scholarly journals An endogenous bioeconomic optimization algorithm to evaluate recovery plans: an application to southern hake

2010 ◽  
Vol 67 (9) ◽  
pp. 1957-1962 ◽  
Author(s):  
José-María Da Rocha ◽  
Santiago Cerviño ◽  
María-José Gutiérrez
Keyword(s):  
Optimization Algorithm ◽  
Optimization Problem ◽  
Dynamic Optimization Problem ◽  
Optimum Trajectory ◽  
Fleet Size ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Optimum Solution ◽  
Current Plan ◽  
Bioeconomic Models

AbstractDa Rocha, J-M., Cerviño, S., and Gutiérrez, M-J. 2010. An endogenous bioeconomic optimization algorithm to evaluate recovery plans: an application to southern hake. – ICES Journal of Marine Science, 67: 1957–1962. Recovery plans were analysed by introducing social and economic behaviour and endogenous disinvestment decisions into bioeconomic models. Considering these endogenous constraints, a dynamic optimization problem was solved to find fishing mortality (F) trajectories that maximize discounted profits per vessel, subject to recovery of the stock to a spawning-stock biomass (SSB) target in 2015. The algorithm developed was used to assess the southern hake recovery plan. Three scenarios were analysed: (1) represents the current plan with an annual 10% reduction in F; (2) represents the optimum trajectory where profits must be positive all along and the SSB target is reached no later than 2015, and (3) represents the optimum trajectory allowing profits to be negative. The results from (3) indicate that if economic and social restrictions are not considered a prior condition, the optimum solution implies a fleet reduction in 2010 and 2011. Comparing (1) and (2), our results suggest that reducing F to 0.30 by 2010 achieves the recovery target in 2012, increases the net present profits by 7.7% relative to the current plan, and is compatible with maintaining the current fleet size.

Artificial Life Optimization Algorithm and Applications

2011 ◽  
pp. 423-449
Author(s):  
Bo-Suk Yang
Keyword(s):  
Genetic Algorithm ◽  
Optimization Algorithm ◽  
Artificial Life ◽  
Optimization Problem ◽  
Global Optimum ◽  
Function Optimization ◽  
Global Function ◽  
Test Function ◽  
Optimum Solution ◽  
Artificial World

This chapter describes a hybrid artificial life optimization algorithm (ALRT) based on emergent colonization to compute the solutions of global function optimization problem. In the ALRT, the emergent colony is a fundamental mechanism to search the optimum solution and can be accomplished through the metabolism, movement and reproduction among artificial organisms which appear at the optimum locations in the artificial world. In this case, the optimum locations mean the optimum solutions in the optimization problem. Hence, the ALRT focuses on the searching for the optimum solution in the location of emergent colonies and can achieve more accurate global optimum. The optimization results using different types of test functions are presented to demonstrate the described approach successfully achieves optimum performance. The algorithm is also applied to the test function optimization and optimum design of short journal bearing as a practical application. The optimized results are compared with those of genetic algorithm and successive quadratic programming to identify the optimizing ability.

scholarly journals A two-stage biomass model to assess the English Channel cuttlefish (Sepia officinalis L.) stock

2014 ◽  
Vol 71 (9) ◽  
pp. 2457-2468 ◽  
Author(s):  
Michaël Gras ◽  
Beatriz A. Roel ◽  
Franck Coppin ◽  
Eric Foucher ◽  
Jean-Paul Robin
Keyword(s):  
Reference Points ◽  
Sea Surface ◽  
Sepia Officinalis ◽  
Sustainable Utilization ◽  
English Channel ◽  
Two Stage ◽  
Stock Biomass ◽  
Exploitation Rate ◽  
Spawning Stock ◽  
Age Structured

Abstract The English Channel cuttlefish (Sepia officinalis) is the most abundant cephalopod resource in the Northeast Atlantic and one of the three most valuable resources for English Channel fishers. Depletion methods and age-structured models have been used to assess the stock, though they have shown limitations related to the model assumptions and data demand. A two-stage biomass model is, therefore, proposed here using, as input data, four abundance indices derived from survey and commercial trawl data collected by Ifremer and Cefas. The model suggests great interannual variability in abundance during the 17 years of the period considered and a decreasing trend in recent years. Model results suggest that recruitment strength is independent of spawning–stock biomass, but appears to be influenced by environmental conditions such as sea surface temperature at the start of the life cycle. Trends in exploitation rate do not reveal evidence of overexploitation. Reference points are proposed and suggestions for management of the sustainable utilization of cuttlefish in the English Channel are advanced.

