New Zealand Journal of Marine and Freshwater Research abstracts
Diel variation in spawning orange roughy (Hoplostethus atlanticus,
Trachichthyidae) abundance over a seamount feature
on the north-west Chatham Rise
B. BULL
I. DOONAN
D. TRACEY
A. HART
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 14 901, Kilbirnie
Wellington, New Zealand
email: b.bull@niwa.cri.nz
Abstract The diel variation in abundance of an orange roughy
(Hoplostethus atlanticus Collett) spawning aggregation on a deepsea
seamount on the Chatham Rise known as "Graveyard" was studied using acoustics.
A 4-day survey was carried out using a Latin cube statistical design. The
acoustic data was echo-integrated and analysis of variance was carried out to
estimate the effects of day, time of day, and transect path. The estimated
biomass of the spawning aggregation did not display any significant diel
variation. We conclude that this result validates the current practice of
acoustically surveying orange roughy on this seamount without considering diel
effects. The aggregation fluctuated in abundance over the survey period,
suggesting that turnover of fish was occurring. Differences in roughy biomass
with transect orientation indicate the importance of randomised radial
transects for these surveys.
Keywords orange roughy; spawning dynamics; diel; diurnal;
acoustics; Latin cube; star design
New Zealand Journal of Marine and Freshwater Research, 2001, Vol. 35:
435-444
0028-8330/01/3503-0435 $7.00 (c) The Royal Society of New Zealand
2001
PDF file of entire paper: medium quality (1311K); (scanned from paper original: notes about this process)
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