The fidelity of red snapper (Lutjanus campechanus) to petroleum platforms and artificial reefs in the northern Gulf of Mexico
Abstract
In May 2003, 125 red snapper were captured with hook and line at several platforms in a 35 km2 portion of the South Timbalier oil and gas lease blocks, 50 km south of Port Fourchon, Louisiana. Following anesthetization with MS-222, an individually coded acoustic pinger was surgically implanted into the peritoneal cavity of each fish. Each fish was also fitted with a Floy® internal anchor tag (FM-95W) bearing a contact number and offer of reward for returned tags. The incisions were sutured and sealed with veterinary glue. After a short recovery period, the red snapper were released at five platforms in the study area. Presences of individual snapper were recorded with omnidirectional acoustic receivers attached to seven platforms and to oneartificial reef, a toppled platform.
The majority of tagged snapper did not exhibit movement between or among receiver locations on a daily, weekly, or even a monthly basis, leading to a conclusion of high site fidelity over the short-term. A small number of tagged red snapper were recaptured outside the study area and displayed little movement in a uniform direction. Of the red snapper that moved, those at liberty longer moved greater distances, as though they gradually dispersed from their area of origin over time. The results of a logistic regression on the probability of a red snapper being present at its site of release suggest that the longer-term (over a period of six months) site fidelity of red snapper is much lower than the short-term fidelity, perhaps approaching zero. This result differs from previous studies that reported high fidelity over long time spans, though none of these studies were conducted at platforms off the Louisiana coast.