August 1966 



COMMERCIAL FISHERIES REVIEW 



19 



corded inshore near Santa Cruz Point. Tem- 

 peratures were fairly uniform at offshore 

 stations, and ranged between 57° and 58° F; 

 the temperature inside Santa Cruz Harbor 

 was 60.8° F. 



Salinities ranged from 32.9 to 34.2, and 

 were generally higher near shore as a result 

 of upwelling occurring at two stations covered. 



Bathythermograph casts made at 8 sta- 

 tions showed a strong thermal gradient be- 

 tween the surface and 150 feet. A clearther- 

 mocline was evident, beginning at 30 feet be- 

 low the surface at a number of stations. 



The salinity and temperature pattern was 

 typical for the Monterey Bay area. The in- 

 fluence of upwelling is apparently less pro- 

 nounced in the Santa Cruz Point area, and 

 this may account for the higher temperatures 

 around the Point and in the harbor area. 



:^ :^ :je :^ :^ 



PELAGIC FISH POPULATION 

 SURVEY CONTINUED: 



M/V " Alaska " Cruise 66-A-3- PelagicFish 

 (April 19-May 4, 1966): The coastal waters 

 of southern California from Santa Catalina 

 Island to San Diego were explored during this 

 cruise by the research vessel Alaska , oper- 

 ated by the California Department of Fish 

 and Game. 



Objectives of the cruise were to: (1) eval- 

 uate midwater trawl openings using various 

 otter door and bridle arrangements; (2) com- 

 pare fishing efficiencies of a 50-foot and 28- 

 foot midwater trawl; (3) study the effect of 

 towing speed on midwafer trawl catches; (4) 

 experiment and gain experience fishing a 

 lampara net for catching anchovies for tag- 

 ging; and (5) develop procedures and tech- 

 niques for tagging anchovies aboard the Alas- 



Mouth openings of a 50 -foot square mid- 

 water trawl and a 28 -foot trawl were observed 

 With a look box. Best results were obtained 

 using 4 hydrofoil otter doors. The large net 

 opened between 45 and 50 feet horizontally 

 and about 35 feet vertically. A poor vertical 

 opening resulted when the two lower hydro- 

 foil doors were replaced with weights. The 

 small net opened both vertically and hori- 

 zontally to an estimated 28 feet which is very 

 close to the designed optimum. 



Santa 

 Catalina Island V 



San clemcnte La 



Cruise track of M/V Alaska Cruise 66-A-3-Pelagic Fish (April 19- 

 May 4, 1966). 



A maximum towing speed of 4.0 knots was 

 attained with each trawl. No problems were 

 encountered although both fished at consider- 

 ably shallower depths than when towed at slow- 

 er speeds. 



Fishing efficiencies of each size trawl were 

 compared by towing each on alternate nights 

 at the same location. Results indicate the 

 large trawl catches about twice as many an- 

 chovies as the small one. 



One comparison was made of anchovy catch- 

 es with the small net towed at two different 

 speeds. The regular speed of 2.80 knots was 

 compared with 4.25 knots. The higher speed 

 resulted in a catch 3.5 times greater than the 

 regular, but the fish were severely damaged. 



A small lampara net was set numerous 

 times from a large skiff to gain experience 

 for future anchovy tagging operations. Foul- 

 ing of the cork and lead line necessitated mod- 

 ification of the net. 



A total of 2,952 anchovies were tagged and 

 released. Several major problems arose dur- 

 ing this operation, most of which were solved 

 at sea. Valuable experience and ideas were 

 gained for improving future tagging operations. 



Anchovies were very abundant throughout 

 the entire area encompassed by the cruise. 

 During flat, calm weather hundreds of breez- 

 ing schools were observed in deep water be- 

 tween the coast and offshore islands. A dozen 

 nightlight stations were occupied, and all at- 



