average shedding rate for each type of tag. Type-I 

 shedding, which occurs immediately after release, 

 was estimated to be 0.040 for plastic and metal 

 dart tags combined. Type-II (instantaneous) shed- 

 ding was estimated to be 0.205 for plastic and 

 metal tags combined on an annual basis. 



The shedding rates for each type of tag were 

 found to vary over the time period studied, and 

 deviations from the assumption of constant shed- 

 ding throughout the life of the tagged fish were 

 noted. Due to these differences, one should not be 

 satisfied with the results of one double-tagging 

 experiment. We recommend that double tagging 

 be employed whenever possible, as long as shed- 

 ding occurs and the rate of shedding is found to 

 vary. Also, tagged fish, especially the ones which 

 have been at liberty for a long time, are more 

 likely to continue to carry at least one tag if they 

 were originally double tagged. The ones that do 

 not continue to carry at least one tag are of no 

 value. Furthermore, relative to the errors inher- 

 ent in a study of this type we do not feel that there 

 is really any important difference in shedding 

 rates between the plastic and metal dart tags. 



Since shedding may increase with time from 

 release, extrapolations based on the assumption of 

 constant L should be made with caution. Also be- 

 cause the tag shedding rates that we found are 

 considerable, efforts should be made to develop a 

 more efficient type of tag with a lower rate of 

 shedding. 



from yellowfin tuna. [In Engl, and Span.] Inter-Am. 

 Trop. Tima Comm., Bull. 10:333-352. 

 FOOD AND AGRICULTURE ORGANIZATION. 



1972. Final report of the working party on tuna and 

 billfish tagging in the Atlantic and adjacent seas. FAO 

 Fish. Rep. 118, Suppl. 1, 37 p. 



Laurs, R. M., W. H. lenarz, and r. n. Nishimoto 



1976. Estimates of rates of tag shedding by Non' acific 

 albacore, Thunnus alalunga. Fish. Bull., U.S. 74:675- 

 678. 

 LENARZ, W. H., F. J. Mather m, J. S. Beckett, a. C. Jones, 

 and J. M. Mason, Jr. 



1973. Estimation of rates of tag shedding by northwest 

 Atlantic bluefin tuna. Fish. Bull., U.S. 71:1103-1105. 



Raymond E. Baglin, Jr. 



Southeast Fisheries Center Miami Laboratory 

 National Marine Fisheries Service, NOAA, Miami, Fla. 

 Present address: National Marine Fisheries Service, NOAA 

 do Alaska Department of Fish and Game 

 P.O. Box 686, Kodiak, AK 99615 



Mark I. Farber 



Southeast Fisheries Center Miami Laboratory 

 National Marine Fisheries Service, NOAA 

 75 Virginia Beach Drive, Miami, FL 33149 



William H. Lenarz 



Southwest Fisheries Center Tiburon Laboratory 

 National Marine Fisheries Service, NOAA 

 3150 Paradise Drive, Tiburon, CA 94920 



John M. Mason, Jr. 



Woods Hole Oceanographic Institution, Woods Hole, Mass. 

 Present address: Mid-Atlantic Fishery Management Council 

 Federal Building, North and New Streets 

 Dover, DE 19901 



Acknowledgments 



We thank W. H. Bayliff of the Inter-American 

 Tropical Tuna Commission and J. Wetherall of the 

 Southwest Fisheries Center Honolulu Laboratory, 

 NMFS, NOAA, for their helpful comments on the 

 manuscript. We also thank all captains and crew- 

 men of commercial and sport fishing vessels, 

 WHOI personnel, George Bell, NMFS personnel, 

 Andy Bertolino, and Dennis Lee, who participated 

 in the bluefin tuna tagging program, and T. 

 Chewning of the Southeast Fisheries Center for 

 computer programming assistance. 



Literature Cited 



Bayliff, W. H., and L. M. Mobrand. 



1972. Estimates of the rates of shedding of dart tags from 

 yellowfin tuna. [In Engl, and Span.] Inter-Am. Trop. 

 Tuna Comm., Bull. 15:439-462. 

 Chapman, d. G., B. D. Fink, and E. B. Bennett. 



1965 . A method for estimating the rate of shedding of tags 



INFLUENCE OF LITTLE GOOSE DAM ON 



UPSTREAM MOVEMENTS OF ADULT CHINOOK 



SALMON, ONCORHYNCHUS TSHAWYTSCHA 



A major environmental and economic concern in 

 the Pacific Northwest is the continuing decline in 

 the numbers of Columbia and Snake River sal- 

 monids. Several investigators (Johnson 1960 and 

 others) have used biotelemetry to study effects of 

 hydroelectric dams (Figure 1) on the upstream 

 movements of adult salmonids. Results indicated 

 upstream movements were delayed at Bonneville 

 (Schoning and Johnson^; Monan and Liscom2.3,4,5)^ 



^Schoning, R. W., and D. R. Johnson. 1956. A measured 

 delay in the migration of adult chinook salmon at Bonneville 

 Dam on the Columbia River. Fish. Comm. Oreg., Contrib. No. 

 23, 16 p. 



^Monan, G. E., and K. L. Liscom. 1971. Final report, radio 

 tracking of adult spring chinook salmon below Bonneville Dam, 



fishery BULLETIN: VOL. 78. NO. 1. 1980. 



185 



