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  • 1
    Online Resource
    Online Resource
    Spatio-temporal patterns in the diversity of demersal fish communities off the south coast of South Africa
    Springer Science and Business Media LLC ; 2010
    In:  Marine Biology Vol. 157, No. 2 ( 2010-2), p. 269-281
    Details
    In: Marine Biology, Springer Science and Business Media LLC, Vol. 157, No. 2 ( 2010-2), p. 269-281
    Type of Medium: Online Resource
    ISSN: 0025-3162 , 1432-1793
    URL: Article
    DOI: 10.1007/s00227-009-1314-y
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2010
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  • 2
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    Exploring the effect of Marine Protected Areas on the dynamics of fish communities in the southern Benguela: an individual-based modelling approach
    Oxford University Press (OUP) ; 2009
    In:  ICES Journal of Marine Science Vol. 66, No. 2 ( 2009-03-01), p. 378-387
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 66, No. 2 ( 2009-03-01), p. 378-387
    Abstract: Yemane, D., Shin, Y-J., and Field, J. G. 2009. Exploring the effect of Marine Protected Areas on the dynamics of fish communities in the southern Benguela: an individual-based modelling approach. – ICES Journal of Marine Science, 66: 378–387. Marine Protected Areas (MPAs) have been suggested as a tool that can achieve some of the goals of an Ecosystem Approach to Fisheries (EAF), e.g. prevention of overexploitation, biodiversity conservation, recovery of overexploited population, but the consequences of their establishment on the dynamics of protected components are often unclear. Spatial and multispecies models can be used to investigate the effects of their introduction. An individual-based, spatially explicit, size-structured, multispecies model (known as OSMOSE) is used to investigate the likely consequences of the introduction of three MPAs off the coast of South Africa, individually or in combination. The simultaneous introduction of the MPAs affected varying proportions of the distribution of the modelled species (5–17%) and 12% of the distribution of the whole community. In general, the introduction of the MPAs in the different scenarios resulted in a relative increase in the biomass of large predatory fish and a decrease in the biomass of small pelagic fish. The simulation demonstrates that consideration of trophic interactions is necessary when introducing MPAs, with indirect effects that may be detrimental to some (mainly smaller prey) species.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsn171
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2009
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  • 3
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    Assessing changes in the distribution and range size of demersal fish populations in the Benguela Current Large Marine Ecosystem
    Springer Science and Business Media LLC ; 2014
    In:  Reviews in Fish Biology and Fisheries Vol. 24, No. 2 ( 2014-6), p. 463-483
    Details
    In: Reviews in Fish Biology and Fisheries, Springer Science and Business Media LLC, Vol. 24, No. 2 ( 2014-6), p. 463-483
    Type of Medium: Online Resource
    ISSN: 0960-3166 , 1573-5184
    URL: Article
    DOI: 10.1007/s11160-014-9357-7
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2014
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    detail.hit.zdb_id: 1498719-3
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  • 4
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    Exploring the effects of fishing on fish assemblages using Abundance Biomass Comparison (ABC) curves
    Oxford University Press (OUP) ; 2005
    In:  ICES Journal of Marine Science Vol. 62, No. 3 ( 2005-01-01), p. 374-379
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 62, No. 3 ( 2005-01-01), p. 374-379
    Abstract: The possible effect of fishing on dominance patterns in the South African south coast demersal trawl fishery is assessed using Abundance Biomass Comparison (ABC) curves for the period 1986–2003. The ABC method compares the ranked distribution of abundance among species against the similar distribution of biomass among species. The temporal pattern in the ABC curves and the W-statistic for two depth groups ( 〈 100 m and 101–200 m), and for the whole area combined, shows a gradient of change in the demersal assemblages from neutral (W ≥ 0) towards negative (W 〈 0), suggesting a disturbed or stressed condition. This corresponds to the onset of longline fishing effort in 1994, still ongoing in 2003, superimposed upon declining trawl effort in the same region. The ABC method shows promise as a guide for assessing the effects of fishing on fish communities, being based on established r- and k-selection theory. More modelling and comparative work is needed to establish acceptable ranges for the W-statistic, and their application in an ecosystem approach to fisheries management.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2005.01.009
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
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  • 5
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    Relating marine ecosystem indicators to fishing and environmental drivers: an elucidation of contrasting responses
    Oxford University Press (OUP) ; 2010
    In:  ICES Journal of Marine Science Vol. 67, No. 4 ( 2010-05-01), p. 787-795
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 67, No. 4 ( 2010-05-01), p. 787-795
