Figure 19. — Graph showing the inverse sex ratio between 

 the trawl- and trap-caught Pacific spiny lobster (P. 

 gracilis). 



Lobster Trapping 



In conformance with the plans, cruises 

 simulated commercial fishing rather than pure 

 exploration. To emphasize the possibility that 

 a self-sustaining commercial operation could 

 be worked on a small scale, cruise 15 was 

 designed to approximate a one-boat, two-man 

 trap-fishing operation with a string of 200 

 traps. As a result of information acquired 

 during the first year of operation, the traps 

 were distributed parallel with the coast and 

 around small islands. Each day 100 traps of 

 the 200 set were hauled, rebaited, and reset. 

 After allowing several days for the traps to 

 season, we watched for any noticeable trendin 

 the catches. Several conditions seemed to af- 

 fect the reactions of the lobsters in relation 

 to their habitat. For example, it was noted 

 that traps on the western side of the islands 

 generally out-produced those set on the eastern 

 side. This apparently was caused by a current 

 flowing in a westerly direction in this area, 

 making the western side of the island the lee 

 or protected side, indicating that lobsters 

 prefer relatively placid water conditions. 



In addition to the effect of currents on 

 lobster production, a temporary wind effect 

 was observed (fig. 20). This occurred during 

 September in the northwestern part of the Bay 

 of Panama. The wind, which had been blowing 

 lightly from the northwest, shifted to the 

 south, increased in velocity to 15 or 20 knots, 



Figure 20. — Spiny lobster trap catch rates for a 22-day 

 period showing adverse effect of unseasoned traps and 

 strong winds. 



and held for several days. During this time, 

 the lobster catch rate dropped 50 percent. After 

 the wind had moderated, the original catch 

 pattern was gradually resumed. Specifically, 

 the effect on the catch was as related in the 

 following paragraphs. 



The daily catch rate during the entire cruise 

 varied from 20 to 109 pounds of lobster per 

 100 traps hauled. As 90 percent of the traps 

 were new, it took about 5 days for the traps 

 to season. During this time, the catch rate 

 averaged only 22 pounds per day. During the 

 9- day period following seasoning, production 

 increased to an average of 87 pounds per day. 

 This represents slightly more than 3 pounds 

 of lobsters per trap per week. Cope (1959) 

 states that under favorable fishing conditions, 

 Florida lobstermen expect a similar yield. 



During the next 4 fishing days, the catch rate 

 suddenly dropped to an average of only 44 pounds 

 per day, apparently because of the shift in 

 direction and increase in velocity of the wind. 

 Subsequent conversations with local shrimp 

 fishermen indicated that they too experienced 

 poor fishing in this period. 



In the final 4 days of the cruise, normal 

 weather conditions returned and the catch rate 

 climbed back to an average of 85 pounds per 

 day. 



The cruise results indicate that the spiny 

 lobster population in the extreme northwest 

 section of the Bay of Panama would support a 

 commercial fishery. Further work would be 

 necessary to determine the geographical limits 

 of the lobster grounds and whether or not sea- 

 sonal fluctuations occur. A reasonable esti- 

 mate of potential lobster production from the 

 area is dependent on answers to these tw 

 factors. 



17 



