Climate-induced shifts in zooplankton communities can influence the survival and recruitment of commercially important fishes worldwide by altering the prey field, potentially causing severe food limitation. Due to the recruitment failure of the western Baltic herring stock over the last decade, we investigated the role of zooplankton and potential environmental drivers of early life stage survival in a major nearshore nursery area in the western Baltic Sea. The seasonal synchrony between predator and prey structures annual secondary production. However, studying the cause-and-effect relations is challenging, as many monitoring programs are static in time and limited to a short period every year. We analysed weekly data from 2008 to 2020, including zooplankton density and community composition together with herring larvae survival. Larval herring productivity has been notably low in recent years, particularly since 2014, reaching a record low in 2020. Annual mean total zooplankton density has also decreased drastically, with the largest decline (~84%) occurring between 2012 and 2013. This decrease was predominantly seen in small organisms (copepod nauplii, bivalve veligers, and rotifers). The total density of these major prey organisms was positively correlated with the larval herring survival index for early herring life stages. The decrease in zooplankton taxa density was most likely induced by changes in phytoplankton phenology expressed by earlier seasonal chlorophyll a peaks. Using these high-resolution time series, we provide a potential mechanism of cascading climate change effects on the survival of young herring in the western Baltic Sea.

Coastal fisheries in Germany are undergoing significant structural changes. Key challenges include the declining productivity of commercially important fish and shellfish stocks, the loss of traditional fishing grounds, a dwindling interest of the younger generation to become fishers, high fuel prices, and an aging fishing fleet. In this context, a workshop was convened to develop a future vision for German coastal fisheries. This study builds upon the findings of the “Future Workshop Coastal Fisheries 2024,” where nine core elements were discussed by participants: diversification strategies for fishers, fishers’ training, technological advancements, fisheries management, fleet capacity, recreational fisheries, aquaculture, marine protected areas, and offshore wind farms. Our interdisciplinary team of authors described these elements in light of current knowledge, critically examined their implications, and explored potential implementation strategies. Three perspectives were then identified: the resource user perspective, the marine resource management perspective, and the spatial dimension. Our findings underline the necessity of an interdisciplinary and transdisciplinary approach of integrating fisheries into a multi-use concept of marine space in the future. This research contributes to the fields’ future research, while offering foundational knowledge about the present state of research on specific aspects of German fisheries. This study also provides valuable insights for policymakers, practitioners, and stakeholders in other EU countries undergoing fisheries transformations.

We reflect on the innovation process that led to the development of the pulse trawl that was successfully trialed at a commercial scale, but eventually ended with the European Parliament passing legislation to ban its use. The ban was imposed despite published and emerging evidence that suggested that the environmental performance and catch efficiency of the pulse trawl was superior to the conventional beam trawl design. We used a stakeholder questionnaire to understand which factors undermined wider acceptance of the pulse trawl. The main factors where a lack of involvement of certain key stakeholders earlier in the process that would have ensured better co-development of innovation and a shared vision of the environmental or governance questions that needed to be addressed. Although the stakeholder process itself was seen to be positive, it was implemented too late in the innovation process, as was the implementation of an independent peer review process. We conclude by identifying a pathway for future fishing gear innovation processes that integrate the lessons learnt from the pulse trawl innovation process.

There is a lack of data on the experience of the use of mobile devices in commercial small-scale fisheries but which are important to evaluate the suitability of these approaches for fisheries monitoring. In February and March 2018, the German Baltic small-scale fishery used a smartphone application for self-reporting of fishing activities to demonstrate compliance with the terms of a fishing closure of cod, which prohibited to fish deeper than 20 m. A total of 1618 trips and 7972 gear activities from 107 vessels were identified and categorized. Data review showed that not all data could be used directly due to operating or technical errors (e.g. mismatch in time and space of self-reported and actual gear activities and missing records on geographical positions). By editing during data evaluation, the proportion of useable trips and gear activities increased from 67 to 78% and from 29 to 69%, respectively. These data provided new insights into the activities of small-scale fishing vessels (<12 m), especially of the data-poor segment of vessels smaller than 8 m (e.g. for gillnets: mean net length of 664 m +/- 538 SD, mean soak time of 30 h +/- 12.9 SD, mean trip duration of 2.9 h +/- 1.6 SD). Due to the high spatio-temporal resolution, the fishers could demonstrate compliance with the closure, with 99% of all recorded gear activities performed in areas shallower than 20 m. Based on the fast and short operation at sea observed, recording intervals of max. 1 min are advisable for small-scale vessels. Potential suggested improvements involve training of fishers, an independent GPS sensor, a remote control and tailored tools for data analysis to properly address future developments of smartphone applications for the use in data collection in small-scale fisheries.

