Lobster Trawling 



During the last cruise ( Pelican cruise 16), 

 trawling for lobsters was emphasized. The 

 region selected was, in 5 to 10 fathoms, 

 between Rio Mar and San Carlos--an area 

 in which Pelican cruise 14 had shown that 

 trawling might be feasible with proper gear. 

 The bottom in this area was hard, with low- 

 lying coral and rock covering the 14 square 

 miles of area worked. Most of the rock and 

 coral was too small to be detected on the 

 vessel's depth recorder; however, large 

 formations could be detected and avoided. 

 The roller-rigged trawl proved to be capable 

 of working the rough bottom encountered 

 with only an occasional breaking of the tickler 

 chain. Only one major tearup of the trawl 

 occurred during 45 drags, and this was caused 

 by a large rock. During early drags, several 

 small holes were found in the bottom of the 

 bag. These resulted from the heavy weight 

 of the catch that caused the bag to bounce 

 along the rough bottom. The condition was 

 corrected by using chafing gear. Except when 

 hangups occurred, drags were 90 minutes 

 long. 



Lobster trawling catches varied from 10 

 to 210 pounds. Relative numbers of the two 

 species of lobsters taken also varied among 

 drags. Composition of the total catch for 

 the cruise, however, was about 60 percent 

 sand lobsters (E. princeps) and 40 percent 

 spiny lobsters (P. gracilis ). 



One of the unexpected results of the lobster 

 dragging was the number of sand lobsters 

 caught. The species had been caught rarely 

 in the lobster traps and only occasionally 

 in the trawls during bait dragging. Local 

 fishermen realized this lobster was present, 

 but they did not know in what amount and 

 had not considered exploiting it commercially. 

 Many had not tasted it. 



The average size and weight ratios of the 

 sexes of the two lobster species were exactly 

 opposite. Adult male spiny lobsters averaged 

 larger and heavier than females, whereas 

 adult male sand lobsters averaged smaller 

 and lighter than females. The meat yield was 

 better from the females in both species, 

 but the highest yield was obtained from female 

 sand lobsters. 



Average percentage meat yields were: 



Spiny lobster. 

 Sand lobster . 



It is common knowledge that spiny lobsters 

 normally live close to rocks or coral, which 

 provide some degree of protection. This was 

 found to be true during the period covered 

 by this report. However, sand lobster move- 

 ments appeared to be less restricted than 



those of spiny lobsters, because they were 

 captured in the trawl and on mud bottom up 

 to 5 miles from land or rock formations. 



To determine if there was any difference 

 in the day versus the night trawl catch rate, 

 a comparative tabulation was made of the 

 catch results and a graph was constructed 

 (fig. 21). Of the 45 drags made, 4 were con- 

 sidered inconclusive and their results were not 

 used in the computation. In addition, 144 of the 

 1,035 spiny lobsters were caught in traps 

 during the first few days of the trip and, 

 therefore, were not also used in the computa- 

 tion. Twenty-five drags (37.2 fishing hours) 

 were completed in the daytime and 16 (24.5 

 fishing hours) at night for a total of 41 drags 

 (61.7 fishing hours). Eight hundred seventy- 

 four spiny lobsters were caught in the 41 

 completed tows. Of these, 547 (63 percent) 

 were caught during the day and 327 (37 percent) 

 at night. A total of 1,779 sand lobsters were 

 caught in the same 41 drags of which 1,031 (58 

 percent) were caught during the day and 748 (42 

 percent) at night. As 60 percent of the fishing 

 was done in the daytime and 40 percent at night, 

 the results indicate round-the-clock trawling 

 for lobsters would be feasible. 



Panama Bay Scallops 



One of the routine functions of exploratory 

 fishing is to gather as much information as 

 possible regarding the fauna observed in 

 the daily operation. Thus, during cruise 15, 

 when one drag for bait in 6 fathoms of water 



100 



;60 



S 20 



a 



£ 



DAY TRAWLING 



NIGHT TRAWLING 



$£:;: HOURS FISHED 



PANULIBUS GRACILIS 



EVIBACUS PRINCEPS 



Figure 21. — Graph showing the similarity between the 



fishing effort and the catch results from day and night 



trawling for the Pacific Ocean lobsters, P. gracilis 

 and E. princeps . 



18 



