Fish Habitat: Essential Fish Habitat and Rehabilitation

Abstract

<em>Abstract.</em> —The Magnuson-Stevens Fishery Conservation and Management Act (Magnuson-Stevens Act) of 1996 requires the identification of essential fish habitat (EFH) for fishery species under federal fishery management plans (FMPs). As defined in the Magnuson-Stevens Act, EFH includes waters and substrate necessary for spawning, breeding, feeding, or growth to maturity. Without EFH, fishery species will be unable to maintain the productivity needed to support a sustainable fishery or contribute ecologically to aquatic ecosystems. The highly productive estuaries in the northern Gulf of Mexico contain many habitat types that are potentially essential for species under FMPs such as brown shrimp <em>Penaeus aztecus, </em> white shrimp <em>P. setiferus</em> , pink shrimp <em>P. duorarum, </em> gulf stone crab <em>Menippe adina, </em> red drum <em>Sciaenops ocellatus</em> , gray snapper <em>Lutjanus griseus</em> , and bluefish <em>Pomatomus saltatrix</em> ; these species spend their juvenile life stages in estuarine nurseries. Estuarine habitats also may be important for prey required as forage by managed species and for other fishery species not under FMPs. My objective in this paper was to summarize information on densities of juvenile fishery species and other animals (all generally <100 mm total length) in shallow-water estuarine areas of Texas and Louisiana. I attempted to identify where these species live (delineate their habitat) and to analyze density patterns within habitats that would be useful in distinguishing EFH. My analysis was restricted to data collected with enclosure sampling techniques because these techniques have been shown to provide comparable density estimates among highly diverse shallow-water areas. Habitat types evaluated included <em>Spartina alterniflora </em> marsh edge (SAME), mixed-vegetation marsh edge, inner marsh (>5 m from open water), submerged aquatic vegetation (SAV), oyster reefs, and shallow nonvegetated bottom (SNB). Data also were categorized by season, salinity regime, estuarine system, and year of collection. Mean densities among habitat types frequently varied in relation to salinity regime, but overall, SAME was used most by brown shrimp, white shrimp, blue crab <em>Callinectes sapidus</em> , spotted seatrout <em>Cynoscion nebulosus</em> , and southern flounder <em>Paralichthys lethostigma</em> . Highest densities of pink shrimp, red drum, and sand seatrout <em>Cynoscion arenarius </em> were found in SAV. Stone crabs had highest mean densities on oyster reefs and gulf menhaden <em>Brevoortia patronus </em> on SNB. Each of the six habitat types examined ranked first or second in use by at least one of these fishery species. Thus, all of these habitat types are likely essential for some fishery species. The analysis highlighted many of the challenges confronted in determining habitat-use patterns and emphasized the need for additional systematic sampling to examine geographic variability in habitat use and to examine distribution patterns within habitats. However, in addition to analyses of intrahabitat densities, the identification of EFH requires information on functional relationships between fishery species and habitat characteristics.