Projects

Ecosystems and fisheries sustainability: Assessment of estuarine population of fisheries and inverte

End Date: 01/31/07

Abstract

The Gulf of Mexico (GOM) encompasses over two million hectares of wetlands, which support a vast array of fisheries. Recent environmental trends, however, suggest that serious problems exist in the GOM with the potential to affect fisheries production. As the recipient of drainage from two-thirds of the contiguous United States, the GOM receives approximately 13 million pounds of toxic substances annually according to the U.S. EPA. Combined with environmental perturbations associated with growth and development in the coastal zone and economic overcapitalization in many fisheries, it is surprising that productivity has remained relatively stable in most fisheries.

Recent analysis of data on population abundances of estuarine-dependent fish and shellfish species suggests that current levels of productivity may not be sustainable in some fisheries in the near future. Declines in species of estuarine finfish and shellfish have recently been detected in long-term fisheries independent data in Mississippi and Alabama. Because multiple species are involved, observed trends may reflect diminished estuarine carrying capacity and suggest that we may be approaching a critical threshold in sustainability of fisheries resources in the GOM.

For this project, we will investigate trends in abundance of economically/ecologically important species of fish and crustaceans in Mississippi and Alabama coastal waters using long-term fishery independent survey data. Innovative analytical approaches, consisting of univariate and multivariate techniques, will be used to examine the dynamics of population fluctuations and to assess the resilience of communities to environmental perturbation. If declines are evident, we will also examine special studies of limited duration to provide additional biological and ecological information useful in assessing factors that may be responsible for observed population decreases.

Because extensive published and unpublished data are available for most blue crab life history stages in Mississippi, we will use this species to illustrate some of the proposed analytical methodologies and use of temporally/spatially limited data sets. Results from a preliminary assessment of the Alabama data will illustrate some of the intended multivariate data analysis techniques. Results are expected to be directly applicable to management agencies for implementation of management regulations and prioritization of research needs. They will provide a starting point toward understanding the incremental impacts of human population growth and industrial development on fisheries productivity in the northern GOM. Further, they will allow for development of strategic plans for mitigation of causative factors and for developing predictive tools incorporating the widespread impacts of human development.

Identifying causes of observed changes, whether declining recruitment or juvenile survivorship, will dictate management actions for recovering fishery resources. Data that will provide this information can be found in currently available data sets; however, most institutions that maintain these databases are merely data holders with limited resources available for the analytical research required for detailed interpretation of long-term complex data sets. Societal benefits accrue from conservation of important coastal resources that provide commercial, recreational, and quality of life benefits. The proposed project addresses issues under the MASGC priority concerned with sustainable fisheries.

Objectives

  1. develop a database for Mississippi from existing monitoring programs and relevant specialized studies; prepare database for analysis and begin the analytical process
  2. continue analysis of long term data for Alabama using innovative univariate and multivariate analytical techniques and newly developed software applications to detect trends in abundance, community structure, and recruitment
  3. meet with relevant committees of the Gulf States Marine Fisheries Commission at their semi-annual 
  4. meetings to discuss analytical results and their interpretation.

Methodology

In Year 1, we will acquire and verify the Mississippi data and begin analysis of data. The Alabama data set has been verified and some preliminary descriptive analyses have been completed. We will continue data analysis using more innovative univariate and multivariate analytical techniques. 

Rationale

The Gulf of Mexico (GOM) produces more shrimp, finfish, and shellfish annually than the South and Mid-Atlantic, Chesapeake, and Great Lakes regions combined. At one time, the GOM was considered too vast to be affected by contaminants and fisheries resources were thought to be inexhaustible. Recent environmental trends, however, suggest that serious problems exist in the GOM with the potential to affect fisheries production. Declines in species of estuarine finfish and shellfish have recently been detected in long-term fisheries independent data in Mississippi and Alabama. Because multiple species are involved, observed trends may reflect diminished estuarine carrying capacity and suggest that we may be approaching a critical threshold in sustainability of fisheries resources in the GOM. We will investigate trends in abundance of commercially important species of fish and crustaceans in Mississippi and Alabama coastal waters using long-term fishery independent survey data. Innovative approaches, using univariate and multivariate techniques, will be used to examine the dynamics of population fluctuations and to assess the resilience of communities to environmental perturbation. This project will use existing data to aid in identification of causes of observed changes, whether declining recruitment or juvenile survivorship. Results of the proposed study will be directly applicable to management agencies for implementation of management regulations and prioritization of research needs. The results of this work will be a starting point toward understanding the incremental impacts of human population growth and industrial development on fisheries productivity in the northern GOM. Because data analyses and subsequent interpretation of results have far-reaching implications for fishery management and thus the fishing industry Gulf-wide, project information will be initially be disseminated 
through the Gulf States Marine Fisheries Commission (GSMFC) committee structure. This will allow for region-wide input to data interpretation and will provide a measure of quality control for analytical techniques employed to examine the data.