814 



Fishery Bulletin 100(4) 



12 -1 



100 



400 



800 1200 

 Disc width (mm) 



1600 



100 



80 



60 



O 



c 

 3 



40 <" 



- 20 



1000 



2000 



3000 



4000 



Total length (mm) 



Figure 3 



The length frequency and cumulative length frequency of r^ys (A) and 

 sharks (B) caught in nets with a standard codend (black columns and solid 

 line) and nets with a TED (grey columns and broken line). 



vival. Their diets include benthic organisms and are likely 

 to include commercial prawns; their range and day and 

 night catchability is unknown. The combination of these 

 factors means that these species are likely to occur in 

 trawl grounds and that they are highly susceptible to cap- 

 ture and mortality due to trawlers. The recovery capacity 

 of populations of these species is also low (Appendix 2). 

 The rarity of the species in the bycatch means that no data 

 are available to estimate the probability of breeding before 

 capture, removal rate, total biomass, or the mortality in- 

 dex for most of these species, and they therefore received 

 ranks of 1 for these criteria. In general these are large 

 animals and are therefore likely to have slower recovery 

 rates for their population than those of smaller species. 

 The annual fecundity was low for all species. 



The pristids are the focus of increasing international 

 concern because their populations are declining worldwide 



(Stevens et al. 2000). They are rarely seen today in areas 

 where they were previously abundant (Simpfendorfer, 

 2000). This decrease in pristid populations has resulted 

 in four species being listed on the lUCN 1996 red list 

 (Bailie and Groombridge, 1996). Of the species studied in 

 our study, P. pectinala and P. microdon are listed as endan- 

 gered. Recent demographic analysis of pristid populations 

 has indicated that their recovery will take several decades 

 even if they are given effective conservation (Simpfendor- 

 fer, 2000). 



In comparison, the species that were most likely to be 

 able to sustain capture in the bycatch of the NPF were H. 

 toslii, E. blockii. C. macloti. and C. tilstoni. These species 

 had a lower susceptibility to capture and mortality due 

 to trawling (Appendix 1). With the exception of H. toshi, 

 these are pelagic species and there is little likelihood of 

 their capture in prawn trawls. For the species for which 



