GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    Trend analysis of indicators: a comparison of recent changes in the status of marine ecosystems around the world
    Oxford University Press (OUP) ; 2010
    In:  ICES Journal of Marine Science Vol. 67, No. 4 ( 2010-05-01), p. 732-744
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 67, No. 4 ( 2010-05-01), p. 732-744
    Abstract: Blanchard, J. L., Coll, M., Trenkel, V. M., Vergnon, R., Yemane, D., Jouffre, D., Link, J. S., and Shin, Y-J. 2010. Trend analysis of indicators: a comparison of recent changes in the status of marine ecosystems around the world. – ICES Journal of Marine Science, 67: 732–744. Time-series of ecological and exploitation indicators collected from 19 ecosystems were analysed to investigate whether there have been temporal trends in the status of fish communities. Using linear and non-linear statistical methods, trends are reported for six indicators (mean length of fish in the community, mean lifespan, proportion of predatory fish, total biomass of surveyed species, mean trophic level of landings, and inverse fishing pressure), and the redundancy of these indicators across ecosystems is evaluated. The expected direction of change for an ecosystem that is increasingly impacted by fishing is a decline in all indicators. A mixture of negative and positive directions of change is recorded, both within and among all ecosystems considered. No consistent patterns in the redundancy of the ecological indicators across ecosystems emerged from the analyses, confirming that each indicator provided complementary information on ecosystem status. The different trends in indicators may reflect differing historical exploitation patterns, management, and environmental regimes in these systems. Commitment to monitoring programmes and development of system-specific baseline, target, and threshold reference levels are required. Improved understanding of the responsiveness and performance of ecological indicators to management actions are needed to address adequately whether ecosystems are recovering from, or being further impacted by, fishing, and whether management targets are being met. The relative effects of multiple environmental and ecological processes as well as multiple human-induced stressors that characterize exploited ecosystems also need to be quantified.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsp282
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
    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
  • 2
    Online Resource
    Online Resource
    Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community
    Oxford University Press (OUP) ; 2012
    In:  ICES Journal of Marine Science Vol. 69, No. 1 ( 2012-01-01), p. 8-22
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 69, No. 1 ( 2012-01-01), p. 8-22
    Abstract: Greenstreet, S. P. R., Fraser, H. M., Rogers, S. I., Trenkel, V. M., Simpson, S. D., and Pinnegar, J. K. 2012. Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community. – ICES Journal of Marine Science, 69: 8–22. Broader ecosystem management objectives for North Sea demersal fish currently focus on restoring community size structure. However, most policy drivers explicitly concentrate on restoring and conserving biodiversity, and it has not yet been established that simply restoring demersal fish size composition will be sufficient to reverse declines in biodiversity and ensure a generally healthy community. If different aspects of community composition, structure, and function vary independently, then to monitor all aspects of community general health will require application of a suite of metrics. This assumes low redundancy among the metrics used in any such suite and implies that addressing biodiversity issues specifically will require explicit management objectives for particular biodiversity metrics. This issue of metric redundancy is addressed, and 15 metrics covering five main attributes of community composition, structure, and function are applied to groundfish survey data. Factor analysis suggested a new interpretation of the metric information and indicated that a minimum suite of seven metrics was necessary to ensure that all changes in the general health of the North Sea demersal fish community were monitored properly. Covariance among size-based and species-diversity metrics was low, implying that restoration of community size structure would not necessarily reverse declines in species diversity.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsr188
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2012
    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
    Estimating gear efficiency in a combined acoustic and trawl survey, with reference to the spatial distribution of demersal fish
    Oxford University Press (OUP) ; 2010
    In:  ICES Journal of Marine Science Vol. 67, No. 4 ( 2010-05-01), p. 668-676
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 67, No. 4 ( 2010-05-01), p. 668-676
    Abstract: Doray, M., Mahévas, S., and Trenkel, V. M. 2010. Estimating gear efficiency in a combined acoustic and trawl survey, with reference to the spatial distribution of demersal fish. – ICES Journal of Marine Science, 67: 668–676. Few analyses have been performed to estimate the efficiency of trawls targeting demersal fish using the ratio of catches and acoustic densities. In summer 2006, acoustic and fishing data were collected simultaneously over 3 d by three fishing vessels equipped with identical pelagic trawls in the Bay of Biscay. Variography identified moderate spatial autocorrelation in the acoustic backscatter at a mean scale of 3 km, a scale slightly smaller than the mean haul length (3.5 km), indicating that fish horizontal availability did not influence trawl efficiency. Acoustic backscattering densities expressed as nautical area scattering coefficients (NASCs) recorded in the trawled layer were compared with equivalent NASC (ENASC) values calculated from the species composition in the trawl, fish-length structure, and available relationships between target strength and fish length. Estimates of trawl efficiency for hake-dominated trawls were computed as the slopes of the relationships ENASC = 0.008 NASC and ENASC = 0.18 NASC0.31 for trawls made by day and night, respectively. For the whole demersal community, the relationships were ENASC = 0.022 NASC and ENASC = 0.17 NASC0.33 for trawls made by day and night, respectively.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsp277
