Suchergebnisse
Filter
17 Ergebnisse
Sortierung:
SSRN
Estimating Discard Mortality in Commercial Fisheries without Fish Dying: A 3R Challenge
SIMPLE SUMMARY: Due to the implementation of a landing obligation in fisheries in the European Union (EU), with an exemption for species with "high survival", discard survival studies (henceforth DSSs) have become one of the most politically prioritized fisheries research areas in European fisheries. In contrast to most fisheries science research areas, DSSs are embedded by the EUs animal research welfare directive. This is a challenge, and there has not been any focus on how to implement animal welfare (AW) regulations experimentally in DSSs. This paper focuses on AW regulations in relation to conducting DSSs, but the outreach is much broader. We investigate experimental procedures by bringing in relevant examples, using the output results, and relating this information to relevant AW guidelines and regulations by focusing on implementing 3R principles. ABSTRACT: Globally, it is estimated that around 10% of the fish that are caught are discarded. This is considered to be a wasteful human marine activity since these fish are often dead or dying. To reduce the high discard rates of commercial fisheries, the European Union (E.U.) has enacted a landing obligation that includes the ability to exempt "species for which scientific evidence demonstrates high survival rates". Therefore, discard survival studies (henceforth DSSs) have become one of the most politically prioritized fisheries research areas in European fisheries. International expert groups have produced guidance reports to promote best practices and to harmonize the methodologies. Nevertheless, there has not been any focus on how to implement animal welfare (AW) regulations experimentally. Discard survival studies are "frontrunners" in fisheries science research areas that are embedded by animal research welfare requirements and are expected to be more restrictive in the future because of an increased public focus on fish welfare. This paper focuses on AW regulations in relation to conducting DSSs, but the outreach is much broader. We investigate ...
BASE
Estimating Discard Mortality in Commercial Fisheries without Fish Dying: A 3R Challenge
In: Madsen , N , Ern , R & Alstrup , A K O 2022 , ' Estimating Discard Mortality in Commercial Fisheries without Fish Dying : A 3R Challenge ' , Animals , vol. 12 , no. 6 , 782 . https://doi.org/10.3390/ani12060782
Globally, it is estimated that around 10% of the fish that are caught are discarded. This is considered to be a wasteful human marine activity since these fish are often dead or dying. To reduce the high discard rates of commercial fisheries, the European Union (E.U.) has enacted a landing obligation that includes the ability to exempt "species for which scientific evidence demonstrates high survival rates". Therefore, discard survival studies (henceforth DSSs) have become one of the most politically prioritized fisheries research areas in European fisheries. International expert groups have produced guidance reports to promote best practices and to harmonize the methodologies. Nevertheless, there has not been any focus on how to implement animal welfare (AW) regulations experimentally. Discard survival studies are "frontrunners" in fisheries science research areas that are embedded by animal research welfare requirements and are expected to be more restrictive in the future because of an increased public focus on fish welfare. This paper focuses on AW regulations in relation to conducting DSSs, but the outreach is much broader. We investigate experimental procedures by bringing in relevant examples, using output results, and relating this information to relevant AW guidelines and regulations by focusing on implementing 3R principles.
BASE
Development and test of selective sorting grids used in the Norway lobster (Nephrops norvegicus) fishery
In: Madsen , N , Holst , R , Frandsen , R & Hansen , K 2017 , ' Development and test of selective sorting grids used in the Norway lobster (Nephrops norvegicus) fishery ' , Fisheries Research , vol. 185 , pp. 26-33 . https://doi.org/10.1016/j.fishres.2016.10.002
Due to generally high discard rates in Norway lobster (Nephrops norvegicus) fisheries, a discard ban coming up and to the cod recovery plan in several areas, selective sorting grids have been tested in many areas and are specified by legislation for use in the Kattegat and Skagerrak area bordering Norway, Denmark and Sweden. Grids are very selective, but they can lead to loss of landable Norway lobster and valuable fish species. To improve retention of these species, we developed three new grids using made by polyurethane to make them flexible: One grid had horizontal bars, one had vertical bars, and one had vertical bars and a guiding funnel in front of the grid. Four unselective net bags were used to collect the catch escaping through different parts of the grid or escaping without passing through the grid. Water flow around the grid bars was measured in a flume tank. The three grids were tested from a commercial trawler in the Kattegat and Skagerrak area. Underwater filming was conducted to assess grid performance and fish behavior. Results showed that a bottom hole in the lower part of the grid allowed species in the lower part of the gear to pass and retained in the bag behind the hole. More flatfish passed the grid with horizontal bars compared to that with vertical bars, but the retention rate was still low. Use of the guiding funnel increased the contact with the grid considerably for both target and unwanted species. In all three grid designs, there were losses of Norway lobster above minimum landing size.
