scholarly journals Towards an integrated forecasting system for pelagic fisheries

2012 ◽  
Vol 9 (2) ◽  
pp. 1437-1479 ◽  
Author(s):  
A. Christensen ◽  
M. Butenschön ◽  
Z. Gürkan ◽  
I. J. Allen
Keyword(s):  
Maximum Sustainable Yield ◽  
Ecosystem Dynamics ◽  
Trophic Levels ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Model Framework ◽  
The North ◽  
Basin Scale ◽  
Forecasting System ◽  
Pelagic Fisheries

Abstract. First results of a coupled modeling and forecasting system for the pelagic fisheries are being presented. The system consists currently of three mathematically fundamentally different model subsystems: POLCOMS-ERSEM providing the physical-biogeochemical environment implemented in the domain of the North-West European shelf and the SPAM model which describes sandeel stocks in the North Sea. The third component, the SLAM model, connects POLCOMS-ERSEM and SPAM by computing the physical-biological interaction. Our major experience by the coupling model subsystems is that well-defined and generic model interfaces are very important for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows for analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and lower trophic levels to quantify the impacts on the higher trophic level, in this case the sandeel population, demonstrated here on the base of hindcast data. The coupled forecasting system is tested for some typical scientific questions appearing in spatial fish stock management and marine spatial planning, including determination of local and basin scale maximum sustainable yield, stock connectivity and source/sink structure. Our presented simulations indicate that sandeels stocks are currently exploited close to the maximum sustainable yield, but large uncertainty is associated with determining stock maximum sustainable yield due to stock eigen dynamics and climatic variability. Our statistical ensemble simulations indicates that the predictive horizon set by climate interannual variability is 2–6 yr, after which only an asymptotic probability distribution of stock properties, like biomass, are predictable.

scholarly journals Towards an integrated forecasting system for fisheries on habitat-bound stocks

Ocean Science ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 261-279 ◽  
Author(s):  
A. Christensen ◽  
M. Butenschön ◽  
Z. Gürkan ◽  
I. J. Allen
Keyword(s):  
Climatic Variability ◽  
Maximum Sustainable Yield ◽  
Ecosystem Dynamics ◽  
Fish Stock ◽  
Generic Model ◽  
Sustainable Yield ◽  
Model Framework ◽  
The North ◽  
Basin Scale ◽  
Forecasting System

Abstract. First results of a coupled modelling and forecasting system for fisheries on habitat-bound stocks are being presented. The system consists currently of three mathematically, fundamentally different model subsystems coupled offline: POLCOMS providing the physical environment implemented in the domain of the north-west European shelf, the SPAM model which describes sandeel stocks in the North Sea, and the third component, the SLAM model, which connects POLCOMS and SPAM by computing the physical–biological interaction. Our major experience by the coupling model subsystems is that well-defined and generic model interfaces are very important for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows for analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and to quantify the impacts on the higher trophic level, in this case the sandeel population, demonstrated here on the basis of hindcast data. The coupled forecasting system is tested for some typical scientific questions appearing in spatial fish stock management and marine spatial planning, including determination of local and basin-scale maximum sustainable yield, stock connectivity and source/sink structure. Our presented simulations indicate that sandeel stocks are currently exploited close to the maximum sustainable yield, even though periodic overfishing seems to have occurred, but large uncertainty is associated with determining stock maximum sustainable yield due to stock inherent dynamics and climatic variability. Our statistical ensemble simulations indicates that the predictive horizon set by climate interannual variability is 2–6 yr, after which only an asymptotic probability distribution of stock properties, like biomass, are predictable.

