199 



Abstract. -The reproduction of 

 blue-eye trevalla, Hyperoglyphe ant- 

 arctica, off Tasmania, southern Austra- 

 lia, is studied in detail through analy- 

 sis of gonad maturation, spawning 

 location and season, size at maturity, 

 fecundity, and spawning frequency. 



Results show that the fecundity of 

 blue-eye trevalla is determinate, and it 

 has a high annual fecundity which in- 

 creases exponentially with the length 

 of females (to a maximum of about 11 

 million oocytes). Females are partial 

 spawners and possibly spawn all their 

 oocytes in 3 or 4 large batches, the size 

 of batches increasing with the length 

 of females. Both sexes reach sexual 

 maturity at large sizes, 71.3 and 61.6 

 cm fork length for females and males, 

 respectively. One major spawning 

 ground was identified off Tasmania 

 where blue-eye trevalla aggregate from 

 October to May. Smaller fish join the 

 aggregation first, at early stages of go- 

 nad maturation, whereas larger fish 

 appear to join the aggregation later, 

 just prior to spawning. Spawning takes 

 place at the end of summer-autumn 

 (early March to early May). 



Biology and dynamics of the 

 reproduction of blue-eye trevalla, 

 Hyperoglyphe antarctica 

 (Centrolophidae), off Tasmania, 

 southern Australia 



Pascale Baelde 



Marine Resources Division, Department of Primary Industry and Fisheries 

 Nubeena Crescent, Taroona, Tasmania 7053, Australia 



Manuscript accepted 21 November 1995. 

 Fishery Bulletin 94:199-211 (1996). 



Blue-eye trevalla, Hyperoglyphe 

 antarctica (Centrolophidae) are 

 widely distributed in the southern 

 oceans, from New Zealand to south- 

 ern Australia, South Africa, and the 

 southern Indian Ocean (Haedrich, 

 1967; McDowall, 1982). In Austra- 

 lia, they are found from central New 

 South Wales to southern western 

 Australia (Fig. 1) and on offshore 

 seamounts. The fishery has devel- 

 oped off southeast Australia, par- 

 ticularly off Tasmania (Fig. 1). Fish- 

 ing is traditionally done with drop- 

 lines on hard sea bottom associated 

 with the continental shelf break, at 

 depths between 300 and 500 m. 

 Commercial landings are relatively 

 small (about 800 metric tons per 

 year), but blue-eye trevalla is an 

 excellent table fish and fresh fish 

 fetch high prices on the domestic 

 market. 



In the late 1980s, a conflict arose 

 between traditional line fishermen 

 and trawl fishermen who intended 

 to develop mid-water trawling tech- 

 niques to target blue-eye trevalla. 

 At that time, there was limited in- 

 formation on the biology and size of 

 the resource, and it was feared that 

 mid-water trawling would increase 

 fishing effort to unsustainable lev- 

 els. As a result, a research program 

 was implemented in 1991 to study 

 the biology of blue-eye trevalla off 

 Tasmania. Anecdotal information 



on the breeding season of this spe- 

 cies was available from Jones 1 in 

 South Australia and from Horn and 

 Massey (1989) in New Zealand; no 

 fecundity study had been under- 

 taken. In this paper the reproduc- 

 tive biology (gonad maturation, size 

 at maturity, spawning frequency, 

 and fecundity) and the composition 

 and dynamics of the main spawning 

 aggregation are studied in detail, and 

 a discussion is provided on some of 

 the implications for the fishery. 



Materials and methods 



Sampling 



Blue-eye trevalla were collected on 

 board commercial vessels during 

 drop-line fishing operations, be- 

 tween November 1991 and July 

 1993. Drop-lines are polypropylene 

 lines that are anchored with a 

 weight to the sea bottom at depths 

 between 300 and 500 m and that are 

 supported vertically by boys. Ten to 

 15 lines are used during fishing, 

 each carrying about 100 hooks. At 

 least one sample was obtained each 



'Jones, O.K. 1988. The biological status 

 of the deepsea trevalla (Hyperoglyphe 

 antarctica) offshore line fishery in South 

 Australian waters. Department of Fish- 

 eries, South Australia, discussion paper, 

 April 1988, 15 p. 



