Historical trends, seasonality and spatial synchrony in green sea turtle egg production

Autoregressive spectral and nonparametric time series decomposition analyses were used to describe the temporal pattern in seasonal egg production and nesting activity at green sea turtle rookeries in the Southeast Asian region. These nesting populations have experienced long-term declines due to overharvesting and incidental capture in trawl fisheries but long-term increases were also evident. There was strong spatial synchrony in temporal fluctuations attributable to regional environmental stochasticity (a Moran effect) but local density dependent factors were also, important. Nesting occurred year round with a distinct dry season peak but non-stationary seasonality was evident. There was also a 2-3 year quasi-periodicity in egg productivity that was a function of environmental stochasticity. These findings provide a basis for developing a better understanding of the dependence of sea turtle population dynamics on environmental variability and for testing the ecological validity of population models. (C) 2001 Elsevier Science Ltd. All rights reserved.