EXPERIMENTAL FISHING TO DETERMINE DISTRIBUTION OF SALMON 

 IN THE NORTH PACIFIC OCEAN, 1955 



INTRODUCTION 



As a part of the research program re- 

 quested by the International North Pacific 

 Fisheries Commission, theU. S. Fish and 

 Wildlife Service undertook in the summer and 

 early fall of 1955 a broad study of the high -seas 

 distribution of salmon in the North Pacific Ocean. 

 Three vessels participated in this work, the 

 Service's own research vessel John N. Cobb and 

 the chartered halibut schooner-type vessels 

 Mitkof and Paragon. 



The aims of this investigation were to 

 gain knowledge of the range and distribution of 

 salmon in the eastern and central North Pacific 

 Ocean and to collect samples of salmon through- 

 out their range for morphological and physio- 

 logical racial analysis . Oceanographic data 

 were also collected simultaneously with the fish- 

 ing operations for analysis by the Department 

 of Oceanography, University of Washington. 

 Ocean tagging on a minor scale was conducted 

 by the Cobb only, with the main tagging program 

 being carried out by the Fisheries Research In- 

 stitute, University of Washington. The ultimate 

 objective of all this work is to determine the ex- 

 tent of intermingling between Asian and North 

 American stocks of salmon and to separate, if 

 possible, the stocks of different continental 

 origin in the high -seas fishing areas. Results 

 are presented in preliminary form to make the 

 data available until detailed biometric analysis 

 now in progress, is completed. 



DESCRIPTION OF VESSELS 



Specifications for the exploratory fish- 

 ing vessel John N . Cobb, 78 net tons, are as 

 follows: 



Length ove all 93' 5-1/4" 



Length, w aterline 85' 0" 



Beam over guards 25' 6-3/4" 



Beam, molded 24' 6" 



Depth, molded 12' 7" 



Draft, molded (mean load). . 8' 6" 

 Draft over keel (mean load).. 9' 6" 



Bunkers, Diesel fuel 12,000 gals . 



Capacity, fresh water 6,000 gals . 



Cruising speed 10 knots 



Maximum speed 10.8 knots 



Number of bunks 14 



The two chartered schooner-type vessels 

 were of the following specifications: 



Vessel MITKOF. 



.PARAGON 



Total length 72 feet 90 feet 



Keel length 66' 1" 80 feet 



Tonnage 42 tons 64 tons 



Breadth 18 ' 4" 19' 5" 



Draft 9'(empty) 9'(empty) 



Cruising speed 9 knots 8.5 knots 



Maximum speed. ... 9.5 knots 9 knots 



Engine & horsepower .Fairbanks, 200H. P. Enter- 

 prise, 165H.P. 

 Number of bunks .... 12 13 



GILL NET CONSTRUCTION AND OPERATION 



The John N . Cobb fished with four sizes 

 of nylon gill nets: 3-1/4-inch, 4-1/2-inch, 5-1/4- 

 inch, and 6-inch stretched mesh measure. The 

 nets were constructed to fish shallow (fig. 4) from 

 the surface to about 20 feet deep. Past experience 

 by the Cobb in 1953 (Schaefers and Fukuhara, 1954) 

 and reports from the Japanese salmon fleet 

 (Fukuhara, 1953) indicated that most salmon were 

 caught close to the surface on the high seas. 



The nets were made up in 50 -fathom shack- 

 les, and on most sets either 20 shackles (1,000 

 fathoms) or 30 shackles (1,500 fathoms) were 

 lashed together and fished in a string. A typical 

 20 -shackle set was made up of two shackles of 

 3-1/4-inch mesh, five shackles of 4-1/2-inch 

 mesh, 11 shackles of 5-1/4-inch mesh and two 

 shackles of 6 -inch mesh, arranged randomly. 

 Lesser amounts of gear were used early in the 

 season and during poor weather on several sets. 

 A total of 1,018 shackles were fished during the 

 trip: 126 shackles of 3 -1/4 -inch mesh, 249 

 shackles of 4-1/2 -inch mesh, 565 shackles of 

 5 -1/4 -inch mesh, and 78 shackles of 6 -inch mesh. 



