PROGRESS IX BIOLOGICAL INQUIRIES, 1937 25 



a large number of offsprinc:. It is highly probable that the effluents 

 of the ]\Iississippi Kiver play an important part in determining the 

 success of spawning. 



As stated in several previous reports, there is evidence in the Gulf 

 of an offshore movement of large shrimp during the winter. This 

 migration is comparable in many respects to that of the South At- 

 lantic coast ; it differs however, in that it is primarily offshore and 

 outside the present commercial fishing range, whereas the South At- 

 lantic movement is coastwise and within the commercial fishing 

 limits. Early in the year the Pelican, a 78-foot Diesel vessel, was 

 transferred to the Gulf for the purpose of making exploratory cruises 

 in order to determine whether or not the winter migrants concentrate 

 in sufficient quantities to permit commercial fishing. Owing to in- 

 sufficient funds, however, the boat was unable to operate during the 

 fiscal year 1937 and it was deemed advisable to postpone operations 

 until January 1938. 



In addition to discovering winter offshore concentrations of shrimp, 

 the work of the Pelican should give valuable data on the length of 

 life of the shrimp, whether or not there is an offshore spawning re- 

 serve in the Gulf, and the extent of the spawning grounds. 



Arrangements have been made with Prof. A. E. Parr of the Bing- 

 ham Oceanographic Institute of Yale University to analyze the 

 salinity samples secured with the Pelican. Similar arrangements 

 have been made with Professors H. V. Howe and R. J. Russell of 

 the Department of Geology of Louisiana State University to analyze 

 the bottom core samples which are taken at each trawling station. 



Tlie Texas program which has been conducted by Kenneth H. 

 ]\Iosher has been primarily that of sampling the commercial fishery, 

 but during the past 2 seasons, through the assistance of Albert Col- 

 lier, Marine Biologist of the Texas Game, Fish, and Oyster Com- 

 mission, tagging operations have been added. 



It is known that temperature and salinity affect the behavior of 

 the shrimp, and during the past year it has been determined that 

 tides also enter as a factor. In the vicinity of Corpus Christi, Tex., 

 it was found that better catches of shrimp, as a rule, were made dur- 

 ing periods of low than of high water. 



John C. Pearson, prior to his transfer to the shad investigations, 

 submitted for publication a manuscript describing the larval stages 

 of the common shrimp and those of four other peneids. This basic 

 work will be of considerable aid in determining the extent of the 

 spawning grounds. 



NORTH PACIFIC AND ALASKA FISHERY INVESTIGATIONS 



Dr. F. a. Davidson, in cluirye 



The North Pacific and Alaska fishery investigations, with head- 

 quarters in the Fisheries Biological Station at Seattle, Wash., are con- 

 fined mainly to the solution of problems concerning the maintenance 

 and rehabilitation of the salmon and herring fisheries of Alaska and 

 the salmon fisheries of Paget Sound and the Columbia River. All 

 of the major investigations in progress in 1936 were continued 

 in 1937. 



