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  • 1
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 66, No. 2 ( 2009-03-01), p. 272-277
    Abstract: Payne, M. R., Hatfield, E. M. C., Dickey-Collas, M., Falkenhaug, T., Gallego, A., Gröger, J., Licandro, P., Llope, M., Munk, P., Röckmann, C., Schmidt, J. O., and Nash, R. D. M. 2009. Recruitment in a changing environment: the 2000s North Sea herring recruitment failure. – ICES Journal of Marine Science, 66: 272–277. Environmentally induced change appears to be impacting the recruitment of North Sea herring (Clupea harengus). Despite simultaneously having a large adult population, historically low exploitation, and Marine Stewardship Council accreditation (implying sustainability), there have been an unprecedented 6 sequential years of poor juvenile production (recruitment). Analysis suggests that the poor recruitment arises during the larval overwintering phase, with recent survival rates greatly reduced. Contemporary warming of the North Sea has caused significant changes in the plankton community, and a recently identified regime shift around 2000 shows close temporal agreement with the reduced larval survival. It is, therefore, possible that we are observing the first consequences of this planktonic change for higher trophic levels. There is no indication of a recovery in recruitment in the short term. Fishing mortality is currently outside the agreed management plan, and forecasts show a high risk of the stock moving outside safe biological limits soon, potentially precipitating another collapse of the stock. However, bringing the realized fishing mortality back in line with the management plan would likely alleviate the problem. This illustrates again that recruitment is influenced by more than just spawning-stock biomass, and that changes in other factors can be of equal, or even greater, importance. In such dynamically changing environments, recent management success does not necessarily guarantee future sustainability.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2009
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  • 2
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 67, No. 9 ( 2010-12-01), p. 1875-1886
    Abstract: Dickey-Collas, M., Nash, R. D. M., Brunel, T., van Damme, C. J. G., Marshall, C. T., Payne, M. R., Corten, A., Geffen, A. J., Peck, M. A., Hatfield, E. M. C., Hintzen, N. T., Enberg, K., Kell, L. T., and Simmonds, E. J. 2010. Lessons learned from stock collapse and recovery of North Sea herring: a review. – ICES Journal of Marine Science, 67: 1875–1886. The collapse and recovery of North Sea herring in the latter half of the 20th century had both ecological and economic consequences. We review the effect of the collapse and investigate whether the increased understanding about the biology, ecology, and stock dynamics gained in the past three decades can aid management to prevent further collapses and improve projections of recovery. Recruitment adds the most uncertainty to estimates of future yield and the potential to reach biomass reference points within a specified time-frame. Stock–recruitment relationships must be viewed as being fluid and dependent on ecosystem change. Likewise, predation mortality changes over time. Management aimed at maximum sustainable yield (MSY) fishing mortality targets implies interannual variation in TACs, and variability in supply is therefore unavoidable. Harvest control rules, when adhered to, aid management greatly. We advocate that well-founded science can substantially contribute to management through improved confidence and increased transparency. At present, we cannot predict the effects of collapse or recovery of a single stock on the ecosystem as a whole. Moreover, as managers try to reconcile commitments to single-species MSY targets with the ecosystem-based approach, they must consider the appropriate management objectives for the North Sea ecosystem as a whole.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
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  • 3
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2014
    In:  ICES Journal of Marine Science Vol. 71, No. 8 ( 2014-10-01), p. 2300-2306
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 71, No. 8 ( 2014-10-01), p. 2300-2306
    Abstract: The use of modelling approaches in marine science, and in particular fisheries science, is explored. We highlight that the choice of model used for an analysis should account for the question being posed or the context of the management problem. We examine a model-classification scheme based on Richard Levins' 1966 work suggesting that models can only achieve two of three desirable model attributes: realism, precision, and generality. Model creation, therefore, requires trading-off of one of these attributes in favour of the other two: however, this is often in conflict with the desires of end-users (i.e. mangers or policy developers). The combination of attributes leads to models that are considered to have empirical, mechanistic, or analytical characteristics, but not a combination of them. In fisheries science, many examples can be found of models with these characteristics. However, we suggest that models or techniques are often employed without consideration of their limitations, such as projecting into unknown space without generalism, or fitting empirical models and inferring causality. We suggest that the idea of trade-offs and limitations in modelling be considered as an essential first step in assessing the utility of a model in the context of knowledge for decision-making in management.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2014
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  • 4
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2009
    In:  ICES Journal of Marine Science Vol. 66, No. 8 ( 2009-09-01), p. 1696-1701
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 66, No. 8 ( 2009-09-01), p. 1696-1701
    Abstract: Oeberst, R., Dickey-Collas, M., and Nash, R. D. M. 2009. Mean daily growth of herring larvae in relation to temperature over a range of 5–20°C, based on weekly repeated cruises in the Greifswalder Bodden. – ICES Journal of Marine Science, 66: 1696–1701. Reported estimates of mean daily growth of herring larvae generally cover the temperature range 1–12°C and few estimates are available for temperatures 〉 15°C. We use larval surveys on Rügen spring-spawning herring in the Strelasund and the Greifswalder Bodden to estimate larval growth over a wider temperature range because the water temperature in that area normally increases from 5 to 20°C during the larval growth period (i.e. from spring to summer). This large temperature increase has a significant influence on the mean daily growth of herring larvae. Growth estimates were based on the modes of length frequencies observed at individual stations or accumulated over strata from consecutive surveys. Mean daily growth (G; mm d−1) of larvae was primarily determined by the ambient temperature (T) during the growth interval (5–7 d), resulting in the following relationship: G = 0.011 + 0.037 T. A non-linear function is also described. Growth rate was not length-dependent over the size range studied (5–20 mm). The study also showed that herring larvae were growing and surviving in temperatures up to 17.5°C.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2009