    Abstract: Link, J. S., Yemane, D., Shannon, L. J., Coll, M., Shin, Y-J., Hill, L., and Borges, M. F. 2010. Relating marine ecosystem indicators to fishing and environmental drivers: an elucidation of contrasting responses. – ICES Journal of Marine Science, 67: 787–795. The usefulness of indicators in detecting ecosystem change depends on three main criteria: the availability of data to estimate the indicator (measurability), the ability to detect change in an ecosystem (sensitivity), and the ability to link the said change in an indicator as a response to a known intervention or pressure (specificity). Here, we specifically examine the third aspect of indicator change, with an emphasis on multiple methods to explore the “relativity” of major ecosystem drivers. We use a suite of multivariate methods to explore the relationships between a pre-established set of fisheries-orientated ecosystem status indicators and the key drivers for those ecosystems (particularly emphasizing proxy indicators for fishing and the environment). The results show the relative importance among fishing and environmental factors, which differed notably across the major types of ecosystems. Yet, they also demonstrated common patterns in which most ecosystems, and indicators of ecosystem dynamics are largely driven by fisheries (landings) or human (human development index) factors, and secondarily by environmental drivers (e.g. AMO, PDO, SST). How one might utilize this empirical evidence in future efforts for ecosystem approaches to fisheries is discussed, highlighting the need to manage fisheries in the context of environmental and other human (e.g. economic) drivers.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsp258
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
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  • 6
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    Using indicators for evaluating, comparing, and communicating the ecological status of exploited marine ecosystems. 2. Setting the scene
    Oxford University Press (OUP) ; 2010
    In:  ICES Journal of Marine Science Vol. 67, No. 4 ( 2010-05-01), p. 692-716
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 67, No. 4 ( 2010-05-01), p. 692-716
    Abstract: Shin, Y-J., Shannon, L. J., Bundy, A., Coll, M., Aydin, K., Bez, N., Blanchard, J. L., Borges, M. F., Diallo, I., Diaz, E., Heymans, J. J., Hill, L., Johannesen, E., Jouffre, D., Kifani, S., Labrosse, P., Link, J. S., Mackinson, S., Masski, H., Möllmann, C., Neira, S., Ojaveer, H., ould Mohammed Abdallahi, K., Perry, I., Thiao, D., Yemane, D., and Cury, P. M. 2010. Using indicators for evaluating, comparing, and communicating the ecological status of exploited marine ecosystems. 2. Setting the scene. – ICES Journal of Marine Science, 67: 692–716. Background is provided to the selection of ecological indicators by the IndiSeas Working Group, and the methodology adopted for analysis and comparison of indicators across exploited marine ecosystems is documented. The selected indicators are presented, how they are calculated is explained, and the philosophy behind the comparative approach is given. The combination of selected indicators is intended to reflect different dynamics, tracking processes that display differential responses to fishing, and is meant to provide a complementary means of assessing marine ecosystem trends and states. IndiSeas relied on inputs and insights provided by the local experts from participating ecosystems, helping to understand state and trend indicators and to disentangle the effect of other potential ecosystem drivers, such as climate variability. This project showed that the use of simple and available indicators under an ecosystem approach can achieve a real, wide-reaching evaluation of marine ecosystem status caused by fishing. This is important because the socio-economics of areas where fishing activities develop differs significantly around the globe, and in many countries, insufficient data are available for complex and exhaustive analyses.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsp294
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
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  • 7
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    Ranking the ecological relative status of exploited marine ecosystems
    Oxford University Press (OUP) ; 2010
    In:  ICES Journal of Marine Science Vol. 67, No. 4 ( 2010-05-01), p. 769-786
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 67, No. 4 ( 2010-05-01), p. 769-786
    Abstract: Coll, M., Shannon, L. J., Yemane, D., Link, J. S., Ojaveer, H., Neira, S., Jouffre, D., Labrosse, P., Heymans, J. J., Fulton, E. A., and Shin, Y-J. 2010. Ranking the ecological relative status of exploited marine ecosystems. – ICES Journal of Marine Science, 67: 769–786. A set of simple, data-based ecological indicators was used to rank exploited ecosystems regarding fishing impacts with respect to their status, trends, and ecosystem EAF attributes. Expected theoretical changes in indicators with respect to increasing fishing impacts were considered, and ecosystems were compared by examining the mean values of indicators in the most recent three years for which data were available and over time (1980–2005 and 1996–2005). Systems were classified into nine potential categories according to whether they were most, moderately, or least impacted, and whether they were becoming more or less impacted, or remaining stationary. The responses of ecological indicators to additional environmental and socio-economic explanatory factors were tested. Ecosystems ranked using short- and long-term trends and states differed because of differences in trends, underscoring the importance of analysing both states and trends in ecosystem analyses. The number of ecosystems classified as unclear or intermediately impacted has increased recently, the proportion of ecosystems classified as less strongly impacted has been maintained, but more now fall within the category more strongly impacted in terms of long-term trends and states. Ecosystem type, fisheries enforcement, primary production, sea temperature, and fishing type were important variables explaining the ecological indicators. The results reflect different changes and processes in the ecosystems, demonstrating that information on ecological, environmental, and fishery histories is crucial to interpreting indicators correctly, while disentangling the effects of fishing and of the environment.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsp261
