874 



Abstract— Between March 2000 and 

 April 2001 two commercial fishing ves- 

 sels fished for toothfish (Dissostichus 

 eleginoides) off South Georgia using 

 pots. A significant number of lithodid 

 crabs (three species of Paralomis 

 spp.) were caught as bycatch. Paralo- 

 mis spinosissima occurred in shallow 

 water, generally shallower than 700 m. 

 Paralomis anamerae, not previously 

 reported from this area and therefore 

 representing a considerable southerly 

 extension in the reported geographic 

 range of this species, had an interme- 

 diate depth distribution from 400 to 

 800 m. Paralomis formosa was present 

 in shallow waters but reached much 

 higher catch levels (and, presumably, 

 densities) between 800 and 1400 m. 

 Differences were also noted in depth 

 distribution of the sexes and size of 

 crabs. Depth, soak time, and area were 

 found to significantly influence crab 

 catch rates. Few crabs (3% of P. spi- 

 nosissima and T7c of P. formosa) were 

 males above the legal size limit and 

 could therefore be retained. All other 

 crabs were discarded. Most crabs ( >99% 

 of P. formosa, >97% off! spinosissima, 

 and >90% of P. anamerae) were lively 

 on arrival on deck and at subsequent 

 discard. Mortality rates estimated 

 from re-immersion experiments indi- 

 cated that on the vessel where pots 

 were emptied directly onto the factory 

 conveyor belt 78-89% of crabs would 

 survive discarding, whereas on the 

 vessel where crabs were emptied down 

 a vertical chute prior to being sorted, 

 survivorship was 38-58%. Of the 

 three, P. anamerae was the most vul- 

 nerable to handling onboard and sub- 

 sequent discarding. Paralomis spino- 

 sissima seemed more vulnerable than 

 P. formosa. 



Distribution, demography, and discard 

 mortality of crabs caught as bycatch 

 in an experimental pot fishery 

 for toothfish {Dissostichus eleginoides) 

 in the South Atlantic 



Martin G. Purves 



Marine and Coastal Management 



P.O. Box X2, Roggebaai 8012 



Cape Town, South Africa 



Present address: Resources Assessment Group 



47 Pnnce's Gate 



London SW7 7QA, United Kingdom 

 E-mail address; m purvesigimpenal acuk 



David J. Agnew 



Renewable Resources Assessment Group 



Imperial College 



Royal School of Mines 



Prince Consort Road 



London, SW7 2BP, United Kingdom 



Guillermo Moreno 



Tim Daw 



MRAG Ltd 



47 Pnnces Gate 



London, SW7 2QA, United Kingdom 



Cynthia Yau 



Zoology Department 



University of Aberdeen 



Aberdeen, AB24 2TZ, United Kingdom 



Graham Pilling 



Centre for Environment, Fisheries and Aquaculture Science (CEFAS) 



Pakefleld Road 



Lowestoft, NR33 OHT, United Kingdom 



Manuscript approved for publication 

 17 April 2003 by Scientific Editor 



Manuscript received 26 June 2003 



at NMFS Scientific Publications Office. 



Fish Bull. 101:874-888 (2003). 



The Commission for the Conservation 

 of Ajitarctic Marine Living Resources 

 (CCAMLR) and its Scientific Committee 

 were pioneers in the development of the 

 "ecosystem approach" for the manage- 

 ment of fisheries. Using this approach 

 the Commission is bound to consider 

 the impact of any fishery on both the 

 target, dependent, and related species. 

 Currently, the most important fishery in 

 CCAMLR waters is the longline fishery 



for Patagonian toothfish (Dissostichus 

 eleginoides) and fishing grounds near 

 South Georgia Island and Shag Rocks in 

 CCAMLR subarea 48.3 (South Atlantic 

 sector) are among the most important. 

 Mitigation measures, including require- 

 ments for setting at night, in the winter, 

 and with specialized gear, have been 

 introduced to reduce incidental mortal- 

 ity of birds being hooked by longlines. 

 However, these measures impose severe 



