44 FISH AND GAME COMMISSION 



MACKEREL 



Over-utilization of mackerel has become much more apparent 

 durino' the biennium and the evidences of deelinin"- abundance have 

 been reported and publicized. Scarcity is admitted by most fishermen 

 and caniiers so that in 1938 they voluntarily imposed upon themselves 

 a closed season and scrupulously observed it for three j^ears. 



The averagre catch of a purse seine boat dropped steadily from 

 1934 to 1938, till the catches of 1938 were only one-quarter of what 

 they were four years before. As a result, most of these boats dropped 

 out of the fishery in 1939, their places being taken by small boats 

 fishing- Avith strikers and dip nets. This type of fishing is cheaper 

 and more successful in small scattered schools, and our excessive total 

 catch has been maintained by the larger number of small boats. In 1939 

 about 400 such boats fished mackerel in southern California. 



Much of the needed biological information has been reported so 

 that more of the research work during the last two years has been 

 directed toward determining at what level this over-worked fishery 

 should be held. Features of the work are : (1) Tagging to show migra- 

 tions and to help in making estimations of population. More than 

 27,000 mackerel have been tagged from Monterey, California, to Turtle 

 Bay, Lower California, and over 1,000 tags have been recovered. (2) 

 Analysis of boat catches as a measure of abundance. (3) Yield from 

 each fishing area. (4) Age composition and mortality rate of popula- 

 tion. (5) Spa-v\aiing extent and volume in the ditferent areas. l;arvae 

 have been discovered in the Gulf of California in February and ecffs 

 found along the west coast of Lower California in January and Feb- 

 ruary, whereas the local spawning season is chiefly during May, June 

 and July. 



TUNA 



At least five species of tuna are caught by California boats along 

 our coast and south to the equator. The solution of several biological 

 and management problems will be influenced greatly by the answer to 

 the question of whether we are drawing upon a single freely migrating 

 l)o])ulation or upon several separated groups or local races. The chief 

 object of the tuna program is therefore to gather biological data for 

 obtaining the answer to this question. This includes studies of the 

 characteristics of the fish from diffei-ent fishing areas and tagging to 

 determine migrations. Life-history data are being gathered and mate- 

 rial accumulated for determining the species and races of the tunas in 

 our fishery. 



Dnriiiii' tlie iiast biennium, the chief accomplishment has l)een 

 valuable contributions to tlie knowledge of fish spoilage, changes taking 

 place during storage bj^ different methods on refrigerated fishing boats, 

 and recommendations as to how losses due to spoilage on boats may be 

 toduced. Preliminary results, as rapidly as available, have been 

 i-e])()rte(l in mimeographed form for distribution to men of the fish 

 trades and others interested in fish refrigeration. 



BOTTOM FISH 



AVork on the Ixtltoni lisli of northern Calil'oniia has been somewhat 

 restricted because the press of other investigations necessitated the 

 use of the research vessels in other waters. However, the collections 



