Projects

Estimating the absolute abundance of red snapper in the U.S. Gulf of Mexico

End Date: 10/1/19

Objectives

This research initiative addresses one of the most pressing issues currently facing U.S. Gulf of Mexico (Gulf) fisheries management – estimating the absolute abundance of red snapper (Lutjanus campechanus). The iconic red snapper supports one of the most economically valuable finfish fisheries in the Gulf. Their immense popularity led to severe stock depletion through historical overfishing, and the stock remains overfished. Best possible management is hindered by the lack of robust abundance data. Thus, our overarching goal is to provide an independent estimate of Age-2 and older red snapper absolute abundance in the northern Gulf of Mexico. We will meet this goal by addressing the following objectives:

  1. To estimate abundance and distribution of red snapper on artificial, natural, and unknown/unconsolidated bottom habitat across the northern Gulf;
  2. To develop, optimize, and implement a large-scale survey design that can be used not only for the red snapper population estimation but also benefit future Gulf-wide population surveys;
  3. To ensure the design will result in estimates that will be used for comparison and integration into the NOAA red snapper stock assessment;
  4. To archive biological samples for future life history studies of age and growth, fecundity, and trophic ecology, and genetic population structure;
  5. To work directly with the Gulf fishing community and engage stakeholders.

Methodology

Principal investigators and collaborators in this consortium are leading fisheries scientists and statisticians with extensive experience using fishery-independent and -dependent techniques to quantify fisheries stock abundance and life history attributes of reef fishes inhabiting natural and artificial reefs and unknown/unconsolidated bottom.

Our combined expertise in these areas makes this consortium the best-qualified to apply methods that are scalable and applicable to the objectives of this proposal across the wide geographic scope of the Gulf. The analytical expertise of members of this team will ensure that appropriate models are used for expansion of habitat-associated densities to an overall absolute abundance estimate suitable for integration into the stock assessment process.

Specifically, we propose to use a suite of methodologies in a multi-regional approach that is appropriate for the regions and habitats sampled, as a single sampling method is not capable of providing abundance estimates in all habitats. We will perform direct visual counts of red snapper across the entire region and various habitats using remotely operated vehicle surveys and towed camera arrays, coupled with active acoustics for calculating fish densities and validating counts from visual surveys. Bolstering these visual approaches, well-established depletion-based methodologies will be used to provide an additional but comparable estimate of abundance. These techniques have proven successful through proof-of-concept work in the Gulf, especially for shallow areas constrained by visibility limitations. Finally, we will employ a tagging study using mark-and-recapture techniques coupled with high-reward tagging to provide an additional estimate of abundance.

Each region has specific habitat features and nuances that require this multi-faceted approach. Additionally, with proper calibration, this multilayered approach provides a means to validate any particular sampling methodology. Our group strongly believes that combining habitat-specific estimates from these distinct but reliable methodologies will provide the most robust absolute abundance estimate for Red Snapper in the Gulf.

Rationale

Red snapper support one of the most economically valuable recreational and commercial fisheries in the Gulf. The stock that was severely depleted through historical overfishing is now undergoing recovery. In accordance with the rebuilding plan and mandates set forth by the Magnuson-Stevens Reauthorization Act of 2006, severe restrictions have been imposed, particularly in the recreational sector, which has led to increasing conflict between stakeholders and federal managers.

Recent funding made available by Congress to estimate red snapper population size provides an important opportunity to conduct Gulf-wide research to address this controversial issue. The overarching goal of the proposed research initiative is to provide an independent estimate of red snapper absolute abundance in the northern Gulf of Mexico. This work, if successful, will allay much of the controversy surrounding the contentious management and build confidence in our understanding of population dynamics for this species across their range and distribution. Specifically, the independent estimate of abundance derived from the proposed research will be compared with the estimate from the stock synthesis assessment model, allowing validation and calibration of the model.

To accomplish this ambitious task, we have assembled a multidisciplinary team of the leading fisheries experts from across the entire U.S. Gulf region and beyond. These individuals have extensive experience conducting red snapper research and have produced some of the most robust data sets available, maintain active research programs, and are knowledgeable in the intricate sampling techniques and specific analytical skills needed for making this difficult population abundance estimation in locations that are unique from region to region. The detailed design, proposed methodology, and resultant estimate of absolute abundance will allow managers to make the most informed management decisions concerning this iconic and controversial Gulf species.