BASE
Organic farming at the farm level:scenarios for the future development
In: Jacobsen , B H , Madsen , N & Ørum , J E 2005 , Organic farming at the farm level : scenarios for the future development . Fødevareøkonomisk Institut - Rapporter , no. 178 , Fødevareøkonomisk Institut .
The purpose of this report is to present possible impacts of new technology and changes in legislation on the profitability of different types of organic farms. The aim is also to look at both the current and future trends in the organic area in Denmark. The farm level analyses are carried out as part of a larger project entitled "Economic analyses of the future development of organic farming – effects at the field, farm, sector and macroeconomic level". The project links effects at the field-level with analyses at the farm level. These effects are then used in sector and macroeconomic analyses, which are described in other reports from Food and Resource Economic Institute (Jacobsen, 2005 and Andersen et al., 2005). This gives coherent results from the field to the macroeconomic level regarding changes in technology and legislation.
BASE
The Baltic cod trawl fishery: The perfect fishery for a successful implementation of the landing obligation?
In: Valentinsson , D , Ringdahl , K , Storr-Paulsen , M & Madsen , N 2019 , The Baltic cod trawl fishery: The perfect fishery for a successful implementation of the landing obligation? in S Uhlmann , C Ulrich & S Kennelly (eds) , The European Landing Obligation : Reducing Discards in Complex, Multi-Species and Multi-Jurisdictional Fisheries . Springer , pp. 197-218 . https://doi.org/10.1007/978-3-030-03308-8_10
The cod fisheries in the Baltic Sea were among the first EU fisheries with a full implementation of the EU Landing Obligation (LO) or so-called 'discard ban', phased in from 2015 onwards. This chapter describes key aspects for the successful management of Baltic cod such as the long history of scientific data collection for stock assessment and cod management as well as a well-documented history of work aimed at increased selectivity in cod trawls. We then analyse how the scientific data used for stock assessment has been affected by the LO and how the knowledge of Baltic cod selectivity has been used and developed since its introduction. We conclude that in spite of many good prerequisites, the introduction of the LO in Baltic cod fisheries has been unsuccessful and has failed to deliver any of the expected benefits. Data quality for stock assessments has deteriorated, discarding of cod has not decreased despite a reduced minimum size and there are no indications of increased gear selectivity in the fishery. Finally, we propose potential explanations for this failure and recommend actions that may be needed to make the Landing Obligation more successful.
BASE
Survival of discarded plaice ( Pleuronectes platessa ) from Norway lobster ( Nephrops norvegicus ) otter-trawl fishery
In: Eskelund , M , Methling , C , Skov , P V & Madsen , N 2019 , ' Survival of discarded plaice ( Pleuronectes platessa ) from Norway lobster ( Nephrops norvegicus ) otter-trawl fishery ' , Journal of Applied Ichthyology , vol. 35 , no. 3 , pp. 645-654 . https://doi.org/10.1111/jai.13888
The introduction of landing obligations in the European Union common fisheries policy, has increased the focus on discard survival. Since species with scientifically proven high survival rates may be exempted from the landing obligations, the economic significance for the fishing industry is large. Landing obligations include individuals below the minimum conservation reference size (MCRS), which are not allowed to be sold for human consumption. The Norway lobster (Nephrops norvegicus) fishery is a high value fishery, but with a substantial amount of bycatch of plaice (Pleuronectes platessa) below the MCRS. In the present study, observations were made on the short‐term survival of plaice at or below the MCRS, discarded from a small otter board trawler targeting Nephrops in Skagerrak (ICES 3a). The average short‐term survival of plaice was 15% at haul level, ranging from 0% to 39%, after 10 days of captive observation. Survival significantly decreased with time on deck and the retention of debris in the codend (p < 0.0001), while survival was not correlated to size. Vitality assessments, using a combined reflex impairment and injury score, were tested as predictor of survival and were significantly associated to survival (p < 0.0001) both for individual fish and when grouped by hauls. Seabird predation behaviour was assessed and it was estimated that seabirds predated or pursued 85% of discarded plaice below the MCRS.