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    detail.hit.zdb_id: 1468003-8
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    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2009
    In:  ICES Journal of Marine Science Vol. 66, No. 8 ( 2009-09-01), p. 1776-1783
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 66, No. 8 ( 2009-09-01), p. 1776-1783
    Abstract: Kell, L. T., Dickey-Collas, M., Hintzen, N. T., Nash, R. D. M., Pilling, G. M., and Roel, B. A. 2009. Lumpers or splitters? Evaluating recovery and management plans for metapopulations of herring. – ICES Journal of Marine Science, 66: 1776–1783. The long-term management of a stock representing a metapopulation has been simulated in a case study loosely based upon herring to the west of the British isles, where stocks are currently assessed and managed by management area, although there is evidence of mixing between stocks (in terms of connectivity, migrations, and exploitation). The simulations evaluate scientific advice (based on virtual population analysis, VPA) and the sustainability of fishing under two population-structure scenarios, corresponding either to discrete stocks, which only mix on the feeding grounds, or where diffusion between stocks takes place. The ability of stock assessment to monitor stock status and exploitation levels was evaluated for defining stocks based on fishing areas and for stocks that combined fishing areas. The study showed that assessment based on VPA of the metapopulation could fail to detect overexploitation of stocks and fail to detect and distinguish between the effects of exploitation and regime shifts.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2009
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    detail.hit.zdb_id: 1468003-8
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  • 6
    In: Fisheries Oceanography, Wiley, Vol. 22, No. 2 ( 2013-03), p. 121-139
    Type of Medium: Online Resource
    ISSN: 1054-6006
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2013
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    SSG: 21,3
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  • 7
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2011
    In:  ICES Journal of Marine Science Vol. 68, No. 7 ( 2011-07-01), p. 1447-1458
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 68, No. 7 ( 2011-07-01), p. 1447-1458
    Abstract: Geffen, A. J., Nash, R. D. M., and Dickey-Collas, M. 2011. Characterization of herring populations west of the British Isles: an investigation of mixing based on otolith microchemistry. – ICES Journal of Marine Science, 68: 1447–1458. Herring along the west coast of the British Isles are managed and assessed as a series of discrete stocks. The relationship between the spawning components, mixed (feeding) aggregations, and juveniles in nursery areas for these stocks was modelled by discriminant analysis and integrated stock mixture analysis based on otolith elemental composition data. The relative elemental concentrations produced otolith signals corresponding to three main groupings of nursery-ground fish representing the Irish Sea, Scottish sea lochs, and the Minch. There were significant differences among spawning groups in the otolith concentrations of Li, Na, Mg, Mn, Sr, and Ba. Inclusion of length-at-age information improved the classification rates, ranging overall from 35 to 100%. Spawning groups consist of individuals from a number of different nursery areas and originate from several different management areas. Each of the mixed aggregations contained at least three spawning components. Results suggest that most west coast herring belong to interconnected populations subject to mixing and that populations are not discrete, so the current practice of assessments based on individual spawning components will probably not provide sufficiently robust information for management advice. The complexity of herring populations needs to be considered for both fisheries and coastal-zone management.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2011
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    SSG: 12
    SSG: 21,3
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  • 8
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2009
    In:  ICES Journal of Marine Science Vol. 66, No. 8 ( 2009-09-01), p. 1667-1672
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 66, No. 8 ( 2009-09-01), p. 1667-1672
    Abstract: Oeberst, R., Klenz, B., Gröhsler, T., Dickey-Collas, M., Nash, R. D. M., and Zimmermann, C. 2009. When is year-class strength determined in western Baltic herring? – ICES Journal of Marine Science, 66: 1667–1672. Weekly surveys of larvae in the Strelasund and the Greifswalder Bodden were used to investigate when year-class strength is determined in western Baltic spring-spawning (WBSS) herring. An abundance metric of larvae reaching a length of 20 mm over the entire spawning season was constructed by accounting for increases in daily growth resulting from seasonal increases in temperature (5–20°C). The index was significantly correlated with the acoustic estimates of age-1 herring in the western Baltic Sea (r = 0.88) and with the estimates of year-class strength obtained from stock assessment (r = 0.65). Previous studies of herring elsewhere have reported that year-class strength is determined during the late larval stage, but we show that year-class strength can already be fixed at a larval length of only 20 mm. Although the index obtained may be used in stock assessment and predictions, the intriguing question remains, namely how can the signal of larval productivity from one single spawning component of WBSS herring reflect the year-class dynamics of the entire stock?
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2009
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    detail.hit.zdb_id: 1468003-8
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    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
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