While stranding numbers are setting new high records compared to the recent past, nesting numbers are setting new lows. Some of the nest protection projects have no nests yet and everyone wants to know "why". Here are some things to consider.
First, as many already have seen, there tends to be somewhat of a cycle in nesting numbers for loggerheads with high, medium and low years. After the last encouraging two years we were due for a low one.
Second, you may remember that in 2001 we lost a lot of adults, especially females, when the TED openings were too small. At least 1/3 of those animals would have been returning this year. But they will not be here this year or ever.
And third, there was a cold-water upwelling last summer along the entire south Atlantic Bight and it moved up into the mid Atlantic states persisting into this spring. It could have affected the turtles themselves, but more importantly, their food resources.
"Before commencing vitellogenesis [egg production], the turtle must be sexually mature, have recovered from any previous reproductive episode, and have accumulated enough energy (fat) reserves to support vitellogenesis. Vitellogenesis requires the mobilization of stored energy (fat) and its modification via the liver under the control of the endocrine system with deposition into the previtellogenetic follicles. To prepare multiple clutches of follicles to support a breeding season requires at least 8 months. The quality and quantity of food are likely to play a major role in the timing of reproduction." (Limpus and Nicholls, 2000).
The cold-water upwelling may have negatively impacted the crabs and whelks upon which loggerheads depend, thus robbing them of the necessary energy to prepare for this breeding season. The timing of the event in relation to this year’s nesting season seems relevant. All three factors may be working together to produce the unusually low nesting numbers being recorded for the entire southeast.