BASE
Codend selectivity in a commercial Danish anchor seine
In: Noack , T , Frandsen , R , Krag , L A , Mieske , B & Madsen , N 2017 , ' Codend selectivity in a commercial Danish anchor seine ' , Fisheries Research , vol. 186 , pp. 283-291 . https://doi.org/10.1016/j.fishres.2016.10.006
Danish seining (or anchor seining) is a fishing technique that is gaining increasing attention because itis considered to be a fuel-efficient fishing method with low environmental impact. However, scientificdocumentation of the selectivity characteristics of Danish seines is lacking, and the gear generally isgrouped with bottom trawls and Scottish seines in fisheries management legislation. In this study, wedeveloped a codend cover to estimate the selectivity of a standard commercial Danish seine codendfor four fish species. The data for the dominant species, dab (Limanda limanda) and plaice (Pleuronectesplatessa), was best described by models that combine two or three logistic models, which indicated thatmore than one selection process was at work. Selectivity of cod (Gadus morhua) was best described by aRichard curve and selectivity of red gurnard (Chelidonichthys lucernus) by a logistic curve. The estimatedselectivity curve of dab indicated, contrary to cod and plaice, low retention of individuals below MLS.Confidence limits for larger length classes of cod and red gurnard were relatively wide. For plaice, theestimated selection factor, which is the length with 50% retention divided by mesh size, was comparableto literature values from trawl studies. The average value for cod was similar for Danish and Scottishseines, but lower for trawls. The results are discussed in the context of fisheries management with focuson the landing obligation of the new Common Fisheries Policy
BASE
Danish seine - An environmental friendly fishing method?
In: Noack , T , Eggers , F , Frandsen , R , Krag , L A & Madsen , N 2014 , ' Danish seine - An environmental friendly fishing method? ' , ICES Symposium 2014 , Tromsø , Norway , 16/06/2014 - 19/06/2014 .
Today, extensive research is devoted to assess the effects of demersal trawling on the marine ecosystem, but only few of such studies considered the Danish seine. Danish seines and bottom trawls are grouped together in the legislation. Trawling is more common and responsible for the major part of the total landings where the seine fleet and catches are decreasing. The Danish seine is a specific type of encircling net to catch demersal fish. It is characterized by moderate fuel consumption and no use of heavy weights or doors, probably resulting in a relatively gentle bottom-contact and low interactions with the seabed compared to e.g. traditional trawling. However, the assumptions on the more environmental friendliness in seining are not sufficiently addressed. The present study aims at increasing the knowledge on Danish seining including its effect on the benthic ecosystem. The study starts with a comparison of existing catch data for Danish seines and trawls and continues with several substudies: Detailed description of all stages of the seining process to get a basis for the following investigations. Selectivity trials to support existing data, whereby both economically valuable and economically non-valuable species will be regarded Estimation of potential interactions of the gear with the sea bottom Assessment of survival chance of discarded animals Observation of fish behavior during capture process Combination of all single parts to provide an overall picture of effects of the Danish seine fishery on the marine environment This study may contribute to increase understanding the catching process in the seine fishery and the gears interaction with seabed during the different stages of the fishing process. The outcome of such studies will be highly relevant in future discussions on the impacts Danish seining may has on the marine environment and the faunal diversity and to maintain viable fisheries in the future
BASE
Codend selectivity in a commercial Danish anchor seine
Danish seining (or anchor seining) is a fishing technique that is gaining increasing attention because itis considered to be a fuel-efficient fishing method with low environmental impact. However, scientificdocumentation of the selectivity characteristics of Danish seines is lacking, and the gear generally isgrouped with bottom trawls and Scottish seines in fisheries management legislation. In this study, wedeveloped a codend cover to estimate the selectivity of a standard commercial Danish seine codendfor four fish species. The data for the dominant species, dab (Limanda limanda) and plaice (Pleuronectesplatessa), was best described by models that combine two or three logistic models, which indicated thatmore than one selection process was at work. Selectivity of cod (Gadus morhua) was best described by aRichard curve and selectivity of red gurnard (Chelidonichthys lucernus) by a logistic curve. The estimatedselectivity curve of dab indicated, contrary to cod and plaice, low retention of individuals below MLS.Confidence limits for larger length classes of cod and red gurnard were relatively wide. For plaice, theestimated selection factor, which is the length with 50% retention divided by mesh size, was comparableto literature values from trawl studies. The average value for cod was similar for Danish and Scottishseines, but lower for trawls. The results are discussed in the context of fisheries management with focuson the landing obligation of the new Common Fisheries Policy.
