Brodeur et al.: Summer distribution of early life stages of Theragra chalcogramma 



615 



Gulf of Alaska 



1 1 r 



166°W 164° 



162° 



"1 1 



160° 



57°N 



56° 



55° 



54° 



53° 



Figure 1 1 



Station groupings from Two-way Indicator Species Analysis displayed on a map of 

 the study area. See Table 3 for the dominant species comprising each station group- 

 ing. Also shown are the isotherms at 50 m measured at the time of sampling. 



al., 1989) and are not usually repre- 

 sented as larvae in Gulf of Alaska 

 ichthyoplankton sampling (Kendall 

 and Dunn, 1985; Rugen 2 ). Rex sole, 

 Errex zachirus, spawn in the south- 

 ern part of their range and are also 

 rarely found in ichthyoplankton col- 

 lections in the area. The other domi- 

 nant trawl species, Clupea pallasi, 

 spawns demersally in shallow water, 

 and the early life stages are gener- 

 ally restricted to nearshore environ- 

 ments. Conversely, several taxa that 

 are abundant in the ichthyoplankton 

 samples are not well represented in 

 the trawl sampling. These include 

 fish of small maximum size (e.g. A. 

 hexapterus, Icelinus spp., Liparis 

 spp.), nearshore distribution (e.g. B. 

 alascanus, Z. silenus, Lumpenus 

 spp.) (Hart, 1973), or mesopelagic 

 species that are found primarily off- 

 shore, but whose larvae are advected 

 onshore (e.g. Stenobrachius leucopsarus 

 Despite the limitations involved with 

 ichthyoplankton abundance surveys wi 



Table 5 



The top 10 most abundant taxa in the western Gulf of Alaska based on re- 

 search trawl surveys during the summer of 1990 and on ichthyoplankton sur- 

 veys during May and July of 1991. 



' Because larvae of Sebastes are presently not identifiable to species, all adult 

 rockfishes from the trawl survey were combined into this category. 



2 Includes larvae of Pleuronectes sp. II which are morphologically similar to 

 P. bilineatus. Adults were not distinguished in the trawl survey. 



). gear type (Suthers and Frank, 1989), our sampling 



conducting with a relatively small number of Methot trawls dur- 



th only one ing mid-summer of 1991 provided abundance 



