Management of Atlantic cod (Gadus morhua L.) under future climate change
Living marine resources are increasingly threatened by combined pressures of fishing and climate change, which put the sustainability of harvesting for yields that can support a fishery at risk. Ocean warming frequently reduces the productivity of commercial fish stocks, aggravating efforts of fishe...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky
2023
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| Online Access: | http://nbn-resolving.de/urn:nbn:de:gbv:18-ediss-114306 https://ediss.sub.uni-hamburg.de/handle/ediss/10643 |
| Summary: | Living marine resources are increasingly threatened by combined pressures of fishing and climate change, which put the sustainability of harvesting for yields that can support a fishery at risk. Ocean warming frequently reduces the productivity of commercial fish stocks, aggravating efforts of fisheries management to reverse effects of overfishing incurred through massive buildup of fishing capacity in the 20th century. A substantial challenge for management approaches that aim for adaptation to climate change is the lack of comprehensive knowledge on the mechanistic nature of climate effects on the dynamics of harvested populations, especially on their little-observed early life stages. Unexpected management response, e.g. delayed or missing rebuilding dynamics, indicate that stocks react in highly non-linear or discontinuous and long-lasting ways to fishing and climate change; ways that can hardly be anticipated or projected within models. Yet, accounting for such dynamics is important for guiding management decisions, as ignoring them can lead to poor stock condition and fixation thereof and economic hardship for fishers. The present dissertation investigates the impact of deep uncertainty in the relationship between temperature, stock size and recruitment (i.e., early-life-stage- / juvenile survival until entry to the fishery), which partly results from the non-linear stock response to stressors, on the potential for long-term future sustainable harvesting under intensifying future climate change. To this end, the dissertation adopts the perspective of “Decision-Making under Deep Uncertainty” (DMDU) by performing a large number of model projections under a very large range of uncertain scenarios, defined i.a. by possible stock-environment-recruitment (SR-) relationships and climate scenarios, in combination with a range of harvesting policies. The aim is not to improve model predictive skill or to infer the most “likely” future development but instead to unveil the potential consequences of harvesting ... |
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