Seasonal Patterns of Recruitment of Juvenile Blue Crabs and Lesser Blue Crabs at a Coastal Site in Louisana

This research tested the null hypothesis that there is no seasonal variation in the recruitment, body size, and growth status of juvenile Callinectes sapidus and Callinectes similis at a soft sediment site at Port Fourchon, LA, which varied in collection salinity between 17 and 37. Monthly collections of 5- to 30.6-mm carapace width (CW) juvenile crabs were made with a push net between March 2007 and February 2009. Juvenile C. sapidus were primarily recruited in March 2007, November 2007 to February 2008, June and July 2008, and in December 2008 and January 2009, whereas the major recruitment times for C. similis were April–October 2007,March–May 2008, August through October 2008 and February 2009. The ratio of juvenile C. sapidus:C. similis was not significantly related to the ambient salinity at the time of collection. The average wet weight, dry weight, and ash-free dry weight of a standard 17.5-mm CW blue crab and lesser blue crab was determined monthly with second-degree polynomial (quadratic equations fit to the data). Juvenile 17.5-mm CW C. sapidus was considerably heavier than C. similis but the percent ash of juvenile crabs of both species was the same. Missing appendages indicative of agonistic interactions or sublethal stress of both species in all collections containing at least 10 crabs were 18.7% of juvenile C. sapidus compared with 16.3%of C. similis. RNA:DNA ratios of both species indicated robust growth potential at all collections. Agonistic pressure on juvenile crabs of both species by adult blue crabs and other predators and other juvenile crabs likely limits the population size of C. sapidus and C. similis in lower Barataria Bay