"2 the economics of Trochus niloticus. 



Trochus is taken by hand on the coral reefs between tide marks, but most is gathered by coloured 

 naked divers in about two fathoms and some even as deep as six fathoms. In the deeper water search 

 is made from the boat with a water telescope and in the water the divers use Japanese water goggles. 

 The extreme record of depth is a statement (Watson, Rep. Chall. Zool. xv., 1886, p. 50) that the 

 " Challenger " dredged T. niloticus in 12 fathoms off Levuka, Fiji. 



Cleaning is done in different ways. The shell brings a better price if the attached growths and 

 lime crusts are pared away. Sometimes the catch is arranged by spreading the shells, still containing 

 the animal, on the beach for the blow flies-to dispose of the flesh. The putrid shells are afterwards 

 washed clean in the sea. If the shells are left too long exposed they suffer by bleaching from sun and 

 rain and the nacre is dulled. A quicker and cleaner method is to boil out the snail, but this has the 

 detrimental effect of slightly cracking the nacre. Sometimes a mixture of both processes is adopted, 

 the shells being first placed in hot or boiling water for twenty minutes, then put aside to decay slightly, 

 till the animal can be extracted with a crooked wire. The best way, that of burying in sand for a short 

 time, does not seem to be practised in the Pacific. 



But the more careful of the Japanese fishermen save both meat and shell. From ten tons of shell 

 a ton of meat is obtainable, worth in China /20 a ton. After boiling for half an hour, -the entire snail 

 is shaken out of the shell, dried and smoked for two days. It is then ready for export. In China this 

 smoked Trochus is esteemed a dainty. It is soaked in cold water till soft, cut into dice, and used as 

 a base of a soup, like beche-de-mer soup. Mr. E. J. Banfield, who supplied me with this information, 

 tried this Trochus soup and reports it as very palatable. 



Trochus obeliscus, which is called " wabisi " at Samarai, is too thin to be of value. But an expert, 

 Mr. W. P. Cottrell, assured me that Angaria delphinus would be excellent material if available in suffi- 

 cient quantity- 



Regulations. 



In Queensland the Government require a license at the rate of £3 per annum for the first ten tons, 

 and 10s. for each additional ton, of the vessels engaged. The man in charge is also licensed at £1 a year. 

 At Samarai, a license is charged of £1 per annum for each cutter or lugger and 10s. for each dingy or 

 canoe. 



In the Philippines it is illegal to take Trochus under eight centimetres (say three inches) diameter. 

 (Seale, Philippine Journ. of Science xi., 1916, p. 262). After the reefs of New Caledonia had been ex- 

 hausted by over fishing, a minimum size of 8 cm. and a close season were imposed (Compton, Geograph. 

 Joum. xliv., 1917, p. 91). Because it is understood that the Trochus breeds in the warmer season, 

 fishing is there permitted only from 1st April to 1st November. 



Neither in Australasia, nor in other British possessions, are any limits set for the size or season, 

 at which Trochus may be taken. The smallest size specified by Japanese buyers is \k inches. It has 

 been suggested by the Suva Chamber of Commerce that a legal minimum of 2 or 2h inches for the 

 " chicken " shell would be beneficial to the industry. Some measure of natural protection is afforded 

 by the fact that it is too troublesome and unprofitable to pick out the snails from the smallest shells. 

 If the natives are correct in asserting that the Trochus come up from deep water on the reefs during 

 the south-east monsoon, then it is probable that the species is preserved during its early stages in rough 

 and inaccessible places at the base of the outer reefs. 



The annual Australian crop is likely soon to deteriorate under the present active fishery. 



EXPLANATION OF PLATES V-VI. 



Fig. I and 2. — Front and base view, slightly reduced, of a specimen of Trochus niloticus from Samarai, 

 5 J inches in diameter. 



Fig. 3. — A shell divided vertically to show the vacated upper chambers, blocked by porcellaneous callus, 

 and to show the pearly frame of the shell, lined and coated v ith i.<>n nacreous layers, reduced. 



