42 results on '"Ulrich, Clara"'
Search Results
2. Identifying choke species challenges for an individual demersal trawler in the North Sea, lessons from conversations and data analysis
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Mortensen, Lars O., Ulrich, Clara, Hansen, Jan, and Hald, Rasmus
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- 2018
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3. Remote electronic monitoring and the landing obligation – some insights into fishers’ and fishery inspectors’ opinions
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Plet-Hansen, Kristian S., Eliasen, Søren Q., Mortensen, Lars O., Bergsson, Heiðrikur, Olesen, Hans J., and Ulrich, Clara
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- 2017
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4. The MSY concept in a multi-objective fisheries environment – Lessons from the North Sea
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Kempf, Alexander, Mumford, John, Levontin, Polina, Leach, Adrian, Hoff, Ayoe, Hamon, Katell G., Bartelings, Heleen, Vinther, Morten, Stäbler, Moritz, Poos, Jan Jaap, Smout, Sophie, Frost, Hans, van den Burg, Sander, Ulrich, Clara, and Rindorf, Anna
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- 2016
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5. Towards transdisciplinary decision-support processes in fisheries: experiences and recommendations from a multidisciplinary collective of researchers
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Macher Claire, Steins Nathalie A., Ballesteros Marta, Kraan Marloes, Frangoudes Katia, Bailly Denis, Bertignac Michel, Colloca Francesco, Fitzpatrick Mike, Garcia Dorleta, Little Rich, Mardle Simon, Murillas Arantza, Pawlowski Lionel, Philippe Manuelle, Prellezo Raul, Sabatella Evelina, Thébaud Olivier, and Ulrich Clara
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ecosystem-based approach to fisheries management ,participatory approach ,stakeholder engagement ,transdisciplinary approaches ,role of science ,collaborative research ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
The shifting policy focus towards Ecosystem Based Management in Fisheries (EBFM) requires the integration of knowledge and disciplines and the engagement of stakeholders to support decision-making processes. Scientists contribute to this through (i) participatory research projects, (ii) stakeholder partnerships and (iii) institutional scientific advice processes. Understanding the role of scientists in such processes, the nature of the interactions between scientists, stakeholders and managers in knowledge integration and the link between science and policy is an emerging field of research addressing transdisciplinary challenges. In 2018, Ifremer-UMR AMURE organized the workshop ‘Science, Partnership and Decision-support in Fisheries’ bringing together international scientists from natural and social sciences to conduct a review based on twenty concrete case studies. Findings indicate that science-stakeholder-manager partnerships for decision-support in fisheries can play an essential role in the transition to EBFM. To foster this transition, eight recommendations are presented that cover the roles of the different participants, the expectations of partnerships, capacity building, the integration of the social sciences, and funding structures. Further, it is recommended that future research and innovation framework programmes into sustainable fisheries and other ocean uses should explicitly include mechanisms to foster transdisciplinary approaches and the development of best practices. Building-up networks and developing reflexive approaches to review experiences and practices for transdisciplinary approaches in EFBM decision-support will contribute to design the next generation transdisciplinary platforms and generating actionable knowledge towards EBFM.
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- 2021
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6. Variability and connectivity of plaice populations from the Eastern North Sea to the Western Baltic Sea, and implications for assessment and management
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Ulrich, Clara, Boje, Jesper, Cardinale, Massimiliano, Gatti, Paul, LeBras, Quentin, Andersen, Michael, Hemmer-Hansen, Jakob, Hintzen, Niels T., Jacobsen, Jonathan B., Jonsson, Patrik, Miller, David C.M., Nielsen, Einar E., Rijnsdorp, Adriaan D., Sköld, Mattias, Svedäng, Henrik, and Wennhage, Håkan
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- 2013
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7. Evaluating the effect of fishery closures: Lessons learnt from the Plaice Box
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Beare, Doug, Rijnsdorp, Adriaan D., Blaesberg, Mette, Damm, Ulrich, Egekvist, Josefine, Fock, Heino, Kloppmann, Matthias, Röckmann, Christine, Schroeder, Alexander, Schulze, Torsten, Tulp, Ingrid, Ulrich, Clara, van Hal, Ralf, van Kooten, Tobias, and Verweij, Marieke
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- 2013
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8. Lessons for fisheries management from the EU cod recovery plan
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Kraak, Sarah B.M., Bailey, Nick, Cardinale, Massimiliano, Darby, Chris, De Oliveira, José A.A., Eero, Margit, Graham, Norman, Holmes, Steven, Jakobsen, Tore, Kempf, Alexander, Kirkegaard, Eskild, Powell, John, Scott, Robert D., Simmonds, E. John, Ulrich, Clara, Vanhee, Willy, and Vinther, Morten
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- 2013
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9. Challenges and opportunities for fleet- and métier-based approaches for fisheries management under the European Common Fishery Policy
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Ulrich, Clara, Wilson, Douglas C.K., Nielsen, J. Rasmus, Bastardie, Francois, Reeves, Stuart A., Andersen, Bo S., and Eigaard, Ole R.
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- 2012
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10. The added value of participatory modelling in fisheries management – what has been learnt?
