A critical look at the potential of Ecopath with ecosim to assist in practical fisheries management
| dc.contributor.author | Plagányi, Éva E | |
| dc.contributor.author | Butterworth, Doug S | |
| dc.date.accessioned | 2016-03-14T10:51:08Z | |
| dc.date.available | 2016-03-14T10:51:08Z | |
| dc.date.issued | 2004 | |
| dc.date.updated | 2016-03-14T10:42:35Z | |
| dc.description.abstract | Ecosystem-orientated thinking is increasingly incorporated into fishery management. Given the complexity of ecosystem processes, there is a need to evaluate the tools used to steer this thinking critically. ECOPATH with ECOSIM (EwE), an aggregate system-modelling package, is currently the most widely employed approach to assess the ecosystem effects of fishing. The basic equations and assumptions, strengths and weaknesses, and the potential of this approach to contribute to practical fisheries management advice are reviewed. Strengths include the structured parameterization framework, the inclusion of a well-balanced level of conceptual realism, a novel representation of predator-prey interaction terms, and the inclusion of a Bayes-like approach (ECORANGER) to take account of the uncertainty associated with values for model inputs. Weaknesses in model structure include the constraining nature of the mass-balance assumption (of ECOPATH) for initiating projections, the questionable handling of life history responses such as compensatory changes in the natural mortality rates of marine mammals, overcompensatory stock-recruit relationships that result from default parameter settings, possible problems in extrapolating from the microscale to the macroscale, as well as some (not too far-reaching) mathematical inconsistencies in the underlying equations. There is a paucity of systematic and stepwise investigations into model behaviour and properties, and users are cautioned against non-critical use of the default settings. An important limitation related to the predominant use of EwE as a "black-box" modelling tool is that some users fail to consider a range of alternative interaction representations. As with all multispecies approaches, the major limitation in applying the EwE approach lies in the quality and quantity of available data. Current EwE applications generally do not adequately address uncertainty in data inputs and model structure. Prudent EwE applications that utilize good data and are based upon rigorous statistical analyses can complement the quantitative predictions of traditional single-species models. They could be particularly useful in some contexts if output in the form of probability distributions encompassing a range of likely ecosystem responses were to be coupled with attempts to extend Operational Management Procedure (OMP) approaches to fisheries management beyond the singlespecies level. In particular, such applications could serve as the operating models of the underlying dynamics that are used for computer simulation testing of OMPs. | en_ZA |
| dc.identifier | http://dx.doi.org/10.2989/18142320409504061 | |
| dc.identifier.apacitation | Plagányi, É. E., & Butterworth, D. S. (2004). A critical look at the potential of Ecopath with ecosim to assist in practical fisheries management. <i>African Journal of Marine Science</i>, http://hdl.handle.net/11427/17764 | en_ZA |
| dc.identifier.chicagocitation | Plagányi, Éva E, and Doug S Butterworth "A critical look at the potential of Ecopath with ecosim to assist in practical fisheries management." <i>African Journal of Marine Science</i> (2004) http://hdl.handle.net/11427/17764 | en_ZA |
| dc.identifier.citation | Plaganyi, E. E., & Butterworth, D. S. (2004). A critical look at the potential of Ecopath with Ecosim to assist in practical fisheries management. African Journal of Marine Science, 26(1), 261-287. | en_ZA |
| dc.identifier.issn | 1814-232X | en_ZA |
| dc.identifier.ris | TY - Journal Article AU - Plagányi, Éva E AU - Butterworth, Doug S AB - Ecosystem-orientated thinking is increasingly incorporated into fishery management. Given the complexity of ecosystem processes, there is a need to evaluate the tools used to steer this thinking critically. ECOPATH with ECOSIM (EwE), an aggregate system-modelling package, is currently the most widely employed approach to assess the ecosystem effects of fishing. The basic equations and assumptions, strengths and weaknesses, and the potential of this approach to contribute to practical fisheries management advice are reviewed. Strengths include the structured parameterization framework, the inclusion of a well-balanced level of conceptual realism, a novel representation of predator-prey interaction terms, and the inclusion of a Bayes-like approach (ECORANGER) to take account of the uncertainty associated with values for model inputs. Weaknesses in model structure include the constraining nature of the mass-balance assumption (of ECOPATH) for initiating projections, the questionable handling of life history responses such as compensatory changes in the natural mortality rates of marine mammals, overcompensatory stock-recruit relationships that result from default parameter settings, possible problems in extrapolating from the microscale to the macroscale, as well as some (not too far-reaching) mathematical inconsistencies in the underlying equations. There is a paucity of systematic and stepwise investigations into model behaviour and properties, and users are cautioned against non-critical use of the default settings. An important limitation related to the predominant use of EwE as a "black-box" modelling tool is that some users fail to consider a range of alternative interaction representations. As with all multispecies approaches, the major limitation in applying the EwE approach lies in the quality and quantity of available data. Current EwE applications generally do not adequately address uncertainty in data inputs and model structure. Prudent EwE applications that utilize good data and are based upon rigorous statistical analyses can complement the quantitative predictions of traditional single-species models. They could be particularly useful in some contexts if output in the form of probability distributions encompassing a range of likely ecosystem responses were to be coupled with attempts to extend Operational Management Procedure (OMP) approaches to fisheries management beyond the singlespecies level. In particular, such applications could serve as the operating models of the underlying dynamics that are used for computer simulation testing of OMPs. DA - 2004 DB - OpenUCT DP - University of Cape Town J1 - African Journal of Marine Science LK - https://open.uct.ac.za PB - University of Cape Town PY - 2004 SM - 1814-232X T1 - A critical look at the potential of Ecopath with ecosim to assist in practical fisheries management TI - A critical look at the potential of Ecopath with ecosim to assist in practical fisheries management UR - http://hdl.handle.net/11427/17764 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/17764 | |
| dc.identifier.uri | http://www.tandfonline.com/doi/abs/10.2989/18142320409504061 | |
| dc.identifier.vancouvercitation | Plagányi ÉE, Butterworth DS. A critical look at the potential of Ecopath with ecosim to assist in practical fisheries management. African Journal of Marine Science. 2004; http://hdl.handle.net/11427/17764. | en_ZA |
| dc.language | eng | en_ZA |
| dc.publisher | National Inquiry Services Centre | en_ZA |
| dc.publisher.department | Marine Resource Assessment and Management Group | en_ZA |
| dc.publisher.faculty | Faculty of Science | en_ZA |
| dc.publisher.institution | University of Cape Town | |
| dc.source | African Journal of Marine Science | en_ZA |
| dc.source.uri | http://www.tandfonline.com/toc/tams20/current | |
| dc.subject.other | assessment | |
| dc.subject.other | ecopath | |
| dc.subject.other | ecosim | |
| dc.subject.other | ewe | |
| dc.subject.other | fisheries | |
| dc.subject.other | foraging arena | |
| dc.subject.other | functional response | |
| dc.subject.other | management | |
| dc.subject.other | multispecies | |
| dc.subject.other | review | |
| dc.title | A critical look at the potential of Ecopath with ecosim to assist in practical fisheries management | en_ZA |
| dc.type | Journal Article | en_ZA |
| uct.subject.keywords | assessment; ecopath; ecosim; ewe; fisheries; foraging arena; functional response; management; multispecies; review | en_ZA |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Article | en_ZA |