FISHERY BULLETIN: VOL. 79, NO. 3 



Table 5. — Summary of fishing data for tidal current speed 

 categories during the eight 24-h fishing stations in which cur- 

 rent speed was recorded. The value given for "Rank sum" is the 

 sum of the ranks assigned to the observations on CPUE for that 

 current speed category in a Friedman test. 



Table 6. — Summary of fishing data for the three fishing depths 

 used during the 10 24-h fishing stations. The value for "Rank 

 sum" is the sum of the ranks assigned to the observations on 

 CPUE for that fishing depth in a Friedman test. Vertical lines 

 are used to indicate significantly different CPUE (a = 0.05, 

 multiple comparisons based on Friedman rank sums). 



Fishing 

 depth 



Hours of 

 fishing 



No. of sharks 

 caught 



tVleanCPUE 

 (shark/h) 



Rank sum 



and night fishing periods. During the day, CPUE 

 differed significantly among fishing depths and 

 was highest at the bottom. In contrast, during the 

 night no difference in CPUE was found among 

 fishing depths (Table 7). At surface and middepth 

 CPUE was substantially higher during the night 

 than during the day on 9 out of 10 and 8 out of 10 

 fishing stations, respectively. In contrast, at the 

 bottom CPUE differed little between day and 

 night periods and was not consistently higher 

 or lower during the night. These observations 

 suggest that the above difference between day 

 and night periods (i.e., depth differences in CPUE 

 during the day but not during the night) was a 

 result of increased CPUE at surface and mid- 

 depth during the night rather than a decrease in 

 CPUE at the bottom. 



Table 7. — Summary of fishing data for time period-fishing 

 depth categories during the 10 24-h fishing stations. The value 

 given for "Rank sum" is the sum of the ranks a-ssigned to the 

 observations on CPUE for that category in a Friedman test. 

 Vertical lines are used to indicate significantly different 

 CPUE (a = 0.05, multiple comparisons based on Friedman 

 rank sums). 



The stomach contents of 80 sandbar sharks 

 were examined to identify food items (Table 8). 

 Items that could be identified included small 

 crustaceans and fishes that are abundant in the 

 study area (pers. obs.). The blue crab, Callinectes 

 sapidus, of all sizes was found in 41% of the 

 stomachs examined (and in over 52% of the 

 stomachs not empty). Two or more different food 

 items were found in 14 stomachs and several 

 stomachs contained unidentifiable items but 

 were very nearly empty. The proportion of empty 

 or nearly empty stomachs (15 empty out of 27 

 examined) for sandbar sharks caught during the 

 night was significantly greater than the propor- 

 tion (16 empty out of 53 examined) for sharks 

 caught during the day (2-tailed chi-square test 

 for differences in probabilities, P = 0.04). 

 Stomach contents were, in general, similar for 

 the 3 study yr, both sexes, all sizes of sharks, and 

 tidal current and capture depth categories. 



The total number of male and female sharks 

 caught (over all 3 yr) did not differ significantly, 

 but yearly differences in sex ratio were found 

 (Table 9). During 1978 and 1979 about equal 

 numbers of male and female sandbar sharks were 

 caught, but in 1977 significantly more females 

 than males were caught. Sex ratios were con- 

 sistent among the 3 study mo (June, July, and 



Table 8.— Stomach contents of 80 young sandbar sharks. 



Table 9. — Number of male and female sandbar sharks caught 

 and probabilities for chi-square goodness of fit test (2-tailed) for 

 each year and the entire study. 



Year 



No, of males 



No. of females 



P-value 



1977 

 1978 

 1979 

 Total 



24 

 60 

 28 



112 



48 

 58 

 22 



128 



<0.01 



0.80<P<0.90 



,30<P<0.50 



.30<P<0.50 



444 



