Catch Distribution and Related Sea Surface Temperature 



For Striped Marlin (Tetrapturus audax) 



Caught off San Diego, California 



JAMES L. SQUIRE, JR. 1 



ABSTRACT 



Records for 4,535 marlin landed at San Diego, California, and related sea surface temperature data 

 were examined for the period 1963 through 1970 to determine time-space distribution and the relationship 

 of catch and sea surface temperatures. For the period 1963 through 1970 the catch of 4,535 marlin was 

 compared to sea surface temperature conditions relative to increased catches. 



Catch distribution based on 1963 to 1967 data showed that 76.49f were caught within a 35- by 

 40-nautical-mile area off San Diego, with the maximum catch being made from mid-August to mid- 

 September. Catch temperatures off southern California calculated for this area from airborne infrared 

 sea surface temperature survey data ranged from 61° F (16.1°C) to 73° F (22.8°C); the mean catch 

 temperature was 67.8° F (19.9°C). 



Sea surface temperature conditions based on 2-week average temperature charts issued by the 

 National Marine Fisheries Service indicate that an initial warming of water to an average temperature of 

 68° F (20.0°C) or above is related to an increase in catch. When average temperatures were below 68° F 

 (20.0°C), 931 fish were caught; between 68 c (20.0°C) and 70° F (21.1°C) the catch was 1,886 fish; and a 

 further increase to 70° F (21.1°C) or above resulted in a catch of 1,718 fish. 



Catch data and isotherm charts, 1963 through 1970, indicate that the continuity of the 68° F (20.0°C) 

 and 70° F (21.1°C) isotherms from off central Baja California to off southern California is associated with 

 improved fishing. When these isotherms were discontinuous the average catch per biweekly period was 

 82.0 fish; when these isotherms were continuous the average catch was 146.1 fish. The highest average 

 catch per biweekly period (205.3 fish) was recorded when the 70° F (21.1°C) isotherm was continuous. 



The striped marlin (Tetrapturus audax) is the ob- 

 ject of a sport fishery in southern California waters 

 during late summer and early fall. Sport fishing for 

 striped marlin in these waters has been conducted 

 since about 1903 (Howard and Ueyanagi, 1965) and 

 striped marlin were caught commercially up to 

 1937. Since 1937 it has been illegal to land the 

 species commercially in California. The early sport 

 and commercial fishery was centered near Catalina 

 Island and between the island and the mainland. In 

 recent times the area off San Diego has experienced 

 increased angling effort, and presently this area 

 yields the largest number of sportcaught striped 

 marlin. Most of the marlin are landed at three points 

 in southern California: the Avalon Tuna Club, Av- 



' National Marine Fisheries Service. Southwest Fisheries 

 Center. La Jolla Laboratory. NOAA. La Jolla. CA 92037. 



alon, Catalina Island; the Balboa Angling Club, 

 Newport Beach; and the San Diego Marlin Club, 

 San Diego. At these clubs each fish is weighed and 

 information is recorded on a weight slip (Fig. 1). 



Changes in sea surface temperature affect the dis- 

 tribution of many pelagic marine fishes commonly 

 caught off southern California. During periods of 

 high temperatures, greater numbers of the more im- 

 portant marine game species, such as Pacific bonito 

 (Sarda chiliensis), yellowtail (Seriola dorsalis), and 

 Pacific barracuda (Sphyraena argentea), which are 

 common to the lower west coast of Baja California, 

 Mexico, migrate northward into higher latitides 

 (Hubbs, 1916. 1948; Walford, 1931). Fishing suc- 

 cess for albacore (Thunnus alalunga) off this area 

 has been related to changes in sea surface tempera- 

 ture (Hester, 1961; Clemens and Craig, 1965). 

 Radovich (1961, 1963) has also described the effects 



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