Paiiups.— Food-supply and Deterioration of Trout. 391 
planted. in the parent stream, the run falls off and may eventually dis- 
appear." These remarks refer to the salmon on the Pacific coast of North 
America. In the state of nature many of the eggs of the adult fish do not 
arrive at maturity, and the mortality among young fish is generally high ; 
but in the artificial condition of the hatchery the loss is small. f 
thousand may have been derived from the same parents significantly inen 
falling off. 
At the present time (1923) the phenomenal increase in weight and size 
of thermal-lake trout is everywhere recognized. It is quite possible from 
facts to hand in regard to present condition of trout, dich i in certain lakes 
average 9 Ib. in weight, that these fish have recovered from what may be 
regarded as a degeneration cycle. Land-locked Salmonidae throughout the 
world have been known to deteriorate at intervals of several years. Many 
immediately to altered conditions of any kind. Apart rom human 
agencies, the geology of the surrounding country, its flora and fauna, 
altitude, latitude, and climatic conditions must a considered when 
dealing "with salmon or trout from a scientific standpoint. 
BIBLIOGRAPHY. 
eat W. J., 1920. Growth and Degeneration of Trout, Salmon and Trout Mag., 
1, pp. 
ATKINS, es ^d. 1910. Foods for imum. Salmonoid Fishes, Bull. U.S. Bur. Fisheries, 
28, pt. 2, pp. 841-5 
Ade ROO 1917. Salmon and "Trout, Salmon and Trout Mag., No. 15, pp. 18-34. 
_— 1919. Studies of Trout and Trout Waters in RR Salmon and Trout Mag., 
o. 18, pp. 16-33. 
Емворү, С. С., 1918. Results of some Trout-feeding Experiments, Trans. Amer. 
isheries Soc., vol. 48, No. 1, pp. 26-33. 
Evermann, B. W., 1894. The Investigation of Rivers and Lakes rg reference to . 
Fish Environment, Bull. U.S. Fish. Comm., vol. 13, pp. 69- 
Норѕох, G. V., 1904. New Zealand it London, "(wi ith Notes on their Relation to 
ndon 
U.S. Bur. Fisheries, Doc. No. 633, 77 pp., 5 figs., 12 pl., and map. 
MILNE, J. A., 1917. Further iai of "olio Reading to the Solution of Practical 
Problems, Salmon and Trout Mag., No. 15, 
cocum МЫ G., 1902. Food of Brook Trout i in Bone Pond, N.Y. State Museum Bull., 
68, pp. 2 
PEARSE, A. М 1918. The Food of the Shore Fishes of certain Wisconsin Lakes, 
Bull. U.S. Bur. Fisheries, Mig 35, pp. 249-92. 
PHILLIPPS, W. J., and Е. J. T. GRIGG, 1922. The тео of the Thermal Lak 
North Island, N.Z., in elation же Problems bearing re the Acclimatized 
Salmonidae, N.Z. Journ. Sci. & Tec „ vol. 5, No. 3, pp. 156- 
RICHMOND, S Ae 1919. About Beinbow Tout, Salmon and Trout Mag., No. 20, 
Trutyarp, В. T 1920 Report on the Neuropteroid Insects of the Hot Springs i 
N.Z ae relation to the Problem of Trout-food, Proc. Linn. Soc. N.S.W., 
pp. 205-13. 
