scholarly journals Sharing the Northeast Atlantic mackerel

2012 ◽  
Vol 70 (2) ◽  
pp. 259-269 ◽  
Author(s):  
Rögnvaldur Hannesson
Keyword(s):  
Time Horizon ◽  
The Other ◽  
Faroe Islands ◽  
Fishing Mortality ◽  
The European Union ◽  
Cooperative Solution ◽  
Northeast Atlantic ◽  
Density Dependent ◽  
Atlantic Mackerel ◽  
Scomber Scombrus

Abstract The sharing of the Northeast Atlantic mackerel (Scomber scombrus) stock is analysed as a game between four parties: the European Union, Norway, the Faroe Islands, and Iceland. Consideration is given to how the outcome depends on the nature of the stock's migrations. Two types of migrations are considered: (i) density-dependent, where the mackerel migrates into the Icelandic economic zone only if it exceeds 3.5 million t, and (ii) stochastic migrations, where the said migrations are stochastic. It is determined that the Faroe Islands would never accept a cooperative solution wherein they can only fish with the globally optimal fishing mortality within their own zone. This is also true for Iceland when the migrations into her zone are stochastic, but not if they are density-dependent. In the latter case, the other players have incentives to retaliate to Icelandic overfishing by fishing harder, which greatly reduces the number of years when mackerel are available in the Icelandic zone. It is assumed that the objective is maximization of the catch volume over a time-horizon of 50 years.

scholarly journals Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus)

2011 ◽  
Vol 68 (5) ◽  
pp. 848-859 ◽  
Author(s):  
E. John Simmonds ◽  
Andrew Campbell ◽  
Dankert Skagen ◽  
Beatriz A. Roel ◽  
Ciaran Kelly
Keyword(s):  
Stock Assessment ◽  
Management Plan ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Functional Forms

Abstract Simmonds, E. J., Campbell, A., Skagen, D., Roel, B. A., and Kelly, C. 2011. Development of a stock–recruit model for simulating stock dynamics for uncertain situations: the example of Northeast Atlantic mackerel (Scomber scombrus). – ICES Journal of Marine Science, 68: 848–859. The assumption of a relationship between recruitment and a spawning stock is the cornerstone of the precautionary approach and may constrain the use of a maximum sustainable yield (MSY) target for fisheries management, because the failure to include such a relationship suggests that providing a measure of stock protection is unnecessary. The implications of fitting different functional forms and stochastic distributions to stock-and-recruit data are investigated. The importance of these considerations is shown by taking a practical example from management: the management plan for Northeast Atlantic mackerel (Scomber scombrus), a fish stock with an average annual catch of 600 000 t. The historical range of spawning-stock biomass is narrow, and historical data from a stock assessment explain only a small proportion of the recruitment variability. We investigate how best to reflect the uncertainty in the stock–recruit relationship. Selecting a single model based on simple statistical criteria can have major consequences for advice and is problematic. Selecting a distribution of models with derived probabilities gives a more complete perception of uncertainty in dynamics. Differences in functional form, distribution of deviations, and variability of coefficients are allowed. The approach appropriately incorporates uncertainty in the stock–recruit relationship for FMSY estimation.

scholarly journals Coalition Formation with Externalities: The Case of the Northeast Atlantic Mackerel Fishery in a Pre- and Post-Brexit Context

2018 ◽  
Vol 20 (02) ◽  
pp. 1850001 ◽  
Author(s):  
Evangelos Toumasatos ◽  
Stein Ivar Steinshamn
Keyword(s):  
Coalition Formation ◽  
Net Present Value ◽  
Growth Function ◽  
The European Union ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Coalition Structures ◽  
Management Regime ◽  
Player Game ◽  
The Uk

The partition function approach is applied to study coalition formation in the Northeast Atlantic mackerel fishery in the presence of externalities. Atlantic mackerel is mainly exploited by the European Union (EU), the United Kingdom (UK), Norway, the Faroe Islands and Iceland. Two games are considered. First, a four-player game where the UK is still a member of the EU. Second, a five-player game where the UK is no longer a member of the union. Each game is modeled in two stages. In the first stage, players form coalitions following a predefined set of rules. In the second stage, given the coalition structure that has been formed, each coalition chooses the economic strategy that maximizes its own net present value of the fishery, given the behavior of the other coalitions. The game is solved using backward induction to obtain the set of Nash equilibria coalition structures in pure strategies, if any. We find that the current management regime is among the stable coalition structures in all eight scenarios of the four-player game but in only one case of the five-player game. In addition, stability in the five-player game is sensitive to the growth function applied and the magnitude of the stock elasticity parameter.

Estimating natural interstage egg mortality of Atlantic mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus) in the Northeast Atlantic using a stochastic model

2007 ◽  
Vol 64 (12) ◽  
pp. 1656-1668 ◽  
Author(s):  
Enrique Portilla ◽  
Eddie McKenzie ◽  
Doug Beare ◽  
Dave Reid
Keyword(s):  
Process Model ◽  
Mortality Rates ◽  
Horse Mackerel ◽  
Fish Biomass ◽  
Trachurus Trachurus ◽  
Northeast Atlantic ◽  
Egg Mortality ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Egg Stages

Egg mortality is a key parameter for understanding early life histories of fish. Small variations in estimated mortality cause large differences on adult fish biomass estimates. Therefore, the assumption of a constant egg mortality rate may be misleading. Here, we show how to estimate mortality rates for the individual egg stages of Atlantic mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus) from triennial surveys conducted since 1977. We use a standard, continuous-time Markov process model that combines the numbers of eggs sampled in each stage with experimental data on egg stage duration (dependent on water temperature). This is the first attempt to study mortality among egg stages in such detail and the first comprehensive effort to estimate horse mackerel egg mortality in the Northeast Atlantic. The results include detailed descriptions of spatial–temporal dependencies in mortality. The daily egg mortality rates estimated are ~0.56·day–1 for Atlantic mackerel (far higher than suggested in the literature) and 0.54·day–1 for horse mackerel. Although it was not possible to estimate stage 1 egg mortality directly, the results suggest high mortality in the first stage. This might lead to underestimation of fish biomass when assessed traditionally by egg survey data alone.

A Surplus Yield Model Incorporating Recruitment and Applied to a Stock of Atlantic Mackerel (Scomber scombrus)

1978 ◽  
Vol 35 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Gilbert G. Walter
Keyword(s):  
Fisheries Management ◽  
Fishing Mortality ◽  
Yield Model ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Stock Biomass ◽  
Equilibrium Yield ◽  
Class Strength ◽  
Nonequilibrium Conditions

A modification of Schaefer's surplus yield model that takes into account variations in year-class strength is introduced. Expressions for long-term equilibrium yield under assumptions of both linear and density-dependent recruitment are derived and compared. Strategies for exploitation under nonequilibrium conditions are discussed and equations derived. The model is fitted to a stock of mackerel and projections for the stock biomass in 1980 under various levels of fishing mortality are made. Key words: mathematical model, fisheries management, stock biomass projections

scholarly journals Quantifying changes in abundance, biomass, and spatial distribution of Northeast Atlantic mackerel (Scomber scombrus) in the Nordic seas from 2007 to 2014

2015 ◽  
Vol 73 (2) ◽  
pp. 359-373 ◽  
Author(s):  
Leif Nøttestad ◽  
Kjell R. Utne ◽  
Guðmundur J. Óskarsson ◽  
Sigurdur Þ. Jónsson ◽  
Jan Arge Jacobsen ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Nordic Seas ◽  
Northeast Atlantic ◽  
Atlantic Mackerel ◽  
Scomber Scombrus
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