Harvesting Strategies in a Fish Stock Dominated by Low-frequency Variability: The Norwegian Spring-spawning Herring (Clupea harengus)

Kaitala, Veijo; Jonzén, Niclas; Enberg, Katja

doi:10.1086/mre.18.3.42629399

Cited by 31 publications

(14 citation statements)

References 35 publications

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“…Comparing these results with those obtained using an unstructured model of the Norwegian spring spawning herring dynamics (Kaitala et al 2003), it is obvious that adding age-structure has a significant effect on the predictions generated. In the unstructured model, none of the strategies (proportional, threshold, and proportional threshold harvesting) performed significantly better, whereas in this study the proportional threshold strategy outperformed the other 2 basic strategies.…”

Section: Discussionmentioning

confidence: 75%

“…The population renewal process is subjected to environmental stochasticity, ε. ε t is taken after a first-order autoregressive process (Ripa & Lundberg 1996): (2) where κ is the autocorrelation parameter. In this study, positively correlated noise was used since the factors affecting growth and survival (such as temperature, Loeng et al 1995, Ottersen & Loeng 2000 are positively autocorrelated; moreover, the herring population dynamics are intrinsically positively autocorrelated (Kaitala et al 2003). The term s is a normallydistributed, random variable with range (1 -w, 1 + w, where w = 0.2); the square root term scales the variance of the generated time series so that its true variance is independent of κ (Heino et al 2000).…”

Section: Methodsmentioning

confidence: 99%

“…In addition, year-class strength and growth co-vary closely with temperature in Norwegian spring spawning herring and other species in the Norwegian and Barents seas (Loeng et al 1995, Ottersen & Loeng 2000. Time series analysis applied to the herring stock dynamics indicates that herring dynamics are intrinsically positively autocorrelated (Kaitala et al 2003). The stock is further characterized by its highly migratory nature; juveniles commonly dwell in the Barents Sea, whereas mature fish undertake extensive feeding migrations after spawning off the Norwegian west coast.…”

Section: Introductionmentioning

confidence: 99%

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Benefits of threshold strategies and age-selective harvesting in a fluctuating fish stock of Norwegian spring spawning herring Clupea harengus

Enberg¹

2005

Mar. Ecol. Prog. Ser.

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The current state of the world's fisheries resources requires further investigation into the means and methods for sustainable use of fish stocks. In this study, I assess the performance of different harvesting strategies on a population model developed for Norwegian spring spawning herring Clupea harengus, a stock historically known as one of the largest and most valuable fish stocks in the world. This stock is further characterized by strong long-term fluctuations in stock size, which considerably complicate successful population management. The results support the use of threshold strategies, where harvesting is only allowed if the population size of the target population is above a predetermined threshold. Threshold strategies are beneficial for maintaining spawning biomass, yield, and prevention of population collapse. The downside of a threshold approach is the fisheries moratoria associated with low stock size. To overcome this, I introduce a precautionary strategy including 2 thresholds for reducing the likelihood and length of moratoria, such that if the population size decreases below an upper threshold, the harvest ratio is decreased in order to achieve fast recovery to the target population size. I also test the effect of changing the timing of fish entering the harvestable stock by means of age-selective harvesting. I show that allowing reproduction, preferably more than once, before the fish become vulnerable to harvesting increases the spawning biomass and yield, and decreases the variability in yield and the risk of stock collapse.KEY WORDS: Harvesting strategy · Threshold · Norwegian spring spawning herring · Age-selective harvesting · Precautionary strategy Resale or republication not permitted without written consent of the publisher

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Section: Discussionmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Benefits of threshold strategies and age-selective harvesting in a fluctuating fish stock of Norwegian spring spawning herring Clupea harengus

Enberg¹

2005

Mar. Ecol. Prog. Ser.

