Pelagic Habitat Use by Benthic Fishes – The Juvenile Scorpaenoids of the Oceanic Gulf of Mexico

The suborder Scorpaenoidei, containing scorpionfishes and their allies, is among the most speciose of all fish taxa. Most adult scorpionfishes live on the ocean bottom but also have a pelagic juvenile phase. Despite being one of the most speciose fish taxa, the juvenile scorpaenoids have historically been ignored as part of pelagic fish assemblages. Although the species descriptions and distributions of adult scorpaenoids within the Gulf are well documented, the assemblage dynamics of pelagic juvenile scorpaenoids is completely unknown due to their poorly resolved taxonomic status. Analysis of an extensive sample set revealed that juvenile scorpaenoids are core members of the epipelagic (upper 200 m) of the Gulf, with a frequency of occurrence in collections rivaling that of lanternfishes (Myctophidae), the dominant mesopelagic migrators of the World Ocean. Twelve unique scorpaenoid morphotypes were defined, with an emphasis on head spines, and given putative identifications. We will be elaborating upon the difficulties associated with juvenile scorpaenoid taxonomy to aid future research efforts. Trophic analysis was conducted for the dominant species of the collected scorpaenoids. The diet composition of the dissected scorpaenoids was found to be composed of the same primary prey item as in lanternfishes, the copepods. However, we determined that the scorpaenoids predate during the day and the lanternfishes predate at night.