First observation of the use of coral habitat by larval northern rockfish (Sebastes polyspinis) in the western Gulf of Alaska

Abstract

— The role of deepwater corals and sponges in the life history of fish species is generally unknown for the larval stage. In 2017, we deployed an autonomous plankton pump into deepwater coral habitat (depths: >50 m) to examine which species were present and captured a single rockfish larva. Using genetic methods, we identified the larva as a northern rockfish ( Sebastes polyspinis ). The unique capture of a free-swimming larva with a plankton pump in this study is the first in situ record of the use of deepwater coral habitat by rockfish larvae. Subsequent reex- amination of coral specimens captured in bottom- trawl surveys that had been conducted in the Gulf of Alaska yielded an additional 10 northern rockfish larvae and a single harlequin rockfish ( S. variegatus ) larva lodged in the pol- yps of 2 species of deepwater coral. The results of this study improve our knowledge of the early life history of rockfish species, a taxonomic group that has limited lifetime dispersal indicated by a high degree of population structure. The capture and identification of the larva also indicate a potential mechanism for larval retention in the area of their extrusion and highlight the further importance of deepwater coral habitat as essential habitat for rockfish species.