39 



Crawfish have been observed in the tanks making 

 attacks on sea urchins, but with httle success. The animal 

 was taken up in the claws oi the crawfish as in the case of the 

 Turho and the spines were bitten off one by one by means of the 

 mandibles till the whole shell was quite bare. All attempts to 

 penetrate the shell or the oral or aboral areas were, however 

 in vain, and the crawfish finally abandons its prey, which 

 then fell a victim to the omnivorous starfish, which is 

 provided with other and more effective means of attack, 

 provided the spines are removed. 



As regards food supply, the crawfish is very easily kept 

 in captivity. It can survive for long intervals without food, 

 and can be fed continuously on the same kind of food. It 

 was never observed to feed on vegetable matter, though that 

 it does so is shown by the stomach contents of captured fish. 



II. Migration and Movements of the Crawfish. 

 Information is wanted on this subject in connection with 

 the alleged difference in the spawning times of the crawfish at 

 different locahties and with reference to other questions. 

 There does not seem to be any extensive migration along the 

 coast and it would appear that the animals are confined more 

 or less to the bays or locahties which they inhabit. A series 

 of experiments with marked fish would be necessary to throw 



light on this point. t^ ui o .1. 



Within a restricted area, however, such as Table Bay, there 

 seems to be a definite movement. Thus at times the animals 

 are found in abundance at one spot for several days, and then 

 suddenly hardly a single one will be found, the whole of them 

 having moved off to some other locahty, where they may be 

 procured as abundantly as before. It has been stated that in 

 Table Bay they move round the Bay in a circle, returnmg to 

 the point from which they started. In the fishing operations 

 of the Canning Factory it was found that large males were 

 caught off Mouille Point from February to April or May 

 (according to the weather). Mostly medium-sized males were 

 caught off Milnerton and Blaauwberg in May and June. 

 Medium-sized males and females were caught off Robben Island 

 between June and October, and during the months of July 

 and August a good proportion were females. Along the coast 

 from Camps Bay to Oude Skip catches are made during March 

 and April, these being nearly all large or medium-sized males. 

 This of course, does not point to an actual movement of the 

 fish from Mouille Point, Milnerton, Blaauwberg and Robben 

 Island, as the fish caught are apparently not the same kind, 

 differing as they do in size and in sex. 

 [C.P. 5— 'I3-] 



