Hook shedding and post-release fate of deep-hooked European eel

-The European eel (Anguilla anguilla) is a commercially and recreationally important fishery target species. In the last decades, the eel has experienced dramatic stock declines and has been listed as critically endangered. To reduce fishing mortality, several European countries have closed the fishery or introduced stricter management measures which increase the likelihood of catch-and-release in the recreational fishery. This study investigated hook shedding mechanisms of deep-hooked, line-cut eels via radiography, and quantified hook shedding rates, post-release mortality and sub-lethal effects in captivity. Eels were caught with four different hook treatments, monitored in a tank for 23 weeks, and radiographed 0, 1, 3, 10, 24, 54, 115 and 163 days after capture. After 163 days, total hook shedding rate was significantly higher for smaller hooks (41.2%) compared to larger hooks (0.0%), and increased with fish length. Post-release mortality rates ranged between 27.3% and 50.0% after 23 weeks (not adjusted for handling and holding) and did not differ significantly between hook treatments. The majority of dead eels showed gastric perforations caused by the hooks leading to internal haemorrhaging and the intrusion of digestive fluids into the body cavity inducing lethal degradation and inflammation of vital organs. Anglers are encouraged to minimise bycatch of eel in countries where eel harvest is prohibited. Anglers targeting eel should use selective and appropriate fishing gears, baits and tactics (e.g. very large hooks, immediate hook setting after a bite) to reduce deep hooking and the catch of undersized eels, ultimately promoting the eel's conservation

Tracking integrated ecosystem assessments in the ICES network: a social network analysis of the ICES expert groups

The advice the International Council for the Exploration of the Sea (ICES) provides to its member countries is crucial for the sustainable management of shared marine resources, and the conservation of relevant marine ecosystems. In 2014, ICES made a strategic decision to integrate marine and social sciences in a new type of assessment framework called “integrated ecosystem assessments” (IEA) to deliver advice on societal trade-offs between different policy options. The IEA-focused expert groups formed before and after this period now cover all major ecoregions. To track the progression of IEAs in the ICES network over time, we conducted a social network analysis (SNA) on expert group attendance for the years 2015–2019. The IEA-focused expert groups generally ranked lower in the overall ICES network. Our study shows that some IEA-groups become more connected over time, while others decline. We also evaluated the role of workshops in the ICES network, particularly their role in the development of IEA knowledge. Our study shows that workshops play an important role in ICES network connectivity. The study demonstrates how social network analysis can be used to study an organization such as ICES and determine the effectiveness, or impact, of that organizational function.publishedVersio

HERRING Governance Report Herring network institutions and governance

The Governance Report presents the research about the governance framework in which the various aspects and sectors that are relevant for spawning ground management are embedded.https://commons.wmu.se/herring/1002/thumbnail.jp

Estimating and mitigating post-release mortality of European eel by combining citizen science with a catch-and-release angling experiment

Several anguillid eel species have experienced severe population declines over the past decades, particularly the European eel (Anguilla anguilla), which is listed as critically endangered by the International Union for Conservation of Nature. To reduce fishing mortality, many European countries have introduced strict recreational eel fishing regulations increasing regulatory catch-and-release (C&R) practice. Despite high release rates, only limited information exists on the potential consequences of C&R on eels. A field experiment was conducted with pre-tagged eels in a semi-natural environment to investigate lethal and sublethal impacts of C&R. The experiment was combined with a citizen science study evaluating the effects of different hooks on catch rates, fish size, and hooking location to develop best practice guidelines. Short-term mortality (≤72 h) ranged from 0.0–18.2%, and adjusted long-term mortality (>72 h) from 0.0–46.2% depending on treatments, resulting in adjusted total mortality rates between 8.4% and 64.4% at the end of the study period (≥43 d). The only significant predictor of mortality was the occurrence of bleeding from hooking injuries. Deep hooking was common, and only few deep-hooked eels for which the fishing line was cut and the hook left in place shed the hook after release. However, no significant effect of C&R on eel condition was found. The citizen science study showed that anglers can significantly decrease the catch of small eels, and thus release rates, by using large J-hooks. Furthermore, large J-hooks or circle hooks reduced the likelihood of deep hooking compared to small J-hooks. Post-release mortality of eels caught in recreational fisheries needs to be considered in future stock assessments and management plans to ensure conservation of the European eel. This study also highlights the strength of combining citizen science with experimental studies to develop best practice guidelines promoting fish conservation.publishedVersio

The impact of marine recreational fishing on key fish stocks in European waters

Marine recreational fishing (MRF) has been shown to substantially contribute to fishing mortality of marine fish. However, European MRF catches are only quantified for a small number of stocks, so it is unclear whether a significant part of fishing mortality is excluded from stock assessments. This study estimated: (i) European MRF removals, which were defined as landings plus dead releases; and (ii) impact at stock level by comparing the percentage contribution to total removal by MRF and commercial fishing. As MRF data were limited for some European countries, catches were reconstructed using a mixture of average release proportions, average fish weights, and extrapolation using the catch per fisher of the nearest country providing catch estimates. Where catch reconstructions exceeded 50%, data were excluded from further analysis. Furthermore, as MRF survey methodology can be variable, semi-quantitative estimates of bias and error were calculated for each stock. Only 10 of the 20 stocks assessed in this study had sufficient MRF data for full reliable estimates. Percentage contribution to total removals (MRF + commercial removals) by MRF ranged between 2% for Atlantic mackerel in the North Sea and Skagerrak and 43% for Atlantic pollack in the Celtic Seas and English Channel. The biomass removed ranged between 297 (± 116) tonnes (Atlantic cod in the western English Channel and southern Celtic seas) and 4820 (± 1889) tonnes (Atlantic mackerel in the North Sea and Skagerrak), but the errors were substantial. Additionally, the bias in the estimated removals was low for most stocks, with some positive biases found. The present study indicates that removals by MRF can represent a high proportion of the total removals for some European marine fish stocks, so inclusion in stock assessments should be routine. To achieve this, regular surveys of MRF are required to collect data essential for stock assessments

HERRING : An analysis of spawning ground management, ecological conditions and human impacts in Greifswald Bay, Vistula Lagoon and Hanö Bight.

