34" 



Pt 









Long Bea 



ch 



i 

















M.BACORE 



422 — Block Mnk*r. 



— Month Sa»mg •on Nth eought 

 09*- SST <rt rtich aost fith mnt 



cosghf. (»C) 

 10.9°- T UtCR-tiao. (°C) 

 1,993- No of fub r«*»ttd 

 E^-Cflle* rtportm, hot < 1,000 fill 



























"C 



rx 



s 











»•- 



•" 









*"— N 



J 806 



8 

 17 7* 



18.6° 

 1,336 











\ Ocaanods tgi _ 



33° 



830 



6 



18.8° 



18.7° 

 1,788 



'T*. 





627 

 8 



177° 

 18 0° 

 1,025 



826 

 8 



18 3° 

 IB 9° 

 1,531 



825 

 8 



20 0° 

 19 7° 

 1,615 











n 





S67\ *. 



ia3° A 



6,862\ 



^ 



848 



6 



20.0° 



19.3° 



1,734 



847 



8 



205° 



19.6° 



3.326 



846 

 8 



200° 

 19 6° 

 2,400 











660 



6 

 --* 20.0° 

 19.3° 

 1,080 



t San Oiego 







868 



18.3° 

 18 5° 



2,:85 



V 



866 

 8 



188° 

 191° 



10,901 



865 

 8 



18 8° 



19 0° 

 6,372 



864 



8 



20.0° 

 19 3° 

 5,654 



863 

 8 



18.8° 

 19 0° 

 1,846 













886 



8 



17.2 



18.6 

 1,841 



885 



e 



18 3 

 183 



5,948 



884 



8 



18.8 



18.4 

 8,010 



683 

 8 



19.4 

 18.4 



7,076 



882 



6 



18.8 



184 



18,027 



861 

 6 



20.0 

 18.9 



5,221 



8B0 



8 



20.0 



19.2 



2,370 































916 



7 



18.3° 



188° 



12,425 





i 



OJ--T 



M3- is t< i a rtpvlM 

 EI3-C«ti> wgrtlJ, Hi < 1.000 fat | 



Figure 18.— Catch and temperature data by block area for albacore caught off 

 southern California. 



usually small, lrunimizing the likelihood of significant statistical rela- 

 tionships. It may well be the case that temperature preference can 

 only be established either by 1 ) the preponderance of evidence in 

 selective sampling investigations, as presented in this report, or 2) 

 intensive investigations within particular temporal-spatial strata. 



The catch and temperature data obtained during the 1972-74 sur- 

 veys were stratified by year and species (Pacific barracuda, yellow- 

 tail, and Pacific bonito). For each species, analyses were conducted 

 using the 3 yr of catch in the block area (916 or 860) having the 

 greatest catch for that species. Using data for all 3 yr, cumulative 

 preference curves (Kolmogorov-Smirnov) of catch vs. temperature, 

 and cumulative temperature curves were plotted. 



In general, graphs show increased catch rates for all species 

 through the midrange temperatures of 17.8° to 20.0°C (64.0° to 

 68.0°F), with a reduction in rate above 20.5°C (69.0°F). Table 1 

 lists the temperature at the 20th, 50th, and 80th percentiles of the 

 catch preference curves for each species. The corresponding percen- 

 tiles of the temperature curve for the 31 -wk period are shown below: 



Block 20% 



860 16.6°C(62.0°F) 

 916 16.1°C(61.0°F) 



50% 

 18.6°C(65.5°F) 

 18.6°C(65.5°F) 



80% 

 20.5°C(69.0°F) 



20.2°C(68.5°F) 



The average temperature at the 20th catch percentile is slightly 

 above the 20th percentile for temperature, indicating that fewer fish 

 were taken at the very lowest temperatures; beyond that, catch 

 appears representative of the temperature distribution. 



Large catches of 30% or more above the means were identified, 

 and the corresponding sea surface temperature for each was 

 recorded. The temperatures for all large catches were averaged by 

 year and are given in Table 2. Overall, large catches ranged in tem- 

 perature from 16.2°C (61.2°F) to 23.0°C (73.5°F), with a mean 

 value of 19.5°C (67. 1 °F) for Pacific barracuda, 18.5°C (65.4°F) for 

 yellowtail, and 19.6°C (67.4°F) for Pacific bonito. 



The relationship of catch and temperature may be examined using 

 Spearman and Kendall nonparametric rank correlation tests assuming 

 fishing effort is equally distributed over the temperature range within 

 any time period. The results of these two tests for the relationships of 

 1 ) temperature and catch of all species per unit effort, and 2) tempera- 

 ture and catch of all species for the 31 wk, are shown in Table 3. The 

 correlations are consistently higher for catch than for CPUE, indica- 

 ting an increase in effort with increasing catch. Thus, the temperature 

 and catch relationship will be confounded with changing levels of 

 effort. Therefore, only the relationship of temperature and CPUE 

 was tested in subsequent analyses. 



For the 3 1 wk being analyzed, one of the nine tests was statistically 

 significant at the .05 level using the Kendall test, and two tests were 

 statistically significant using the Spearman test. Since the assumption 

 of equal distribution of effort over the temperature range became less 

 likely as the fishing season progressed, similar tests were carried out 

 for a 17- and a 12-wk period. These results are shown in Table 3. For 

 the 17-wk period, three Kendall and five Spearman tests were statis- 

 tically significant; for the 12-wk period, two Kendall and six Spear- 

 man tests were statistically significant. The Kendall test is more 

 conservative in all cases. On the average, about one-half of the indi- 

 vidual tests were statistically significant at the .05 level. 



The distribution of catch over the temperature range appeared dis- 

 proportionate only in the lower temperature range. To examine the 

 possibility of a similar relationship for temperature and CPUE, 

 cumulative CPUE curves were obtained for the three species, and the 

 temperature distribution withing each percentile range (0-20, 20-40, 

 40-60, 60-80, and 80-100) was recorded. The results for all data 

 combined are shown below. Numbers in parentheses indicate how 

 often catches would be expected in a particular temperature range if 

 temperature had no effect of CPUE. 





Cumulat 



if CPU E 











(0-obser\'ed/E-expected) 











0-20 



20-40 



40-60 



60-80 



80-100 





E 



E 



E 



E 



E 



I2.7°.15.6°C(55°-60°F) 



28 (18) 



2 (5) 



1 (4) 



(3) 



1 (2) 



15.6"-18.3°C(60°-65°F) 



44 (50) 



21 (15) 



5 (11) 



9 (7) 



9 (5) 



18.3°-21.1°C(65°-70°F) 



69 (73) 



19 (23) 



25 (16) 



11 (10) 



6 (8) 



21.r-23.9°C(70°-75°F) 



8 (8) 



4 (3) 



2 (2) 



1 (1) 



(1) 



13 