Globally, marine recreational fishing is a popular activity that contributes substantially to fishing mortality for some stocks and therefore should be considered in stock assessments and fisheries management. Using the example of the German western Baltic Sea recreational cod fishery, this study examines the effects of the first-time introduction of a bag limit on a previously largely unregulated marine recreational fishery. Furthermore, the study simulates and compares effects of different bag limits, seasonal closures, minimum length, and harvest slot limits to inform scientists, stakeholders, and managers about alternative management strategies and their potential effects on the fishery. After the first-time introduction of the bag limit, recreational removals decreased more than expected and the fishing participation slightly declined. The simulations showed that management measures adapted to the fishing methods reduced recreational removals but with different effects on cod length distributions and angler welfare. A combination of a high bag limit, seasonal closure and size/slot limits were most suitable for limiting cod removals with minimal impacts on angler welfare. This study demonstrates that recreational fisheries management measures need to be evaluated considering fishing methods and angler preferences before their implementation to avoid unexpected biological, social, and economic consequences.

Shallow estuaries, bays, and lagoons are generally considered hot spots of ocean productivity that often adjust rapidly to seasonal variations in atmospheric temperatures. During spring when biological reproductive processes begin in the temperate zones, regional climate variability can be immense and uncovering a non-linear biological response, such as fish recruitment to changing temperature regimes might be challenging. Using herring as a paradigm for a response of coastal spring productivity to regional climate drivers, we demonstrated how the annual timing of spawning periods can significantly affect the reproductive success of spring-spawning herring (Clupea harengus) in the western Baltic Sea. An investigation of spawning phenology in consecutive years indicated a temperature threshold range of 3.5–4.5°C triggering initial spawning in the coastal zone. Based on this finding, we analyzed the timing of larval hatching peaks, larval survival and recruitment to the adult population relative to multi-decadal time-series of seasonal sea-surface temperatures. The results revealed that the late seasonal onset of cold periods the corresponding elongation of the period where larvae hatch from the eggs and early larval hatching peaks significantly reduced larval production in a coastal nursery area and finally lead to a reduced abundance of juveniles in the entire distribution area. Using a combination of field research and time series analysis, we presented precedence for shifting regional winter regimes providing a present-day stressor to reproductive capacity of a central component of the coastal food web.

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.

Erratum zu: G. Hempel, K. Bischof, W. Hagen (Hrsg.), Faszination Meeresforschung, https://doi.org/10.1007/978-3-662-49714-2 Aufgrund aktueller Entwicklungen ist es notwendig die Abbildungen 39.2 , 39.3 , 39.5 und deren Bildunterschriften zu aktualisieren. Außerdem wurde die folgende Literaturstelle im Kapitel ergänzt. ICES (2019) ICES Stock Assessment Database. Copenhagen, Denmark. ICES. [01.11.2019]. http://standardgraphs.ices.dk Springer-Verlag GmbH Deutschland 2019

Despite regular reforms, problems under the EU's Common Fisheries Policy (CFP) persist. In order to identify priorities for future reforms of the policy, we developed an analytical framework consisting of 17 criteria and specifying indicators, derived from scientific, wider fisheries, and common resources literature. We applied the framework to the CFP governance system, its regulations, institutions, and processes at EU as well as member state level. The results show that the CFP does not fully meet any of the 17 criteria for an effective resource policy. Its performance was assessed as "neutral" regarding 10 criteria and "negative" regarding seven criteria. Trend analysis shows that there is a slightly positive trend regarding the CFP's performance, with five criteria trending positively, 11 showing a neutral trend and only one criterion trending negatively (simplicity of rules). The analysis identified five criteria which are performing badly and have not improved over time: simplicity of rules, user-pays principle, resource efficiency, accountability, and compliance mechanisms. Future reforms of the CFP should first and foremost address these criteria while continuing efforts to improve the CFP's performance regarding other criteria. The evaluation of the CFP demonstrates the applicability of the analytical framework which can also be applied to other multilevel fisheries governance systems. Moreover, the results can inform reforms of Regional Fisheries Management Organisations. Like the CFP, these institutions manage transboundary fisheries and have not effectively addressed the issues of resource rent capture and resource efficiency.

