Population Variability of Four Sympatric Penaeid Shrimps (Farfantepenaeus spp.) in a Tropical Coastal Lagoon of Mexico

Abstract

Spatial and temporal variations in the relative abundance of the species and population components ofFarfantepenaeus shrimps were investigated in Celestun Lagoon, Mexico. The influence of salinity, water temperature and aquatic vegetation biomass on the distribution and abundance of shrimps was evaluated. The paper documents for the first time an annual analysis of the population variability of Farfantepenaeus notialis in its new range extension for the north-western Atlantic Ocean. A total of 11335 shrimps belonging to four Farfantepenaeus species (F. aztecus, F. brasiliensis, F. duorarum and F. notialis) were collected monthly during 1997 at three hydrological zones (seaward, middle, inner). The species represented 9·3, 25·1, 31·5 and 22·4% respectively of the total collection, the remaining 11·7% corresponding to small unidentified shrimps classified as recruits. The four penaeid species occurred throughout the year. Recruits, juveniles and subadults had a clear bimodal pattern, with a gap of 1–4 months between peaks of each population component, indicating a strong linkage between life stages. Two major peaks of recruits occurred during December–February and May–June: the first might be related to F. duorarum and F. notialis, while the second one could be attributed to F. brasiliensis and F. aztecus, suggesting differential recruitment timing. An ontogenetic spatial partitioning is also suggested to explain the observed patterns. The climatic seasons generated strong differences in temperature, salinity and aquatic vegetation biomass, which in turn affected the spatial patterns of shrimp density. The significant preference of all species, recruits and juveniles for the seaward zone highlights its strong nursery role for Farfantepenaeus species.