Abstract. — Species diversity 

 and abundance offish eggs in shelf 

 waters of the western Gulf of 

 Alaska were similar in both surface 

 neuston net tows and subsurface 

 bongo net tows, but a unique group 

 of fish larvae appear to be associ- 

 ated with the neuston in this re- 

 gion. The dominance of larvae of an 

 osmerid, several hexagrammids, 

 cottids, bathymasterids, Anoplo- 

 poma fimbria, Cryptacanthodes 

 aleutensis, and Ammodytes hexap- 

 terus in this group resembles the 

 neustonic assemblage offish larvae 

 found in the California Current 

 region along the U.S. west coast 

 and most of these taxa are consid- 

 ered obligate members of the neus- 

 ton. Several taxa, however, appear 

 to be abundant in the neuston only 

 at night suggesting a facultative 

 association with the neuston through 

 a diel pattern of vertical migration. 

 The facultative association of cer- 

 tain species of larvae with the neus- 

 ton varies with larval size. 



The distribution patterns ob- 

 served for most taxa of fish larvae 

 in the neuston during this study 

 suggest that during spring, spawn- 

 ing and emergence of larvae into 

 the plankton and subsequently into 

 the neuston take place mainly 

 around Kodiak Island (except along 

 the seaward side) and along the 

 Alaska Peninsula to the southwest. 

 Analysis of multispecies spatial 

 patterns using recurrent group 

 analysis and numerical classifica- 

 tion did not reveal the existence of 

 more than one neustonic assem- 

 blage of fish larvae in the study 

 area. Apart from perhaps Pleuro- 

 grammus monopterygius larvae, 

 which are known to occur through- 

 out the Gulf of Alaska, and to a 

 lesser extent A. fimbria and Hemi- 

 lepidotus hemilepidotus, members 

 of this neustonic assemblage of lar- 

 vae are not commonly found in the 

 oceanic zone. 



The ecological significance of a 

 neustonic existence for larvae of 

 fish that are primarily demersal 

 spawners in the Gulf of Alaska is 

 considered to be trophic in nature. 

 Neustonic fish larvae seem to be 

 able to exploit to their advantage 

 the unique feeding conditions 

 which exist at the sea surface. 



Manuscript accepted 25 September 1994. 

 Fishery Bulletin 93:231-253 ( 1995). 



Neustonic ichthyoplankton in the 

 western Gulf of Alaska during spring 



Miriam J. Doyle 



William C. Rugen 



Richard D. Brodeur 



Alaska Fisheries Science Center 



National Marine Fisheries Service. NOAA 



7600 Sand Point Way NE. Seattle. WA 981 I 5-0070 



The Fisheries Oceanography Coor- 

 dinated Investigations (FOCI) is a 

 long-term cooperative research pro- 

 gram conducted by National Oce- 

 anic and Atmospheric Administra- 

 tion (NOAA) biological and physi- 

 cal scientists to describe processes 

 leading to recruitment variability of 

 commercially important fish and 

 shellfish stocks of the Gulf of Alaska 

 and Bering Sea (Schumacher and 

 Kendall, 1991). To date, most effort 

 has concentrated on walleye pol- 

 lock, Theragra chalcogramma, in the 

 western Gulf of Alaska, specifically 

 in Shelikof Strait and along the 

 Alaska Peninsula. Understanding 

 the dynamics of the spring spawning 

 of this species in Shelikof Strait and 

 the subsequent hatching, drift, 

 growth, and survival of the larvae, in 

 interaction with the physical and bio- 

 logical oceanographic environment, 

 have been the primary goals of FOCI. 



Ancillary to the information col- 

 lected on the early life history 

 stages of walleye pollock, are data 

 on the distribution and abundance 

 patterns of eggs and larvae of other 

 fishes that spawn in the coastal 

 waters and adjacent deeper waters 

 of the western Gulf of Alaska. These 

 observations can contribute to our 

 understanding of the biology and 

 ecology of fish populations in this 

 region and the relationships be- 

 tween their life history strategies 

 and the environment. 



Prior to the onset of FOCI inves- 

 tigations in the early 1980's, plank- 

 ton collections in the vicinity of 

 Kodiak Island were generally lim- 



ited in scope but still yielded infor- 

 mation on species composition and 

 spatio-temporal patterns in abun- 

 dance offish eggs and larvae ( Rogers 

 et al., 1979; Kendall and Dunn, 

 1985; Kendall et al. 1 ). Based on 

 early FOCI plankton collections, 

 large-scale patterns in the ichthy- 

 oplankton have been documented 

 for a more extensive portion of the 

 continental shelf along the Alaska 

 Peninsula (Rugen and Matarese 2 ; 

 Rugen 3 ). There remains, however, 

 considerable data from the more 

 recent FOCI spring cruises, the 

 analysis of which may improve our 

 understanding of the ecological re- 

 lationships among the fish popula- 

 tions inhabiting this region. 



* This paper is contribution FOCI-0 187 from 

 the Fisheries Oceanography Coordinated 

 Investigations program of the National 

 Oceanic and Atmospheric Administration. 



1 Kendall, A. W., Jr., J. R. Dunn, R. J. 

 Wolotira Jr., J. H. Bowerman Jr., D. B. Dey, 

 A. C. Matarese, and J. E. Munk. 1980. 

 Zooplankton, including ichthyoplankton 

 and decapod larvae, of the Kodiak Shelf. 

 U. S. Dep. Commer., NOAA, Natl. Mar. 

 Fish. Serv., Alaska Fish. Sci. Cent., 7600 

 Sand Point Way NE, Seattle, WA 98115. 

 Proc. Rep. 80-8, 393 p. 



2 Rugen, W. C, and A. C. Matarese. 1988. 

 Spatial and temporal distribution and rela- 

 tive abundance of Pacific cod (Gadus 

 macrocephalus ) larvae in the western Gulf 

 of Alaska. U.S. Dep. Commer., NOAA, 

 Natl. Mar. Fish. Serv., Alaska Fish. Sci. 

 Cent., 7600 Sand Point Way NE, Seattle, 

 WA, 98115. Proc. Rep. 88-18, 53 p. 



3 Rugen, W. C. 1990. Spatial and temporal 

 distribution of larval fish in the western 

 Gulf of Alaska, with emphasis on the pe- 

 riod of peak abundance of walleye pollock. 

 U.S. Dep. Commer., NOAA, Natl. Mar. 

 Fish. Serv., Alaska Fish. Sci. Cent., 7600 

 Sand Point Way NE, Seattle, WA, 98115. 

 Proc. Rep. 90-01, 162 p. 



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