Developing and field testing sustainable synthetic baits for the blue crab (Callinectes sapidus) fishery

Our aim was to develop for the blue crab fishery a synthetic bait that is effective, economically viable, and made from sustainable products. Our approach was to formulate mixtures of commercially available chemicals that are proven to be feeding stimulants for crustaceans. We tested several artificial mixtures: a 32-component mixture that mimics menhaden (= Menhaden Artificial Mixture), the bait used by crab fishers; and three other artificial mixtures based on shrimp muscle that are demonstrated chemostimulants for other crustacean species. We added these artificial mixtures to a matrix to create synthetic baits that release chemicals at the same rate and duration as does menhaden bait. Laboratory behavioral studies showed that these artificial mixtures, especially Menhaden Artificial Mixture, and extracts of synthetic baits containing the artificial mixtures stimulate alerting and grabbing behaviors by crabs, though less than extracts from menhaden itself. Synthetic baits were also ingested by crabs thus demonstrating that they are palatable. However, when synthetic baits containing these artificial mixtures were tested in trapping studies in the Ogeechee and Altamaha Rivers of Georgia, they caught fewer crabs than menhaden-baited traps and no more than no-bait traps. We offer several hypotheses as to why our synthetic traps with artificial mixtures that stimulate feeding behavior in the laboratory are less effective in the field than in the laboratory.