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
    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
  • 4
    Online Resource
    Online Resource
    Pelagic habitat: exploring the concept of good environmental status
    Oxford University Press (OUP) ; 2017
    In:  ICES Journal of Marine Science Vol. 74, No. 9 ( 2017-12-01), p. 2333-2341
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 74, No. 9 ( 2017-12-01), p. 2333-2341
    Abstract: Marine environmental legislation is increasingly expressing a need to consider the quality of pelagic habitats. This paper uses the European Union marine strategy framework to explore the concept of good environmental status (GES) of pelagic habitat with the aim to build a wider understanding of the issue. Pelagic ecosystems have static, persistent and ephemeral features, with manageable human activities primarily impacting the persistent features. The paper explores defining the meaning of “good”, setting boundaries to assess pelagic habitat and the challenges of considering habitat biodiversity in a moving medium. It concludes that for pelagic habitats to be in GES and able to provide goods and services to humans, three conditions should be met: (i) all species present under current environmental conditions should be able to find the pelagic habitats essential to close their life cycles; (ii) biogeochemical regulation is maintained at normal levels; (iii) critical physical dynamics and movements of biota and water masses at multiple scales are not obstructed. Reference points for acceptable levels of each condition and how these may change over time in line with prevailing oceanographic conditions, should be discussed by knowledge brokers, managers and stakeholders. Managers should think about a habitat hydrography rather than a habitat geography. Setting the bounds of the habitats requires a consideration of dimension, scale and gradients. It is likely that to deal with the challenges caused by a dynamic environment and the relevance of differing spatial and temporal scales, we will need to integrate multidisciplinary empirical data sets with spatial and temporal models to assess and monitor progress towards, or displacement from GES of the pelagic habitat.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsx158
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2017
    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
  • 5
    Online Resource
    Online Resource
    Comparison of approaches for incorporating depredation on fisheries catches into Ecopath
    Oxford University Press (OUP) ; 2020
    In:  ICES Journal of Marine Science Vol. 77, No. 7-8 ( 2020-12-01), p. 3153-3167
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 77, No. 7-8 ( 2020-12-01), p. 3153-3167
    Abstract: Ecosystem-based approaches are increasingly used in fisheries management to account for the direct trophic impacts of fish population harvesting. However, fisheries can also indirectly alter ecosystem structure and functioning, for instance via the provision of new feeding opportunities to marine predators. For instance, marine depredation, where predators feed on fishery catches on fishing gear, is a behaviour developed by many marine species globally. This behaviour can modify both the ecological role of predators and fisheries performance. Yet, these ecosystem-wide effects of depredation are rarely considered holistically. In this study, we explored different ways of incorporating depredation into an Ecopath trophic model. We assessed, through a subantarctic case study, how three alternative model structures can account for depredation effects on fishery catches, predator and non-commercial prey populations, as well as target fish stocks. While none adequately addresses all facets of depredation, the alternative models can to some extent capture how depredation can lead to increased fishing pressure on stocks. As structural specificities of Ecopath prevented us from representing other depredation effects such as provisioning effects for predator populations, we conclude this study with a set of guidance to effectively capture the complex effects of depredation in marine ecosystems and fisheries models.
    Type of Medium: Online Resource
    ISSN: 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsaa219
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2020
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 6
    Online Resource
    Online Resource
    Close-kin mark–recapture abundance estimation: practical insights and lessons learned
    Oxford University Press (OUP) ; 2022
    In:  ICES Journal of Marine Science Vol. 79, No. 2 ( 2022-03-10), p. 413-422
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 79, No. 2 ( 2022-03-10), p. 413-422
    Abstract: We present practical lessons learned from applying the recent close-kin mark–recapture (CKMR) abundance estimation method to thornback ray (Raja clavata). For CKMR, related individuals are identified from their genotypes and their number and pattern is used for abundance estimation. We genotyped over 7000 individuals collected in the Bay of Biscay using Single Nucleotide Polymorphism (SNP) markers finding 99 parent–offspring pairs. The estimated number of adult thornback rays in the central Bay of Biscay was around 135000 (CV 0.19) in 2013. In total, four lessons were drawn: (i) CKMR helps identifying metapopulation structure, which if ignored might affect abundance estimates and/or time trends. There was strong evidence for two distinct local populations of thornback ray with no demographic connectivity. (ii) Demographic sample composition can affect precision and needs to include a range of birth years, which turned out to be difficult for thornback ray. (iii) Reasonable age information for potential offspring is essential. (iv) The sex of potential parents is needed and might be identified from sex-related SNPs. Reliable abundance estimation by CKMR appears feasible for a wide range of species provided that: sampling adequately covers potential local population structure, has appropriate demographic composition, and the age of potential offspring is reasonably well-known.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsac002
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    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
  • 7
    Online Resource
    Online Resource
