CXXXVI KEPOKT OF COMMISSIOA'ER OF FISH AND FISHERIES. 



the herriug from difl'ereut localities with reference to their structural 

 peculiarities and variations. Although it is impossible to keep the 

 erratically moving fish under direct or continuous observation, by indi- 

 rect methods conclusive information may be gained as to the composi- 

 tion of the schools. If, for example, the school which spawns in s])ring 

 has for a long time been quite distinct in its membership from the 

 school which spawns in summer and autumn, the individuals of one 

 school would show more or less constant minor structural differences 

 from those of the others. The distinctness of the schools could thus be 

 demonstrated by the detailed examination of fish taken at different 

 seasons and jjlaces. Over 5,000 accurate measurements were made by 

 Dr. Moore, but many more will be necessary to furnish material for final 

 discussion. 



NATURAL HISTORY OF PACIFIC SALMON. 



The inquiries of Mr. Cloudsley Eutter and Mr. F. M. Chamberlain 

 regarding the habits, movements, growth, food, etc., of the salmon of 

 the Sacramento River, referred to in previous reports, were continued 

 during the present year, beginning July 6, 1898, and extending with- 

 out material interruption to May 13, 1899. In May and June of the 

 l)revious fiscal year, when all parts of the Sacramento had been visited 

 and seining stations established at intervals of about 17 miles between 

 Redding and Sacramento, the last of the regular downstream migration 

 of the fry was found. 



On the resumption of the investigation the same ground was again 

 gone over, and, in addition, the lakes at the source of the Sacramento 

 were visited and the Pitt River basin was explored, the distribution of 

 the salmon therein being determined. One station favorable for obser- 

 vation, located at Sims, on the Upper Sacramento, Avas visited monthly 

 from April to December in order to ascertain the relative numbers and 

 growth of the young salmon remaining in that part of the stream. 



During October and November a trap arranged for catching even the 

 smallest salmon fry — set in Battle Creek and tended by Mr. Rutter — 

 yielded some noteworthy results. Another trap in an adjacent part of 

 the Sacramento River was visited regularly by Mr. Chamberlain from 

 January to April. A third, placed in Georgianna Slough at Walnut 

 Grove, in the lower course of the river, was tended by Mr. N. B. Scofield 

 and Mr. Rutter from January to May. 



The inquiries are now practically complete, and a comprehensive 

 report on the natural history of the salmon is being prepared by Mr. 

 Rutter. The following are some of the facts regarding the life of the 

 salmon in the Sacramento River established by the investigation : 



(1) Adult salmon may be found in the Sacramento at almost any 

 time of the year; the smallest numbers are observed in the lower river 

 during winter. 



(2j There are two main runs of salmon, known as the spring and 

 summer runs in the lower part of the river, and as the summer and 

 fall runs in the upper waters. The fish in the early run ascend to tne 

 headwaters because the water is high and suitable spawning-grounds 



