Monitoring of discarding and retention by trawl fisheries in Western Waters and the Irish Sea in relation to stock assessment and technical measures
| Autor: | Allen, M. (Michelle), Araujo-Fernández, M.H. (María Hortensia), Armstrong, M. (Mike), Briggs, R. (Richard), Caslake, R. (Richard), Díez, G. (Guzmán), Findlay, M. (Malcom), Godden, N. (Nigel), Hewer, A. (Alison), Hugues-Dit-Ciles, E. (Emily), Kingston, A. (Allen), Lart, W. (William), Lucio, P. (Paulino), Pérez-Contreras, M.N. (María Nélida), Pawson, M. (Mike), Quincoces, I. (Iñaki), Reese, R.A. (Allan), Santurtún, M. (Marina), Schön, P.J. (Pieter Jan), Scott, R. (Robert), Searle, A. (Allen), Senior, R. (Rebbecca) |
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| Rok vydání: | 2002 |
| Předmět: |
Fishery statistics
Fish discards Fishery surveys Fishery management Fishery economics Irish Sea Celtic Sea Bay of Biscay North East Atlantic Marine fish Marine ecology Fishery resources Fishing gear By catch Fishery data Fishery stock assessment Fishing technology Commercial species Dermersal fisheries Trash fish Fish catch statistics |
| Zdroj: | e-IEO. Repositorio Institucional Digital de Acceso Abierto del Instituto Español de Oceanografía instname e-IEO: Repositorio Institucional Digital de Acceso Abierto del Instituto Español de Oceanografía Instituto Español de Oceanografía |
| Popis: | Westem Waters fisheries face major challenges in relation to the depleted state of the fishery resources and in implementing the adjustments required to bring exploitation of these resources on to a more sustainable basis. Fisheries assessments, as carried out by ICES working groups, use data from market sampling of the landed catch, reported landings and effort figures and also research vessel data to assess the state of fish stocks and to produce short term forecasts for setting Total Allowable Catches. Since the discards may constitute a significant source of extra mortality in some fisheries there is clearly a requirement to adequately describe the levels of discarded fish in order to improve stock assessment and the likelihood of sustainability. In deciding a strategy for improved sustainability there is also a requirement to understand the factors motivating the fishers to target and retain, or discard, fish of a given species and to relate this to the current management and market situation. This, and stock assessment information, could be used to guide research into the most appropriate technology and measures to reduce discarding and hence place the harvesting of these stocks on a more sustainable basis. The project studied the pattem of discarding and retention, using an onboard observer programme, in the main demersal trawl fisheries of the participating nations' in Westem Waters (ICES Divisions VIa,b VIIa,b,c,e(western part), f,g,h and k and from VIIIa,b,c,d and IXa) and describes the use of these data in ICES stock assessments. It assessed the feasibility of using these data to understand the economic aspects of discarding and retention, to assess the impact of technical measures and investigated the effects of trawling on ecosystems. Data on discarded megrim from Spanish Baka trawlers were used in the assessment of the Northem Stock of this species at the ICES Southem Shelf Demersal Working Group. These results show that including discard data in the assessment improved the description of the strength of incoming year classes, growth and spawning stock biomass. The impact of technical measures designed to reduce discarding was assessed by examining the effect of the implementation of EC regulation 850/98 on Jan 1st 2000. In the midwater demersal trawl fishery in the Irish Sea there was a reduction in the catch per effort of discarded and retained whiting. For the baka trawlers exploiting megrim in Sub areas VI and VII there was a change in the discarding practices. Discarding and retention is discussed in relation to economic factors and the exploitation pattem. Possible changes in some métiers were suggested but the very mixed nature some of the fisheries means that what is selective for one species could result in the loss of economically important catch of other species. It was found that discarding practices were most closely related to economic values, which were a stronger influence than fishery management measures. Measures which are designed to reduce discarding without taking into account market forces, are unlikely to succeed. Limited studies of the impact of technical measures were carried out by developing a model designed to predict the returns which could be obtained by improving selectivity, but these were intended only to develop the model not to use it on Westem Waters fisheries during this project. |
| Databáze: | OpenAIRE |
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