Management of evolving fish stocks

1998 ◽  
Vol 55 (8) ◽  
pp. 1971-1982 ◽  
Author(s):  
Mikko Heino
Keyword(s):  
Maximum Sustainable Yield ◽  
Evolutionary Change ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Harvest Rate ◽  
Fish Stocks ◽  
Population Dynamics Model ◽  
Before And After ◽  
Age Structured ◽  
Delayed Maturation

Mortality caused by harvesting can select for life history changes in the harvested stock. Should this possibility be taken into account in the management of renewable resources? I compare the performance of different harvest strategies when evolutionary change is accounted for with the help of an age-structured population dynamics model. Assuming that age of first reproduction is the only evolving trait, harvesting of only mature individuals selects for delayed maturation and results in increased sustainable yields. Unselective harvesting of both mature and immature fish selects for earlier maturation which causes the sustainable yield to decrease. Constant stock size and constant harvest rate strategies perform equally well in terms of maximum sustainable yield, both before and after evolutionary change. The maximum sustainable yield for fixed-quota strategies is lower. All those strategies have similar evolutionary consequences given a similar average harvest rate. Coevolutionary dynamics between fish stock and the stock manager indicate that the evolutionary benefits of selective harvesting are attainable without incurring yield losses in the near future.

Combined analyses reveal environmentally driven changes in the North Sea ecosystem and raise questions regarding what makes an ecosystem model’s performance credible?

2014 ◽  
Vol 71 (1) ◽  
pp. 31-46 ◽  
Author(s):  
Steven Mackinson
Keyword(s):  
Primary Production ◽  
North Sea ◽  
Ecosystem Model ◽  
Ecosystem Approach ◽  
Trophic Levels ◽  
Fish Stock ◽  
Supporting Evidence ◽  
Sea Temperature ◽  
The North ◽  
The North Sea

When an ecosystem model of the North Sea is calibrated to data from multiple trophic levels, the model estimated the primary production required to support the food web correlates temporally with observed changes in sea temperature and nutrient levels, supporting evidence from empirical analyses. However, a different result is given from an alternative calibration using fish stock data only. The inference taken from the emergent primary production – temperature relationship and empirical data are that, on balance, there is stronger overall evidence to support the calibration constrained at multiple trophic levels. Two important implications of the findings are (i) that the relative importance of fishing and environmental effects is likely to be interpreted differently depending on the calibration approach and (ii) the contrasting model calibrations would give different responses to fishing policies. It raises questions regarding how to judge the performance (and credibility) of an ecosystem model and the critical importance of conducting empirical and modelling analyses in parallel. Adopting a combined approach to ecosystem modelling is an important step in the pursuit of operational and defensible tools to support the ecosystem approach to management.

scholarly journals Basin-wide mechanisms for spring bloom initiation: how typical is the North Atlantic?

2015 ◽  
Vol 72 (6) ◽  
pp. 2029-2040 ◽  
Author(s):  
Harriet S. Cole ◽  
Stephanie Henson ◽  
Adrian P. Martin ◽  
Andrew Yool
Keyword(s):  
Interannual Variability ◽  
Mixed Layer ◽  
North Atlantic ◽  
Spring Bloom ◽  
Phytoplankton Bloom ◽  
Ecosystem Dynamics ◽  
Trophic Levels ◽  
Theoretical Understanding ◽  
The North ◽  
The North Atlantic

Abstract The annual phytoplankton bloom is a key event in pelagic ecosystems. Variability in the timing, or phenology, of these blooms affects ecosystem dynamics with implications for carbon export efficiency and food availability for higher trophic levels. Furthermore, interannual variability in phytoplankton bloom timing may be used to monitor changes in the pelagic ecosystem that are either naturally or anthropogenically forced. The onset of the spring bloom has traditionally been thought to be controlled by the restratification of the water column and shoaling of the mixed layer, as encapsulated in Sverdrup's critical depth hypothesis. However, this has been challenged by recent studies which have put forward different mechanisms. For example, the critical turbulence hypothesis attributes bloom initiation to a reduction in turbulent mixing associated with the onset of positive net heat fluxes (NHFs). To date, the majority of studies on bloom initiation mechanisms have concentrated on North Atlantic datasets leaving their validity in other subpolar regions unknown. Here, we use chlorophyll output from a model that assimilates satellite ocean colour data to calculate bloom initiation timing and examine the basin-wide drivers of spatial and interannual variability. We find that the date that the NHF turns positive is a stronger predictor for the date of bloom initiation, both spatially and interannually, across the North Atlantic than changes in the mixed layer depth. However, results obtained from the North Pacific and Southern Ocean show no such basin-wide coherency. The lack of consistency in the response of the subpolar basins indicates that other drivers are likely responsible for variability in bloom initiation. This disparity between basins suggests that the North Atlantic bloom initiation processes are unique and therefore that this region may not be a suitable model for a global, theoretical understanding of the mechanisms leading to the onset of the spring bloom.

