Red snapper (Lutjanus campechanus) movement patterns based on acoustic positioning around oil and gas platform in the northern Gulf of Mexico

Abstract

Offshore oil and gas platforms provide habitat for many marine fish species in the northern Gulf of Mexico. By law, the owning company is required to remove obsolete platforms. The most economical method is explosive removal, but such removals usually result in high mortalities of economically important red snapper (Lutjanus campechanus). The present study used telemetry methods to examine the movement patterns and residency of red snapper (n = 54) around three oil and gas platforms in the northern Gulf of Mexico from March 2017 to May 2018. Site fidelity was 30% yr-1 and residency time was 11 months. Water temperature and dissolved oxygen (DO) had a significant effect on fine-scale area use patterns (home range = 95 % kernel density estimates (KDE)). Salinity showed little change and was well within the tolerance range for Lutjanidae. Seasonal area use increased in the summer and fall (F(3, 257) = 27.22, P < 0.0001). Diel area use significantly differed among sites (F(23, 4255) = 8.42 P < 0.0001). Red snapper at the lighted-manned East and Center sites showed no diel area use patterns, however fish at the unlighted-unmanned West site had larger area use during the day. Fish in the present study displayed homing behavior with frequent short-term forays away from their home reef from August through November (n = 19, 88% < 4-d). Fish also showed a high affinity for platform structure (98% of all positions within or near platform structure) suggesting that offshore platforms provide important habitat for red snapper in the Gulf of Mexico. Fishing mortality was high on platforms (F = 0.75 (0.35 - 1.36, 95% confidence limit)). Natural mortality was low with only two natural mortalities during the study (M = 0.06 (0.01 - 0.22)). The present study indicated that the optimum time for explosive removal would be in August and September after fishers have removed many of the resident red snapper during the intensive fishing effort in June and July.