Fisheries management measures often include spatio-temporal closures during the spawning period of the fish with an overarching aim of improving the stock status. The different mechanisms how a spawning closure potentially can influence the stock are often not explicitly considered when designing such closures. In this paper, we review and synthesize the available data and knowledge on potential effects of the implemented spawning closures on cod in the Baltic Sea. The Baltic cod example represents a relatively data rich case, which allows demonstrating how a closure might affect different parameters of stock status via different mechanisms, including potential unintended negative effects. We conclude that designing relatively small area closures appropriately is highly complex and data demanding, and may involve tradeoffs between positive and negative impacts on the stock. Seasonal closures covering most of the stock distribution during the spawning time are more robust to data limitations, and less likely to be counterproductive if suboptimally designed.

General information Publication status: Published Organisations: Section for Ecosystem based Marine Management, National Institute of Aquatic Resources, Section for Monitoring and Data, Public Sector Consultancy Contributors: Mortensen, L. O., van Helmond, A., Schreiber Plet-Hansen, K., Ulrich, C., Needle, C. L., Oesterwind, D., Kindt-Larsen, L., Catchpole, T., Mangi, S., Zimmermann, C., Olesen, H. J., Bailey, N., Bergsson, H., Dalskov, J., Elson, J. , Hosken, M., Poos, J. J. Publication date: 2018 Peer-reviewed: No Event: Abstract from ICES Annual Science Conference 2018, Hamburg, Germany.

The eastern Baltic (EB) cod (Gadus morhua) stock was depleted and overexploited for decades until the mid-2000s, when fishing mortality rapidly declined and biomass started to increase, as shown by stock assessments. These positive developments were partly assigned to effective management measures, and the EB cod was considered one of the most successful stock recoveries in recent times. In contrast to this optimistic view, the analytical stock assessment failed in 2014, leaving the present stock status unclear. Deteriorated quality of some basic input data for stock assessment in combination with changes in environmental and ecological conditions has led to an unusual situation for cod in the Baltic Sea, which poses new challenges for stock assessment and management advice. A number of adverse developments such as low nutritional condition and disappearance of larger individuals indicate that the stock is in distress. In this study, we (i) summarize the knowledge of recent changes in cod biology and ecosystem conditions, (ii) describe the subsequent challenges for stock assessment, and (iii) highlight the key questions where answers are urgently needed to understand the present stock status and provide scientifically solid support for cod management in the Baltic Sea.

The ICES Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD), chaired by External Chair Jean-Jacques Maguire, Canada and ICES Chair Marie Storr-Paulsen, Denmark, and attended by two invited externa ...

Margit Eero1*, Joakim Hjelm2, Jane Behrens1, Kurt Buchmann3, Massimiliano Cardinale2, Michele Casini2, Pavel Gasyukov4, Noél Holmgren5, Jan Horbowy6, Karin Hüssy1, Eskild Kirkegaard7, Georgs Kornilovs8, Uwe Krumme9, Friedrich W. Köster1, Rainer Oeberst9, Maris Plikshs8, Krzysztof Radtke6, Tiit Raid10, Jörn Schmidt11, Maciej T. Tomczak12, Morten Vinther1, Christopher Zimmermann9, and Marie Storr-Paulsen1 National Institute of Aquatic Resources, Technical University of Denmark, Jægersborg Alle 1, DK2920 Charlottenlund, Denmark Department of Aquatic Resources, Institute of Marine Research, Swedish University of Agricultural Sciences, Turistgatan 5, 45330 Lysekil, Sweden Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 7, 1870 Copenhagen, Denmark AtlantNIRO, 5 Dmitry Donskogo Street, RU-236000 Kaliningrad, Russian Federation Systems Biology Research Center, University of Skövde, SE-541 28 Skövde, Sweden National Marine Fisheries Research Institute, ul. Kollataja 1, 81-332 Gdynia, Poland International Council for the Exploration of the Sea (ICES), H. C. Andersens Boulevard 44-46, 1553 Copenhagen, Denmark Institute of Food Safety, Animal Health and Environment “BIOR”, Daugavgrivas Str. 8, LV-1048 Riga, Latvia Thünen Institute of Baltic Sea Fisheries, Alter Hafen Sued 2, 18069 Rostock, Germany Estonian Marine Institute, University of Tartu, Mäealuse 14, EE-12618 Tallinn, Estonia Department of Economics, Christian-Albrechts University of Kiel, