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A Santa Marta JG Ferreira GC Pitcher J Lencart e Silva 《African Journal of Marine Science》2020,42(2):151-166
The carrying capacity for bivalve shellfish culture in Saldanha Bay, South Africa, was analysed through the application of the well-tested EcoWin ecological model, in order to simulate key ecosystem variables. The model was set up using: (i) oceanographic and water-quality data collected from Saldanha Bay, and (ii) culture-practice information provided by local shellfish farmers. EcoWin successfully reproduced key ecological processes, simulating an annual mean phytoplankton biomass of 7.5 µg Chl a l–1 and an annual harvested shellfish biomass of about 3 000 tonnes (t) y–1, in good agreement with reported yield. The maximum annual carrying capacity of Small Bay was estimated as 20 000 t live weight (LW) of oysters Crassostrea gigas, or alternatively 5 100 t LW of mussels Mytilus galloprovincialis, and for Big Bay as 100 000 t LW of oysters. Two production scenarios were investigated for Small Bay: a production of 4 000 t LW y–1 of mussels, and the most profitable scenario for oysters of 19 700 t LW y–1. The main conclusions of this work are: (i) in 2015–2016, both Small Bay and Big Bay were below their maximum production capacity; (ii) the current production of shellfish potentially removes 85% of the human nitrogen inputs; (iii) a maximum-production scenario in both Big Bay and Small Bay would result in phytoplankton depletion in the farmed area; (iv) increasing the production intensity in Big Bay would probably impact the existing cultures in Small Bay; and (v) the production in Small Bay could be increased, resulting in higher income for farmers. 相似文献
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Individual transferable quota (ITQ) markets are being used successfully to distribute quotas in single region and single species fisheries. In many parts of the world, the development of well crafted markets for multispecies or multiregional fisheries is still evolving. As a result, there exists an opportunity to inform policy by providing research insights into the relative merits of alternative market designs for such fisheries.This study explored the relative merits of a simultaneous ascending auction design and an iterative combinatorial auction design for a hypothetical multiple region quota market. In a simultaneous auction, separate auctions are run in parallel for individual species or regions. During intermediate rounds, fishers can adjust their bids in auction depending on their position in the other auction. In a combinatorial auction, a fisher can purchase a combination of quotas (or a package quota) for different fish species or regions in the same auction. Being able to acquire bundles of species or regions allows fishers to take advantage of complementarities. To date, the potentials of such auctions have not been thoroughly tested in fisheries quota markets. This study found that while a simultaneous auction design was more efficient than combinatorial auction design overall, combinatorial market design took fewer rounds to make final allocations and performed better in high synergy environments. 相似文献
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Socioeconomic developments in Japan since World War Two have influenced the supply of wild pig meat (inoshishi niku) from Japanese domestic sources. Trends in the supply of meat from wild boar as well as the development of the farming of wild boar in Japan are discussed. The special nature of trading in wild pig meat in Japan is outlined. Australian exports of wild pig meat to Japan depend upon developments within Japan and the relevant links are identified. Some historical background is also provided on the Australian game industry supplying wild pig meat, the location and the structure of the industry are specified and the economic value of the industry is discussed, including its exports and prices paid for wild pig meat. Comparative aspects of the industry and of trade in wild pig meat in Japan and in Australia are highlighted. In conclusion, difficulties involved in identifying the Australian product in the Japanese market are noted. 相似文献
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