Assessing the Effects of Freshwater Inflows and Other Key Drivers on the Population Dynamics of Blue Crab and White Shrimp Using a Multivariate Time-Series Modeling Framework

Natural freshwater inflow (FWI) from rivers, streams, and rainfall maintains nutrients, sediments, and salinity regimes within estuaries. These factors, together, produce a healthy and sustainable estuary for juvenile and adult finfish and invertebrates that utilize an estuary for foraging, refuge, and reproduction. Other key drivers, such as droughts and human contributed impacts have negative effects on estuaries. Reduced FWI can affect the population dynamics of commercially and ecologically important species such as blue crab, Callinectes sapidus, and white shrimp, Litopenaeus setiferus. Past studies have indicated that less FWI is reaching the Texas coast, but little work has been done to evaluate the impacts of inflow variability on focal species inhabiting Mission-Aransas and Guadalupe estuaries. This two-part report 1) reviews studies related to blue crab and white shrimp abundances in the Mission-Aransas and Guadalupe estuaries, and 2) describes a multivariate autoregressive (MAR) analysis of the long-term Texas Parks and Wildlife Department (TPWD) fisheries independent survey species abundance data done to assess the effects of FWI and other potential drivers on local abundances of blue crab and white shrimp in the Mission-Aransas and Guadalupe estuaries.