AbStfclCt. — A midwater trawl sur- 

 vey was conducted during July 1991, 

 to examine the large-scale distribution 

 patterns of late larval and early juve- 

 nile walleye pollock, Theragra chalco- 

 gramma, and associated fish taxa in the 

 western Gulf of Alaska. Gear compari- 

 sons between the anchovy and Methot 

 trawls were conducted to evaluate 

 which was the more efficient sampler 

 for the size range of T. chalcogramma 

 present during this time of the year. 

 Both gears showed similar densities 

 through the dominant size class offish 

 caught, but the Methot trawl caught 

 significantly more T. chalcogramma in 

 the smallest (mostly larval ) size ranges 

 available. Accordingly, a grid of stations 

 was occupied in which only the Methot 

 trawl was used. 



Although 53 fish taxa were collected 

 overall in the 61 Methot trawls, the 

 majority (84%) of the larval catch con- 

 sisted of only five taxa: flathead sole, 

 Hippoglossoides elassodon ; walleye pol- 

 lock, T. chalcogramma: arrowtooth 

 flounder, Atheresthes stomias; Pacific 

 cod, Gadus macrocephalus; and uniden- 

 tified sculpins, Icelinus spp. Theragra 

 chalcogramma and G. macrocephalus 

 were the dominant (>99'7r) juveniles 

 collected in the survey. The highest 

 catches of larval (13-25 mm SL) and 

 juvenile (26-52 mm SL) T. chalco- 

 gramma were found inshore along the 

 Alaska Peninsula and near offshore is- 

 land groups. Recurrent Group Analy- 

 sis and Two-way Indicator Species 

 Analysis both showed that T. chalco- 

 gramma tended to be frequently asso- 

 ciated with a large heterogeneous 

 grouping of taxa, including G. macro- 

 cephalus, several pleuronectids, and 

 other winter-spring spawning species. 

 The rankings of the dominant taxa in 

 the Methot trawl survey exhibited a 

 greater coherence to the rankings of 

 adult fishes from bottom trawl surveys 

 in the previous year than did those of 

 an ichthyoplankton survey that used 

 bongo nets a few months earlier than 

 the Methot trawl survey. 



Summer distribution of early life 

 stages of walleye pollock, 

 Theragra chalcogramma, and 

 associated species in the 

 western Gulf of Alaska* 



Richard D. Brodeur 

 Morgan S. Busby 

 Matthew T. Wilson 



Alaska Fisheries Science Center, National Marine Fisheries Service 

 7600 Sand Point Way NE, Seattle, Washington 981 15-0070 



Manuscript accepted 15 June 1995. 

 Fishery Bulletin 93:603-618 (1995). 



The spatiotemporal distribution of 

 the pelagic early life stages of ma- 

 rine fishes is influenced by a num- 

 ber of biotic and oceanographic pro- 

 cesses. Thus, with sufficient elapsed 

 time since spawning, the distribu- 

 tion of late larvae and early juve- 

 niles of many species shows only a 

 limited relationship to the distribu- 

 tion of spawning adults. The taxa 

 that make up an assemblage of lar- 

 val fishes show a high diversity of 

 sizes, stage durations, morpholo- 

 gies, and behaviors (Moser, 1981; 

 Matarese et al., 1989; Moser and 

 Smith, 1993) that can affect their 

 distribution patterns in a dynamic 

 and fluid environment, as is the 

 situation in most coastal areas. The 

 early larval stages have received 

 the most attention from fisheries 

 oceanographers because of their 

 presumed importance in regulating 

 recruitment variability but also be- 

 cause of the ease of sampling such 

 weakly swimming organisms (Heath, 

 1992). Recent observations, how- 

 ever, have given rise to the sugges- 

 tion that later larval and early ju- 

 venile stages may be as important 

 as early larval stages in regulating 

 year-class strength (Peterman et 

 al., 1988; Campana et al., 1989; 

 Bailey and Spring, 1992), which has 

 stimulated development of new 



sampling gear to quantitatively as- 

 sess the abundance of larger ichthyo- 

 plankton and micronekton (Methot, 

 1986; Munk, 1988; Potter et al., 

 1990; Dunn et al., 1993). 



The Fisheries Oceanography Co- 

 ordinated Investigations (FOCI) 

 program is a joint effort by scien- 

 tists at the Alaska Fisheries Science 

 Center (AFSC) and the Pacific Ma- 

 rine Environmental Laboratory 

 (PMEL) to understand the biologi- 

 cal and physical processes which 

 cause variability of recruitment in 

 commercially valuable fish and 

 shellfish stocks in Alaskan waters. 

 The primary goal of the FOCI pro- 

 gram is to understand the effects of 

 the biotic and abiotic environment 

 on the early life stages of walleye 

 pollock, Theragra chalcogramma, in 

 the western Gulf of Alaska (Schu- 

 macher and Kendall, 1991). A sec- 

 ondary objective is to provide quan- 

 titative estimates of population size 

 to predict recruitment strength for 

 fisheries management (Schumacher 

 and Kendall, 1991; Bailey and 

 Spring, 1992). Other than the study 

 of Hinckley et al. (1991) in late 



Contribution 0216 from the Fisheries 

 Oceanography Coordinated Investigations 

 Program of the National Oceanic and At- 

 mospheric Administration. 



603 



