Meeting Abstract
Female blue crabs undertake a seaward spawning migration, migrating from low-salinity mating grounds to high-salinity areas where spawning takes place. While the estuarine portion of the migration has been subject of much research, little is known about movement once crabs leave the estuaries. Offshore migration patterns and spawning locations determine the ultimate settlement location of offspring, which are transported passively by currents during most of their larval period, and thus drive connectivity patterns among estuaries. In March, 2016, we began a Gulf-wide mark-recapture study to examine regional-scale migratory patterns of the Gulf of Mexico blue crab spawning stock. 4,000 female blue crabs have been tagged on their journey towards high-salinity waters where they spawn. 640 crabs have been recaptured at this time, a 16% recapture rate, with numerous individuals recaptured after crossing state boundaries. Each tag possesses a unique identification number, an offer of a monetary reward, and instructions for reporting recaptured crabs and claiming the reward. A dedicated phone line, web page, and voice mailbox are available 24/7 for the reporting of captured crabs. We have also conducted directed trawl surveys in offshore areas known to be spawning habitat for female blue crabs. In addition to geographic data, reproductive analysis on females acquired from known estuaries is being completed to assess regional reproductive potentials. This project involves collaboration with state agencies, commercial crabbers, and educators, and results will help identify the extent of connectivity versus isolation of the Gulf of Mexico spawning stock(s), and the subsequent implications for larval dispersal and recruitment.