This book compiles the findings of the HERRING project which was conducted from 2012 until 2015 and part-financed by the EU South Baltic Programme. The main objective of the HERRING project is to improve the consideration of including herring spawning grounds in coastal management. Herring as a resource recourse would be part of the economic development of coastal areas, and HERRING strongly emphasizes the importance of foster an integrated coastal management in the South Baltic Sea. Three case study areas in Germany, Poland and Sweden serve as the basis of the approach, which can be roughly distinguished in two parts. The analysis of the ecological parameters and conditions as well as the impacts of present and future human activities, spatial uses and natural changes The analysis and compilation of the multi-level institutions and manage- ment instruments that govern the use and protection of coastal herring spawning grounds. The management of coastal spawning areas can function as an example to show the huge diversity of interest, demands and actors that need to be considered for the sustainable use of resources and ecosystems.https://commons.wmu.se/mer_book/1002/thumbnail.jp

Recreational sea fishing in Europe in a global contextParticipation rates, fishing effort, expenditure, and implications for monitoring and assessment

Marine recreational fishing (MRF) is a high-participation activity with large economic value and social benefits globally, and it impacts on some fish stocks. Although reporting MRF catches is a European Union legislative requirement, estimates are only available for some countries. Here, data on numbers of fishers, participation rates, days fished, expenditures, and catches of two widely targeted species were synthesized to provide European estimates of MRF and placed in the global context. Uncertainty assessment was not possible due to incomplete knowledge of error distributions; instead, a semi-quantitative bias assessment was made. There were an estimated 8.7 million European recreational sea fishers corresponding to a participation rate of 1.6%. An estimated 77.6 million days were fished, and expenditure was Euro5.9 billion annually. There were higher participation, numbers of fishers, days fished and expenditure in the Atlantic than the Mediterranean, but the Mediterranean estimates were generally less robust. Comparisons with other regions showed that European MRF participation rates and expenditure were in the mid-range, with higher participation in Oceania and the United States, higher expenditure in the United States, and lower participation and expenditure in South America and Africa. For both northern European sea bass (Dicentrarchus labrax, Moronidae) and western Baltic cod (Gadus morhua, Gadidae) stocks, MRF represented 27% of the total removals. This study highlights the importance of MRF and the need for bespoke, regular and statistically sound data collection to underpin European fisheries management. Solutions are proposed for future MRF data collection in Europe and other regions to support sustainable fisheries management.Institut Francais de Recherche pour l'Exploitation de la Mer; French Ministry of Fisheries Management; Greek National Data Collection Programme; European Commission, Data Collection Framework; Department for Environment, Food and Rural Affairs [MF1221, MF1230, MI001]; Norges Forskningsrad [267808]; State Department of Agriculture, Food Security and Fisheries Mecklenburg-Western Pomerania; Interreg IVa 2 Seas; Dutch Ministry of Economic Affairs; European Fishery Fund; Government of Galicia [ED481B2014/034-0

Global responses to the COVID-19 pandemic by recreational anglers: considerations for developing more resilient and sustainable fisheries

The global COVID-19 pandemic resulted in many jurisdictions implementing orders restricting the movements of people to inhibit virus transmission, with recreational angling often either not permitted or access to fisheries and/or related infrastructure being prevented. Following the lifting of restrictions, initial angler surveys and licence sales suggested increased participation and effort, and altered angler demographics, but with evidence remaining limited. Here, we overcome this evidence gap by identifying temporal changes in angling interest, licence sales, and angling effort in world regions by comparing data in the 'pre-pandemic' (up to and including 2019); 'acute pandemic' (2020) and 'COVID-acclimated' (2021) periods. We then identified how changes can inform the development of more resilient and sustainable recreational fisheries. Interest in angling (measured here as angling-related internet search term volumes) increased substantially in all regions during 2020. Patterns in licence sales revealed marked increases in some countries during 2020 but not in others. Where licence sales increased, this was rarely sustained in 2021; where there were declines, these related to fewer tourist anglers due to movement restrictions. Data from most countries indicated a younger demographic of people who participated in angling in 2020, including in urban areas, but this was not sustained in 2021. These short-lived changes in recreational angling indicate efforts to retain younger anglers could increase overall participation levels, where efforts can target education in appropriate angling practices and create more urban angling opportunities. These efforts would then provide recreational fisheries with greater resilience to cope with future global crises, including facilitating the ability of people to access angling opportunities during periods of high societal stress.CG and CS received funding from the Danish Rod and Net Fish Licence funds (project 39122). CS, MSW and the German telephone survey have been cofounded by the European Commission’s Data Collection Framework (DCF). WCL and HVS received financial support from the Federal Ministry of Education and Research of Germany in the framework of marEEshift (project no. 01LC1826B). WMP and KH were supported by the One Ocean Hub, an independent programme for collaborative research for development, funded by UK Research and Innovation (UKRI) through the Global Challenges Research Fund (GCRF).Peer reviewe