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- Aps, R., et al.
(författare)
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Central Baltic Sea herring : effect of environmental trends and fishery management
- 2011
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Ingår i: Ecosystems and Sustainable Development VIII. - Southampton : BioMed Central Ltd.. - 9781845645106 - 9781845645113 ; , s. 69-80
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Konferensbidrag (refereegranskat)abstract
- Uncertainty is an endemic condition of the Baltic Sea herring (Clupea harengus membras, L) fishery management. It is a condition exacerbated by the fishing fleet overcapacity and consequent exploitation of the herring stock at a level believed to be unsustainable. Some sources of uncertainty are mainly related to biology and fishing technique: the unsolved problem of herring assessment and management units, the recruitment–environment relationship and the reduction in mean weights-at-age, uncertain ageing of fish, the problem of unaccounted fishing mortality caused by the fish selection through the trawl net. Fishing fleet overcapacity is believed to be behind of the regulatory overfishing when setting the Total Allowable Catches (TACs) higher than the scientific advice (decision overfishing) and tolerating the extensive underreporting of catches (implementation overfishing). Two scenarios for the Central Baltic Sea herring fishery management options are constructed and the Bayesian networks are used to represent and update uncertainties encountered in the process of the management related situation assessment. First scenario represents the current status of the fishery management resulting in fishing mortality (F) higher than FMSY – the fishing mortality that corresponds to the Maximum Sustainable Yield (MSY). The second scenario demonstrates the assumed potential impact of economic incentives (e.g.zoning, individual transferable quotas (ITQs), territorial use rights etc.) on the reduction of excessive fishing capacity and bringing actual fishing mortality closer to FMSY.
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- Aps, R., et al.
(författare)
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Fisheries management : from linear to collaborative science-policy interface
- 2011
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Ingår i: Management of Natural Resources, Sustainable Development and Ecological Hazards III. - : WIT Press. - 9781845645328 - 1845645324 ; , s. 3-14
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Konferensbidrag (refereegranskat)abstract
- The context of fisheries management, according to recent studies, tends to be complex, uncertain and controversial and it cannot be adequately addressed based on work done within the “linear” science-policy interface (SPI). It is believed that moving towards a more participatory and “collaborative” SPI model would favour implementation of more efficient economic incentives to reduce the fishing fleet capacity and bring the actual fishing mortality closer to the levels considered to be sustainable. Focusing the participatory research basically on fish biology and fish stock assessment seems to be too narrow while, on the other hand, it does not embrace many other important issues of contemporary fisheries management. It is suggested that further involvement of stakeholders into the full-scale bio-economic modelling based participatory research would contribute to better understanding of the dynamics of human natural interface concerned and, consequently, would improve the consensus between different interests.
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- Holmgren, Noél M. A., et al.
(författare)
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MSY oriented management of the Baltic Sea herring under regime shifts
- 2011
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Ingår i: ICES report of the Baltic Fisheries Assessment working Group (WGBFAS). - Copenhagen : ICES. ; , s. 752-798
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The ecosystem of the baltic sea has undergone dramatic changes, perhaps a regime-shift, during the last four decades. The Baltic Sea Herring SSB has declined to a third and weight-at-age has halved due to plankton prey deficits. The management objective of the herring is currently in the transition to a cautionary maximum sustainable yield (MSY). We modelled the main basin Baltic Sea herring under the currernt regime, and analysed the effect of a ercovery of the cod stock and the food availability as they were in the early 1980s. We recommend a target F MSY of 0.16, but with a recovery of the cod, recommended target F MSY is is 0.10. A simultaneous increase in both cod and food availability is estimated to increase the yield with 40% at the target F MSY is 0.20. We present functions to calculate F MSY and estimate the expected yield depending on the abundance of cod and food-availability. A retrospective application of our functions indicates over-fishing in the 1990s and early 2000s, and a net loss in yields with a landing value of about E440 Millions.
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