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Röckmann, Christine, Ulrich, Clara, Dreyer, Marion, Bell, Ewen, Borodzicz, Edward, Haapasaari, Päivi, Hauge, Kjellrun Hiis, Howell, Daniel, Mäntyniemi, Samu, Miller, David, Tserpes, George, and Pastoors, Martin
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- 2012
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11. Unravelling the scientific potential of high resolution fishery data
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Plet-Hansen Kristian Schreiber, Larsen Erling, Mortensen Lars Olof, Nielsen J. Rasmus, and Ulrich Clara
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fisheries ,haul-by-haul information ,science-industry cooperation ,sea-packing commercial fishery data ,size distribution ,spatial and seasonal selectivity ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
Fisheries science and fisheries management advice rely on both scientific and commercial data to estimate the distribution and abundance of marine species. These two data types differ, with scientific data having a broader geographical coverage but less intensity and time coverage compared to commercial data. Here we present a new type of commercial data with high resolution and coverage. To our knowledge, the dataset presented in this study has never been used for scientific purposes. While commercial datasets usually include the total weight by species on per haul basis, the new data also include the commercial size class for the species landed, recorded directly on a haul-by-haul basis. Thus, this dataset has the potential to provide knowledge on landed fish with as high spatio-temporal resolution as when coupling logbooks and sales slips but with the addition of detailed knowledge on the size distribution. Such information may otherwise be obtained through on-board observer programmes but unlike the observers’ data, the dataset presented here is routinely collected on most of the trips of the vessels involved, which means that the coverage of the data for the individual vessel is larger than observers’ data. Furthermore, the risk of changes in fishing behaviour due to the presence of an observer on-board is avoided. This paper describes the coverage and completeness of the dataset, and explores the reliability of the data available. We conclude that the main limitation is the small number of fishing vessels covered by the program, but that the data from those vessels are accurate, detailed, and relatively reliable.
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- 2018
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12. Annual trends in catchability and fish stock assessments
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Marchal Paul, Ulrich Clara, Korsbrekke Knut, Pastoors Martin, and Rackham Brian
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hybrid method ,extended survivors analysis ,fish stock assessment ,catchability ,fishing power ,north sea ,trends ,retrospective pattern ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
A key assumption of many fish stock assessment models is that catchability is constant over time. We assume here that trends in catchability may occur through fishing power creeping. The tuning fleets, which are prone to fishing power development, may be identified using the Hybrid method. A range of catchability trends, including values derived from the Hybrid method, is then implemented to standardise the fishing effort of some tuning fleets used in the stock assessments performed by XSA (eXtended Survivors Analysis). Stocks being assessed are the North Sea cod, saithe, plaice and sole. The performances of the new and traditional XSA assessments are compared using criteria based on the precision of catchability estimates, stationarity of Log-catchability residuals and retrospective patterns relative to fishing mortality, spawning stock biomass and recruitment estimates. The performances of the North Sea cod, plaice and sole assessments could be enhanced by accounting for an overall annual increase in the catchability of some of the tuning fleets. No significant trends could be detected in the catchability of the tuning fleets relative to the assessment of the North Sea saithe. By contrast with the traditional assessment, the spawning biomass of cod is expected not to have increased between 1997 and 1998, while the fishing mortality of sole is expected to have increased over the same period.
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- 2003
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13. Discarding of cod in the Danish Fully Documented Fisheries trials
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Ulrich, Clara, Olesen, Hans Jakob, Bergsson, Heirikur, Egekvist, Josefine, Håkansson, Kirsten Birch, Dalskov, Jørgen, Kindt-Larsen, Lotte, and Storr-Paulsen, Marie
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- 2015
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14. Improving the definition of fishing effort for important European fleets by accounting for the skipper effect
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Marchal, Paul, Andersen, Bo, Bromley, David, Iriondo, Ane, Mahevas, Stephanie, Quirijns, Floor, Rackham, Brian, Santurtun, Marina, Tien, Nicola, and Ulrich, Clara
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Fish industry -- Methods ,Fisheries -- Methods ,Terms and phrases ,Earth sciences - Abstract
Abstract: The scope of this paper is to quantify, for a wide selection of European fisheries, fishing tactics and strategies and to evaluate the benefits of adjusting the definition of [...]
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- 2006
15. Regional métier definition: a comparative investigation of statistical methods using a workflow applied to international otter trawl fisheries in the North Sea
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Deporte, Nicolas, Ulrich, Clara, Mahévas, Stéphanie, Demanèche, Sébastien, and Bastardie, Francois
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- 2012
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16. Short-term choice behaviour in a mixed fishery: investigating métier selection in the Danish gillnet fishery
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Andersen, Bo Sølgaard, Ulrich, Clara, Eigaard, Ole Ritzau, and Christensen, Anne-Sofie
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- 2012
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17. Reconciling single-species TACs in the North Sea demersal fisheries using the Fcube mixed-fisheries advice framework
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Ulrich, Clara, Reeves, Stuart A., Vermard, Youen, Holmes, Steven J., and Vanhee, Willy
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- 2011
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18. Economic effort management in multispecies fisheries: the FcubEcon model
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Hoff, Ayoe, Frost, Hans, Ulrich, Clara, Damalas, Dimitrios, Maravelias, Christos D., Goti, Leyre, and Santurtún, Marina
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- 2010
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19. Comparative evaluation of a mixed-fisheries effort-management system based on the Faroe Islands example
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Baudron, Alan, Ulrich, Clara, Nielsen, J. Rasmus, and Boje, Jesper
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- 2010
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20. Influence of trends in fishing power on bioeconomics in the North Sea flatfish fishery regulated by catches or by effort quotas
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Ulrich, Clara, Pascoe, Sean, Sparre, Per J, Wilde, Jan-Willem De, and Marchal, Paul
