THIRTY-FOURTH BIENNIAL REPORT 51 



An outstanding feature of the recent sardine work is the tagging 

 of fish in an attempt to substantiate our previous determination of 

 migrations. As individual fish are not handled in the reduction plants, 

 we have used an internal tag inserted in the body cavity of the sardine 

 and recovered by electromagnets from the fish meal. This work was 

 started in 1935 and results from it are not yet available. 



Mackerel. i 



The mackerel fishery is our newest large scale industry and our 

 research plans for this species were put into operation a few months 

 after the sudden rise to prominence of mackerel canning. Already we 

 have a satisfactory knowledge of the distribution of the species, the 

 spawning habits, identity of eggs and larvae, proportion of sizes in the 

 commercial catch at San Pedro, size at maturity, age, and rate of 

 growth. We have partial knowledge of the spawning localities with the 

 intensity of spawning in each, but little is yet known of the movements 

 of larvae, young fish or the migrations of the adults. Work with the 

 larvae and young fish is gradually supplying this information and a 

 tagging program has been instituted to determine the volume and 

 extent of adult migrations. A depletion study involving a statistical 

 analysis of individual boat catches is not yet feasible in this new and 

 rapidly changing fishery, but a study of the composition of the commer- 

 cial catch has suggested a possible criterion for judging relative abund- 

 ance of supply from year to year. 



Tuna. I I 



The tuna fishery is third in volume and second in value among the 

 fisheries industries of the State. At least five different species are 

 involved and the area fished extends from Monterey Bay to below the 

 equator, which offers the possibility of several spawning localities 

 throughout this wide extent with possible local races complicating the 

 problem. As nearly all the tuna fishing is conducted far distant from 

 state waters, a study of this fishery offers difficulties, and we have felt 

 the lack of a research vessel specially assigned to tuna investigations. 

 In spite of the difficulties inherent in this problem, progress has been 

 made in the study of this fishery. As j-et the work has necessarily been 

 of a preliminary nature with the gathering of data for future use. A 

 preliminary study was made of the losses of fish due to faulty refrigera- 

 tion. Catch composition sampling has been initiated, data for growtli 

 studies collected, racial studies started, and preliminary spawning data 

 gathered. Scouting trips have been made with two of the patrol boats 

 to locate schools of tuna, specially albacore, for our own information 

 and as an aid to commercial fishermen. 



One of the two outstanding accomplishments to date has been the 

 introduction of a system of ships ' logs voluntarily kept by boat captains 

 to give us definite records of fishing localities, bait hauls and fishing 

 effort expended in making the catches. A program of tagging the 

 three most important species has also been started to give us knowledge 

 of migrations and to serve as a basis for the solution of some of the 

 other problems of this fishery. 



