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  • 1
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    Comment on “Does the fall phytoplankton bloom control recruitment of Georges Bank haddock, Melanogrammus aeglefinus , through parental condition?”Appears in Can. J. Fish. Aquat. Sci. 65 : 1076–1086.
    Canadian Science Publishing ; 2009
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 66, No. 5 ( 2009-05), p. 869-872
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 66, No. 5 ( 2009-05), p. 869-872
    Abstract: In the paper “Does the fall phytoplankton bloom control recruitment of Georges Bank haddock, Melanogrammus aeglefinus , through parental condition?”, Friedland et al. (Can. J. Fish. Aquat. Sci. 65(6): 1076–1086, 2008) examine a sizable number of hypotheses aiming to explain the recruitment patterns observed in Georges Bank haddock. The authors focus on a correlation between the size of the autumnal phytoplankton bloom and the survivor ratio (recruitment), concluding this to be the main factor determining recruitment, via the mechanism of adult condition at the time of spawning. Here we examine this result in close detail and re-analyse some of the data presented in the paper. We show that the recruitment metric upon which Friedland et al. base their conclusions inadvertently biases the analysis in favour of high recruitment events and against low recruitments. As a consequence, Friedland et al. disregard correlations that are, in fact, significant. Furthermore, we show that the parental condition hypothesis hinges upon a single, highly uncertain data point, without which the correlation is no longer significant. We find that evidence for the parental condition hypothesis is weak, and that in performing the analysis in the chosen manner, Friedland et al. have overlooked alternative hypotheses.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/F09-043
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2009
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  • 2
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    Recruitment in a changing environment: the 2000s North Sea herring recruitment failure
    Oxford University Press (OUP) ; 2009
    In:  ICES Journal of Marine Science Vol. 66, No. 2 ( 2009-03-01), p. 272-277
    Details
    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
    URL: Article
    DOI: 10.1093/icesjms/fsn211
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2009
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  • 3
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    Does Operational Oceanography Address the Needs of Fisheries and Applied Environmental Scientists
    The Oceanography Society ; 2011
    In:  Oceanography Vol. 24, No. 01 ( 2011-03-01), p. 166-171
    Details
    In: Oceanography, The Oceanography Society, Vol. 24, No. 01 ( 2011-03-01), p. 166-171
    Type of Medium: Online Resource
    ISSN: 1042-8275
    Uniform Title: English
    URL: Journal
    URL: Article
    DOI: 10.5670/oceanog
    DOI: 10.5670/oceanog.2011.14
    Language: Unknown
    Publisher: The Oceanography Society
    Publication Date: 2011
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  • 4
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    Does larval mortality influence population dynamics? An analysis of North Sea herring (Clupea harengus) time series : North Sea herring larval mortality
    Wiley ; 2011
    In:  Fisheries Oceanography Vol. 20, No. 6 ( 2011-11), p. 530-543
    Details
    In: Fisheries Oceanography, Wiley, Vol. 20, No. 6 ( 2011-11), p. 530-543
    Type of Medium: Online Resource
    ISSN: 1054-6006
    URL: Article
    DOI: 10.1111/j.1365-2419.2011.00600.x
    Language: English
    Publisher: Wiley
    Publication Date: 2011
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  • 5
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    Lessons learned from stock collapse and recovery of North Sea herring: a review
    Oxford University Press (OUP) ; 2010
    In:  ICES Journal of Marine Science Vol. 67, No. 9 ( 2010-12-01), p. 1875-1886
    Details
    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
    URL: Article
    DOI: 10.1093/icesjms/fsq033
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
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  • 6
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    Hazard warning: model misuse ahead
    Oxford University Press (OUP) ; 2014
    In:  ICES Journal of Marine Science Vol. 71, No. 8 ( 2014-10-01), p. 2300-2306
    Details
    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
    URL: Article
    DOI: 10.1093/icesjms/fst215
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2014
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  • 7
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    Realized habitats of early-stage North Sea herring: looking for signals of environmental change
    Oxford University Press (OUP) ; 2011
    In:  ICES Journal of Marine Science Vol. 68, No. 3 ( 2011-03-01), p. 537-546
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 68, No. 3 ( 2011-03-01), p. 537-546
