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  • 1
    Online Resource
    Online Resource
    Factors for the variability of discards: assumptions and field evidence
    Canadian Science Publishing ; 2005
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 62, No. 1 ( 2005-01-01), p. 224-235
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 62, No. 1 ( 2005-01-01), p. 224-235
    Abstract: Discarding is an issue of increasing concern and there is a growing number of studies aiming at estimating discard amounts and characteristics. However, the sampling design and methods used in these studies generally rely on implicit assumptions. In this perspective, we examine the available evidence in favour of or refuting these assumptions. We find that (i) the assumptions most commonly used for estimating discards, namely that discards are proportional to catch or to effort, are generally not supported by the available evidence, (ii) both environmental conditions and fishing methods influence the amounts and composition of discards, but because of the huge variability, sampling stratification according to these factors might not result in any improvement of the precision of discard estimates, and (iii) many intricate factors can play a role in determining discards in a particular fishery. We conclude that assumptions should be more carefully checked prior to being taken for granted in discard studies and that more studies designed to improve knowledge of the discarding processes are needed.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/f04-185
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2005
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  • 2
    Online Resource
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    Which community indicators can measure the impact of fishing? A review and proposals
    Canadian Science Publishing ; 2003
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 60, No. 1 ( 2003-01-01), p. 86-99
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 60, No. 1 ( 2003-01-01), p. 86-99
    Abstract: Population and community descriptors that might be used as indicators of the impact of fishing are reviewed. The criteria used for the evaluation of these indicators are meaning, expected effect of fishing, exclusiveness to fishing effects, and measurability. Population indicators such as total mortality rate, exploitation rate, or average length are the most operational indicators because their meaning is clear and the expected effect of fishing on them is well understood so that reference points can be set. On the other hand, indicators based on the composition of species assemblages such as diversity indices and ordination of species abundances are difficult to interpret, and the effect of fishing on them is not easily predicted. Robust indicators describing the community functions of interest (production and transfer of biomass to large fish), such as size spectra descriptors or the proportion of piscivorous fish in the community, are more promising but are not yet well developed. New candidate indicators are proposed: the change in fishing mortality required to reverse population growth rate, the proportion of noncommercial species in the community, and the average length and weight in the community.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/f02-164
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2003
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  • 3
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    How to provide scientific advice for ecosystem‐based management now
    Wiley ; 2018
    In:  Fish and Fisheries Vol. 19, No. 2 ( 2018-03), p. 390-398
    Details
    In: Fish and Fisheries, Wiley, Vol. 19, No. 2 ( 2018-03), p. 390-398
    Abstract: In this paper, I argue that we have at hand what is needed to provide scientific advice for ecosystem‐based management of small pelagics and other species groups now. The ingredients for this advice are (i) large marine ecosystems as spatial management units; (ii) maintaining ecosystem productivity and exploiting at multispecies maximum yield as overarching management objectives; (iii) assessment of ecosystems by evaluating changes in primary productivity; (iv) an operational management procedure in which single‐species catch proposals are adjusted to ecosystem productivity using a set of control rules. Inspection of historic landings for small pelagics and other small species in the Northeast Atlantic ( ICES area) reveals that most likely fisheries exploitation does not, and never did, exceed system productivity in most LME s and is therefore overall sustainable, although not necessarily for individual stocks.
