2013 HABITAT ASSESSMENT IMPROVEMENT PROJECTS

Improving the identification of directed fishing effort when calculating CPUE using the relationship between habitat and reef fish abundance derived from fishery independent surveys

Principal Investigator: Doug DeVries
Co-Principal Investigators: Chris Gardner, Steven Saul


kellisonProject001-b.png Reliable abundance indices are a main input to stock assessment models, and those that are uncertain or do not accurately reflect annual changes in fish populations can lead to incorrect management advice.  In the Gulf of Mexico (Gulf), because the reef fish fishery catches multiple species on any given trip, it is often difficult to identify directed fishing effort toward any one species. Ideally, this would be done by identifying trips occurring in habitats where a particular species lives, but specific location or habitat information is not collected in fishery dependent surveys in the Southeast. As a result, when constructing indices of abundance using fishery dependent data, various statistical and ad-hoc approaches are used to try and identify directed fishing effort towards the species being assessed. These approaches generally use trip species composition to infer the habitat fished during that trip and thus determine whether the species being assessed could have been caught on that trip. Although a novel concept, the efficacy of these approaches to identify species specific directed effort in Gulf reef fish fisheries has never been assessed.

 

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Examples of side scan images and ground truth photos of two major habitat types – scattered reef and sponge/gorgonian reef.

The primary objectives of this study are to determine the relationships between habitat and the presence/absence, abundance, and/or size and age structure of three commercially important reef fish species (red snapper, Lutjanus campechanus, red grouper, Epinephelus morio, and gag, Mycteroperca microlepis); and using these relationships, test the performance of data sub-setting techniques on a fishery independent dataset where the habitat of each sampling event is known. The primary dataset to be tested is the NMFS Panama City Lab reef fish stationary video survey. This survey, begun in 2005, provides annual indices of relative abundance as well as information on recruitment, demographics, and distribution of many species of exploited reef fishes on the inner and mid shelf of the NE Gulf off NW Florida. The cameras also provide detailed information on habitat associations and structure, including biotic components, as well as fish community structure. In addition, side scan data which provides detailed information on reef size, rugosity, relief, overall form (solid, scattered, ledge, etc.), and nearness to other reefs, is available for most sites sampled since 2010.

 

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Distribution and numbers of red grouper (maximum number visible in any one frame of a 20 min video) from the 2010 and 2011 Panama City lab reef fish survey.

This project will improve stock assessments by increasing understanding of how habitats affect estimates of catch per unit effort by evaluating the performance of the data sub-setting techniques used to identify directed fishing effort. This study will also identify habitat critical to three key species in the Gulf reef fish fisheries, and in some cases to specific life history stages. Determining the relationships between abundance and habitat may also improve stock assessments by enabling sampling to be stratified by habitat and allowing post-stratification of survey data by habitat, both of which would yield more accurate and precise parameter estimates. Finally, data such as this, from which the correlation between habitat and species presence/absence and abundance can be inferred, has broad applicability toward parameterizing spatial and ecosystem-based models.


Project #

13-013

InPort ID#

 

 

Region

Southeast Fisheries Science Center (SEFSC)

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