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Please use this identifier to cite or link to this item:
http://hdl.handle.net/1834/2758
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| Title: | Report of the second horse mackerel otolith reading workshop |
| Corporate Author: | MFMR(Natmirc)
Benefit |
| ASFA Terms: | Aging |
| Issue Date: | 2001 |
| Abstract: | Age estimation of commercially exploited fish species in the Benguella region. Stocks of the two species of horse mackerel that occur in the Benguela region, namely Cape
(Trachurus trachurus capensis) and Cunene horse mackerel (Trachurus trecae) are being
exposed to increasing levels of commercial exploitation, highlighting the requirement for
effective management measures to ensure their sustainable utilization. Such measures can only
be implemented with confidence if they are based on reliable stock assessment procedures. Sizestructured
stock assessment models have been found to be unsuitable for Southern African horse
mackerel stocks, and the decision has recently been made to move to an age-structured VPA
approach. A fundamental requirement for this approach to stock assessment is the availability of
robust information concerning the age structure of the population(s). This requirement has been
highlighted in the BENEFIT Science Plan, and more recently during the International Workshop
on the Research and Management of Horse Mackerel in Namibian Waters convened in
Swakopmund, Namibia (26 – 30 March, 2001). The lack of representative age length keys for
horse mackerel in the Benguela has been identified as a major shortcoming of current stock
assessment models employed in the region (the age length key currently used for Namibian horse
mackerel dates back to 1987).
To overcome this obstacle, effort has been directed towards developing an age estimation
program for horse mackerel using periodic features in sagittal otoliths. The first step in
implementing such a program is to develop the best method of preparing, examining and
analyzing otoliths. Once the method been developed, it has to be validated. The validation
process is comprised of two phases, the first testing the accuracy of the age estimates obtained
using the method, and the second testing the precision and consistency with which researchers
obtain the age estimates. The first phase of validating age estimation from horse mackerel
otoliths is the subject of an otolith-marking project currently being conducted at the Marine and
Coastal Management Research Aquarium in Cape Town, South Africa, under the auspices of
BENEFIT. |
| URI: | http://hdl.handle.net/1834/2758 |
| Appears in Collections: | Conference Papers
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