scholarly journals Development of the large fish indicator and associated target for a Northeast Atlantic fish community

2014 ◽  
Vol 71 (9) ◽  
pp. 2403-2415 ◽  
Author(s):  
Larissa Modica ◽  
Francisco Velasco ◽  
Izaskun Preciado ◽  
Maria Soto ◽  
Simon P. R. Greenstreet
Keyword(s):  
North Sea ◽  
Fish Community ◽  
Ecosystem Approach ◽  
Time Lags ◽  
Bay Of Biscay ◽  
Large Fish ◽  
Biodiversity Indicator ◽  
Eu Member States ◽  
The North ◽  
The North Sea

AbstractThe large fish indicator (LFI) was developed to support the North Sea fish community Ecological Quality Objective (EcoQO) pilot study, intended to establish an operational ecosystem approach to management. Subsequently, procedures established in the North Sea were applied to the Celtic Sea to derive an LFI and target specific to this region. The Marine Strategy Framework Directive (MSFD) requires EU Member States sharing marine regions to cooperate using the Regional Seas Conventions, and using indicators already adopted by them. The MSFD explicitly suggests the LFI as a foodweb indicator, but it could equally well be used to monitor biodiversity. Here, we apply the established rationale to develop an LFI and target specific to the southern Bay of Biscay. Despite declining in the 1990s, the LFI subsequently recovered to near original values in 2008. Previously, relationships between the LFI and fishing pressure have involved lengthy time-lags. We observe a similar relationship, but with shorter lag. The nature of the larger species responsible for much of the change in the LFI may explain this difference, and might also suggest that, in the Bay of Biscay, the LFI is more appropriately used as a biodiversity indicator, rather than a foodweb indicator.

scholarly journals Changes in the North Sea fish community: evidence of indirect effects of fishing?

2005 ◽  
Vol 62 (2) ◽  
pp. 177-188 ◽  
Author(s):  
Niels Daan ◽  
Henrik Gislason ◽  
John G. Pope ◽  
Jake C. Rice
Keyword(s):  
North Sea ◽  
Indirect Effects ◽  
Fish Community ◽  
Fishing Effort ◽  
Time Lags ◽  
The North ◽  
Exploitation Rate ◽  
The North Sea ◽  
Sea Fish

Abstract We investigate changes in the North Sea fish community with particular reference to possible indirect effects of fishing, mediated through the ecosystem. In the past, long-term changes in the slope of size spectra of research vessel catches have been related to changes in fishing effort, but such changes may simply reflect the cumulative, direct effects of fishing through selective removal of large individuals. If there is resilience in a fish community towards fishing, we may expect increases in specific components, for instance as a consequence of an associated reduction in predation and/or competition. We show on the basis of three long-term trawl surveys that abundance of small fish (all species) as well as abundance of demersal species with a low maximum length (Lmax) have steadily and significantly increased in absolute numbers over large parts of the North Sea during the last 30 years. Taking average fishing mortality of assessed commercial species as an index of exploitation rate of the fish community, it appears that fishing effort reached its maximum in the mid-1980s and has declined slightly since. If the observed changes in the community are caused by indirect effects of fishing, there must be a considerable delay in response time, because the observed changes generally proceed up to recent years, although both size and Lmax spectra suggest some levelling off, or even recovery in one of the surveys. Indeed, significant correlations between all community metrics and exploitation rate were obtained only if time lags ≥6 years were introduced.

scholarly journals Interpreting the large fish indicator for the Celtic Sea

2011 ◽  
Vol 68 (9) ◽  
pp. 1963-1972 ◽  
Author(s):  
Samuel Shephard ◽  
David G. Reid ◽  
Simon P. R. Greenstreet
Keyword(s):  
North Sea ◽  
Fish Community ◽  
Small Fish ◽  
Large Fish ◽  
The North ◽  
The North Sea ◽  
Celtic Sea ◽  
Using Data ◽  
Induced Changes ◽  
The Relationship

Abstract Shephard, S., Reid, D. G., and Greenstreet, S. P. R. 2011. Interpreting the large fish indicator for the Celtic Sea. – ICES Journal of Marine Science, 68: 1963–1972. The large fish indicator (LFI) was developed in the North Sea as a size-based indicator of fish community state. It is now established as OSPAR's fish community Ecological Quality Objective (EcoQO) metric and will be applied across all OSPAR regions. To produce a protocol for use when developing regional LFIs, the North Sea experience is interpreted using data from the Celtic Sea. Differences in fish community species composition and size distribution were reflected in a different species complex and large fish threshold (50 cm) for the Celtic Sea LFI. However, a lag of 12–14 years in the relationship between assemblage-averaged fishing mortality Fcom,y and the LFI suggested similar underlying ecological mechanisms to the North Sea. The indicator responded to changes in small fish biomass that follow fishing-induced changes in the level of predation by large demersal piscivores. The Celtic Sea LFI showed maximum observed values >0.40 before 1990, and 0.40 is here proposed as an EcoQO. Development of regional LFIs demands a flexible process rather than a strictly prescriptive protocol.

scholarly journals Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community

2012 ◽  
Vol 69 (1) ◽  
pp. 8-22 ◽  
Author(s):  
Simon P. R. Greenstreet ◽  
Helen M. Fraser ◽  
Stuart I. Rogers ◽  
Verena M. Trenkel ◽  
Stephen D. Simpson ◽  
...  
Keyword(s):  
North Sea ◽  
Fish Community ◽  
Size Structure ◽  
Demersal Fish ◽  
Community Size ◽  
The North ◽  
Management Objectives ◽  
The North Sea ◽  
Composition Structure ◽  
And Function

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.

scholarly journals Comparing conceptual frameworks for a fish community MSY (FCMSY) using management strategy evaluation—an example from the North Sea

2019 ◽  
Vol 76 (4) ◽  
pp. 813-823 ◽  
Author(s):  
Robert B Thorpe ◽  
José A A De Oliveira
Keyword(s):  
North Sea ◽  
Management Strategy ◽  
Fish Community ◽  
Parameter Uncertainties ◽  
Management Strategy Evaluation ◽  
The North ◽  
Strategy Evaluation ◽  
The North Sea ◽  
Definition Of

Abstract Maximum sustainable yield (MSY) is a well-established concept that is mandated by legislation, and has a clear theoretical meaning in terms of a single stock. However, its definition is problematic in a multispecies setting, which makes it more difficult to apply the MSY principle. In this study of the North Sea fish community, we consider several possible MSY candidates, and evaluate them in terms of their ability to produce optimum long-term yield whilst avoiding unacceptable risk of stock impairment. We perform this evaluation with an ensemble of size-structured models using a management strategy evaluation approach, in which harvest control rules (HCRs) are used to determine levels of fishing as a function of the proposed MSY target and stock status, taking account of recruitment and model parameter uncertainties. We find that HCRs of the type considered here are always useful in the scenarios we tested, as they reduce overfishing risk much more than average long-term yield. This is independent of the precise form of the HCR, so it is more important to implement one rigorously than obsess over the rule details. For a lax definition of overfishing, which accepts relatively severe stock depletion (B < 10% B0), and using HCRs, risks are “low” across all strategies, and the Nash equilibrium is the best performing MSY approach considered here. For more stringent definitions of “at risk” (e.g. likelihood of B < 20% of B0), the application of HCRs can allow a range of alternative formulations of MSY. Thus, the definition of MSY may be sensitive to judgements about acceptable levels of risk, and consistent application of a sensible management framework may be more important than developing the best possible theoretical definition of MSY.

scholarly journals OSPAR Ecological Quality Objectives: the utility of health indicators for the North Sea

2008 ◽  
Vol 65 (8) ◽  
pp. 1392-1397 ◽  
Author(s):  
Peter Heslenfeld ◽  
E. Lisette Enserink
Keyword(s):  
North Sea ◽  
Health Indicators ◽  
Ecosystem Approach ◽  
Current Status ◽  
Test Case ◽  
Ecological Quality ◽  
Marine Research ◽  
The North ◽  
History Of ◽  
The North Sea

Abstract Heslenfeld, P., and Enserink, E. L. 2008. OSPAR Ecological Quality Objectives: the utility of health indicators for the North Sea. – ICES Journal of Marine Science, 65: 1392–1397. Committed to the ecosystem approach to management, OSPAR has accumulated 15 years of experience in developing a conceptual framework for ecological indicators and objectives, and in applying the framework to the North Sea as a test case. These Ecological Quality Objectives (EcoQOs) have become a model for the implementation of the new European Marine Strategy Framework Directive. We describe the history of EcoQO development, its current status, and future needs. We also present our positive and negative experiences in developing the approach, and conclude that regional sea conventions and marine research institutes in Europe should join forces to accelerate the development of ecosystem indicators and objectives, using existing concepts.

scholarly journals Evidence of a relationship between weight and total length of marine fish in the North-eastern Atlantic Ocean: physiological, spatial and temporal variations

