6 U. S. BUEEAU OF FISHERIES. 



For many years investigations have been directed particularly 

 at the Pacific salmon, and the facts of life histories which are easiest 

 to secure have been acquired, but yet we are far from havinir ])os- 

 session of the full knowledge necessary to direct propagation most 

 efficiently, or to determine correctly the restrictive measures which 

 may be enforced with least interference Avith the proper utilization 

 of the fishes. The problems before us now are those requiring the 

 closest and most persistent study, and yielding solution only slowly 

 and by small stages. 



IMMATXTRE SALMON IN THE OCEAN. 



The investigations of salmon in Pacific Coast States have been 

 conducted by Willis H. Rich, special assistant. The study of salmon 

 taken by troll and purse seine in the open ocean has practically been 

 completed. A preliminary report was i)repared and, by authority 

 of this Bureau, was published by the California Fish and Game 

 Commission. The conclusions reached may be briefly summarized. 



The fish taken in the ocean off the mouth of the Columbia River 

 contain, in the si:)ring and early summer, approximately 70 per cent 

 of individuals which will not become sexually mature for one or two 

 years, but by the middle of August this condition has changed so 

 that nearly 90 per cent are fish which will soon enter the river for the 

 purpose of spawning. The rate at which this change takes place 

 and the time at which it occurs have not yet been determined, but 

 will be taken up in a later report. A comparatively small per- 

 centage of the fish found just within the mouth of the Columbia 

 River are immature. It should be mentioned in this connection that 

 it is only occasionally, when unusual tidal conditions obtain, that any 

 immature fish are taken inside the mouth of the stream. 



The fish taken by troll in Monterey Bay in June contain a con- 

 siderable proportion of immature individuals. The data obtained 

 in 1018 are most reliable and indicate that only about 40 per cent 

 of the fish taken would have spawned during the same year. The 

 data for 1915 indicate that 75 per cent were mature, but selection 

 may well have taken place in making this collection which consisted 

 of e<i<j: samples only. 



The fish taken near Drakes Bay and Fort Bragg in July and 

 August, 1918, contain approximately 30 per cent of immature fish. 

 It is of interest to note that this is an approach to the conditions 

 found off the mouth of the Columbia River in August and suggests 

 that the composition of all the schools found near the coast changes 

 materially during the summer season. 



It is understood that the preliminary report was used to advan- 

 tage in the recent movement restricting the operations of both troll- 

 ers and purse seiners off the coasts of Oregon and Washington. Ad- 

 ditional data will be embodied in a later report. 



Incidental to the work with the fish taken in the ocean considerable 

 data have been collected which will apply to the report dealing with 

 the general life history of the chinook salmon. Progress has been 

 made in the identification of races, and additional evidence from the 

 scales of returned marked fish has confirmed the work done last year 

 on the significance of the various types of nuclear growth. 