scholarly journals POTENTIAL PRODUCTION OF DEMERSAL FISH STOCK IN THE MALACCA STRAIT OF INDONESIA

2015 ◽  
Vol 21 (1) ◽  
pp. 45 ◽  
Author(s):  
Purwanto Purwanto
Keyword(s):  
Demersal Fish ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Optimum Level ◽  
Fish Production ◽  
Potential Production ◽  
Malacca Strait

Malacca Strait is one of the main fishing areas for demersal fishery in Indonesia. To support the management of that fishery, an assessment of the demersal fish stock was conducted. This study estimated that the maximum sustainable yield and the optimal catch per unit effortof demersal fishery in the Malacca Strait were about 106.8 thousand tons/year and 28.5 tons per unit of Danish seine, respectively, resulting from the operation of 3,752 Danish seines. Unfortunately, fishing effort was higher than its optimum level and the fish stock was over-exploited since 2003. To recover the demersal fish stock to its optimum level and to ensure the optimal fish production from demersal fishery in the Malacca Strait, it was necessary to reduce fishing effort at about 67% from its level in 2011.

scholarly journals Preventing overfishing: evolving approaches and emerging challenges

2014 ◽  
Vol 71 (2) ◽  
pp. 153-156 ◽  
Author(s):  
Michael M. Sissenwine ◽  
Pamela M. Mace ◽  
Hans J. Lassen
Keyword(s):  
Fishery Management ◽  
Scientific Information ◽  
Maximum Sustainable Yield ◽  
Ecosystem Dynamics ◽  
Current Paper ◽  
Scientific Uncertainty ◽  
Sustainable Yield ◽  
Marine Science ◽  
Common Elements ◽  
Multispecies Fisheries

Abstract Sissenwine, M. M., Mace P. M., and Lassen, H. J. 2014. Preventing Overfishing: Evolving Approaches and Emerging Challenges. – ICES Journal of Marine Science, 71: 153–156. The evolution of fishery management frameworks to prevent overfishing is the theme of the eight papers that follow in this issue of the ICES Journal of Marine Science. The current paper describes common elements of the frameworks. All the frameworks are based on the maximum sustainable yield concept. Frameworks to prevent overfishing have evolved to be increasingly prescriptive. This evolution probably reflects past abuse of flexibility which led to overfishing. The outcome has been a decline in the proportion of stocks suffering from overfishing. However, loss of flexibility may result in large foregone yields from multispecies fisheries, create a mis-match between the expectations for scientific information and the realities of scientific uncertainty, and fail to recognize ecosystem dynamics.

scholarly journals NATURAL-ANTHROPOGENIC REGIMES IN SIMPLE MODELS OF THE GLOBAL MARINE FISHERIES

2019 ◽  
Vol 3 (1) ◽  
pp. 210-222
Author(s):  
Alexander Ryzhenkov
Keyword(s):  
Marine Fish ◽  
Feedback Loop ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Marine Fisheries ◽  
The World ◽  
Key Variables ◽  
Time Frames ◽  
Dynamics Method

The study applies the system dynamics method in upgrading the World Bank’s global marine fisheries models in the interest of achieving the UN goals of sustainable development. The key variables are a global marine fish stock, its natural growth, as well as the fisheries’ effort and catch. The equations for the reproduction of the fish stock in the regimes of maximum sustainable yield, overfishing or undercatch are derived. Determined are collapse time frames in result of typical overfishing varieties. A new positive feedback loop has been proposed in regulating global marine fish stock to ensure maximum sustainable yield asymptotically.

scholarly journals ERSEM 15.06: a generic model for marine biogeochemistry and the ecosystem dynamics of the lower trophic levels

2016 ◽  
Vol 9 (4) ◽  
pp. 1293-1339 ◽  
Author(s):  
Momme Butenschön ◽  
James Clark ◽  
John N. Aldridge ◽  
Julian Icarus Allen ◽  
Yuri Artioli ◽  
...  
Keyword(s):  
Food Web ◽  
Current Model ◽  
Marine Ecosystem ◽  
Ecosystem Model ◽  
Essential Elements ◽  
Ecosystem Dynamics ◽  
Trophic Levels ◽  
Global Ocean ◽  
Generic Model ◽  
The North

