FORTY-FIRST BIENNIAL REPORT 53 



would have grown enough to be saleable in another year or so. A result 

 of this condition was the industry's agreement to the passage of a law 

 limiting otter trawls to a mesh of 4^ inches. The 4i-ineli mesh require- 

 ment now enforced corresponds quite closely to the pre-1940 five-inch 

 mesh voluntary agreement. This is because in the older agreement the 

 mesh size was measured from center of knot to center of knot; Avhereas, 

 the modern law requires that the measurement be of the clear opening 

 between the knots. When the present law was passed, it stated that the 

 nets should be five inches clear opening between knots, but this was 

 later reduced to 4^ inches at the request of the industry. Tt is too early 

 for this mesh-restriction law^ to have shown any results in the improve- 

 ment of the fishery. 



Work on the trawl fishery by the Bureau of Marine Fisheries has 



included a study of the trawl boat logs, going into some detail as to 



the species caught, the catch localities, catch depths, and so on. All this 



work is necessary in order to keep an accurate track of the conditions of 



. the fishery and its progress from year to year. 



Research work on the vessel N. B. Scofield has included a study of 

 the etfects of different sizes of trawl mesh on the release of young fish, 

 and some exploratory work to determine the fishing potential of the 

 deep sea off the coast of California. 



Several species of bottom fish have been tagged in order to learn 

 something about their movements and rate of survival. We have been 

 getting excellent cooperation from fishing boat crews in the return 

 of these fish. This is especially gratifying in view of the fact that on 

 board a trawler flatfish are definitely a bulk product, and the fishermen 

 must keep their eyes open in order to spot the tagged individuals. In- 

 evitabh^ some tags are missed by the fishermen. Many of these are found 

 and returned to us by the men and women in the fish processing plants. 



Almost all of the returns of flatfish tags have been made within 20 

 miles of the place where the fish were released, showing that most of 

 the species move relatively little. Exceptions to this were two English 

 sole which were tagged off Eureka and recovered off San Francisco. 



SABLEFISH 



The sablefish (block cod) fishery of the Pacific Coast has shown 

 alarming signs of depletion. Concern for the future has led the industry 

 to request that the Pacific Marine Fisheries Commission start an investi- 

 gation of the species. The commission in turn has asked that the biological 

 staffs of California, Oregon, and Washington start this work. 



Before a suitable conservation program can be developed, it is neces- 

 sary to know whether we are dealing with a single coastwide popidation 

 of sablefish or with a number of smaller populations each of which re- 

 mains in a somewhat restricted area. In order to answer this question 

 all three states are tagging sablefish to determine the extent of their 

 movements. As another way of getting at the same problem, the three 

 states, Canada, and Alaska are all collecting sablefish samples for ship- 

 ment to the California State Fisheries Laboratory at Terminal Island 

 where meristic counts are being taken and where a comparison is being 

 made between fish from the different areas. 



