H-43 



RESEARCH PROGRAMMES 



2. Growth. 



This is difficult to measure in decapods. Tagging and recovery after mouUing and short 

 term holding experiments can provide good data on growth of adults. Polymodal frequency 

 analysis can indicate growth rates of juvenile specimens. 



3. Mortality. 



Size composition data combined with growth information may provide rough estimates of 

 total mortality, or natural mortality if size composition information is collected in the early 

 stages of fishing. The rate of decline in catch per unit effort, during a short fishing season, in 

 relation to the catch, can also provide an estimate of total mortality. The above techniques 

 require that catchabiUty remains constant with size and throughout the fishing season. Tagging 

 experiments probably provide the most promising means of estimating fishing mortality. Tag 

 loss is usually confined to the moult. 



4. Yield assessments. 



Trends in catch size composition and catch per unit effort reflect the impact of fishing on 

 the stock. Better yield assessments can be made from stock production curves if a suitable time 

 series of catch and effort data is available. If growth and mortaUty data are available, yield per 

 recruit curves can be calculated to evaluate the sensitivity of the stock to changes in effort and 

 sizes at first capture. 



The above proposals refer mainly to stock assessment needs. Biological studies which 

 would enhance population models and management should encompass the following: seasonal 

 migrations; stock separation; feeding and predation; and larval dispersion, and recruitment. 



SELECTED REFERENCES 



Anon. 1971. Kaiyo-Maru's survey report - New Zealand southern waters - for the year 1910. Japanese 



Fishing Agency, unpublished report. 

 Arnaud, p. and Do Cm, C. 1976. Proposals for the study of living resources of the Southern Ocean: the 



Lithodidae (Crustacea, Anomura). UnpubUshed report. 

 Mills, E. L. 1975. Benthic organisms and the structure of marine organisms. Journal of the Fisheries 



Research Board of Canada, Vol 32, p 1657-1663. 

 Pollock, D. E. 1976. Assessment of the rock lobster (Jasus tristini) stocks. Cape Town, Sea Fisheries 



Branch, unpubUshed report. 

 Ritchie, L. D. 1970. Southern spider crab {Jacquinotia edwardsii) at the Auckland Islands, October 1971. 



Fisheries Technical Report, No 101. 

 Ritchie, L. D. 1973. Commercial fishing for southern spider crab (Jacquinotia edwardsii) at the Auckland 



Islands, October 1971. Wellington, Ministry of Agriculture and Fisheries. (Fisheries Technical Report 



No 101.) 

 Ryff, M. R and VoLLER, R. W. 1976. Aspects of the southern spider crab (Jacquinotia edwardsii) 



fishery of southern New Zealand islands and Pukaki Rise. Fisheries Technical Report , No 143. 

 VrANCKX, R. 1974. Evolution du stock de langoustes sur les fonds de peche des Ties St Paul et Nouvelle 



Amsterdam de 1962 a 1970. Bulletin du Museum National d'Histoire Naturelle (Paris), No 155, 



p 193-204. 

 Vranckx, R and HuREAU, J.-C, in press. Production de langoustes dans les eaux des Ties St Paul et 



Amsterdam. In: DUNBAR, M. ed. Polar oceans. Calgary, Arctic Institute of North America. 



2.9 Seaweeds 



2.9.1 Introduction 



The littoral zones of the Antarctic and sub-Antarctic are particularly rich in benthic 

 seaweeds. About 700 species belonging to 300 genera have been recorded from the Southern 