BASE
Fishing profiles of Danish seiners and bottom trawlers in relation to current EU management regulations
In: Noack , T , P. Fransen , R , Wieland , K , Krag , L A , Berg , F & Madsen , N 2017 , ' Fishing profiles of Danish seiners and bottom trawlers in relation to current EU management regulations ' , Fisheries Management and Ecology , vol. 24 , no. 6 , pp. 436-445 . https://doi.org/10.1111/fme.12244
Danish seines and bottom trawls operate differently and have different catching processes. Both gears belong to the same legislative category in European fisheries, but different management strategies in other countries and criticism by fishers on grouping Danish seines and trawls together indicate disagreement on current gear classification. This study compared both gears in terms of their fishing characteristics and catches of commercial species based on 16 years of observer data. Danish seining is a specialised fishing method that targeted few species but with higher total catch rates than bottom trawlers. Bottom trawling is a more all-purpose fishing method that targets a larger number of species, and bottom trawlers use larger engines than Danish seiners. A generalised additive mixed model indicated that catch rates of flatfish are generally higher for Danish seines, and catch rates of roundfish species are higher for trawlers. The results do not directly suggest a separation of the gears in terms of legislation as the quantities of fish below current minimum size were similar, but for example future survival studies may reach different conclusions. Additional factors were found to be important in determining catches of both gears.
BASE
Initial experiments to assess short-term survival of discarded plaice ( Pleuronectes platessa ) caught in trammel nets during winter season
In: Ern , R , Molbo , K , Jensen , T H , Kucheryavskiy , S V , Møller , P R & Madsen , N 2022 , ' Initial experiments to assess short-term survival of discarded plaice ( Pleuronectes platessa ) caught in trammel nets during winter season ' , Fisheries Research , vol. 251 , 106308 . https://doi.org/10.1016/j.fishres.2022.106308
European plaice (Pleuronectes platessa) is a key species in commercial fisheries in the North Sea, Skagerrak, Kattegat, and Baltic Sea. The reformed European Union Common Fisheries Policy includes the possibility of exemptions from the landing obligation for "species for which scientific evidence demonstrates high survival rates". Discard survival from set-net fisheries is poorly studied. Trials were conducted on two commercial fishing vessels over seven trips from November to February 2017–2018 in the Baltic Sea. The nylon trammel nets had a nominal bar size for the inner/outer wall of 75/350 mm and 85/400 mm. Soaking time was 23–47 h, water depth 7–18 m, and deck temperature was −0.1–6.0 °C. Following commercial practice, the trammel nets were hauled back onto the vessel, after which netting and fish passed through a net hauler onto a steel sorting table where the entire fish catch were manually untangled by the fishers and plaice collected by scientists. We used a storage system for housing the captured fish inside fishing harbours during observations. Catch-damage-index (CDI) and Reflex Action Mortality Predictor (RAMP) scores were used to assess fish condition immediately after capture and at the end of observation periods. All plaice below 40 cm were sampled with a total number of 118 individuals from 13 fleets (several nets joined together). The fish were assessed for short-term survival for 4–10 days with full survival (100%). The majority of fish exhibited no reflex impairments. Minor bruises, fraying, and net marks were frequently observed on captured fish. The overall condition of the fish did not change during observation periods.
