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Policy options for Namibian fisheries
Policy options for Namibian fisheries
The first land-based commercial fishery in Namibia was established in 1851. Traditionally fish were caught with hook and line from rowboats, salted and sun dried, then shipped to South Africa, from where they were exported to Mauritius. The fishery caught silver kob (Argyrosomus spp.), steenbras (Lithognathus aureti), sea barbel (Galeichthys feliceps), hake (Merluccius merluccius) and snoek (Thyrsites atun), and also exported fish oil that consisted of shark liver oil, whale and seal blubber of the Cape fur seal (Arctcephalus pusillus pusillus). However, the really high impacting commercial fisheries only started in the 1950s when fish oil production and fish canning were based in Walvis Bay.
South African fishers were restricted in their own country and began moving into Namibian waters. By the 1960s their catches had expanded hugely with sardine, hake and horse mackerel being the main commercial species. These fisheries have impacted the ecosystem and decreased the biomass of the main commercial species, while increasing other species such as jellyfish and gobies.
Dr Sheila Heymans from SAMS (in collaboration with colleagues from the Fisheries Centre, UBC) used an ecosystem model of the Northern Benguela off Namibia to look at the alternative policy scenarios that the managers of this system might have. The scientists tested scenarios for optimizing the discounted profit from the fisheries in the ecosystem, maximizing the jobs that can be provided by the fisheries, maximizing a measure of ecosystem status, and analyzing tradeoffs between these management options. Discounted profit takes the use of future generations of this ecosystem service into consideration, and the team used two discount rates: 4% indicating a more future generation friendly rate, where future generations are taken explicitly into consideration, and 15%, which is similar to the discount rate used by private businesses in Namibia. The results show that the discount rate is most important when optimizing for profits, or when tradeoffs are being made between profit, jobs and ecosystem structure. Fishing effort of the most profitable fleet is significantly increased when discount rate is low, which increases the discounted profit to the fleet. Some fleets catch more profitable species, such as the demersal fleet that targets hake and monkfish, and the commercial line fishery that targets snoek and the effort of these fleets will be increased when optimizing for profit.
Obviously different fleet employ different numbers of workers, and therefore when optimizing for jobs, some fisheries do better than others. Specifically the purse seine, demersal, lobster and commercial line fisheries did best, but this can only happen if the fisheries become non-profitable.
Ecosystem longevity is only improved with a reduction in effort by all fleets while seaweed harvesting (at the lowest trophic level) would require the least reduction in “fishing” effort.
The full publication can be found at Science Direct