Environmental Factors Affecting Burrowing Behavior of Penaeid Shrimp and Catch Efficiency in Towed Nets

Juvenile penaeid shrimp are common inhabitants of estuaries in the northern Gulf of Mexico, and estimating their abundance using towed nets is a primary objective of many resource surveys. Both brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus burrow in the sediment, however, and burrowing affects catchability in these gear. The intensity of burrowing differs between the species, and in laboratory experiments under simulated daylight conditions, 89% of brown shrimp were burrowed and only 30% of white shrimp. We examined the effects of substrate type, salinity, size, density, and hunger level.  All of these factors affected burrowing in one or both species. Other studies have shown that water temperature, water clarity, and light levels are important factors affecting this behavior in shrimp. We are using these data to develop a model, predict whether shrimp are burrowed, and estimate actual abundance from trawl catch data.