Zeldis et al. : An estimate of biomass of Hoplostethus atlanticus 
593 
Use in stock assessment 
Although the biomass estimates derived from this 
DFRM survey were rather imprecise (CV=0.50), they 
were capable of having a dramatic effect on the as- 
sessment of the mid-east coast stock. In 1994, an 
estimate of 45,000 t recruited biomass (CV=0.40) 
from a preliminary analysis of these data was used 
in assessing this stock (Field et al. 2 : this estimate 
differs from those given above because some data 
errors have subsequently been corrected and the 
analyses have been refined). The inclusion of this 
estimate greatly improved the precision of the as- 
sessment (Fig. 10), which resulted in a 2-year stepped 
reduction in TACC from 10,333 t in 1993-94 to 2500 
t in 1995-96. 
Acknowledgments 
The authors would like to thank Kevin Sullivan for 
statistical advice and revision of the manuscript, 
Steve Chiswell for assistance with geostrophic analy- 
sis, Karen Field for laboratory assistance, and Alan 
Hart, Jack Fenaughty, and the officers and crew of 
Tangaroa for assistance at sea (all at NIWA). We 
thank Tony Koslow (CSIRO) for provision of St. 
Helen’s seamount orange roughy egg data, and the 
external reviewers for their comments. This work was 
partly funded by the New Zealand Ministry of Fish- 
eries under project DOR609. 
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