H-41 



RESEARCH PROGRAMMES 



Rates of tagging at Tristan and neighbouring islands have been insufficient to provide good 

 estimates of mortahty. Stock sizes and mortahty have been calculated from catch per unit 

 effort information at Amsterdam and St Paul. Estimates of stock range from 7 000 to 14 000 

 tons (Vranckx, 1974). 



Catch per unit effort trends, as well as catch size composition, suggest that stocks are not 

 over-exploited at Tristan and adjacent islands, and that present catch levels of about 800 metric 

 tons nominal weight can be maintained without increasing fishing effort (Pollock, 1976). 

 Similar analysis at Amsterdam/St Paul has indicated that stocks have decUned, and the yield of 

 900 metric tons obtained in the past may be too high (Vranckx and Hureau, in press). 



(b) lithodid crabs. 



In recent years, exploratory fishing surveys have been conducted by France to collect 

 biological information on and to assess the potential of lithodid crabs, particularly Lithodes 

 murrayL Experimental fishing resulted in large catches around the Crozet islands. Few crabs 

 were caught at Prince Edward Island and catches were negative at Marion and Kerguelen islands 

 (Amaud and Do Chi, 1976). It was felt that further surveys were required to evaluate 

 completely the potential of these islands. In the course of the surveys, biological observations 

 on reproduction, parasites and feeding were also made. 



PLATE 8. A lithodid crab (Lithodes murrayi). 



(c) Spider crabs. 



The spider crab Jacquinotia edwardsii is endemic to southern New Zealand and the New 

 Zealand sub-Antarctic (40°-50°S, 100°-165°E). It has been recorded in decreasing quantities at 

 Pukaki Rise, Auckland Islands, Campbell Island, Bounty Islands (Anon, 1971), Stewart Island 

 Shelf, Puysegur Bank and off the east coast of the southern South Island. The presence of large 

 stocks in depths of less than 200 m at the Auckland Islands has also been shown (Ritchie, 1970, 

 1973; Ryff and Voller, 1976). Experimental fishing by a joint New Zealand-Japanese 

 expedition during the austral summer found a resource at the Pukaki Rise which was about 