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- 2002
21. The value of commercial fish size distribution recorded at haul by haul compared to trip by trip.
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Plet-Hansen, Kristian S., Bastardie, François, and Ulrich, Clara
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Data from commercial fishing vessels may enhance the range of observations available for monitoring the marine environment. However, effort and catch data provide information on fish distribution with a bias due to spatial targeting and selectivity. Here, we measured the shortcomings of standard fishery-dependent data and advocate for the utilization of more precise datasets indirectly collected by the commercial fishery. Data from a Danish traceability system, which records size of commercial fish at the haul level, are held against the set-up of current eLog and sales slips’ data collected for the Danish fisheries. We showed that the most accurate mapping of the spatial distribution of catches per size group is not only possible through size records collected at the haul level but also by high resolution on fishing effort data. In Europe, the regulation to land all catches with a quota or minimum size limit, including unwanted, has increased the focus on avoidance and discards; we show the potential of such data sources to inform on fish abundance and distribution, especially of importance where fishery-dependent data are the only source of information. [ABSTRACT FROM AUTHOR]
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- 2020
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22. Fishing for euros: how mapping applications can assist in maintaining revenues under the Landing Obligation.
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Calderwood, Julia, Plet-Hansen, Kristian Schreiber, Ulrich, Clara, and Reid, David G
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FISHERIES ,FISHING ,SPECIES distribution ,EURO ,RESPONSIBILITY ,SMALL-scale fisheries - Abstract
With the introduction of the Landing Obligation (LO) in EU fisheries, there is an increasing need for fishers to avoid unwanted catches while maximizing revenues. Improving understanding of the spatio-temporal dynamics of unwanted catches could assist the fishing industry optimize catches by altering where they fish. How following such advice relates to revenues and fishery dynamics requires more consideration. We take an existing hotspot mapping methodology and examine how it could be used to identify fishing opportunities under the LO in Irish (Celtic Sea) and Danish (North Sea and Skagerrak) demersal fisheries. We consider if fishing effort can be relocated to avoid unwanted catches while maintaining revenues. The value per unit effort of fishing activity in both areas was often linked to high catch rates of key demersal species (cod, haddock, hake, and whiting). Our analyses indicated, however, that there are options to fish in areas that could provide higher revenues while avoiding below minimum conservation reference size catches and choke species. This was evident across both case study areas demonstrating that hotspot mapping tools could have wide applicability. There does, however, remain a need to explore how the displacement of vessels may further alter species distributions and fleet economics. [ABSTRACT FROM AUTHOR]
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- 2020
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23. Electronic monitoring in fisheries: Lessons from global experiences and future opportunities.
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Helmond, Aloysius T.M., Mortensen, Lars O., Plet‐Hansen, Kristian S., Ulrich, Clara, Needle, Coby L., Oesterwind, Daniel, Kindt‐Larsen, Lotte, Catchpole, Thomas, Mangi, Stephen, Zimmermann, Christopher, Olesen, Hans Jakob, Bailey, Nick, Bergsson, Heidrikur, Dalskov, Jørgen, Elson, Jon, Hosken, Malo, Peterson, Lisa, McElderry, Howard, Ruiz, Jon, and Pierre, Johanna P.
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ELECTRONIC surveillance ,FISHERIES ,SENSOR placement ,TWENTY-first century - Abstract
Since the beginning of the 21st century, electronic monitoring (EM) has emerged as a cost‐efficient supplement to existing catch monitoring programmes in fisheries. An EM system consists of various activity sensors and cameras positioned on vessels to remotely record fishing activity and catches. The first objective of this review was to describe the state of play of EM in fisheries worldwide and to present the insights gained on this technology based on 100 EM trials and 12 fully implemented programmes. Despite its advantages, and its global use for monitoring, progresses in implementation in some important fishing regions are slow. Within this context, the second objective was to discuss more specifically the European experiences gained through 16 trials. Findings show that the three major benefits of EM were as follows: (a) cost‐efficiency, (b) the potential to provide more representative coverage of the fleet than any observer programme and (c) the enhanced registration of fishing activity and location. Electronic monitoring can incentivize better compliance and discard reduction, but the fishing managers and industry are often reluctant to its uptake. Improved understanding of the fisher's concerns, for example intrusion of privacy, liability and costs, and better exploration of EM benefits, for example increased traceability, sustainability claims and market access, may enhance implementation on a larger scale. In conclusion, EM as a monitoring tool embodies various solid strengths that are not diminished by its weaknesses. Electronic monitoring has the opportunity to be a powerful tool in the future monitoring of fisheries, particularly when integrated within existing monitoring programmes. [ABSTRACT FROM AUTHOR]
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- 2020
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24. An evaluation of European initiatives established to encourage industry‐led development of selective fishing gears.