    Disentangling the effects of capture efficiency and population abundance on catch data using random effects models
    Oxford University Press (OUP) ; 2005
    In:  ICES Journal of Marine Science Vol. 62, No. 8 ( 2005-01-01), p. 1543-1555
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 62, No. 8 ( 2005-01-01), p. 1543-1555
    Abstract: We propose a random effects model for disentangling population abundance and capture efficiency effects on bottom-trawl catches. The spatial distribution of individual fish is assumed random leading to a Poisson distribution for the number of individuals in the trawl path (no schooling). Capture efficiency, i.e. the proportion of individuals in the trawl path being retained by the gear, is modelled as a random variable. We propose model extensions that include the effects of body size on haul efficiency. We applied the models to several species from the Celtic Sea groundfish community based on small-scale repetitive hauls. The resulting abundance estimates allowed us to study population abundance ratios; the estimated capture efficiencies were comparable between species and showed that generally gear efficiency increases for larger species with the exception of haddock (Melanogrammus aeglefinus), which had low estimated gear efficiency despite its large body size. Model identifiability was studied using simulations and an independent trawl data set from the same area.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2005.05.010
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
    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
  • 8
    Online Resource
    Online Resource
    Combining indicator trends to assess ongoing changes in exploited fish communities: diagnostic of communities off the coasts of France
    Oxford University Press (OUP) ; 2005
    In:  ICES Journal of Marine Science Vol. 62, No. 8 ( 2005-01-01), p. 1647-1664
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 62, No. 8 ( 2005-01-01), p. 1647-1664
    Abstract: We present a method for combining individual indicator results into a comprehensive diagnostic of fishing impacts on fish populations and communities. A conceptual framework for interpreting combined trends in a set of simple indicators is proposed, relying beforehand on qualitative expectations anchored in ecological theory. The initial state of the community is first assessed using published information. Which combinations of trends are acceptable or undesirable is decided, depending on the initial status. The indicators are then calculated from a time-series and their time trends are estimated as the slopes of linear models. Finally, the test results are combined within the predefined framework, providing a diagnostic on the dynamics of fishing impacts on populations and communities. The method is demonstrated for nine coastal and shelf-sea fish communities monitored by French surveys. Most communities were persistently or increasingly impacted by fishing. In addition, climate change seems to have contributed to changes in East Atlantic communities. Cet article propose une méthode utilisant des indicateurs pour élaborer un diagnostic sur les effets de la pêche sur les populations et les peuplements de poissons. Un cadre conceptuel permet d'interpréter les tendances conjointes d'indicateurs à partir de la théorie écologique. L'état initial du peuplement est d'abord évalué sur la base d'informations publiées. En fonction de l'état initial et des objectifs de gestion, les combinaisons des tendances sont qualifiées d'indésirables ou satisfaisantes. Les indicateurs sont ensuite estimés à partir de données de campagnes de pêches scientifiques: abondance et longueur moyenne d'une sélection de populations, nombre, biomasse totale, poids moyen et longueur moyenne dans le peuplement, et la pente du spectre de taille multispécifique. Les tendances temporelles de ces indicateurs sont testées au moyen d'un modèle linéaire, et les résultats des tests sont combinés en un diagnostic final. La méthode est mise en œuvre pour neuf peuplements de poissons côtiers et du plateau continental, suivis par des campagnes françaises. Il en résulte que la plupart de ces peuplements sont affectés par la pêche de manière stationnaire ou croissante. Par ailleurs, les changements climatiques dans l'Atlantique Nord-Est contribuent aussi à des modifications dans les peuplements de poissons de cette région.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2005.06.009
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
    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
  • 9
    Online Resource
    Online Resource
    Using qualitative and quantitative stakeholder knowledge: examples from European deep-water fisheries
    Oxford University Press (OUP) ; 2011
    In:  ICES Journal of Marine Science Vol. 68, No. 8 ( 2011-09-01), p. 1815-1824
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 68, No. 8 ( 2011-09-01), p. 1815-1824
    Abstract: Lorance, P., Agnarsson, S., Damalas, D., des Clers, S., Figueiredo, I., Gil, J., and Trenkel, V. M. 2011. Using qualitative and quantitative stakeholder knowledge: examples from European deep-water fisheries. – ICES Journal of Marine Science, 68: 1815–1824. Stakeholder knowledge was collected through questionnaires and cognitive maps and used to summarize biological, environmental, technical, management, and socio-economic factors for several deep-water fisheries, identifying regional management issues and solutions. The questionnaires and cognitive maps revealed different technical, environmental, and management concerns in these fisheries. Dissatisfaction with management was more at an implementation than a conceptual level, because the existing management measures were mostly considered fit for purpose. Further, catch-and-effort data provided by the fishing industry were used to calculate standardized landings per unit effort. The results suggested different trends over time for three deep-water stocks exploited by the same fleet. The examples demonstrate how stakeholder involvement and use of qualitative knowledge and quantitative data might improve the management process and stock assessments when data are limited.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsr076
    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
  • 10
    Online Resource
    Online Resource
    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
    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
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...