THE GREAT BARRIER REEF OF AUSTRALIA. 32? 



In regard to their annual export value the oyster- fisheries of 

 Queensland occupy the third position upon the list of the leading 

 fishery industries of the colony. " Pearl shell " takes the lead, 

 with an average yearly export value of £70,000. The Beche-de- 

 mer yields in like manner an average of £'23,000, while the 

 oyster-fisheries for the past ten years have not exceeded an 

 average of £8000, but almost half as much again may be set 

 down as the value of those for home consumption, bringing the 

 total for oysters to about £12,000. 



There is but one species of oyster of any commercial value 

 in Queensland, namely, the so-called " rock-oyster," Ostrea 

 glomerate; but of this form there are, as might be expected, 

 several varieties, which are duly described. 



Mr. Saville Kent states that the largest edible oyster is that 

 known as the cockscomb-oyster, Ostrea crista-galli, a salt-water 

 form restricted to the tropics, and found plentifully among the 

 coral reefs of Torres Strait and the Great Barrier system. A 

 pair of its shells will weigh from 5 to 7 lbs., and have a diameter 

 of from 8 to 12 inches. 



As to the antagonism of star-fishes and oysters, the author 

 observes — 



" Star-fishes of all descriptions, but more especially the ordinary five- 

 rayed varieties, Asteriada, are universally held up for condemnation, as 

 representing the most insatiable foes of the oyster tribe. Whether this 

 wholesale condemnation is a just one, there are some reasons for doubting. 

 In many instances it has been observed that the Star-fishes were merely 

 acting as scavengers, and preying on dead or dyiug bivalves. The direct 

 experiment was carried out by the author, some years since, in one of the 

 large English public aquaria, of keeping oysters and star-fish, including 

 the accredited most aggressive species, Asterias (U raster) rubens, in the 

 same tank. The pre-supposed aggressors and their helpless victims were 

 thus maintained, side by side, in perfect health, for many months, without 

 a single instance occurring of molestation of the oysters on the part of the 

 Star-fish. The Ecbinoderms, however, demonstrated their possession of 

 normal healthy appetites by feeding freely on portions of cut-up fish occa- 

 sionally placed in the tanks. How far this vindication of the Star-fish's 

 character would hold good in association with the common shore species of 

 South Queensland has yet to be demonstrated. 



" In the interim it is desirable, in the interests of the oyster grower, to 

 recommend t the clearance of this intruder as far as possible from off his 

 beds or banks. In this connection, a suggestion concerning the destruction 