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Feekings, Jordan, O'Neill, Finbarr G., Krag, Ludvig, Ulrich, Clara, and Veiga Malta, Tiago
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FISH development ,FISH populations ,FISHERY policy ,GEARING machinery - Abstract
There are numerous examples from across Europe where collaborative science‐industry initiatives, which provide a bottom‐up approach to trawl gear development, have been successful in developing selective gears. For fishers, the collaborative approach creates a sense of ownership and control over the gears developed and often a greater desire for them to achieve their objectives. Despite the many benefits of collaborative initiatives, a lack of clarity and transparency, incorrect incentives, unclear communication, and distrust or diverging perceptions can inhibit their performance. The present review examines the different collaborative approaches to fishing gear development that have been established within Europe, highlighting their salient features, comparing their objectives, and discussing the types and effectiveness of the incentives offered. Also examined is how the reform of the European Union's (EU) Common Fisheries Policy (CFP), together with the proposed reform of the technical measures framework, can potentially improve the flexibility in the technical regulations and allow for such initiatives to be a central part in improving the state of fish stocks throughout the EU. Finally, a framework is proposed on how initiatives pertaining to industry‐led fishing gear development might look like under the reformed CFP. [ABSTRACT FROM AUTHOR]
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- 2019
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25. Testing spatial heterogeneity with stock assessment models.
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Jardim, Ernesto, Eero, Margit, Silva, Alexandra, Ulrich, Clara, Pawlowski, Lionel, Holmes, Steven J., Ibaibarriaga, Leire, De Oliveira, José A. A., Riveiro, Isabel, Alzorriz, Nekane, Citores, Leire, Scott, Finlay, Uriarte, Andres, Carrera, Pablo, Duhamel, Erwan, and Mosqueira, Iago
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GADUS ,SARDINA ,FISH populations ,FISHERY management ,STOCHASTIC analysis ,PHYSIOLOGY - Abstract
This paper describes a methodology that combines meta-population theory and stock assessment models to gain insights about spatial heterogeneity of the meta-population in an operational time frame. The methodology was tested with stochastic simulations for different degrees of connectivity between sub-populations and applied to two case studies, North Sea cod (Gadus morua) and Northeast Atlantic sardine (Sardina pilchardus). Considering that the biological components of a population can be partitioned into discrete spatial units, we extended this idea into a property of additivity of sub-population abundances. If the additivity results hold true for putative sub-populations, then assessment results based on sub-populations will provide information to develop and monitor the implementation of finer scale/local management. The simulation study confirmed that when sub-populations are independent and not too heterogeneous with regards to productivity, the sum of stock assessment model estimates of sub-populations’ SSB is similar to the SSB estimates of the meta-population. It also showed that a strong diffusion process can be detected and that the stronger the connection between SSB and recruitment, the better the diffusion process will be detected. On the other hand it showed that weak to moderate diffusion processes are not easy to identify and large differences between sub-populations productivities may be confounded with weak diffusion processes. The application to North Sea cod and Atlantic sardine exemplified how much insight can be gained. In both cases the results obtained were sufficiently robust to support the regional analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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26. Reducing discards without reducing profit: free gear choice in a Danish result-based management trial.
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Mortensen, Lars O., Ulrich, Clara, Olesen, Hans Jakob, and Eliasen, Søren
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FISHERY policy , *FISHERY laws , *FISHERY management , *FISHERY economics , *FISHERY gear , *SELECTIVITY of fishery gear - Abstract
The 2013 Common Fisheries Policy introduced a landing obligation on a range of species, bringing more focus on the full accountability of all catches. To investigate the potentials and challenges of these paradigm shifts, a 6-months ‘unrestricted gear’ trial was performed in Denmark in 2015. Twelve trawlers were challenged to test their own solutions to reduce unwanted bycatch and/or choke species, while maintaining profitable. The participating fishers tested different options depending on their fishery and the type of issues they faced individually, and adjusted their test fishery over time through incremental small steps. Nine vessels reduced discard ratio in the test fishery, one showed no difference between test and control fishery, while two vessels displayed an increase in discard ratio. Catch compositions also differed, with fewer “choke species” occurring in the test fisheries and a more valuable size composition. Ultimately, despite smaller landings in multiple vessels, no vessel showed reduction in value-per-unit-effort (VPUE) and one Baltic vessel significantly increased the VPUE. This trial showed that relaxing technical regulations combined with proper incentives has a potential to provide some flexibility to cope with the landing obligation, where unwanted catches could be reduced to some extent without negative effects on economic viability. [ABSTRACT FROM AUTHOR]
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- 2017
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27. Achieving maximum sustainable yield in mixed fisheries: a management approach for the North Sea demersal fisheries.
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Ulrich, Clara, Vermard, Youen, Dolder, Paul J., Brunel, Thomas, Jardim, Ernesto, Holmes, Steven J., Kempf, Alexander, Mortensen, Lars O., Poos, Jan-Jaap, and Rindorf, Anna
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FISHERY management , *MAXIMUM sustainable yield (Population ecology) , *FISH stocking , *SPECIES diversity , *FISH mortality - Abstract
Achieving single species maximum sustainable yield (MSY) in complex and dynamic fisheries targeting multiple species (mixed fisheries) is challenging because achieving the objective for one species may mean missing the objective for another. The North Sea mixed fisheries are a representative example of an issue that is generic across most demersal fisheries worldwide, with the diversity of species and fisheries inducing numerous biological and technical interactions. Building on a rich knowledge base for the understanding and quantification of these interactions, new approaches have emerged. Recent paths towards operationalizing MSY at the regional scale have suggested the expansion of the concept into a desirable area of "pretty good yield", implemented through a range around FMSY that would allow for more flexibility in management targets. This article investigates the potential of FMSY ranges to combine long-term single-stock targets with flexible, short-term, mixed-fisheries management requirements applied to the main North Sea demersal stocks. It is shown that sustained fishing at the upper bound of the range may lead to unacceptable risks when technical interactions occur. An objective method is suggested that provides an optimal set of fishing mortality within the range, minimizing the risk of total allowable catch mismatches among stocks captured within mixed fisheries, and addressing explicitly the trade-offs between the most and least productive stocks. [ABSTRACT FROM AUTHOR]
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- 2017
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28. Effectiveness of fully documented fisheries to estimate discards in a participatory research scheme.
