SYMONS, p. e. k. 



1971. Estimating distances between fish schooling in an 

 aquarium. J. Fish. Res. Board Can. 28:1805-1806. 

 VAN OLST, J. C, AND J. R. HUNTER. 



1970. Some aspects of the organization of fish schools. J. 

 Fish. Res. Board Can. 27:1225-1238. 

 WILLIAMS, G. C. 



1964. Measurement of consociation among fishes and 

 comments on the evolution of schooling. Publ. Mus. 

 Mich. State Univ., Biol. Ser. 2:349-384. 



John Graves 



Southwest Fisheries Center 



National Marine Fisheries Service, NOAA 



La Jolla, CA 92038 



FEEDING BY ALASKA WHITEFISH, 



COREGONUS NELSONI, 



DURING THE SPAWNING RUN 



It seems to be generally agreed that most 

 coregonids feed but little, if at all, during their 

 prespawning run and only minimally until 

 spawning has taken place (Wagler 1927; Hart 

 1930, 1931; Birrer and Schweizer 1936; Van Oos- 

 ten and Deason 1939; Slack et al. 1957; Qadri 

 1961; A. H. Townsend and Ray Baxter, Alaska 

 Department of Fish and Game, pers. commun.). 

 Coregonids are, however, known to feed, at least to 

 some extent, during the spawning period, but we 

 have not found any published indications of 

 whether such feeding is pre- or post-spawning of 

 the individual fish. Until the individual fish has at 

 least begun to spawn, feeding is at a very low level 

 (Wagler 1927; Hart 1930, 1931; Birrer and 

 Schweizer 1936; Jacobsen 1974). Subsequent to 

 spawning, feeding intensity increases greatly, 

 apparently compensating for the loss of condition 

 due to spawning. Coregonid and other fish eggs are 

 often an important food item at this time (Bajkov 

 1930; Jacobsen 1974). The few eggs taken by 

 presumed prespawners are probably ingested 

 incidentally to normal respiratory movements 

 rather than by deliberate feeding (Hart 1930). 



The purpose of the present paper is to document 

 an instance of active feeding by a coregonid species 

 during the prespawning run. 



The least cisco, Coregonus sardinella, and 

 Alaska whitefish (Coregonus nelsoni = C. 

 clupeaformis complex of McPhail and Lindsey 

 1970) of the rivers of interior Alaska exhibit 

 highly concentrated spawning runs. In the 

 Chatanika River, near Fairbanks, these fishes 



begin their upstream movement in late June and 

 early July. The larger fish begin their migration 

 first, moving upstream in a seemingly rather 

 indefinite fashion across the Minto Flats. As the 

 summer progresses, the fish congregate in the 

 lower reaches of the river east of the Minto Flats. 

 In the middle to latter part of September, there is a 

 concentrated upstream movement of virtually the 

 entire adult population. This is a journey of ap- 

 proximately 150 km to the spawning areas and is 

 accomplished in a period of 2 to 4 wk (Kepler 1 ; 

 Townsend and Kepler 2 ). 



On 2 October 1975, we collected 25 ( 10 males, 15 

 females) Alaska whitefish and 23 least cisco in the 

 Chatanika River near Fairbanks, Alaska. The fish 

 were seined at two locations, one approximately 

 6.6 river km below the Elliott Highway bridge ( lat. 

 65°4.5'N, long. 147°45.6'W), the other 3.1 km 

 farther downstream (lat. 65°3.7'N, long. 

 147°47.3'W) between 1000 and 1200 h. Water 

 depths were 0-2.5 m; water temperature was 

 1.5°C. These locations are within the major 

 spawning area of the least cisco in the Chatanika 

 River. A few Alaska whitefish also spawn in this 

 part of the river, but their major breeding grounds 

 lie some 15-25 km farther upstream. All the least 

 cisco were fully ripe and running eggs or milt. The 

 Alaska whitefish were all mature but not quite 

 fully ripe. Most of the eggs of the females were still 

 in fairly firm skeins. We estimated that these fish 

 would not have spawned for another 2 wk. 



The stomachs of all the fish were removed after 

 return to the laboratory in the evening and stored 

 in 10% Formalin 3 and the contents analyzed dur- 

 ing the following 2 wk. Egg counts of each stomach 

 were made by counting the eggs in each of two 

 1-ml samples, then estimating the total by 

 comparison with the total volume of eggs in the 

 stomach. 



The stomachs of all least cisco were much re- 

 duced in size. Except for one containing six fish 

 eggs and another with five unidentified seeds, all 

 were empty. By contrast, the stomachs of all the 



'Kepler, P. P. 1973. Population studies of northern pike 

 and whitefish in the Minto Flats complex with emphasis on the 

 Chatanika River. Alaska Dep. Fish Game, Fed. Aid Fish 

 Restoration, Annu. Prog. Rep. Proj. F-9-5, Job G-II- J. 14, 23 p. 



2 Townsend, A. H., and P. P. Kepler. 1974. Population 

 studies of northern pike and whitefish in the Minto Flats com- 

 plex with emphasis on the Chatanika River. Alaska Dep. Fish 

 Game, Fed. Aid Fish Restoration, Annu. Prog. Rep. Proj. F-9-6, 

 Job G-II-J. 15, 21 p. 



3 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



234 



