Red snapper recruitment to and disappearance from oil and gas platforms in the northern Gulf of Mexico

Abstract

The red snapper Lutjanus campechanus is a potentially large and long-lived species that can achieve ages approaching 60 years and weights of more than 22 kg. In the northern Gulf of Mexico, oil and gas platforms provide the preponderance of both vertical relief and hard substrate habitat for red snapper and other reef-associated fishes. In July 1998, we collected morphometric data and sagittal otoliths from 300 red snapper randomly selected from among the mortalities manifested subsequent to the explosive removal of an obsolete gas platform. Ages estimated from counts of otolith annuli ranged from 1 to 9 years among these specimens. The virtual absence of age-1 red snapper (0.68%) and the preponderance of age-2 red snapper (53%) at the platform demonstrate that red snapper recruit to platforms sometime during their second year. Truncation of the age distribution results from natural mortality, fishing mortality, and emigration to other habitats after several years of residency. Assuming this population to be typical, the age distributions of the commercial and recreational harvests suggest that oil and gas platforms serve as essential habitats for younger red snapper. Conversely, platforms may make red snapper at ages 4, 5, and 6 years more vulnerable to fishing mortality as they are perhaps being harvested in proportions greater than their numbers in the population at large.