Early Life Ecology of Dolphinfishes in the Northern Gulf of Mexico

Dolphinfish (Coryphaena hippurus) and pompano dolphinfish (C. equiselis) are economically and ecologically valuable pelagic species found in tropical and subtropical waters worldwide. Although they support both commercial and recreational fisheries, knowledge of their habitat use and ecology during early life is limited. The aim of this study is to examine the distribution and abundance of dolphinfish larvae in the northern Gulf of Mexico, and assess the role of this region as spawning and/or nursery habitat of both species.  Larvae of both species were collected during ichthyoplankton surveys of surface waters in the northern Gulf off of Texas and Louisiana (27 – 28° N 87 - 93° W) during June and July of 2007 and 2008. Dolphinfish larvae were relatively common in our sampling area (frequency of occurrence 56%) and of the 569 larvae collected during this study, 89.9% were C. hippurus. Distribution and abundance of both C. hippurus and C. equiselis larvae varied temporally with catch numbers highest in 2007 and densities peaking during June surveys in 2007 and 2008 (16.04 and 2.80 larvae per 1000 m² for C. hippurus and C. equiselis, respectively). The effect of several environmental conditions on catch was examined, and we observed that density of larvae was inversely related to sea surface height (SSH), suggesting that cold-core features (negative SSH) may represent an important nursery habitat for dolphinfish in this region.  Results of this study indicate that C. hippurus and C. equiselis larvae are abundant throughout the northern Gulf and that this region may represent important spawning/nursery grounds for these species.