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  • Oxford University Press (OUP)  (3)
  • Pope, John G.  (3)
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  • Oxford University Press (OUP)  (3)
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  • 1
    Online Resource
    Online Resource
    Modelling an exploited marine fish community with 15 parameters – results from a simple size-based model
    Oxford University Press (OUP) ; 2006
    In:  ICES Journal of Marine Science Vol. 63, No. 6 ( 2006-01-01), p. 1029-1044
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 63, No. 6 ( 2006-01-01), p. 1029-1044
    Abstract: To measure and predict the response of fish communities to exploitation, it is necessary to understand how the direct and indirect effects of fishing interact. Because fishing and predation are size-selective processes, the potential response can be explored with size-based models. We use a simulation approach to describe the relationship between size spectrum slope and overall fishing mortality and to try to understand how a linear spectrum might be maintained. The model uses 15 parameters to describe a 13-“species” fish community, where species are defined by their maximum body size and the general relationship between size and life-history characteristics. The simulations allow us to assess the role of changes in the strength and type of density dependence in controlling the response to fishing, and to investigate the trade-off between catches and stock status of the different species. The outputs showed that the linear slope of the size spectrum was a function of community exploitation rate. Density-dependent controls, specifically predation mortality and the extent of compensation in the stock-recruit relationship, were key mechanisms in maintaining a linear spectrum. A linear spectrum emerged independent of the rate of compensation in the stock-recruit relationship. When this rate was low, the effects of changes in fishing mortality on predator abundance dominated those on spawning-stock biomass, whereas the dominance was reversed when the compensation rate in the stock-recruit relationship was high. The approach allows us to explore the effects of different fishing mortality schedules on properties of the fish community, to assess how fishing affects species with different life histories in mixed fisheries, and to assess the effects of selectively fishing different size classes. The simulations indicate that the size classes to be included when developing and interpreting size-based metrics must be carefully considered in relation to the trophic structure and likely strength of predatory interactions in the community. Runs with different fishing mortality by size suggest that the dynamics of predation cannot compensate fully for changing rates and patterns of exploitation, implying that the effects of selectively fishing different size classes should be assessed on a case-by-case basis.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2006.04.015
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2006
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Coexistence in North Sea fish communities: implications for growth and natural mortality
    Oxford University Press (OUP) ; 2008
    In:  ICES Journal of Marine Science Vol. 65, No. 4 ( 2008-05-01), p. 514-530
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 65, No. 4 ( 2008-05-01), p. 514-530
    Abstract: Gislason, H., Pope, J. G., Rice, J. C., and Daan, N. 2008. Coexistence in North Sea fish communities: implications for growth and natural mortality. – ICES Journal of Marine Science, 65: 514–530. For a fish community to persist over time, all species must be able on average to replace themselves on a one-for-one basis over their lifetime. We use this principle and a size-based equilibrium model where asymptotic length is used as a functional trait to investigate how natural mortality should scale with size within and across pelagic and demersal species of North Sea teleosts. The model predicts natural mortality to scale with body length raised to a power of −1.66 at current levels of exploitation. Additionally, natural mortality of demersal species should be proportional to asymptotic length raised to a power of 0.80, so generating a higher natural mortality at a given length for large species than for small ones. The model also suggests that the exponent in the scaling of the von Bertalanffy growth parameter K with asymptotic length should be more negative for pelagic than for demersal species. We test our results by analysing independent estimates of predation mortality, the scaling of maximum recruitment per unit of spawning-stock biomass with asymptotic length, and the general relationship between K and asymptotic length for demersal and pelagic families of fish. All tests are consistent with our modelling results.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsn035
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2008
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Apocalypse in world fisheries? The reports of their death are greatly exaggerated
    Oxford University Press (OUP) ; 2011
    In:  ICES Journal of Marine Science Vol. 68, No. 7 ( 2011-07-01), p. 1375-1378
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 68, No. 7 ( 2011-07-01), p. 1375-1378
    Abstract: Daan, N., Gislason, H., Pope, J. G., and Rice, J. C. 2011. Apocalypse in world fisheries? The reports of their death are greatly exaggerated. – ICES Journal of Marine Science, 68: 1375–1378. The catch-based methods underlying the forecast that by 2048 all commercially exploited stocks will have collapsed have been severely criticized, and a recent and more-elaborate analysis by a group of scientists that included the lead author of the original article has led to a quite different interpretation. Nonetheless, the 2006 forecast of a forthcoming apocalypse in the oceans is still uncritically referred to by critics of current management and fisheries science. In the title, the quote by Mark Twain is paraphrased to underline the fact that this prediction is both technically and conceptually flawed: (i) any series of random numbers subjected to the algorithm underlying the prediction will show a pattern similar to that observed in catch statistics; (ii) this pattern should be accounted for in making predictions; and (iii) interpreting the period of maximum harvest in a time-series as generally reflecting a period during which a stock was fully exploited is incorrect, because history often has shown that these maximum yields were taken during a period of overexploitation and could not have been sustainable.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsr069
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2011
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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