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
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  • 8
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    Identifying and characterizing demersal fish biodiversity hotspots in the Benguela Current Large Marine Ecosystem: relevance in the light of global changes
    Oxford University Press (OUP) ; 2013
    In:  ICES Journal of Marine Science Vol. 70, No. 5 ( 2013-09-01), p. 943-954
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 70, No. 5 ( 2013-09-01), p. 943-954
    Abstract: Kirkman, S. P., Yemane, D., Kathena, J., Mafwila, S. K., Nsiangango, S. E., Samaai, T., Axelsen, B., and Singh, L. 2013. Identifying and characterizing demersal fish biodiversity hotspots in the Benguela Current Large Marine Ecosystem: relevance in the light of global changes. – ICES Journal of Marine Science, 70: 943–954. This study made use of distribution and abundance data of demersal fish and cephalopod species targeted during trawl surveys off Angola, Namibia and the west coast of South Africa, to determine species richness patterns including the location of diversity hotspots in the Benguela Current Large Marine Ecosystem. The reliability of alternative techniques for determining species richness patterns over the study domain, including geostatistical and non-geostatistical interpolation methods and regression type modelling, was tested using a cross-validation method. Generalized additive models were found to be the most effective method and were used to generate horizontal maps of species richness for different periods in each country. Despite changes in community structure that have been documented during the study period and which may be associated with climatic changes, this study showed the presence of consistently predictable hotspot areas over a 20–30-year study period (depending on country). The relationship between species richness and physical/environmental variables was inconsistent between countries, but generally hotspots of species richness were associated with greater depths and cooler bottom temperatures. Range shifts of species associated, for example, with warming of temperatures could conceivably affect the spatio-temporal persistence of hotspots in the long term.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fst040
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2013
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  • 9
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    Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends
    Oxford University Press (OUP) ; 2010
    In:  ICES Journal of Marine Science Vol. 67, No. 4 ( 2010-05-01), p. 807-832
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 67, No. 4 ( 2010-05-01), p. 807-832
    Abstract: Shannon, L. J., Coll, M., Yemane, D., Jouffre, D., Neira, S., Bertrand, A., Diaz, E., and Shin, Y-J. 2010. Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends. – ICES Journal of Marine Science, 67: 807–832. A suite of ecological indicators was selected for communicating, in a comparable way, how fishing affects the state of several upwelling ecosystems and others in which small pelagic fish play key ecological roles. Detailed background and understanding of system-specific processes and changes is needed for proper interpretation of results. In particular, environmental forcing is important in driving dynamics in upwelling systems; fishing impacts cannot be understood without understanding the corresponding dynamics of the environment. The Saharan Coastal (Morocco) and southern Benguela, both having experienced upsurges in low-trophic-level species, differed from other ecosystems when considering indicator trends. The ecosystem off Portugal emerged as showing reduced signs of fishing impacts in recent years, although the change may also be reflecting climate change favouring recruitment and abundance of demersal stocks. The indicator suite confirmed general understanding that the Mediterranean ecosystems have been notably degraded for several decades. Results and conclusions from this descriptive synthesis are compared with other comparisons of more complex, model-derived indicators. Even in upwelling and comparable systems, the simple data-based indicators are useful in synthesizing information on the status of an ecosystem, in particular on the ecosystem effects of fishing, to provide an ecological diagnosis at the ecosystem level, to be used in decision-making. Indicators of recent ecosystem state and trends over time are needed to assess the effects of fishing, but more indicators measuring biodiversity attributes and environmental change would complement the suite, providing fuller assessment of the status of upwelling and comparable ecosystems.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsp270
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2010
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
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  • 10
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    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
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