Discussion 



Although lunar rhythmicity in marine organ- 

 isms, particularly marine invertebrates, has long 

 been recognized (Palmer 1974), lunar rhythms in 

 which a single peak of activity occurs each month 

 in fishes appear to be rare (Gibson 1978). Most 

 accounts of variations in catch rate of commer- 

 cially important species which correlate with 

 moon phase refer to clupeids (Gibson 1978). Blax- 

 ter and Holliday (1963) suggested several possi- 

 ble explanations for the apparent lunar rhythmic- 

 ity of clupeid catches including: 1) intensity of 

 moonlight, 2) effect of tides, and 3) fishermen be- 

 havior. 



Gulf butterfish are normally trawled during 

 daylight when they concentrate near bottom fol- 

 lowing nocturnal vertical migration. However, 

 this migration is difficult to describe because con- 

 ventional echo sounding equipment poorly tracks 

 gulf butterfish movement owing to atrophy of the 

 swim bladder in gulf butterfish over 100 mm 

 standard length (Horn 1970). Differences in catch 

 rates between lunar phases may be attributed to 

 changing vertical movements of gulf butterfish in 

 the water column. The lunar pattern is probably 

 not due to onshore-offshore movement out of the 

 fishery's area of operation. In the three research 

 cruises, sampling was stratified by bottom depth 

 (36-585 m) and data do not suggest horizontal 

 movements of gulf butterfish outside these 

 depths. 



In conclusion, further work on lunar rhythmic- 

 ity relationships of gulf butterfish is needed. Re- 

 sults may greatly enhance commercial and scien- 

 tific efforts in harvesting and surveying gulf 

 butterfish, respectively, by identifying alternate 

 fishing methods (e.g., midwater trawling) that 

 successfully target gulf butterfish during all 

 moon phases. 



Literature Cited 



Allen. R L., J H Render. A W Liebzeit, and G W Bane 



1986. Biology, ecology, and economics of butterfish and 

 squid in the northern Gulf of Mexico. La. State Univ., 

 Coastal Fish. Inst. Publ. 86-30, 169 p. 

 Blaxter. J. H S , AND F. G T Holliday 



1963. The behavior and physiology of herring and other 

 clupeids. In F. S. Russell (editor). Advances in marine 

 biology, Vol. 1, p. 262-393. Acad. Press, Lond. 

 Gibson, R N. 



1978. Lunar and tidal rhythms in fish. In J. E. Thorpe 

 (editor!. Rhythmic activity of fishes, p. 201-213. Acad. 

 Press, Lond. 

 Grace. M. 



1984. U.S.-Japan squid survey, 10/11-11/17/84, Nisshin 



Maru No. 201. U.S. Dep. Commer. Natl. Oceanic At- 



mos. Adm., Natl. Mar. Fish. Serv., Cruise Rep., 18 p. 

 1985. U.S.-Japan squid survey, 4/18-5/29/85, Nisshin 



Maru No. 201. U.S. Dep. Commer., Natl. Oceanic At- 



mos. Adm., Natl. Mar. Fish. Serv., Cruise Rep., 18 p. 

 Horn, M. H. 



1970. Systematics and biology of the stromateid fishes of 



the Genus Peprilus. Bull. Mus. Comp. Zool. 140:164- 



271. 

 Palmer, J. D. 



1974. Biological clocks in marine organisms. Wiley, 



Lond., 173 p. 

 SAS Institute, Inc. 



1982. SAS user's guide: Statistics. 1982 ed. SAS 



Institute, Gary NC, 584 p. 



Jeffrey H. Render 

 Robert L. Allen 



Coastal Fisheries Institute 

 Louisiana State University 

 Baton Rouge, LA 70803-7503 



MOVEMENTS OF COHO, ONCORHYNCHUS 



FJSUTCH, AND CHINOOK, O. TSHAWYTSCHA, 



SALMON TAGGED AT SEA OFF OREGON, 



WASHINGTON, AND VANCOUVER ISLAND 



DURING THE SUMMERS 1982-85 



Knowledge of the migration patterns of 

 salmonids in the ocean is an important consider- 

 ation in developing fishery management plans. 

 Catches of coded- wire tagged salmon in the ocean 

 have yielded much information on general distri- 

 bution patterns of different stocks and species of 

 salmon (see for example Hunter [1985], Garrison 

 [1985], and Howell et al. [1985]). Other studies 

 have dealt with movements of salmon tagged in 

 offshore waters of the northern North Pacific 

 Ocean (Hartt 1962, 1966; French et al. 1975; God- 

 frey 1965; Godfrey et al. 1975) and in coastal 

 waters of British Columbia, Washinton, Oregon, 

 and California (Milne 1957; Vernon et al. 1964; 

 Kauffman 1951; Van Hyning 1951; Fry and 

 Hughes 1951). Movements of juvenile salmon in 

 coastal waters of the Gulf of Alaska were studied 

 by Hartt and Dell (1986); in Georgia Strait, 

 British Columbia, by Healey (1980); and in 

 coastal waters off Oregon and Washington by 

 Pearcy and Fisher (unpubl. manuscr.)^ 



^W. C. Pearcy and J. P. Fisher. Migration of coho salmon 

 (Oncorhynchus kisutch ) during their first summer in the 

 oceans. Unpubl. manuscr. College of Oceanography Oregon 

 State University, Corvallis, OR 97331. 



FISHERY BULLETIN: VOL. 85, NO. 4, 1987. 



819 



