UNION OF SOUTH AFRICA. 

MARINE BIOLOGICAL REPORT. 

I.— CRAWFISH INVESTIGATIONS, INCLUDING EX- 
PERIMENTAL HAULS, ARTIFICIAL REARING AND 
MIGRATORY MOVEMENTS OF THE CAPE CRAW- 
FISH, ([ASUS LALANDII.) 
The chief objects kept in view in this work have been (1) 
the continuation of the series of hauls at regular intervals 
and at definite places in order (a) to ascertain if any varia- 
tion in the supply of crawfish is taking place, (b) to obtain 
further information as to times of spawning and condition of 
fish, and:if any variation in this takes place from time to time, 
(c) to ascertain in what localities mature females and young 
occur with a view to their protection in such areas. 
(2) To obtain further information as to the life history of 
the crawfish, some of the stages of which are not yet fully 
known. 
(3) To carry out experiments in artificial hatching, with 
a view to ascertain some practical method of supplementing 
the supply of crawfish, should this become necessary. 
(4) To ascertain if there is any extensive migration or 
movement of crawfish from one locality to another, in con- 
nection with such questions as the possibility of a natural 
restocking of exhausted areas, and the utility of establishing 
sanctuaries, where crawfish may congregate more or less 
permanently. | 
The work has been hampered to a considerable extent by 
the impossibility of obtaining the requisite equipment. 
Dredges, trawls, townets, etc., were ordered some months 
ago, but have not arrived, owing to present war conditions. 
Great difficulty was also expérienced in procuring a suitable 
boat for carrying out the work. 
(1) Experimental Hauls.—These have been continued on 
the same lines as.in previous years with the exception of a 
short period during which a temporary close season was 
imposed from 15th May to 15th June. During this period, 
at the request of the canning companies, the method was 
slightly altered, namely, when no fish were procured at a 
_locality other hauls were made in-the neighbourhood until 
fish were got. This had the advantage of procuring more 
[C.P. 3—1918] 
