472 



Fishery Bulletin 98(3) 



^1 Spectra 1 -mm, n = 4028 

 I I Contiol. n = 511 



2 30- 



^H Momoi 1 7-mm, n = 4153 

 I I Conlrol, n= 4914 



u/6 6/8 u/10 9/12 13/15 16/20 21/30 



Commercial prawn grades (number per pound) 



Figure 6 



Commercial size categories of western king prawns (Penaeiis 

 latisulcatus) caught with the (A) spectra-1-mm and con- 

 trol trawls and (Bi momoi-1.7-mm and control trawls 

 (u=underi. 



discarded bycatch-to-prawn ratios were 1:1 for the spec- 

 tra-l-mm and 1:1.3 for the niomoi-1.7-mm trawl bodies. 

 Ongoing monitoring is still required, however, to assess 

 any potential effects on selectivity associated with opera- 

 tional refinements to the current trawl configi.u'ations. 



Acknowledgments 



This study was funded by the Australian Fishing Industry 

 Research and Development Corporation. We thank Simon 

 Boxshall and Brian McDonald for logistical support and 

 assistance in the field and Jim Raptis (A. Raptis and Sons, 

 PTY LTD) for the use of his vessel Jillian Sandra. We are 

 grateful for the assistance and advice provided by Less 

 Lowe (Gulf Net mending PTY LTD), Kim Redman, Hec 

 Kavenagh, and all Gulf St. Vincent prawn trawlers. We 

 would also like to acknowledge the Conselho National de 

 Ensino e Pesquisa (CNPq) in Brazil for their contribution 

 to the involvement of Matt Broadhurst. 



Literature cited 



Alverson, D. L., M. H. Freeberg, S. A. Murawski, and J. G. Pope. 

 1994. A global assessment of fisheries bycatch and discards. 

 FAO Fish. Tech. Paper 339, Rome, 233 p. 

 Andrew, N. L., K. J. Graham, S. J. Kennelly, and M. K. Broadhurst. 



1991. The effects of trawl configuration on the size and compo- 

 sition of catches using benthic prawn trawls off the coast of 

 New South Wales, Australia. ICES J. Mar. Sci. 48:201-209. 



Andrew, N. L., and J. G. Pepperell. 



1992. The bycatch of shrimp trawl fisheries. Oceanogr. 

 Mar. Biol. Annu. Rev. 30:527-565. 



Armstrong, D. W., R. S. T. Ferro, D. N. MacLennan, and 

 S. A. Reeves. 



1990. Gear selectivity and the conservation offish. J. Fish 

 Biol. 37A:261-262. 

 Bainbridge, R. 



1958. The speed of swimming offish as related to size and 

 to the frequency and amplitude of the tailbeat. J. E.\p. 

 Biol. 35:109-133. 

 Beamish, F W. H. 



1978. Swimming capacity. In Fish physiology, vol: VII, 

 Locomotion (W. S. Hoar and D. J. Randall, eds. ), p. 101-187. 

 Academic Press, New York, NY. 

 Broadhurst, M. K. 



In press. Modifications to reduce bycatch in prawn trawls: 

 a review and framework for development. Rev. Fish Biol. 

 Fish. 

 Broadhurst, M. K.. and S. J. Kennelly. 



1996. Effects of the circumference of codends and a new 

 design of square-mesh panel in reducing unwanted bycatch 

 in the New South Wales oceanic prawn-trawl fishery, Aus- 

 tralia. Fish. Res. 27:203-214. 



1997. The composite square-mesh panel: a modification to 

 codends for reducing unwanted bycatch and increasing 

 catches of prawns throughout the New South Wales oce- 

 anic prawn-trawl fishery. Fish. Bull. 95:653-64. 



Broadhurst, M. K., S. J. Kennelly and G. O'Doherty. 



1996. Effects of square-mesh panels in codends and of haul- 

 back-delay on bycatch reduction in the oceanic prawn- 

 trawl fishery of New South Wales, Australia. Fish. Bull. 

 94:412-22. 

 Broadhurst, M. K., R. B. Larsen, S. J. Kennelly and P McShane. 

 1999. Use and success of composite square-mesh codends in 

 reducing bycatch and in improving size-selectivity of prawns 

 in Gulf St. Vincent, South Australia. Fish. Bull. 97:434-48. 

 FAO (Food and Agi'iculture Organization of the United Nations). 

 1972. Catalogue offishing gear designs. Fishing news books 

 Ltd., Farnham, Surrey. England, 160 p. 

 High, W. L., I. E. Ellis, and L. D. Lusz. 



1969. A progress report on the development of a shrimp 

 trawl to separate shrimp from fish and bottom-dwelling 

 animals. Comm. Fish. Rev 31:20-33. 

 Isaksen, B., J. W. Valdemarsen, R. B. Larsen, and L. Karlsen. 

 1992. Reduction of fish bycatch in shrimp trawl using a 

 rigid separator grid in the aft belly. Fish. Res. 13:3,5-52. 

 MacLennan, D. N. 



1992. Fishing gear selectivity: an overview. Fish. Res. 13: 

 201-204. 

 Millar, R. B., and S. J. Walsh. 



1992. Analysis of trawl selectivity studies with an applica- 

 tion to trouser trawls. Fish. Res. 13:205-220. 

 Pope. J. A., A. R. Margetts, J. M. Hamley, and E. F Akyuz. 



1975. Manual methods for fish stock assessment. Part III: 

 selectivity of fishing gear. FAO Fisheries Technical Report 

 41 (revision 1 1, 65 p. I^AO, Rome. 