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Mortensen, Lars O., Ulrich, Clara, Olesen, Hans Jakob, Bergsson, Heiðrikur, Berg, Casper W., Tzamouranis, Nikolaos, and Dalskov, Jørgen
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FISHERY management , *FISHERY sciences , *BYCATCHES , *COMPUTER network resources , *SELF-evaluation , *DATA analysis - Abstract
A key challenge for fisheries science and management is the access to reliable and verifiable catch data. In science, the challenge is to collect reliable, precise and traceable data to provide sound advice. In management, the challenge is that catch documentation is necessary to enforce regulations. Currently, catch inspection at sea, self-reporting through e-log and on-board observers are the primary methods to document catches at sea. However, at-sea control and on-board observers are costly and have limited coverage, while self-reporting is susceptible to fraud and provides limited coverage. New cost-effective methods are currently emerging involving Remote Electronic Monitoring (REM) and on-board cameras. Previous studies have tested REM with promising results. However, evaluation of the potential biases of REM is needed before full benefits can be obtained. We deployed REM with on-board cameras on 14 fishing vessels and were able to inspect 56% of 1523 hauls made in the 6 month trial period, using an estimated 582 man-hours of video audit. The results showed an overall good agreement between the fishers self-reported discards and the video inspectors discard estimates. However, there was large variation in precision between individual vessels and species. Additionally, trial setup and process errors were shown to have a large effect on the precision of the video inspectors discard estimates. Nevertheless, despite challenges, REM was evaluated to have the potential to streamline monitoring and scientific documentation in a medium-size fishing fleet. [ABSTRACT FROM AUTHOR]
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- 2017
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29. Food for thought: pretty good multispecies yield.
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Rindorf, Anna, Dichmont, Catherine Mary, Levin, Phillip S., Mace, Pamela, Pascoe, Sean, Prellezo, Raul, Punt, André E., Reid, David G., Stephenson, Robert, Ulrich, Clara, Vinther, Morten, and Clausen, Lotte Worsøe
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FISHERY management ,SPECIES diversity ,SUSTAINABILITY ,FISH mortality ,FISHING - Abstract
MSY principles for marine fisheries management reflect a focus on obtaining continued high catches to provide food and livelihoods for humanity, while not compromising ecosystems. However, maintaining healthy stocks to provide the maximum sustainable yield on a single-species basis does not ensure that broader ecosystem, economic, and social objectives are addressed. Weinvestigate how the principles of a "pretty good yield" range of fishing mortalities assumed to provide .95% of the average yield for a single stock can be expanded to a pretty good multispecies yield (PGMY) space and further to pretty good multidimensional yield to accommodate situations where the yield from a stock affects the ecosystem, economic and social benefits, or sustainability. Wedemonstrate in a European example that PGMY is a practical concept. As PGMY provides a safe operating space for management that adheres to the principles of MSY, it allows the consideration of other aspects to be included in operational management advice in both data-rich and data-limited situations. PGMYfurthermore provides away to integrate advice across stocks, avoiding clearly infeasible management combinations, and thereby hopefully increasing confidence in scientific advice. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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30. Variability and connectivity of plaice populations from the Eastern North Sea to the Baltic Sea, part II. Biological evidence of population mixing.
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Ulrich, Clara, Hemmer-Hansen, Jakob, Boje, Jesper, Christensen, Asbjørn, Hüssy, Karin, Sun, Hailu, and Clausen, Lotte Worsøe
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PLAICE , *HYDRODYNAMICS , *GENETIC markers - Abstract
A multi-disciplinary study was conducted to clarify stock identity and connectivity patterns in the populations of European plaice ( Pleuronectes platessa ) in the Skagerrak-Kattegat transition area between the Eastern North Sea and the Baltic Sea. Five independent biological studies were carried out in parallel. Genetic markers suggested the existence of different genetic populations in the transition area. Growth backcalculation with otoliths resulted in significant although limited differences in growth rates between North Sea and Skagerrak, indicating weak differentiation or important mixing. Hydrogeographical drift modelling suggested that some North Sea juveniles could settle along the coast line of the Skagerrak and the Kattegat. Tagging data suggested that both juveniles and adult fish from the North Sea perform feeding migrations into Skagerrak in summer/autumn. Finally, survey data suggested that Skagerrak also belongs to the area distribution of North Sea plaice. The outcomes of the individual studies were then combined into an overall synthesis. The existence of some resident components was evidenced, but it was also demonstrated that North Sea plaice migrate for feeding into Skagerrak and might constitute a large share of the catches in this area. The mixing of different populations within a management area has implications for stock assessment and management. Choice must be made to either lump or split the populations, and the feasibility and constraints of both options are discussed. The outcomes of this work have directly influenced the management decisions in 2015. [ABSTRACT FROM AUTHOR]
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- 2017
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31. TEMAS: fleet-based bio-economic simulation software to evaluate management strategies accounting for fleet behaviour.