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“…An earlier study (Kaitala et al 2003), considering a sole owner case, suggests that increase in the threshold value (B pa ) in the proportional threshold strategy will increase the variability in the yield. This pattern changes when competition is present.…”

Section: Table 10 Around Herementioning

confidence: 98%

Stability of International Fisheries Agreements Using Precautionary Bioeconomic Harvesting Strategies

Rahikainen

Lindroos

Kaitala

2013

SBE

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“…Overexploitation is one of the most serious problems in the world fisheries and, to avoid it, different policies are applied (Hjerne & Hansson 2001, Kaitala et al 2003. The most commonly used policies in the area of harvesting are: (i) the constant escapement policy, which seeks to maintain the stock at a target level by harvesting all fish in excess of the target and by not harvesting if estimated stock size is below the target; (ii) the constant harvest effort policy (Loehle 2006), which removes a desired fraction of the estimated stock each year (the harvest is directly proportional to the estimated stock size); and (iii) the threshold policy (TP), which is intermediate between the well-known constant escapement and constant harvest rate policies (Collie & Spencer 1993, Quinn & Deriso 2000.…”

Section: Introductionmentioning

confidence: 99%

Control of Nonlinear Dynamic Models of Predator-Prey Type

Bhaya

Meza

2012

Oecol Aust

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In the ecological context, a large class of population dynamics models can be written as dynamical systems of one or two variables, i.e., each variable represents a population density of a species. When one or more species is removed from the system (harvested), it is necessary to introduce a control (harvest policy) in order to avoid the extinction of species, due to harvesting. A threshold policy (TP) and a threshold policy with hysteresis (TPH) reviewed and discussed in this paper can be used to avoid the collapse of population densities, governed by predator-prey models. A threshold policy changes the dynamics of a predator-prey dynamical system in such a way that a stable positive equilibrium point is achieved. In other words, coexistence of both species occurs. A threshold policy with hysteresis changes the dynamics so that a limit cycle (bounded oscillation) is achieved, i.e., coexistence of species with a bounded oscillation in population densities occurs. This paper studies the continuous and discrete logistic model for one species and the Lotka-Volterra and RosenzweigMacArthur models for two species. The TP and TPH are seen to be versatile and useful in renewable resources management, being simple to design and implement, with some advantages in a situation of overexploitation, as well as in the presence of different types of uncertainties. The design of the policies is carried out by appropriate choice of virtual equilibria in a simple and intuitive manner, and the mathematics used is simple. Keywords: Nonlinear predator-prey models; threshold policy; threshold policy with hysteresis. RESUMO CONTROLE DE MODELOS DINÂMICOS NÃO LINEARES DO TIPO PREDADOR-PRESA.No contexto ecológico, uma ampla classe de modelos de dinâmica populacional pode ser escrita como sistemas dinâmicos não lineares em uma ou duas variáveis, i.e., cada variável representa uma densidade populacional de uma espécie. Quando uma ou mais espécies são removidas do sistema (colheita), é necessário introduzir um controle (política de colheita) para evitar a extinção das espécies devido à colheita. Uma política de limiar (TP do inglês) e uma política de limiar com histerese (TPH do inglês) revisadas e discutidas neste artigo podem ser utilizadas para evitar o colapso das densidades populacionais governadas pelos modelos do tipo predadorpresa. Uma política de limiar muda a dinâmica de um sistema predador-presa de maneira que um ponto de equilíbrio positivo estável é alcançado. Em outras palavras, permite a coexistência das espécies. Uma política de limiar com histerese muda a dinâmica de maneira que um ciclo limite é alcançado (oscilação limitada), isto é, ocorre a coexistência das espécies com oscilação limitada nas densidades populacionais. Este artigo estuda o modelo logístico contínuo e discreto de uma espécie e os modelos Lotka-Volterra e Rosenzweig-MacArthur de duas espécies. A TP e a TPH parecem ser versáteis e úteis na gestão de recursos renováveis , sendo simples para projetar e implementar, com algumas vantagens em uma situaç...

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Harvesting Strategies in a Fish Stock Dominated by Low-frequency Variability: The Norwegian Spring-spawning Herring (Clupea harengus)

Abstract: Heavy positively autocorrelated natural fluctuations in a fisheries

Cited by 31 publications

References 35 publications

Benefits of threshold strategies and age-selective harvesting in a fluctuating fish stock of Norwegian spring spawning herring Clupea harengus

Benefits of threshold strategies and age-selective harvesting in a fluctuating fish stock of Norwegian spring spawning herring Clupea harengus

Stability of International Fisheries Agreements Using Precautionary Bioeconomic Harvesting Strategies

Control of Nonlinear Dynamic Models of Predator-Prey Type

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