Abstract. The European Regional Seas Ecosystem Model (ERSEM) is one of the most established ecosystem models for the lower trophic levels of the marine food web in the scientific literature. Since its original development in the early nineties it has evolved significantly from a coastal ecosystem model for the North Sea to a generic tool for ecosystem simulations from shelf seas to the global ocean. The current model release contains all essential elements for the pelagic and benthic parts of the marine ecosystem, including the microbial food web, the carbonate system, and calcification. Its distribution is accompanied by a testing framework enabling the analysis of individual parts of the model. Here we provide a detailed mathematical description of all ERSEM components along with case studies of mesocosm-type simulations, water column implementations, and a brief example of a full-scale application for the north-western European shelf. Validation against in situ data demonstrates the capability of the model to represent the marine ecosystem in contrasting environments.

scholarly journals Achieving maximum sustainable yield in mixed fisheries: a management approach for the North Sea demersal fisheries

2016 ◽  
Vol 74 (2) ◽  
pp. 566-575 ◽  
Author(s):  
Clara Ulrich ◽  
Youen Vermard ◽  
Paul J. Dolder ◽  
Thomas Brunel ◽  
Ernesto Jardim ◽  
...  
Keyword(s):  
North Sea ◽  
Regional Scale ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Management Approach ◽  
Sustainable Yield ◽  
Total Allowable Catch ◽  
The North ◽  
Trade Offs ◽  
The North Sea

Achieving single species maximum sustainable yield (MSY) in complex and dynamic fisheries targeting multiple species (mixed fisheries) is challenging because achieving the objective for one species may mean missing the objective for another. The North Sea mixed fisheries are a representative example of an issue that is generic across most demersal fisheries worldwide, with the diversity of species and fisheries inducing numerous biological and technical interactions. Building on a rich knowledge base for the understanding and quantification of these interactions, new approaches have emerged. Recent paths towards operationalizing MSY at the regional scale have suggested the expansion of the concept into a desirable area of “pretty good yield”, implemented through a range around FMSY that would allow for more flexibility in management targets. This article investigates the potential of FMSY ranges to combine long-term single-stock targets with flexible, short-term, mixed-fisheries management requirements applied to the main North Sea demersal stocks. It is shown that sustained fishing at the upper bound of the range may lead to unacceptable risks when technical interactions occur. An objective method is suggested that provides an optimal set of fishing mortality within the range, minimizing the risk of total allowable catch mismatches among stocks captured within mixed fisheries, and addressing explicitly the trade-offs between the most and least productive stocks.

scholarly journals ERSEM 15.06: a generic model for marine biogeochemistry and the ecosystem dynamics of the lower trophic levels

2015 ◽  
Vol 8 (8) ◽  
pp. 7063-7187 ◽  
Author(s):  
M. Butenschön ◽  
J. Clark ◽  
J. N. Aldridge ◽  
J. I. Allen ◽  
Y. Artioli ◽  
...  
Keyword(s):  
Food Web ◽  
Current Model ◽  
Marine Ecosystem ◽  
Essential Elements ◽  
Ecosystem Dynamics ◽  
Trophic Levels ◽  
Global Ocean ◽  
Generic Model ◽  
North West ◽  
The North

Abstract. The ERSEM model is one of the most established ecosystem models for the lower trophic levels of the marine food-web in the scientific literature. Since its original development in the early nineties it has evolved significantly from a coastal ecosystem model for the North-Sea to a generic tool for ecosystem simulations from shelf seas to the global ocean. The current model release contains all essential elements for the pelagic and benthic part of the marine ecosystem, including the microbial food-web, the carbonate system and calcification. Its distribution is accompanied by a testing framework enabling the analysis of individual parts of the model. Here we provide a detailed mathematical description of all ERSEM components along with case-studies of mesocosm type simulations, water column implementations and a brief example of a full-scale application for the North-West European shelf. Validation against in situ data demonstrates the capability of the model to represent the marine ecosystem in contrasting environments.

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