous implications for management programs.

If maturation is more than 30 years ... and it seems to us that measuring carapace lengths is a more reliable way of estimating maturation than finding nesting notched turtles which could perhaps have received their notch in some natural way ... there still remain many questions to be answered. Are slow growth rates characteristic of all species and populations of sea turtles? For instance, what about ridleys? It may take the ridley arribadas in Mexico many years to recover from the extensive harvesting they are being subjected to at present (Marine Turtle Newsletter No. 7, April 1978).

It is also notable if a slow maturing animal is so prodigal with its egg production, because delayed reproduction and slow development are usually associated with high parental investment and low infant mortality (Daly, M. and Wilson, M. 1978, Sex, Evolution and Behavior, Duxbury Press, Mass. USA, p. 125). But perhaps there is some error in reasoning and marine turtles have some unusual form of growth curve, with a rapid spurt prior to first laying? We hope the important findings reported below by Balazs and by Limpus will be scrutinized and debated as much as possible.