An assessment of juvenile Pacific Ocean perch ( Sebastes alutus) habitat use in a deepwater nursery

Abstract

It is believed that juvenile habitats are important to determining recruitment to adult fish populations through density dependence that occurs in nursery areas. For deepwater marine fishes, the characteristics of nursery areas are generally unknown. The objectives of this study were to examine a potential nursery area for juvenile Pacific ocean perch (POP, Sebastes alutus), determine the specific microhabitats used by juvenile POP, and compare the distribution of juvenile POP to adults. Juvenile POP habitat use was examined at three sites near Samalga Pass in the Aleutian Islands. Presence or absence and density estimates of juvenile POP were made from underwater video collected at 11 transects and from 6 bottom tows at the study sites. Juvenile POP were found predominantly in mixed sand and boulder substrata to the exclusion of most other habitat types. Juvenile POP were found within one body length of complex structure such as boulders, upright coral or sponges. There were higher densities of juvenile POP at the site south of Samalga Pass than at the other sites, while adult POP were found in highest abundance at the site north of Samalga Pass. An examination of large-scale patterns of juvenile and adult POP distribution indicates that juveniles use shallower depth zones on the continental shelf. Combined with the geographic separation we observed in this study, this suggests juvenile POP use nursery habitats that are different from adult POP. Conservation and management of this species should address the habitat requirements of juveniles to maintain the goal of healthy adult populations.