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Ulrich, Clara, Andersen, Bo Sølgaard, Sparre, Per J., and Nielsen, J. Rasmus
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FISHERY management , *FISHING , *FISH stocking , *FISH population measurement , *MATHEMATICAL models , *COMPUTER software - Abstract
Ulrich, C., Andersen, B. S., Sparre, P. J., and Nielsen, J. R. 2007. TEMAS: fleet-based bio-economic simulation software to evaluate management strategies accounting for fleet behaviour. – ICES Journal of Marine Science, 64: 647–651. TEMAS (technical management measures) is a fleet-based bio-economic software for evaluating management strategies accounting for technical measures and fleet behaviour. It focuses on mixed fisheries in which several fleets can choose among several fishing activities to target different stocks in one or several areas. The software combines a management strategy evaluation framework, using a forward-running operating model and a management procedure with a fleet behaviour module simulating both short-term (effort allocation) and long-term (entry/exit) fleet dynamics. The suite of models behind TEMAS can be thought of as an extension of the traditional ICES forecast model. Alternative management scenarios can be compared and evaluated for their bio-economic consequences and robustness to parameter uncertainty. The software is generic and user-friendly, and can be run at several space and time scales. [ABSTRACT FROM PUBLISHER]
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- 2007
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32. Dynamics of fisheries, and the flexibility of vessel activity in Denmark between 1989 and 2001
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Ulrich, Clara and Andersen, Bo Sølgaard
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FISHING , *FISHERIES , *SHIPS - Abstract
Danish fishing vessels can be characterized by their diversity of fishing practice in terms of fishing gear and target species, and by their operational flexibility in respect of these fishing practices throughout the year. We describe the temporal fluctuations in this flexibility by following the activity of individual fishing vessels between 1989 and 2001. Initially, a typology of fisheries (classification of fishing trips) and vessel groups (classification of fishing vessels) was established through multivariate analyses of catch and effort data for 1999. In all, 54 fisheries and 25 vessel groups were identified. These typologies were then applied to all data for the whole time period, and the dynamics of fisheries and vessel groups investigated. The dynamics of vessels groups are studied both within groups (main and secondary fisheries, changes in activity patterns) and between groups (tracking of vessels shifting between groups). Results show average stability of vessel activity in terms of the main fishery, along with a great diversity of secondary fisheries and some possibilities for shifting between gears and areas. We conclude that the level of technical interactions is high, and that separation into distinct management units is difficult. [Copyright &y& Elsevier]
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- 2004
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33. A multi-species multi-fleet bioeconomic simulation model for the English Channel artisanal fisheries
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Ulrich, Clara, Le Gallic, Bertrand, Dunn, Matthew R., and Gascuel, Didier
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SMALL-scale fisheries , *FROZEN desserts - Abstract
Considering the large number of technical interactions between various fishing activities, the English Channel (ICES divisions VIId and VIIe) fisheries may be regarded as one large and diverse multi-country, multi-gear and multi-species artisanal fishery, although rarely studied as such. A whole-scale bioeconomic model has been constructed. It does not take into account biological interactions, but focuses on competition among fleets. A large amount of biological and economic data have been preliminarily gathered, leading to a substantial increase of the quantitative knowledge available. The main purpose of the model is to study the long-term consequences of various management alternatives on the economic situation of the English and French fleets fishing in the area and on exploited resources. The model describes this feature through the links between three entities on the one hand (stocks, fleets and “métiers”, i.e.
gear×target species×fishing area), and three modules on the other hand (activity, biological production and economics). The model is described and some simulation results are presented. An example simulating a decrease of one fleet segment effort illustrates these technical interactions among fleets and underlines the interest of a large-scale approach for these fisheries. [Copyright &y& Elsevier]- Published
- 2002
- Full Text
- View/download PDF
34. Sensitivity of some biological reference points to shifts in exploitation patterns and inputs uncertainty for three North Sea demersal stocks
- Author
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Ulrich, Clara and Marchal, Paul
- Subjects
- *
FISHING catch effort , *RESAMPLING (Statistics) , *MONTE Carlo method - Abstract
This study examines the sensitivity of six biological reference points (BRPs), both to variability and uncertainty of their input parameters, and to shifts in exploitation patterns. These shifts arise from accounting for the trends in catchability in extended survivors analysis (XSA) tuning fleets derived from the “hybrid method”. By using non-parametric resampling and Monte Carlo stochastic procedures, we test whether such shifts in exploitation patterns significantly affect reference point values and probability distributions, for various levels of variation of input parameters. This method is applied to North Sea plaice, sole and cod stocks. We show that accounting for catchability trend generally induces only slight changes in reference point mean values. In particular, it is mostly significant over the last decade, especially for plaice, but not when introducing medium levels of uncertainty for the natural mortality. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
35. A comparison of three indices of fishing power on some demersal fisheries of the North Sea
- Author
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Marchal, Paul, Ulrich, Clara, Korsbrekke, Knut, Pastoors, Martin, and Rackham, Brian
- Subjects
- *
EFFORT in fisheries , *FISHING , *FISH mortality , *FISHES - Abstract
The scope of this study is to identify temporal dynamics in fishing power, by deriving three different indices (IFP1, IFP2, IFP3) based on three independent methods. IFP1 is derived from the GLM analysis of the relationship between fishing mortality and fishing effort, assuming that total fishing mortality estimates from XSA (eXtended Survivors Analysis) are accurate. IFP2 is derived from the GLM analysis of the difference between the Log-CPUE of a vessel and the average Log-CPUE of a set of reference vessels, which are chosen with regards to the stability of their Log-CPUE over time. IFP3 is derived from the GLM analysis of the Log-CPUE of a vessel relative to some external survey abundance index. Particular attention is paid to the horsepower and year effects in IFP1, IFP2, and IFP3. This methodology is applied to the Danish, Dutch, English and Norwegian demersal fisheries of the North Sea. The fishing power estimated by all indices increases with horsepower, particularly in relation to target species. Despite less consensus in the estimation of annual variations in fishing power, some important features are highlighted. First, there are cases where fishing power has consistently increased over the period of investigation, possibly through an overall increase in fishing efficiency. Second, there are examples where fishing power has increased relative to one species, and remained constant or even decreased in relation to another one. In the context of mixed-species fisheries, this feature might reveal a shift in fishing tactics. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
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36. Area-based management and fishing efficiency
- Author
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Marchal, Paul, Ulrich, Clara, and Pastoors, Martin
- Subjects
FISHING ,PLAICE - Abstract
Copyright of Aquatic Living Resources is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2002
37. More data for the money: Improvements in design and cost efficiency of electronic monitoring in the Danish cod catch quota management trial.
