Effect of trawling on juvenile red snapper (Lutjanus campechanus) habitat selection and life history parameters

This study documents ontogenetic habitat shifts of red snapper (Lutjanus campechanus) and highlights possible impacts of shrimp trawling on age-0 fish life history parameters on the northern Gulf of Mexico (GOM) continental shelf. Red snapper were collected quarterly during 2004 and 2005 over sand, low-relief shell rubble, high-relief shell rubble, and natural high-relief reef habitats within a de facto nontrawl area and in similar habitats on the open shelf where commercial shrimp trawling occurred. Age-0 red snapper were most dense over sand and low-relief shell rubble habitats and moved to higher-relief shell rubble and natural reef habitats by age-1. Habitat-specific daily growth rates of age-0 fish were highest over sand (range 0.65-1.03 mm.day(-1)). Densities of age-0 red snapper were highest over trawled sand, but higher over nontrawled shell rubble by 6 months of age (age-0.5+). Red snapper collected over sand and low-relief shell rubble areas exposed to trawling had truncated size distributions, higher mortality estimates, and lower production potential (the latter evaluated with G-Z and P-B ratios) compared with fish over nontrawled areas of similar habitat. Results suggest that juvenile red snapper residing over nontrawled areas may have a higher probability of survival than fish in areas exposed to commercial shrimp trawling.