    Abstract: Röckmann, C., Dickey-Collas, M., Payne, M. R., and van Hal, R. 2011. Realized habitats of early-stage North Sea herring: looking for signals of environmental change. – ICES Journal of Marine Science, 68: . Realized habitats of North Sea herring for two larval and two juvenile stages were estimated over the past 30 years, using abundances from surveys tied to modelled estimates of temperature and salinity. Newly hatched larvae (NHL) were found mainly in water masses of 9–11°C, pre-metamorphosis larvae (PML) around 5–6°C, juveniles aged 0 in summer around 13–14°C, and juveniles aged 1 in winter around 4–5°C. The median salinity in which the NHL were distributed was 34.4–35.0 and 33.7–33.9, respectively, for PML and juveniles. Interannual variations in temperature and geographic variables in the North Sea were compared with the time-series of realized habitats. The realized temperature habitats of the NHL did not change over time, but the habitat of juveniles in summer may be associated with higher temperatures. Juveniles aged 1 in winter are found in waters colder than the average for the North Sea, a result also reflected in their geographic shift east into shallower water. The results suggest that juveniles could be limited by temperature, but may also track changes in food or predator distribution, and/or internal population dynamics. Time-series analysis of realized salinity habitats was not possible with the available data because of differences between model outputs.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsq171
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2011
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  • 8
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    International perceptions of an integrated, multi-sectoral, ecosystem approach to management
    Oxford University Press (OUP) ; 2017
    In:  ICES Journal of Marine Science Vol. 74, No. 1 ( 2017-01-01), p. 414-420
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 74, No. 1 ( 2017-01-01), p. 414-420
    Abstract: The Ecosystem Approach to Management (EAM) has emerged over the past decades, largely to promote biodiversity conservation, and more recently sectoral tradeoffs in the management of marine ecosystems. To ascertain the state of practice of EAM operationalization, a workshop was held, which included a pre-workshop online survey. The survey gauged international participants’ perspectives regarding capacity, knowledge, and application of EAM. When asked about the subject, most survey respondents had a general understanding of EAM, and provided a clear definition. Major perceived challenges to EAM objectives by those surveyed included limited knowledge, conflicting interests, insufficient communication, and limited organizational legal frameworks or governance structures. Of those directly involved in an ecosystem approach, the majority responded that processes were in place or developed for application of integrated knowledge toward assessing key issues within their respective sectors (i.e. fisheries, conservation, energy), and that capacity was generally high. Our results show that most respondents, irrespective of sector or geography, see value in considering an integrated, broader ecosystem approach as they manage their sector. Although many participants were from the North Atlantic region, our results suggest that much of the international community is converging toward continued understanding of broad-scale, integrated approaches to marine resource management.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsw214
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2017
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  • 9
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    Variation that can be expected when using particle tracking models in connectivity studies
    Elsevier BV ; 2017
    In:  Journal of Sea Research Vol. 127 ( 2017-09), p. 133-149
    Details
    In: Journal of Sea Research, Elsevier BV, Vol. 127 ( 2017-09), p. 133-149
    Type of Medium: Online Resource
    ISSN: 1385-1101
    URL: Article
    DOI: 10.1016/j.seares.2017.04.009
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
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  • 10
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    Precisely wrong or vaguely right: simulations of noisy discard data and trends in fishing effort being included in the stock assessment of North Sea plaice
    Oxford University Press (OUP) ; 2007
    In:  ICES Journal of Marine Science Vol. 64, No. 9 ( 2007-12-01), p. 1641-1649
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 64, No. 9 ( 2007-12-01), p. 1641-1649
    Abstract: Dickey-Collas, M., Pastoors, M. A, and van Keeken, O. A. 2007. Precisely wrong or vaguely right: simulations of noisy discard data and trends in fishing effort being included in the stock assessment of North Sea plaice. – ICES Journal of Marine Science, 64: 000–000. ICES stock assessments of North Sea plaice are routinely carried out with eXtended Survivors Analysis (XSA), based on landings and survey data. Recently, the assessments included data on discarded young fish, sampled with high variance. Fishing effort has been declining since the mid-1990s, so conditioning the estimated fishing mortality (F) on the recent past could introduce bias into the perceived stock size. Simulated populations with North Sea plaice-like characteristics are used to explore the dependence of the perceived stock dynamics on the inclusion of discards data at different sampling noise, using the same methods and XSA settings as ICES. The sensitivities of the results were tested against different trends in fishing effort and recruitment, and different scenarios for “shrinkage” (i.e. the way in which the past is used to estimate the most recent fishing mortality). Within the bounds of the simulation assumptions, the perception of population trends from an XSA stock assessment can be biased when there are trends in fishing effort: decreasing effort leads to underestimating SSB and overestimating F. When discards are not included, bias in SSB is greatest when effort decreases, and bias in F is greatest when effort increases. Bias in SSB and F were removed by including discard data, but at substantial loss of precision. If effort shows a clear trend and discards are substantial and estimated noisily, the recent trend in the target population may be hard to track with an XSA-type assessment methodology.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsm155
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2007
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