Platform-recruited reef fish, Phase I: do platforms provide habitat that increase the survival of juvenile reef fishes?

Abstract

This paper describes work to be done and does not provide final data from that work. From the Introduction: “First, we will test whether association with oil and gas platforms during early life imparts a detectable ‘trace element isotope ratio fingerprint’ in the otoliths of juvenile reef fishes (Phase I of the project). Secondly, we will test whether adult fishes containing the ‘platform fingerprint’ in their otoliths contribute disproportionately to adult stocks on nearby natural and artificial reefs (Phase II of the project).

Results of this project will enhance our understanding of reef fish life history and provide much needed EFH information to state and federal fishery managers. Additionally, this project will establish methods and protocols for future research concerning the role platforms may play as essential fish habitat. We will employ the latest analytical techniques to develop ‘elemental isotope ratio fingerprints’ of juvenile reef fish otoliths, and then compare the elemental fingerprints between fishes collected in association with, and distant from, oil and gas platforms in the northern GOM. We have used otolith microchemical techniques similarly to distinguish (for the first time) between juvenile red snapper collected in different nursery regions of the shallow GOM. The results are briefly summarized below as a ‘proof of concept’. We reason that if oil and gas platforms provide high quality habitat and refuge from shrimp trawls, then high numbers of adult recruits should be derived from the pool of individuals who utilize said habitat, particularly off Louisiana and other areas where natural habitat is scarce. By focusing on recruitment to adult populations in Phase II, our quantitative approach will provide a more direct assessment of the relative contribution of different juvenile reef fish habitats than is possible via traditional habitat suitability approaches. If this method proves successful, we will be able sub-sample from otoltihs of adult fish to determine age-specific habitat affinity, and to determine if the new recruits nowexpanding into the eastern GOM as the red snapper population rebuilds were associated with oil and gas platforms during some portion of their early life."