Modelling the effects of establishing a marine reserve for mobile fish species

2002 ◽  
Vol 59 (3) ◽  
pp. 405-415 ◽  
Author(s):  
P Apostolaki ◽  
E J Milner-Gulland ◽  
M K McAllister ◽  
G P Kirkwood
Keyword(s):  
Fish Species ◽  
Marine Reserve ◽  
High Mobility ◽  
Merluccius Merluccius ◽  
Seasonal Movements ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Short And Long Term ◽  
Immature Fish

We present a model of the effects of a marine reserve on spawning stock biomass (SSB) and short- and long-term yield for a size-structured species that exhibits seasonal movements. The model considers the effects of protecting nursery and (or) spawning grounds under a range of fishing mortalities and fish mobility rates. We consider two extremes of effort redistribution following reserve establishment and analyze the effects of a reserve when the fishery targets either mature or immature fish. We apply the model to the Mediterranean hake (Merluccius merluccius) and show that a marine reserve could be highly beneficial for this species. We demonstrate benefits from reserves not just for overexploited stocks of low-mobility species, but also (to a lesser extent) for underexploited stocks and high-mobility species. Greatly increased resilience to overfishing is also found in the majority of cases. We show that a reserve provides benefits additional to those obtained from simple effort control. Benefits from reserves depend to a major extent on the amount of effort redistribution following reserve establishment and on fishing selectivity; hence, these factors should be key components of any evaluation of reserve effectiveness.

Comparative investigation of the moth-flame algorithm and whale optimization algorithm for optimal spur gear design

2021 ◽  
Vol 63 (3) ◽  
pp. 266-271
Author(s):  
Hammoudi Abderazek ◽  
Ferhat Hamza ◽  
Ali Riza Yildiz ◽  
Sadiq M. Sait
Keyword(s):  
Optimization Algorithm ◽  
Optimization Problem ◽  
Spur Gear ◽  
Comparative Investigation ◽  
Whale Optimization Algorithm ◽  
Solution Quality ◽  
Gear Design ◽  
Geometric Conditions ◽  
Swarm Algorithms ◽  
Whale Optimization

Abstract In this study, two recent algorithms, the whale optimization algorithm and moth-flame optimization, are used to optimize spur gear design. The objective function is the minimization of the total weight of the spur gear pair. Moreover, the optimization problem is subjected to constraints on the main kinematic and geometric conditions as well as to the resistance of the material of the gear system. The comparison between moth-flame optimization (MFO), the whale optimization algorithm (WOA), and previous studies indicate that the final results obtained from both algorithms lead to a reduction in gear weight by 1.05 %. MFO and the WOA are compared with four additional swarm algorithms. The experimental results indicate that the algorithms introduced here, in particular MFO, outperform the four other methods when compared in terms of solution quality, robustness, and high success rate.

scholarly journals Does predation by grey seals (Halichoerus grypus) affect Bothnian Sea herring stock estimates?

2012 ◽  
Vol 69 (8) ◽  
pp. 1448-1456 ◽  
Author(s):  
Anna Gårdmark ◽  
Örjan Östman ◽  
Anders Nielsen ◽  
Karl Lundström ◽  
Olle Karlsson ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Older Individuals ◽  
Standard Assessment ◽  
Abundance Estimates ◽  
Stock Biomass ◽  
Key Species ◽  
Spawning Stock ◽  
Bothnian Sea

Abstract Gårdmark, A., Östman, Ö., Nielsen, A., Lundström K., Karlsson O., Pönni, J., and Aho, T. 2012. Does predation by grey seals (Halichoerus grypus) affect Bothnian Sea herring stock estimates? – ICES Journal of Marine Science, 69: . Mortality of small pelagic fish due to marine mammals is generally considered to be low compared with other sources of mortality. With recent recoveries of marine mammal predators worldwide, this may no longer hold. The grey seal (Halichoerus grypus) population in the Bothnian Sea has increased fivefold since 1985. Its main prey, herring (Clupea harrengus), is a key species for fisheries in the region. Yet, current stock assessments assume constant natural mortality, leading to a risk of biased stock estimates with increasing predation and misleading analyses of herring population dynamics. We estimated grey seal predation from diet data and reanalysed herring spawning stock biomass (SSB) during 1973–2009. Accounting for predation increased the herring SSB 16% (maximum 19%), but this was within the confidence intervals when ignoring predation. Although mortality in older individuals was inflated when accounting for seal predation, this did not change the conclusions about drivers of herring dynamics. Accounting for grey seal predation is important for abundance estimates of old herring, but currently not for SSB estimates, given the great uncertainties in the standard assessment. The grey seal impact on Bothnian Sea herring will need to be reassessed if stock age composition, grey seal feeding preferences, or total stock development change.

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