Title: The Namibian Horse Mackerel fishery: juveniles or adults?

Author(s): Rauna Mukumangeni
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Bio-economic analysis of the horse mackerel fisheries off Namibia was undertaken with the purpose of defining sustainable management measures to support the decision-making process available to fisheries managers for the development of the fishery. A bio-economic model was applied to carry out projections, starting from the current situation and projecting into the future with the purpose of analysing the behaviour of the fishery under different conditions/management measures. Three scenarios are presented: Scenario1: reduction of the TAC for horse mackerel adults and juveniles from 272,432 mt to 250,000 mt and 45,000 mt to 40,000 mt respectively; Scenario 2: reduction in the juvenile allocation by 20,000 mt; Scenario 3: increase in the juvenile allocation to 50,000 mt. Two fishing fleets harvest horse mackerel. Purse-seiners target juveniles and mid-water trawlers target adult horse mackerel. This paper focuses on the biological and economical characteristics of the two different fishing methods. The Beverton and Holt stock recruitment model was applied. For each of the three scenarios, a projection was carried forward through a 12 year period. The results from the model analysis suggest that an increase in the juvenile allocation leads to reduced stock and reduced recruitment as well as reduced profitability of the fishery for adult horse mackerel. The increase results in the fishery being unsustainable and if the current management of the fishery is not changed, the stock will be depleted in the future according to the model.

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