Intrapopulation variation in habitat use by two abundant coastal fish species

Decline of marine fisheries has become one of the most severe global environmental crises. In typical fishery management efforts, fish populations are often treated as homogeneous units, thereby tacitly ignoring potential intrapopulation variation within taxonomic groupings. We used acoustic telemetry and stable isotope analysis to examine movement patterns of 20 gray snapperLutjanus griseusand 20 schoolmaster snapperL. apodusin a Bahamian tidal creek and wetland. In particular, we examined (1) if intrapopulation variation in fish habitat use and movement patterns existed, (2) whether that variation was a function of body size, and (3) if there was evidence of specialization in habitat use among individuals. We found that movement varied substantially among individuals, but was independent of body size. Some individuals exhibited frequent, repeated, movements to certain areas of the study site. δ13C values of individual snapper were significantly related to movement metrics, suggesting that movement differences were related to specific patterns of foraging behavior. Our findings suggest the importance of incorporating intrapopulation niche variation—a source of variation that is often overlooked in traditional conservation and management strategies—into the study of coastal fish populations.