Distribution, abundance, and habitat associations of red tree corals (Primnoa spp.) and other sessile macroinvertebrates off southeastern Alaska

Red tree corals (Primnoa spp.) and other sessile macroinvertebrates such as the anemone Metridium farcimen and glass sponges (i.e., Rhabdocalyptus dawsoni, Farrea occa, and Heterochone calyx) provide habitat for several commercially important groundfishes and have been identified as habitat areas of particular concern by the North Pacific Fishery Management Council. Primnoa spp. exhibit extreme longevity, slow growth, and fragile, branching morphology. Because of these characteristics, red tree corals are susceptible to fishing disturbance and recovery from trawl damage appears to be quite slow. In order to identify and conserve Primnoa spp. and other sessile macroinvertebrate populations, their distribution, abundance, and habitat associations were determined off southeastern Alaska through a contract with the Alaska Department of Fish and Game. This is a necessary first step in understanding the ecological relationships of these species and their role as habitat for juvenile and adult groundfishes. Video data previously collected with the Delta manned submersible during rockfish (Sebastes spp.) stock assessment surveys in the eastern Gulf of Alaska were used for analysis. These surveys were conducted within three commercial fishing management areas off southeastern Alaska and therefore facilitated regional comparisons. Primnoa spp. were found primarily in association with boulders and high-relief rock and population densities differed significantly among management regions. Metridium farcimen was the most commonly observed macroinvertebrate species and typically occurred on boulders, high-relief rock, and rock pavement, often in association with Primnoa spp. Sponges were reported from a variety of rocky habitats and showed some species-specific habitat differences. This project demonstrates the ability to derive new information from a previously collected submersible data set for a separate objective at relatively little additional cost. A technical report detailing these results was published by the Alaska Department of Fish and Game in 2002. Fish and invertebrate associations have additionally been analyzed, and a manuscript describing all project results is in preparation.

 

Top | About Us | Site Map | Privacy Policy | Contact US | ©2004 Center for Habitat Studies