DECAPODA 343 



Sub-order BRACHYURA 



Family CANCRID^ 

 Cancer pagurus, Linn. British Edible Crab 



In 1885 Mr S. C. Farr, on behalf of the Canterbury Society, 

 shipped 12 crabs by the 'Kaikoura,' but they all died in the tropics. 



No further attempt seems to have been made till the Portobello 

 Fish Hatchery Board decided to introduce them. In August, 1907, 

 there were landed from the 'Karamea,' three male and five female 

 crabs; and on her next voyage in 1908, seven males and one female. 

 The females all bore ova, but no attempt was made to deal with the 

 larvae as they hatched. They were liberated from the station with 

 the outgoing tide, and considerable numbers were carried outside the 

 Otago Heads and set free at a distance off shore. In this way it was 

 estimated that up to 1912, over 20,000,000 fry had been liberated. 



In 1913 there were shipped on the 'Karamea' at Plymouth, 

 50 crabs (17 males and 33 females), and of these 43 were landed 

 at the hatchery. They did not thrive, however, and no fewer than 

 1 6 died at the approach of the cold season. It was therefore 

 thought advisable to liberate most of the remainder, so 19 were 

 set free in a suitable locality, and eight were retained in the 

 ponds. Of these two died the following season. The number of 

 larvae liberated in 1914-15 was estimated to be 12,000,000. It is 

 probable therefore that some 40,000,000 larvae have been distributed 

 since the first experimental introduction in 1907. As the larvae remain 

 in a pelagic condition for a long time, and pass through several 

 metamorphoses, the death-rate must be very high; but making allow- 

 ance for this the chances are that ere long specimens of this crab will 

 be found on the New Zealand coast. 



It has been found very difficult to keep these crabs under observa- 

 tion at the Portobello Hatchery, as they burrow in the mud, get under 

 stones and even under the foundations of the walls of the ponds. 

 It is probable also that the winter temperature of the ponds in Otago 

 Harbour is too low for them, and this may account for the high death- 

 rate. In British seas it is known that they move into deep water at the 

 approach of winter. While the temperature of the open sea outside 

 Otago Heads seldom falls to 50 F. in the middle of winter, that of 

 the Harbour itself often touches 40 F., and in the ponds has been 

 found as low as 32 F. Lobsters can stand these low temperatures, 

 but they appear to be very detrimental, if not always fatal to this 

 species of crab. 



