154 Part IT1.—Twenty-third Annual Report 
VII.—A NOTE ON THE HATCHING OF THE CRAB (CANCER 
PAGURUS). By H. Cas. Wititamson, M.A., D.Se., Marine 
Laboratory, Aberdeen. 
In the summer of 1902 a quantity of the fry of the edible crab was 
distributed in the sea off the coast of Aberdeenshire. 
Nine berried crabs (breester, pea-parten) were obtained chiefly in the 
neighbourhood of Aberdeen. They were kept in two concrete tanks 
until the larve hatched out. Shelter was afforded the crabs in cavities 
formed by building stones up on the sand-covered bottom of the tank. 
When the fry hatched out it was attracted to the glass front of the 
tank, from which side the light entered, and when present in quantity 
the fry formed a thick white cloud. The young crabs were drawn off 
into the carboys by means of a syphon. All the fry of the crab 
deposited near Fraserburgh and Findochty was in the first zoéa stage. 
The crab fry was disposed of as follows :— 
August 6, 1902.—About 1 million set free about 1 mile norch of 
Fraserburgh. 
August 7, 1902.—About 2 millions set free about 3 mile off 
Cairnbulg. 
August 19, 1902.—About 1 million set free about # mile off St. 
Combs. 
September 15, 1902.——About 3 million set free about ? mile north of 
Findochty. 
The method of estimating the numbers of crab fry was as follows. 
The fry that was set free was provided by nine berried crabs, and at the 
low average of half a million eggs to each crab, should number 
41 millions. The proportion of this total set free at each of the four 
above-mentioned places was apportioned approximately by the number of 
carboys required for the consignment. 
The crabs hatched out in August, September, and October. The 
vitality of the crab fry was tested in the following manner. Crab fry 
were crowded into a glass jar. The water was heated to 174° C., and 
then allowed to cool. Next forenoon the majority was alive and lively. 
On one of the journeys the water in one of the carboys was cooled to 
about 7° C. The crab fry in this carboy did not, at the end of the 
journey, appear to be in any better condition than those which had been 
filled with water at the temperature of the hatchery. 
The crabs which furnished the fry were kept alive when the hatching 
was finished, and some lived until the spring of 1905. The history of 
the members of the 1902 group throws some light on certain of the 
problems of the life-history of this species. It has been already outlined.* 
In January 1903 two of these crabs were dissected; one had died, 
the second was killed. In the former the ovary was white, with a very 
slight pink tinge. ‘There were a few red eggs in a bunch near the 
oviduct. The eggs were degenerating ; they were disorganised internally. 
* Vide Williamson. ‘‘Contributions to the Life-histories of the Edible Crab (Cancer 
pagurus) and of other Decapod Crustacea, &c.”—Twenty-second Annual Report of the 
Fishery Board for Scotland, Part IIT., 1904. 
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