Ronald Baker

NRC Post-doctoral Proposal Abstract
 

White shrimp Litopenaeus setiferus support a highly important fishery in the northern Gulf of Mexico (GOM). Over past decades annual catch has varied widely and there is only a weak spawner stock-fishery recruitment relationship. The lack of such a relationship indicates that environmental and habitat interactions in the juvenile stages are important in determining annual recruitment of white shrimp to the fishery. The life cycle of white shrimp is typical of many fishery species in the northern GOM; adults spawn in coastal waters, and larvae are transported into estuaries where they settle in nursery habitats. Recruitment of subadults to the coastal fishery depends upon growth and mortality rates in early life stages of this species, but relatively little is known about these rates. Indices developed to predict recruitment to the fishery require a better understanding of these vital rates and the role of the environment and habitats in regulating these rates.
While the importance of estuarine habitats as nurseries for juvenile white shrimp has long been recognized, the relative importance of fluctuations in critical parameters (e.g., habitat-related mortality) to adult stock size is yet to be quantified. The goal of this study is to determine the relative importance of mortality rates in different life-stages and habitats to overall population growth of white shrimp, and to examine the ecological processes important in structuring mortality rates of critical life-stages. To achieve this goal, a number of specific objectives will be addressed:

1. Construct a life-table for white shrimp.
2. Using a matrix modeling approach, determine which life stages and habitat specific mortality rates have the greatest influence on population growth and recruitment to the fishery.
3. Refine modeled mortality rates for the estuarine life stage by measuring white shrimp mortality in an estuarine nursery and identifying related environmental and habitat factors. Examine trophic dynamics and identify environmental factors controlling prey selection by shrimp predators.