- Author
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Plet-Hansen, Kristian S., Bergsson, Heiðrikur, and Ulrich, Clara
- Subjects
- *
ELECTRONIC monitoring in fisheries , *FISHERY laws , *TRAWLERS (Vessels) , *GILLNETTING - Abstract
• Electronic Monitoring (EM) with video can measure discards with high precision. • Technical developments has increased EM reliability. • Video audit time has been reduced via improved procedures and technical solutions. • EM is a cost-effective tool to ensure compliance with discard regulations. Electronic Monitoring (EM) with video is a tool often mentioned to ensure compliance with fishing regulations while vessels are at sea. Since 2008, several trials have been conducted in the European Union on the use of EM. One of the largest and longest running European trials was the 2010–2016 Cod Catch Quota Management trial (CCQM) in Denmark. This paper reviews the methods and experiences gained from this trial, with focus on the last two years where criteria for video audits were expanded and major technical developments took place. The cost-effectiveness and potential of EM for compliance, management and scientific purposes is discussed. The present study demonstrates that EM is capable of high precision detection of non-compliance with a discard ban and that developments in the transmission of EM data allowed for a smoother and more reliable Monitoring, Control and Surveillance (MCS) system. Although further developments are needed, especially within the field of automated image analysis, we conclude that EM is one of the few feasible tools where fisheries information and compliance can be ensured under a Landing Obligation. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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38. Detailed mapping of fishing effort and landings by coupling fishing logbooks with satellite-recorded vessel geo-location
- Author
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Bastardie, Francois, Nielsen, J. Rasmus, Ulrich, Clara, Egekvist, Josefine, and Degel, Henrik
- Subjects
- *
FISHING , *LOGBOOKS , *FISHERY statistics , *FISHERY management , *ARTIFICIAL satellites , *SHIPS , *FISHING boats - Abstract
Abstract: Individual tracking of commercial fishing vessels from vessel monitoring systems (VMS) is now widely available across Europe for scientific purposes. This enables analyses of the spatial and temporal distribution of disaggregated fishing activity as well as high resolution determination of the consequent relative fishing pressure on stocks, provided that an accurate method can link these data with the declaration of catches (logbooks). In the present study, logbook analyses to allocate the fishing activity due to various fisheries (fleet segments) are integrated with processing of raw satellite-recorded data for identifying trips at sea and fishing sequences. Both data sources are linked into one output dataset. A robust method is developed to allocate logbook catches to VMS positions, with focus on potential mismatch. The method is applied to data on the Danish Skagerrak–Kattegat fishing fleets from 2005 to 2008, where 52–56% of the VMS total effort perfectly matched (representing approximately 80% of landings); 14–18% partially matched; and 30% failed to match the logbook data, which was partially related to fleet type, area and year. Comparison of three methods for generating high resolution determination of grid-based fishing effort demonstrated only minor differences, suggesting a mainly equal dispatch of landings between each of the merged fishing positions. Despite possibly poor matching success for this particular region, we demonstrate that the approach can cope with the potentially large sources of error in the data, including the current low accuracy of available VMS pre-processing algorithms and the possible misreporting of areas and catch dates in fishermen''s logbook declarations. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
39. Challenges in integrating short-term behaviour in a mixed-fishery Management Strategies Evaluation frame: A case study of the North Sea flatfish fishery
- Author
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Andersen, Bo Sølgaard, Vermard, Youen, Ulrich, Clara, Hutton, Trevor, and Poos, Jan-Jaap
- Subjects
- *
FLATFISH fisheries , *FISHERY management , *FISHERIES , *CASE studies , *SIMULATION methods & models , *FISH populations , *FISHERY economics - Abstract
Abstract: This study presents a fleet-based bioeconomic simulation model to the international mixed flatfish fishery in the North Sea. The model uses a Management Strategies Evaluation framework including a discrete choice model accounting for short-term temporal changes in effort allocation across fisheries. A simplified random utility model was used based on the expected revenue (or economic attractiveness) and two tradition parameters related to short and long term historical fishing patterns. All three parameters were significant. Even though reactions and adaptations vary between fleets, the estimated conservative behaviour of the main fleets led to only marginal effect at the stock level. The importance of accounting for fleet behaviour was then evaluated using an elasticity analysis to explore how increased weight of economic attractiveness contributes to changes in the biological output and positive increase in the economic performance of the individual fleets. This showed the existence of a window of sensitivity of the model to the behaviour assumptions. The study highlights the challenge of implementing an effort allocation model in a general framework of Management Strategies Evaluation for mixed-fisheries, and illustrates the necessary trade-offs between very detailed numerical relationships and the representation of aggregated processes. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
