Table 6 Frequency distribution of length and weight of pearl oysters. 



The relationship between the weight of "both valves and the maxinur. length of the 

 oyster, measured at right angle to the hinge, is shown in Tig. 2k. The curve is of the 

 type which exoresses similar relationships in other organisms, and is almost identical 

 v;ith the length-vjeight curve described for the Hawaiian pearl oyster, Pinctada galtsoffi 

 Bartsch (Galtsoff, 1933)* 



Ho information is available regarding the rate of growth of the Panama oyster. 

 Pearl fishermen of the Pearl Islands believe that small oysters about 5-6 cm. long are a 

 few weeks old, and that in about 6 months their size increases up to S-10 cm. These young 

 oysters may weigh about 200 grams. This opinion is based on observations of those fishermen 

 who visited the grounds, at intervals of several weeks or months and noticed the size of 

 young oysters v/hich were too small to be used in commerce. How accxirate this infomation 

 is cannot be ascertained without adeouate stud;/. Reporting on his observations on the rate 

 of growth of the black-lip pearl oyster ( Pinctada margaritifera ) of Australia, Nicholls 

 (1930) stated that from October to July of the same year the increase in the diameter of 

 shells of young oysters was about 20 mm. Nine months after the beginning of the experi- 

 ment, the size of the oyster varied from 33 to 73 ™n« I* is quite possible that the 

 Panamanian fishermen have misjudged the rate of growth of the Panana pearl oyster, and that 

 it grows at approximately the same rate as reported by Hicholls for the Australian species. 



Prom the Inquiries made among the -oearl-shell dealers in Panama, I infer that 

 the majority of oysters exported from Panama were from 12 to lU cm. long, each weighing 

 about 1 pound. 



Pearl-shell dealers who outfit their own crews consider thatf to make the enter- 

 prise profitable, a diving boat must average from 200 to 25O pounds of shells a day. A 

 satisfactory catch of a naked diver is from I5 to 20 pounds. 



The snail number of pearl oysters obtained during the present svirvey by an 

 experienced diver is convincing evidence of an almost complete exhaustion of pestrl-oyster 

 resources of Panama. 



Deatd shells 



As has been sho\m in Table U, the number of dead oysters collected by the diver 

 far exceeded the number of live ones. Among the 181 dead oysters, only five were found 

 with both valves still connected by a hinge and with the inside surface of valves clear of 

 any fouling organisms. It was obvious that these five were oysters which had died only 

 recently. Both sides of the shells of other oysters were covered i/ith a dense grovrth of 



38 



