FORTY-SECOND BIENNIAL REPORT 69 



there has not been a really good hatch since 1947, the catch has dropped 

 to its present low of slightly more than one-fifth the peak 1935-36 season. 



Also completed and published during the biennium was a study of the 

 races or populations of Pacific mackerel (Fish Bulletin 84) . This included 

 detailed comparisons of fish taken between British Columbia and the 

 Gulf of California. Statistical analysis of the data revealed the proba- 

 bility of two distinct populations within this range with the California 

 fishery drawing upon the mackerel population from Canada to central 

 Baja California. 



Routine sampling of the commercial catch continued without interrup- 

 tion. Most of the basic information for the numerous biological studies is 

 acquired from this sampling. 



The Pacific mackerel once supported a lucrative fishery but catches in 

 recent years have declined seriously. 



JACK MACKEREL 



The jack mackerel catch in the Los Angeles region was considerably 

 higher during this biennium than the last. Slightly more than 100 million 

 pounds were landed here during the 1950-51 season and nearly 69 mil- 

 lion pounds during 1951-52. Monterey reported the second highest catch, 

 but only in September, 1950, when some 27 million pounds were taken, 

 did monthly landings exceed five million pounds at that port. 



Biological work which originally consisted of routine sampling and 

 age analysis was expanded during the biennium to include studies of 

 maturity and egg production, food habits, and a racial or population 

 investigation. 



In conjunction with the food analysis work, two short trips were made 

 on the department's research boat, Yellowpin. These trips were nec- 

 essary in order to obtain stomachs from daytime-caught mackerel to 

 compare the contents with food organisms from stomachs of jack mack- 

 erel caught at night. 



Studies of fishing methods included rides in a plane, which was used 

 by the fishermen during the spring of 1952 to locate schools of jack 

 mackerel during daylight hours. Much useful information was obtained 

 on methods for identification of schools of sardines, anchovies, and jack 

 mackerel. 



