HABITAT MODELS FOR JUVENILE PLEURONECTIDS AROUND KODIAK ISLAND, ALASKA

Juveniles of four species of pleuronectid flatfishes were abundant in bays and nearshore areas around Kodiak Island, Alaska, during August 1 991 and 1992. The four most abundant species of juvenile (age-0 or age -1) flatfishes were rock sole (Pleuronectes bilineatus), flathead sole (Hippoglossoides elassodon), Pacific halibut (Hippoglossus stenolepis ), and yellowfin sole (Pleuronectes asper). These species appeared to share nursery areas; however, physical characteristics of the nursery areas occupied by each species limited the amount of true overlap amon g species. Tree-based regression of catch-per-unit-of-effort data on p hysical parameters was used to refine conceptual models of species dis tribution, which were originally based only on 1991 data. Threshold va lues of the physical parameters were specified that best discriminated among stations with different abundances. Highest abundances of age-0 rock sole were found on sand or muddy sand at temperatures greater th an 8.7 degrees C, as well as on other mixed sand stations less than 28 m deep. Age-0 flathead sole were most abundant at temperatures less t han 8.9 degrees C and on mixed mud substrates. At warmer temperatures, abundances were high only if the depth was greater than 48 m, regardl ess of sediment type. Age-0 Pacific halibut were most abundant in dept hs less than 40 m at sites more than 2.9 km outside the mouths of bays . Inside bays, halibut were found in lower abundances in water over 9. 0 degrees C and on sediments containing both sand and mud. Age-1 yello wfin sole were always found in depths less than 28 m on mixed mud subs trates. They were usually found within bays, with highest abundances a t heads of large bays more than 32 km from the bay mouth. These four m ost abundant flatfishes therefore appeared to partition the available habitat in ways that minimized resource competition.