Risk of collapse in the eastern Baltic cod fishery

Jonzén, Niclas; Cardinale, Massimiliano; Gårdmark, Anna; Arrhenius, Fredrik; Lundberg, Per

doi:10.3354/meps240225

Cited by 38 publications

(12 citation statements)

References 42 publications

(48 reference statements)

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“…The coalescence‐based simulations showed that around 30 lineages (alleles) could still be present after a severe bottleneck lasting for 10 generations or less, which was compatible both with the levels of variability and with the onset of over‐exploitation of North Sea cod (Cook et al . 1997) and Baltic Sea cod (Jonzén et al . 2002).…”

Section: Discussionmentioning

confidence: 99%

Long‐term stability and effective population size in North Sea and Baltic Sea cod (Gadus morhua)

Nielsen²,

et al. 2005

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DNA from archived otoliths was used to explore the temporal stability of the genetic composition of two cod populations, the Moray Firth (North Sea) sampled in 1965 and 2002, and the Bornholm Basin (Baltic Sea) sampled in 1928 and 1997. We found no significant changes in the allele frequencies for the Moray Firth population, while subtle but significant genetic changes over time were detected for the Bornholm Basin population. Estimates of the effective population size (Ne) generally exceeded 500 for both populations when employing a number of varieties of the temporal genetic method. However, confidence intervals were very wide and Ne's most likely range in the thousands. There was no apparent loss of genetic variability and no evidence of a genetic bottleneck for either of the populations. Calculations of the expected levels of genetic variability under different scenarios of Ne showed that the number of alleles commonly reported at microsatellite loci in Atlantic cod is best explained by Ne's exceeding thousand. Recent fishery-induced bottlenecks can, however, not be ruled out as an explanation for the apparent discrepancy between high levels of variability and recently reported estimates of Ne << 1000. From life history traits and estimates of survival rates in the wild, we evaluate the compatibility of the species' biology and extremely low Ne/N ratios. Our data suggest that very small Ne's are not likely to be of general concern for cod populations and, accordingly, most populations do not face any severe threat of losing evolutionary potential due to genetic drift.

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Section: Discussionmentioning

confidence: 99%

Long‐term stability and effective population size in North Sea and Baltic Sea cod (Gadus morhua)

Nielsen²,

et al. 2005

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“…However, in some years even these adaptations are insufficient to ensure reproductive success (Köster et al , 2005). Continued high fishing pressure in combination with frequent periods of detrimental environmental conditions for egg survival suggests that this population may collapse (Jonzen et al , 2002; ICES, 2005a), as happened to the central Baltic dab and plaice stocks during the 20th century (Temming, 1989). If the eastern Baltic cod population were to collapse, then recovery would be very slow or perhaps impossible even under low or no fishing mortality.…”

Section: Fisheries Management During 21st Century Climate Changementioning

confidence: 99%

Impact of 21st century climate change on the Baltic Sea fish community and fisheries

MacKenzie

Gislason

Möllmann

et al. 2007

Global Change Biology

174

139

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The Baltic Sea is a large brackish semienclosed sea whose species-poor fish community supports important commercial and recreational fisheries. Both the fish species and the fisheries are strongly affected by climate variations. These climatic effects and the underlying mechanisms are briefly reviewed. We then use recent regional -scale climate -ocean modelling results to consider how climate change during this century will affect the fish community of the Baltic and fisheries management. Expected climate changes in northern Europe will likely affect both the temperature and salinity of the Baltic, causing it to become warmer and fresher. As an estuarine ecosystem with large horizontal and vertical salinity gradients, biodiversity will be particularly sensitive to changes in salinity which can be expected as a consequence of altered precipitation patterns. Marine-tolerant species will be disadvantaged and their distributions will partially contract from the Baltic Sea; habitats of freshwater species will likely expand. Although some new species can be expected to immigrate because of an expected increase in sea temperature, only a few of these species will be able to successfully colonize the Baltic because of its low salinity. Fishing fleets which presently target marine species (e.g. cod, herring, sprat, plaice, sole) in the Baltic will likely have to relocate to more marine areas or switch to other species which tolerate decreasing salinities. Fishery management thresholds that trigger reductions in fishing quotas or fishery closures to conserve local populations (e.g. cod, salmon) will have to be reassessed as the ecological basis on which existing thresholds have been established changes, and new thresholds will have to be developed for immigrant species. The Baltic situation illustrates some of the uncertainties and complexities associated with forecasting how fish populations, communities and industries dependent on an estuarine ecosystem might respond to future climate change.

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“…There have been increasing efforts to analyze the risk of collapse in fisheries (e.g., Johnston and Sutinen 1996;Myers, Hutchings, and Barrowman 1997;Hutchings 2000;Jonzén et al 2002;Escudero et al 2004;Hutchings and Reynolds 2004;Mullon, Fréon, and Cury 2005;Mitra and Roy 2006). Many scientists and managers consider fisheries collapse to be a result of purely economic or administrative mismanagement (Mullon, Fréon, and Cury 2005), and many of these studies have concentrated on overfishing as a cause of fisheries depletion and collapse.…”

Section: Introductionmentioning

confidence: 99%

Stochastically Induced Critical Depensation and Risk of Stock Collapse

Poudel

Sandal

Kvamsdal

2015

Marine Resource Economics

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A B S T R A C TThis article investigates the risk of stock collapse due to stochastically induced critical depensation in managed fisheries. We use a continuous-time surplus production model and an economic model with downwardsloping demand and stock-dependent costs. First, we derive an optimal exploitation policy as a feedback control rule by applying the Hamilton-Jacobi-Bellman approach and analyze the effects of stochasticity on the optimal policy. Then, we characterize the long-term sustainable optimal state and estimate the risk of stock collapse due to stochastically induced critical depensation. We find that the optimal harvest policy in the stochastic setting is conservative at low stochasticity and approaches the myopic solution at high stochasticity. The risk of stock collapse is increasing with the stochasticity and decreasing with stock sizes.

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Risk of collapse in the eastern Baltic cod fishery

Cited by 38 publications

References 42 publications

Long‐term stability and effective population size in North Sea and Baltic Sea cod (Gadus morhua)

Long‐term stability and effective population size in North Sea and Baltic Sea cod (Gadus morhua)

Impact of 21st century climate change on the Baltic Sea fish community and fisheries

Stochastically Induced Critical Depensation and Risk of Stock Collapse

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