    Type of Medium: Online Resource
    ISSN: 1467-2960 , 1467-2979
    URL: Issue
    URL: Article
    DOI: 10.1111/faf.2018.19.issue-2
    DOI: 10.1111/faf.12263
    Language: English
    Publisher: Wiley
    Publication Date: 2018
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  • 4
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    Environmental DNA complements scientific trawling in surveys of marine fish biodiversity
    Oxford University Press (OUP) ; 2023
    In:  ICES Journal of Marine Science ( 2023-09-21)
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), ( 2023-09-21)
    Abstract: Environmental DNA (eDNA) metabarcoding is a method to detect taxa from environmental samples. It is increasingly used for marine biodiversity surveys. As it only requires water collection, eDNA metabarcoding is less invasive than scientific trawling and might be more cost effective. Here, we analysed data from both sampling methods applied in the same scientific survey targeting Northeast Atlantic fish in the Bay of Biscay. We compared the methods regarding the distribution of taxonomic, phylogenetic, and functional diversity. We found that eDNA captured more taxonomic and phylogenetic richness than bottom trawling and more functional richness at the local scale. eDNA was less selective than trawling and detected species in local communities spanning larger phylogenetic and functional breadths, especially as it detected large pelagic species that escaped the trawl, even though trawling detected more flat fish. eDNA indicated differences in fish community composition that were comparable to those based on trawling. However, consistency between abundance estimates provided by eDNA metabarcoding and trawl catches was low, even after accounting for allometric scaling in eDNA production. We conclude that eDNA metabarcoding is a promising method that can complement scientific trawling for multi-component biodiversity monitoring based on presence/absence, but not yet for abundance.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsad139
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2023
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  • 5
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    Contributing to ecosystem-based management: a personal scientific journey
    Oxford University Press (OUP) ; 2024
    In:  ICES Journal of Marine Science ( 2024-05-10)
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), ( 2024-05-10)
    Abstract: After three decades of working as a research scientist, I am stepping back to consider the events, questions, and principles that have guided my scientific journey. Important questions and research objectives have been how to implement the ecosystem approach to fisheries management in practice, the development of new data uses, the application of new observation methods and models, and estimating and accounting for uncertainty. Stakeholder engagement—why and how—is a topic that has increased in importance over time. While our observation methods did not change much over many decades, they are now changing rapidly due to new technological developments, but also societal and environmental changes.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsae065
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2024
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  • 6
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    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
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    detail.hit.zdb_id: 1468003-8
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  • 7
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    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
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    detail.hit.zdb_id: 29056-7
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  • 8
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    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
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    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
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  • 9
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    Online Resource
    Performance of indicators derived from abundance estimates for detecting the impact of fishing on a fish community
    Canadian Science Publishing ; 2003
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 60, No. 1 ( 2003-01-01), p. 67-85
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 60, No. 1 ( 2003-01-01), p. 67-85
    Abstract: Population and community indicators for the impact of fishing are often estimated using abundance estimates instead of raw sampling observations. Methods are presented for testing null hypotheses of nonsignificant impacts and, where possible, for calculating the statistical power. The indicators considered concern populations (intrinsic growth rate, total mortality, exploitation rate, and a new indicator, the change in fishing mortality required to reverse population growth) and communities (k- and partial-dominance curves, a biodiversity index, size spectrum, and proportions of various population groups). The performance of these indicators is compared for the Celtic Sea groundfish community based on achieved precision, statistical power, and availability and estimation method of reference points. Among population indicators, mean length of catch was most precisely estimated and the corresponding hypothesis tests had consistently large powers. Total mortality performed reasonably well. In contrast, both the intrinsic population growth rate and the exploitation rate gave unreliable results. All tested community indicators performed similarly well. Indicators for which the direction of change caused by fishing is predictable, such as the proportion of noncommercial species or piscivores in the community, are promising indicators at the community level.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/f02-163
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2003
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    detail.hit.zdb_id: 1473089-3
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  • 10
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    A framework for evaluating management plans comprehensively
    Wiley ; 2015
    In:  Fish and Fisheries Vol. 16, No. 2 ( 2015-06), p. 310-328
    Details
    In: Fish and Fisheries, Wiley, Vol. 16, No. 2 ( 2015-06), p. 310-328
    Abstract: We present a framework for evaluating fisheries management plans comprehensively, both rebuilding plans and others. The framework includes a first rapid appraisal of the likelihood that the plan will result in management meeting its objectives, and guides subsequent quantitative analyses of potential weaknesses in the proposed plan. The framework includes four steps: (i) evaluating if a set of management objectives, if achieved, would result in a sustainable fishery, (ii) using qualitative analysis of a bio‐economic model to evaluate whether the set of stock management tactics might be capable of achieving the specified fisheries objectives, (iii) using empirical criteria derived from the literature to evaluate if other management measures in the plan related to the ecological, social or economic context of the fishery actually contribute to sustainability, and (iv) carrying out quantitative simulations to compare alternative implementation options. Generally, several management measures have to be combined to increase stock size without sacrificing the economic benefits to the fishers remaining in the fishery. We demonstrate application of the framework for evaluating the stock rebuilding plan for plaice ( Pleuronectes platessa ) and sole ( Solea solea ) in the North Sea and, the management measures currently in place for the roundnose grenadier ( Coryphaenoides rupestris ) stock exploited to the west of the British Isles.
    Type of Medium: Online Resource
    ISSN: 1467-2960 , 1467-2979
    URL: Issue
    URL: Article
    DOI: 10.1111/faf.2015.16.issue-2
    DOI: 10.1111/faf.12058
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 2024569-5
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