Objectives

1. To assess abundance, seasonality, and distribution of spawning female blue crabs in the vicinity of the Mississippi barrier islands.
2. To characterize temporal and spatial variation in fecundity and egg quality of the Mississippi blue crab spawning stock.
3. To determine movements patterns of spawning female blue crabs in Mississippi waters.
4. To quantify fishing mortality on spawning female blue crabs passing through the vicinity of the Mississippi barrier islands.

Methodology

Objective 1 will be completed using a fishery independent monitoring program at Cat, Ship, and Horn Islands. Crab pots (21–36 per island per month) will be set each month during the spawning season to assess sex ratios and distribution and abundance of spawning female blue crabs.

Objective 2 will be completed using the same monthly monitoring program, using samples collected from oviparous female crabs to examine fecundity, egg size, and egg dry weight.

Objective 3 will be completed using a mark-recapture study, with 2400 crabs tagged in the vicinity of Cat, Ship, and Horn Islands. Recapture data from commercial and recreational fishers and the general public will be used to determine movement rates, trajectories, and directions for female blue crabs passing through the vicinity of the barrier islands.

Objective 4 will rely on the same mark-recapture study as Objective 3, and will use the high-value tagging method (releasing a combination of low- and high-value tags) to estimate fishing mortality from both commercial and recreational sectors.

Rationale

Blue crabs, Callinectes sapidus, support valuable commercial fisheries throughout much of their range, including the Gulf of Mexico. Gulf-wide commercial landings exceeded 23.3 metric tons in 2016 (the most recent year for which data are available) for a dockside value of over $64.5 million. Despite active management on the state level, many states have seen declines in blue crab harvest and fishery independent estimates of abundance in recent years, which could be indicative of declines in spawning stock abundance, larval abundance, and/or postlarval recruitment. Blue crab management and stock assessment efforts in the Gulf of Mexico have typically lagged behind the primary crab-harvesting states of the Atlantic Coast due to a lack of fishery independent data on spawning stock abundance and a lack of understanding of blue crab life history, connectivity and movements within and among Gulf Coast estuaries.

We seek to address reseach needs identified by the Mississippi Department of Marine Resources (MDMR) and contibute to Mississippi-Alabama Sea Grant Consortium’s priority area of Sustainable Fisheries and Aquaculture. The overarching goal of this project is to conduct a management-driven assessment of blue crab abundance, reproductive output, migratory movements, and fishing mortality in the vicinity of the Mississippi barrier islands, a valuable spawning area for blue crabs in the northcentral Gulf of Mexico. The study plan outlined here has been developed in consultation with the MDMR Shrimp & Crab Bureau.