Essential Habitat Identification for Age-0 Rockfish along the Central Oregon Coast

—The habitat needs of nearshore juvenile rockfish Sebastes spp. have rarely been studied but are an essential component of habitat identification for management. We investigated the relationships between habitat type, species composition, and growth of juvenile rockfish after settlement into nearshore reefs and estuaries in central Oregon. We identify and prioritize essential fish habitat (EFH) for blue rockfish S. mystinus and black rockfish S. melanops caught by minnow traps and by scuba divers with hand nets. Species were confirmed through genetic analysis. Our nearshore samples were dominated by blue rockfish, while estuary samples contained almost exclusively black rockfish. Settlement patterns suggest that black rockfish had a strong preference for anthropogenic habitat (docks, pilings, jetties) within the Yaquina Bay estuary. Growth was not significantly different among habitats or sampling years for either black rockfish or blue rockfish. We identify estuaries as EFH for black rockfish juveniles along the central Oregon coast and confirm nearshore reef areas as EFH for blue rockfish juveniles. Small sample sizes of juvenile yellowtail rockfish S. flavidus and widow rockfish S. entomelas suggest that estuaries are also important for these species. All marine fishes require healthy habitats for feeding, growth to maturity, and reproductive success. Identification of critical habitat for commercially exploited fish species and understanding the role of habitat in recruitment processes are essential to successful management of marine fisheries. In spite of this significant need, critical habitat requirements for many temperate marine species are still poorly known. Protection and monitoring of critical habitats require an understanding of the role habitat plays in population dynamics and ecosystem function. However, before critical habitat can be designated and protected, it must first be accurately identified. On the U.S. West Coast, concerns about the status of rockfish Sebastes spp. have prompted investigations of habitat requirements for commercially important species. The 1996 amendments to the Magnuson–Stevens Fishery Conservation and Management Act define essential fish habitat (EFH) as ‘‘those waters and substrate necessary to fish for spawning, breeding, feeding or growth to maturity’’ (National Oceanic and Atmospheric Administration 2006). This broad definition means that habitat used by all life stages of all managed species must be identified. Prioritization of habitats is needed given limited management resources and identification of critical areas for additional spatial management. Only a few managed groundfish species have been studied sufficiently to fully identify EFH, largely due to a lack of basic biological information on juvenile life history stages (Love et al. 2002). At least 62 species of rockfish inhabit the coastal waters of Pacific North America (Eschmeyer and Herald 1983; Love et al. 2002), and many of these species are important in both commercial and recreational fisheries. Insufficient data on the habitat needs of these species need to be addressed (PFMC 2005). Identification of nursery habitat for declining rockfish stocks is a critical step to conserving and rebuilding overexploited populations. In an effort to streamline the process of EFH description and identification, the National Marine Fisheries Service has adopted a four-level system based on a hierarchy of biological detail originally proposed by Minello (1999) and Able (1999). The first requirement for the establishment and description of EFH is presence–absence data (level 1). This classification simply allows elimination of areas that are not serving as habitat for species under investigation. Inference about the importance of habitat from level 1 data is limited in that it only describes the geographical distribution of a species in relation to habitat. Level 2 data include the habitat-specific densities of fish. This Subject editor: Tim Essington, University of Washington, Seattle * Corresponding author: [email protected] Received August 5, 2009; accepted October 14, 2009 Published online March 18, 2010 60 Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science 2:60–72, 2010 Copyright by the American Fisheries Society 2010 DOI: 10.1577/C09-032.1 [Article]