BASE
Bycatch And Discards: Management INdicators, Trends and locatiON (BADMINTON)
In: Vassilopoulou , V , Marie-Joëlle Rochet , M-J R , Helmond , A T M V , Bellido Millán , J M , Catchpole , T , Eliasen , S , Margeirsson , S , Madsen , N & Feekings , J P 2012 , Bycatch And Discards: Management INdicators, Trends and locatiON (BADMINTON) .
Discarding keeps being an important issue in world fisheries; it is a way for fishers to adjust their landings to the legal and market constraints, but is largely considered as a waste of rare natural resources and as contributing to the depletion of stocks bearing a high fishing pressure. Many jurisdictions, including the European Commission, are preparing regulations to reduce or ban discards. To design effective regulations, an understanding of the extent and processes of the issue is required. The MariFish BADMINTON project aimed to build up the knowledge of discarding patterns and factors in European fisheries, evaluate the efficacy of selective devices and other discard management measures that have been implemented in the past, and improve methods to analyse, monitor, and manage bycatch and discarding. Specific objectives included the provision of discard estimates for selected European fisheries, and of appropriate indicators; the determination of the most important factors affecting discard amounts and composition; and the elaboration of integrated management approaches to the discard issue. BADMINTON relied on two types of approaches to fulfill these aims and objectives. First was the analysis of onboard observer data, since intensive collection of catch and discard data onboard commercial vessels has been undertaken in European countries under the European Union Data Collection Regulation (2002) followed and intensified by the Data Collection Framework (2008). Thus, one significant contribution of the project was to collate onboard observer data from several European Union member states, given the many differences between national onboard observer programmes sampling schemes, protocols, details of data recorded, and data storage formats. This first step paves the way towards a future better integration of national onboard observer programmes. The second approach was to conduct stakeholder interviews and expert consultation, which was meant to complement the data analyses with fishers perspectives on the discard issue, and to provide an integrated approach toward management. Both approaches lead to the following two broad conclusions: • Discard patterns exhibited high diversity across regions, countries, gear types, vessel sizes, and species, with variability being more pronounced among regions. Thus, discard management approaches might be devised at a regional level – consistent with the proposed regionalization of the currently discussed reform of the European Union Common Fisheries Policy. • Discards amounts, patterns, and composition, are determined by a multitude of interacting natural and human (economic and social) factors in a given place and time, and usually no simple explanations can suffice. The latter affects the effectiveness of mitigation measures, and solutions are to be found down at a very detailed level such as the fishing operation, fishing trip, or vessel, which suggests that a bottom-up, or results-based approach seems to be the most advisable form to tackle the discards problem. Then, effective discard management strategies should be devised at various scales, from individual fishers implementation of detailed species-, gear- and area-specific tools, to producer organizations, member states, regional levels, and the broad European Union. The project has developed a number of tools, distinguished in three categories ie. selectivity related tools (including a modelling tool to estimate gear selectivity based on fish morphology, and preliminary indicators of fishing selectivity at the fleet and ecosystem scales), tools to appraise and understand the discarding issue in a given region, area or fishery (including modelling tools to establish catch and discard maps and devise spatial approaches to the management of discards, based on onboard observer data; a series of discard indicators embedded in a discard indicator dashboard, to monitor and manage the discards in a given fishery; a generic model to determine the relative importance of inferred discard drivers; a list of factors to be used in semi-structured stakeholder interviews, and interview methodology), and tools that can be used to assist in devising management strategies at various scales (including a framework to develop a fishery-specific mitigation strategy based on inferred drivers of discarding behaviour; a detailed evaluation of 12 discard mitigation measures, alone and in combination). It should be underlined, however, that BADMINTON findings suggest that as discarding is in most cases an unavoidable consequence of a series of constraints on the fishing activities and production, managing discards implies taking account of the whole fishery management system. Hence, a discard management strategy should not include only a combination of discard mitigation measures; if discards are to be reduced, appropriate and consistent incentives need to be mended together
BASE
How can discards in European fisheries be mitigated? Strengths, weaknesses, opportunities and threats of potential mitigation methods
In: Marine policy, Band 51
ISSN: 0308-597X
How can discards in European fisheries be mitigated? Strengths, weaknesses, opportunities and threats of potential mitigation methods
In: Marine policy: the international journal of ocean affairs, Band 51, S. 366-374
ISSN: 0308-597X