collect the necessary seasonal information. 

 An indication that additional species of lobsters 

 might be available was revealed by the capture 

 of one specimen of a small species of spiny 

 lobster, P. guttatus , and one specimen of the 

 Caribbean sand lobster, Scyllarides aequi- 

 noctialis, in 8 fathoms off the northwest coast 

 of Panama. 



With the exception of a portion of the trawl 

 catches, all lobsters were separated by sex, 

 weighed, and measured. The maturity stage 

 of the female lobster was noted. The total 

 weight was recorded to the nearest ounce, 

 and the dorsal length of the carapace was 

 recorded in millimeters. These data have 

 been compiled, and the more salient aspects 

 are given separately for each of the three 

 species of lobsters. 



Spiny Lobster — Life History Notes 



Spiny lobsters are usually found in rocky 

 bottom areas, which provide them with pro- 

 tection from large predacious fish, including 

 snapper, groupers, and sharks. Their best 

 defense against these predators, when they 

 are exposed in unprotected areas, is their 

 long spiny antennae and their ability to swim 

 backwards with short bursts of speed. They 

 normally are nocturnal and forage primarily 

 for stationary or slow moving marine 

 organisms. They have strong mouth parts and 

 are capable of crushing shellfish, which they 

 use as a source of food. 



The sexes are separate and can be deter- 

 mined by the location of the genital duct 

 openings. These are located for the female 

 at the base of the third pair of legs and for 

 the male at the base of the fifth pair. Also, 

 the paired swimmerettes of the female are 

 large and overlap while the male swimmerettes 

 are small and do not overlap. 



Templeman (1940) reported from experi- 

 ments with the American lobster that mating 

 usually takes place a few hours after the female 

 has molted and is still in a soft- shell condi- 

 tion. A limited number of field observations 

 indicate that this probably holds true for the 

 spiny lobster also. During mating, the male 

 deposits a white viscous substance containing 

 sperm on the ventral side of the female's 

 thorax. The outside of this sperm sac hardens 

 and becomes dark. The female retains this 

 sac until she is ready to fertilize her eggs. 

 As the eggs are extruded, she releases the 

 sperm by scratching open the sperm sac 

 with the tips of her fifth pair of legs. It was 

 noticed in Panama that the female usually 

 opened the posterior end of the sperm sac 

 first, working anteriorally until all the eggs 

 were fertilized. The number of eggs produced 

 varies, dependent to a large degree on the 

 size of the female, for example, the larger 

 the female, the more eggs produced. After 

 the eggs are fertilized, they become attached 



to filamentous parts under the tail where 

 they are protected and aerated by the large 

 swimmerettes until hatched. The newly de- 

 posited eggs are bright orange, but as the 

 embryos develop, the eggs become brown. 

 Smith (1959) states the eggs of P. argus turn 

 almost colorless just before hatching. This 

 condition was not observed among the Pacific 

 spiny lobsters examined in Panamanian waters. 

 After the eggs hatch, the larvae spend 

 several months drifting in the ocean currents. 

 Thorson (1961) believes that panulirid larvae 

 have a larval life of 150-180 days. Those 

 larvae that survive change into a transparent 

 form of the adult and settle to the bottom. 

 They soon acquire lime that enables their 

 shell or exoskeleton to become rigid, and 

 assume adult coloration. Growth occurs after 

 each molt, and the growth rate is dependent 

 on the local environment. 



Pacific Spiny Lobster (P. gracilis) 



For convenience and clarity, the ratios of 

 gravid and nongravid female lobsters from 

 the inshore fishing areas are arranged in 

 3-month periods (fig. 23). As only one offshore 

 trawling cruise was made, these data are, 

 as indicated, limited to 1 month. The term 

 gravid, as used here, includes both the berried 

 (egg-bearing) lobster and those with sperm 

 sacs, because we observed during field ex- 

 aminations that those female lobsters which 

 had sperm sacs were in a ripe or ripening 

 condition and would shortly be releasing eggs. 

 Only adults were included in the nongravid 

 category. The data from the juvenile catch 

 were not used. 



The inshore fishing was conducted primarily 

 between 5 and 10 fathoms and from 50 yards to 

 1 mile from land. Because of the extensive 

 Continental Shelf in the Gulf of Panama, the 

 offshore fishing was also in the 5- to 10- 

 fathom depth range, but the distance from 

 the nearest land varied between 2 and 5 

 miles. 



Gravid and nongravid females were taken 

 from inshore waters throughout the year 

 (fig. 23). Proportionally, these two categories 

 varied only slightly. The percentage of all 

 the inshore catch results for the entire survey 

 period were 47 percent gravid and 53 percent 

 nongravid. As there are no pronounced sea- 

 sonal temperature changes which might affect 

 the lobster's environment such as occur in 

 the temperate zones, spawning continues 

 throughout the year. Conversely, the off- 

 shore catch results showed a wide margin 

 between the two conditions. The figures for 

 that area are 92 percent gravid and 8 percent 

 nongravid. Although there was time for only 

 one trawling cruise, the results showed gravid 

 lobsters, in significant amounts, offshore. If 

 it could be determined that an offshore migra- 

 tion coincides throughout the year with the 



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