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Fishery Bulletin 98(4) 



herring fisheries of southern British Columbia (Shultz et 

 al., 1932). 



Both years in which Pacific sardines were observed in 

 southeastern Alaska were exceptionally warm and at the 

 end of strong El Nino periods. The occurrence of sardines 

 in Alaska reported in our study followed the exceptionally 

 strong 1997-98 El Nino and is similar to the 1931 occur- 

 rence of Pacific sardines in Alaska, which followed the 

 1930-31 El Niiio. Increased water temperature associated 

 with El Niiio events typically results in northward range 

 extensions and anomalous distributions of fishes (Radov- 

 ich, 1961; Schoener and Fluharty 1985; Mearns, 1988). 

 Although not specifically associated with sardines, several 

 fishes were recorded north of their normal ranges during 

 the 1930-31 (Walford. 1931; Mearns, 1988), 1982-83, and 

 1997-98 El Nihos (Table 2). Included in 1997-98 records 

 is an unconfirmed report of coho salmon, Oncorhynchus 

 kisutch, feeding on northern anchovy, Engraulis mordax, 

 near Yakutat, Alaska. Northern anchovy previously have 

 not been reported north of the Queen Charlotte Islands, 

 British Columbia. Interannual variations of El Niiios and 

 their effects on the distribution of marine organisms 

 are difficult to assess because adequate time series data 

 are lacking (Schoener and Fluharty. 1985), especially for 

 Alaska coastal waters before 1960. In addition, not all 

 unusual occurrences associated with El Ninos are range 

 extensions. More frequently, these occurrences are the 

 result of anomalous strayings beyond normal ranges or 

 are the result of changes in abundance or shifts in habi- 

 tats (Table 2). 



Although water temperature is a factor determining sar- 

 dine distribution (Radovich, 1961), other factors may deter- 

 mine abundance and whether a range extension persists. 

 Most Pacific sardine spawning occurs off southern Califor- 

 nia at 15-18°C temperatures (at a lower threshold limit 



Table 2 



Inter-El Nifio comparison of unusual northern occurrences 

 of marine fishes in Alaska coastal waters. Occurrences 

 were coded according to Schoener and Fluharty (1985). E 

 = range extension, H = habitat anomaly, A = range anom- 

 aly, C = change in abundance (+ or -). Sources: 1930-31 

 (Shultz et al., 1932); 1957-58 (Radovich, 1961); 1982-83 

 (Karinen et al., 1985; Pearcy and Schoener, 1987); 1991-94 

 (Wing, unpublished files); 1997-98 (Wing, unpubl. files). 



Species 



Sardinops sagax E 



Alosa sapidissima 

 Engi-aulis mordax 

 Cololabis saira 

 Sarda chdiensis 

 Scorn berjapon icus 

 Thunnus alalunga 

 Thunnus thynnus 

 Senola lalandi 

 Trachurus synimetricus 

 Merluccius productus 

 Sphyraena argentea 

 Mola mola 

 Bra ma Japan ica 

 Atractoscion nohilis 

 Balistes polylepis 

 Prionace glauca 

 Carcharodon carcharias 



