Publication Date
5-2009
Series Number
192
Publisher
Department of Fisheries, Western Australia
City
Perth
ISBN
1 921258 56 X
ISSN
1035 - 4549
Abstract
Final FRDC Report – Project 2004/042
Objectives
1. Determine for the 20 major WA scalefish species (4 - 5 in each bioregion) the relative accuracy of structures used to estimate age (e.g. Sectioned/whole otoliths, lengths, otolith weight, other otolith dimensions or some combination of these).
2. For each stock, examine the relative impact on the calculated age-compositions and their effect on model outputs and conclusions from varying (i) the method of ageing used (only where this is possible from available data) (ii) the number of individuals used in the samples (iii) the spatial distribution of the samples used (iv) if possible, the frequency of sampling.
3. Using agreed levels of precision for the model outputs, undertake cost benefit analyses to generate the most appropriate long-term age-structured monitoring program for each major scalefish species in WA by assessing the method(s) of ageing, sampling intensity within each year and the frequency of sampling among years.
Outcomes achieved
Cheaper methods of ageing fish have been developed for 20 of the 23 stocks of Western Australian scalefish examined in this study. These cost reductions were not always large, but the conclusive result that monitoring programs can utilize methods of ageing fish other than relying on counting rings on thin sections of otoliths (ear bones) is the norm and not the exception will have positive flow on effects for fisheries research and management in Western Australia. The most expensive part of any age monitoring program is the collection of samples. The minimum sample size required is ~300, with ~500 fish preferable. The clear depiction of the relative sampling and processing costs provided in this report can be used as a basis for developing better sampling programs that involve industry support.
Number of Pages
110
Keywords
Department of Primary Industries and Regional Development, otoliths, annuli, robust regression, mixture analysis
Disciplines
Aquaculture and Fisheries | Environmental Monitoring | Natural Resources Management and Policy
Recommended Citation
Montgomery Craine, M., Rome, B., Stephenson, P., Wise, B., Gaughan, D., Lenanton, R., Steckis, R. (2009). Determination of a cost effective methodology for ongoing age monitoring needed for the management of scalefish fisheries in Western Australia. Final report to Fisheries Research and Development Corporation on Project No. 2004/042. Fisheries Research Report No. 192. Department of Fisheries, Western Australia. 110p.
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