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40. Managing mixed fisheries in the European Western Waters: Application of Fcube methodology
- Author
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Iriondo, Ane, García, Dorleta, Santurtún, Marina, Castro, José, Quincoces, Iñaki, Lehuta, Sigrid, Mahévas, Stephanie, Marchal, Paul, Tidd, Alex, and Ulrich, Clara
- Subjects
- *
FISHERY management , *FISH communities , *ANIMAL species , *SENSITIVITY analysis , *PARAMETER estimation , *ERROR analysis in mathematics - Abstract
Abstract: Fisheries management is moving towards ecosystem based management instead of traditional single species based advice. To progress towards an ecosystem approach, a new methodology called “Fleet and Fisheries Forecast” (Fcube) has been proposed. In the application of the method, a precise initial fleet and metier segmentation used is important to get representative results in the analysis. Once they were defined, different data aggregations for fleets and metiers were tested with the objective of getting the best aggregation level to get equilibrium between detailed results and real management. Results showed that the difference in the forecast catches in different aggregation levels was low. Finally, hindcasting analyses were carried out to evaluate how sensitive forecasts are to different parameters. Stock indicators and catchability show the highest source of error and the effort share the lowest. In this analysis, Western Waters fleet management results show consistency between stocks and their respective TACs. The study highlights that it is possible to deliver advice within the context of mixed fisheries using the Fcube method. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
41. VMStools: Open-source software for the processing, analysis and visualisation of fisheries logbook and VMS data
- Author
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Hintzen, Niels T., Bastardie, Francois, Beare, Doug, Piet, Gerjan J., Ulrich, Clara, Deporte, Nicolas, Egekvist, Josefine, and Degel, Henrik
- Subjects
- *
FISHERIES , *OPEN source software , *LOGBOOKS , *SPATIO-temporal variation , *DATABASES , *TRAWLERS (Vessels) , *SOFTWARE development tools - Abstract
Abstract: VMStools is a package of open-source software, build using the freeware environment R, specifically developed for the processing, analysis and visualisation of landings (logbooks) and vessel location data (VMS) from commercial fisheries. Analyses start with standardized data formats for logbook (EFLALO) and VMS (TACSAT), enabling users to conduct a variety of analyses using generic algorithms. Embedded functionality handles erroneous data point detection and removal, métier identification through the use of clustering techniques, linking logbook and VMS data together in order to distinguish fishing from other activities, provide high-resolution maps of both fishing effort and -landings, interpolate vessel tracks, calculate indicators of fishing impact as listed under the Data Collection Framework at different spatio-temporal scales. Finally data can be transformed into other existing formats, for example to populate regional databases like FishFrame. This paper describes workflow examples of these features while online material allows a head start to perform these analyses. This software incorporates state-of-the art VMS and logbook analysing methods standardizing the process towards obtaining pan-European, or even worldwide indicators of fishing distribution and impact as required for spatial planning. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
42. Stock-based vs. fleet-based evaluation of the multi-annual management plan for the cod stocks in the Baltic Sea
- Author
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Bastardie, Francois, Vinther, Morten, Nielsen, J. Rasmus, Ulrich, Clara, and Paulsen, Marie Storr
- Subjects
- *
FISHERY management , *FISH population measurement , *COD fisheries , *STRATEGIC planning , *FISHERY libraries , *ECONOMIC models , *STOCHASTIC analysis , *SIMULATION methods & models - Abstract
Abstract: This study evaluated the EU 2008 multi-annual plan for Baltic cod stock recovery. The plan combines harvest control rules that set TACs with reductions in direct effort (E) and fishing mortality (F). Performance and robustness of the plan are tested with a management strategy evaluation model (MSE). Stochastic simulations are carried out under different scenarios of recruitment and sources of uncertainties. Under the different magnitudes of errors investigated, the plan in its current design is likely to reach precautionary targets for the Eastern and the Western Baltic cod stocks by 2015. It is, however, more sensitive to implementation errors (e.g. catch misreporting) than to observation errors (e.g. data collection) when the (i) current settings of the ICES single-stock assessment model are maintained, (ii) intended fishing effort reduction is fully complied with, and (iii) biological parameters are assumed constant. For the Eastern Baltic stock, additional sources of uncertainties from fishery adaptation to the plan are tested using a fleet-based and spatially explicit version of the model which leads to higher reductions in F and no significant change in management robustness. The relative difference between both approaches is mainly due to differences in exploitation patterns in catching the same amount of fish. The effort control is demonstrated to be more efficient when supplemented with a TAC and avoids un-intended effects from fishery responses, e.g. spatial effort reallocation. Medium term economic evaluation of fishery performance shows an initial reduction in profit with effort and TAC reductions, but profit is always positive. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
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