Evolution of Future Black Sea Fish Stocks under Changing Environmental and Climatic Conditions

Salihoğlu, Barıș; Arkin, Sinan S.; Akoğlu, Ekin; Fach, Bettina

doi:10.3389/fmars.2017.00339

Cited by 19 publications

(8 citation statements)

References 60 publications

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“…We obtained maximum economic yield for the constant harvest rate when the constant harvest rate is 0.32 under the upper bound of 0.35. These results for the maximum harvest rate and maximum economic yield in the constant harvesting strategy for a sustainable ecosystem roughly matches one of the current studies presented by Salihoglu, Arkin, Akoglu, and Fach ().…”

Section: Discussionsupporting

confidence: 90%

Optimal sustainable fishery management of the Black Sea anchovy with food chain modeling framework

Demir

Lenhart

2019

Natural Resource Modeling

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Food chain models with interactions between key species are useful tools for ecological conservation and economic sustainability in commercial fisheries. In this study, we build a food chain model coupled with optimal control theory and focus on the Black Sea anchovy population in the southern part of the Black Sea. Our objective is to find the optimal harvesting strategy that maximizes the discounted net profit value of the anchovy fishery with seasonal harvesting, and that offers sustainable anchovy fishery. As a result, we obtain profitable and sustainable harvesting strategies.We also discuss the benefits of using food chain models in fishery management rather than using single-species models. Finally, we derive a schedule for the number of fishing vessels that are needed in the implementation of the optimal harvesting strategy. Recommendations for Resource Managers• Food chain modeling framework offers more reliable harvesting strategies than single-species modeling framework.• Managing the harvest effort using optimal control theory results in a more profitable anchovy fishery on the southern part of the Black Sea.• By quantifying the relationship between the annual landing and the number of fishing vessels, we can approximate the needed number of fishing vessels to achieve an optimal landing. • Applying an optimal control strategy yields more anchovy landing and profit in the long term, when we compare with the current harvesting strategy used in the anchovy fishery. These strategies also offer a sustainable anchovy fishery, which is crucial for the fate of this fishery.

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Section: Discussionsupporting

confidence: 90%

Optimal sustainable fishery management of the Black Sea anchovy with food chain modeling framework

Demir

Lenhart

2019

Natural Resource Modeling

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“…The Black Sea anchovy fishery is regarded as a very good example of a fishery whose catch is greatly affected by high volatility (Gücü et al, 2017;Libralato et al, 2019). It should also be stressed that fluctuations of small pelagics such as anchovy are more likely to be heavily influenced by climatic variability than by exploitation per se (Salihoglu et al, 2017;Tsikliras et al, 2018). Despite the current lack of operational state indicators for understanding pelagic fish assemblages, the MSFD clearly requires considering the state of the biotic community, the environmental status of pelagic habitats, and the functioning of pelagic components of the food web (Shephard et al, 2014).…”

Section: Challenges In Assessing Stocksmentioning

confidence: 99%

First Large-Scale Eastern Mediterranean and Black Sea Stock Assessment Reveals a Dramatic Decline

2020

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The Mediterranean Sea is classified as a "data-poor" region in fisheries due to its low number of assessed stocks given its biodiversity and number of exploited species. In this study, the CMSY method was applied to assess the status and exploitation levels of 54 commercial fish and invertebrate stocks belonging to 34 species fished by Turkish fleets in the Eastern Mediterranean (Levantine) and Black Seas, by using catch data and resilience indices. Most of these marine taxa currently lack formal stock assessments. The CMSY method uses a surplus production model (SPM), based on official catch statistics and an abundance index derived from scientific surveys. The SPM estimates maximum sustainable yield (MSY), fishing mortality (F), biomass (B), fishing mortality to achieve sustainable catches (F msy ), and the biomass to support sustainable catches (B msy ). Our results show the estimated biomass values for 94% of the stocks were lower than the required amount to support sustainable fisheries (B msy ). Of the 54 stocks, 85% of them can be deemed as overfished; two stocks were not subject to overfishing (Sardina pilchardus and Trachurus mediterraneus in the Marmara Sea) while only one stock (Sprattus sprattus in the Black Sea) is healthy and capable of producing MSY. Annual values of the stock status indicators, F/F msy and B/B msy , had opposing trends in all regions, suggesting higher stock biomasses could only be achieved if fishing mortality is drastically reduced. Recovery times and levels were then explored under four varying F/F msy scenarios. Under the best-case scenario (i.e., F = 0.5F msy ), over 60% of the stocks could be rebuilt by 2032. By contrast, if normal fishing practices continue as usual, all stocks will soon be depleted [if not already] (F = 0.95F msy ), whose recover may be impossible at later dates. The results of this study are supported by previous regional assessments confirming the overexploitation of Turkish fisheries is driving the near-total collapse of these marine wild fisheries. Hence, the need to urgently rebuild Turkey's marine fisheries ought to be prioritized to ensure their future viability.

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“…Nearly all models spatially and dynamically resolve herbivorous zooplankton as a major mortality factor for phytoplankton, but little attention is often paid to carnivorous grazing. As empirical, system-wide studies on carnivorous grazing rates are rare, most models use a global “closure” parameter and a few resolve a more extended food-chain including fish [18, 19, 20]. However, the first approach ignores potentially large differences in the spatio-temporal distribution of carnivory [21], while the second approach faces the difficulty to represent highly diverse migratory behaviors of fish [22, 23], or other mechanisms that regulate the distribution pattern of carnivores.…”

Section: Introductionmentioning

confidence: 99%

Physics or biology? Persistent chlorophyll accumulation in a shallow coastal sea explained by pathogens and carnivorous grazing

Wirtz

2019

PLoS ONE

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One of the most striking patterns at the land–ocean interface is the massive increase of chlorophyll-a (CHL) from continental shelves towards the coast, a phenomenon that is classically linked to physical features. Here I propose that the coastal–offshore CHL gradient in a shallow sea has biological origins related to phytoplankton mortality that are neglected in state-of-the-art biogeochemical models. I integrate a trait-based ecosystem model into a modular coupling framework that is applied to the southern North Sea (SNS). The coupled model very well reproduces daily, seasonal and inter-annual (2000-2014) dynamics and meso-scale patterns in macronutrients, zooplankton biomass, and CHL as observed in situ and by remote sensors. Numerical experiments reveal that coast–offshore CHL gradients may predominantly arise from a trophic effect as resolved by an increase in carnivorous grazing towards shallow waters. This carnivory gradient reflects higher near-coast abundance of juvenile fish and benthic filter feeders. Furthermore, the temporal evolution of CHL can be much affected by viral infection as a fast-responding loss process at intermediate to high phytoplankton concentrations. Viral control in the model also prevents excessive and unrealistic blooms during late spring. Herbivores as often only ecological factor considered for explaining the spatio-temporal phytoplankton distribution are in this study supplemented by pathogens as well as pelagic and benthic carnivores as powerful agents, which are barely represented in current modeling but can mediate physical drivers of coastal ecosystems.

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Evolution of Future Black Sea Fish Stocks under Changing Environmental and Climatic Conditions

Cited by 19 publications

References 60 publications

Optimal sustainable fishery management of the Black Sea anchovy with food chain modeling framework

Optimal sustainable fishery management of the Black Sea anchovy with food chain modeling framework

First Large-Scale Eastern Mediterranean and Black Sea Stock Assessment Reveals a Dramatic Decline

Physics or biology? Persistent chlorophyll accumulation in a shallow coastal sea explained by pathogens and carnivorous grazing

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