HOMING INSTINCT OF PINK SALMON 
39 
the number of bands of growth rings on their scales, was in every case consistent with 
the age at which they actually matured and returned to spawn. The scales of the 
pink salmon that have appeared in Snake Creek and in other streams in southeastern 
Alaska on different years have been examined and all show bands of growth rings on 
their scales similar to those on the scales of the marked Snake Creek salmon. The 
scales of the unmarked pink salmon that appeared in the 1931 run in the Duckabush 
River were likewise similar to the scales of the marked salmon that were recovered 
in the run. 
Additional evidence in regard to the age at which the pink salmon mature is 
found in the original establishment of pink-salmon runs in a number of streams in 
the New England States. Large shipments of eyed pink-salmon eggs were sent to 
the hatcheries in the New England States in 1913 and 1915. The fry that developed 
from these eggs in the spring of 1914 and the spring of 1916 were liberated in a number 
of streams along the coast. In the summer and fall of 1915 a substantial run of adult 
pink salmon returned to the streams in which the fry were liberated. A similar run 
of pink salmon occurred in the summer and fall of 1917. Dr. C. H. Gilbert, an author- 
ity on the Pacific salmon, examined some of the scales taken from the adult pink 
salmon in these streams in 1917 and claimed that, in spite of their new environment, 
the pink salmon retained their original habit of returning to the rivers to spawn 
and die at 2 years of age. 
All of the evidence thus far collected indicates that the pink salmon mature at 
2 years of age and until contradictory evidence is found, it may be assumed with 
relative certainty that they consistently mature at the close of their second year of life. 
LITERATURE CITED 
Foerster, R. E. 1929. An investigation of the life history and propagation of the sockeye salmon 
( Oncorhynchus nerka ) at Cultus Lake, British Columbia. No. 3. The down-stream migration 
of the young in 1926 and 1927. Contr. Canad. Biol, and Fish., N.S., vol. 5, no. 3, Oct. 12, 1929. 
Toronto. 
Gilbert, Charles H. 1913. Age at maturity of Pacific coast salmon of the genus Oncorhynchus. 
Bull., U.S. Bur. Fish., vol. XXXII, 1912 (1913), pp. 1-22, 29 figs. Washington. 
Pritchard, A. L. 1932. Return of marked pink salmon in 1932. Prog. Reports, Pacific Biol. Sta. 
Nanaimo, B.C., and Fish. Exper. Sta., Prince Rupert B.C., no. 15, 1932, pp. 10-11. Prince, 
Rupert, B.C. 
Rich, Willis H., and Harlan B. Holmes. 1928. Experiments in marking young chinook salmon 
on the Columbia River, 1916 to 1927. Bull., U.S. Bur. Fish., vol. XLIV, 1928 (1929), pp. 215- 
264, 85 figs. Washington. 
Snyder, J. O. 1921. Three California marked salmon recovered. Calif. Fish and Game, vol. 7, no. 1, 
Jan. 1921, pp. 1-6, figs. 1-4. Sacramento. 
Snyder, J. O. 1922. The return of marked king salmon grilse. Calif. Fish and Game, vol. 8, 
no. 2, Apr. 1922, pp. 102-107, figs. 40-50. Sacramento. 
Snyder, J. O. 1923. A second report on the return of king salmon marked in 1919, in Klamath 
River. Calif. Fish and Game, vol. 9, no. 1, Jan. 1923, pp. 1-9, figs. 1-5. Sacramento. 
Snyder, J. O. 1924. A third report on the return of king salmon marked in 1919 in Klamath 
River. Calif. Fish and Game, vol. 10, no. 3, July 1924, pp. 110-114, pis. 1-2. Sacramento. 
