Atlantic menhaden processing plant test tagging data

Atlantic menhaden are a schooling forage fish species, which are subject to a large commercial purse seine fishery. Atlantic menhaden are harvested for reduction into fish oil and fish meal products. Historically, the Atlantic menhaden fishery was one of the largest by volume in the United States. Thus, scientists and managers wanted a better understanding of Atlantic menhaden life history including movements on an annual basis. As a consequence, an adult tagging study was conducted from 1966-1971. Adult fish were tagged each year with small metal tags inserted into the abdominal cavity of the fish. Fish were then released. Recaptures of fish occurred at the reduction plants. Magnets were placed in each plant along most of the east coast of the United States. A total of five magnets were placed throughout the plant in order to collect the metal tags as the fish were processed. Magnets were checked each day or two to collect any tags that had become attached to the magnets. As part of this project, a sub-sample of fish were aged at the Beaufort Laboratory. Tags and data on the collected tags were then returned to the Beaufort Laboratory. In order to test the efficiency of the tag recovery process, menhaden were inserted with tags and salted into the catch at specific plants. Then, researchers could determine the exact number of tags that went into a facility and the number of tags that were recaptured. This allowed for the development of capture efficiency values.