2016 ◽  
Vol 98 (3) ◽  
pp. 617-625 ◽  
Author(s):  
Kélig Mahé ◽  
Elise Bellamy ◽  
Jean Paul Delpech ◽  
Coline Lazard ◽  
Michèle Salaun ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Sea ◽  
Temporal Variations ◽  
Bay Of Biscay ◽  
English Channel ◽  
Total Length ◽  
The North ◽  
Eastern Atlantic Ocean ◽  
North Eastern ◽  
The North Sea

Weight–Body Length relationships (WLR) of 45 fish species (37 Actinopterygii and eight Elasmobranchii) were investigated. A total of 31,167 individuals were caught and their biological parameters measured during the four quarters from 2013 to 2015, on five scientific surveys sampling the North-eastern Atlantic Ocean from the North Sea to the Bay of Biscay (ICES Divisions IVb, IVc, VIId, VIIe, VIIg, VIIh, VIIj, VIIIa and VIIIb). Among 45 tested species, all showed a significant correlation between total length (L) and total weight (W). The influence of sex on WLR was estimated for 39 species and presented a significant sexual dimorphism for 18 species. Condition factor (K) of females was always higher than for males. Moreover, a spatial effect on the WLR according to five ecoregions (the Bay of Biscay, the Celtic Sea, the Western English Channel, the Eastern English Channel and the North Sea), was significant for 18 species among 38 tested species. The temporal effect was tested according to components (year and quarter/season). The seasonality effect on WLR is more frequently significant than the year especially for the Elasmobranchii species, and can be related to the spawning season. Finally, depressiform species (skates, sharks and flatfish) are characterized by positive allometric growth, whereas there is no such clear pattern regarding roundfishes growth, whatever their body shape is.

scholarly journals A reassessment of trends in the North Sea Large Fish Indicator and a re-evaluation of earlier conclusions

2012 ◽  
Vol 69 (2) ◽  
pp. 343-345 ◽  
Author(s):  
Simon P. R. Greenstreet ◽  
Stuart I. Rogers ◽  
Jake C. Rice ◽  
Gerjan J. Piet ◽  
Emma J. Guirey ◽  
...  
Keyword(s):  
North Sea ◽  
Previous Analysis ◽  
Fish Communities ◽  
Marine Science ◽  
Large Fish ◽  
The North ◽  
The North Sea ◽  
Corrected Data ◽  
Sea Fish

Abstract Greenstreet, S. P. R., Rogers, S. I., Rice, J. C., Piet, G. J., Guirey, E. J., Fraser, H. M., and Fryer, R. J. 2012. A reassessment of trends in the North Sea Large Fish Indicator and a re-evaluation of earlier conclusions. – ICES Journal of Marine Science, 69: 343–345. Previous analysis of the Large Fish Indicator, the basis for the North Sea “fish communities” EcoQO, suggested a strong recovery between 2001 and 2008. Discovery of a mistake in this earlier analysis now suggests that this recovery is not as strong as first thought, but reanalysis of the corrected data still supports the majority of conclusions drawn in the original paper.

Combined analyses reveal environmentally driven changes in the North Sea ecosystem and raise questions regarding what makes an ecosystem model’s performance credible?

2014 ◽  
Vol 71 (1) ◽  
pp. 31-46 ◽  
Author(s):  
Steven Mackinson
Keyword(s):  
Primary Production ◽  
North Sea ◽  
Ecosystem Model ◽  
Ecosystem Approach ◽  
Trophic Levels ◽  
Fish Stock ◽  
Supporting Evidence ◽  
Sea Temperature ◽  
The North ◽  
The North Sea

When an ecosystem model of the North Sea is calibrated to data from multiple trophic levels, the model estimated the primary production required to support the food web correlates temporally with observed changes in sea temperature and nutrient levels, supporting evidence from empirical analyses. However, a different result is given from an alternative calibration using fish stock data only. The inference taken from the emergent primary production – temperature relationship and empirical data are that, on balance, there is stronger overall evidence to support the calibration constrained at multiple trophic levels. Two important implications of the findings are (i) that the relative importance of fishing and environmental effects is likely to be interpreted differently depending on the calibration approach and (ii) the contrasting model calibrations would give different responses to fishing policies. It raises questions regarding how to judge the performance (and credibility) of an ecosystem model and the critical importance of conducting empirical and modelling analyses in parallel. Adopting a combined approach to ecosystem modelling is an important step in the pursuit of operational and defensible tools to support the ecosystem approach to management.

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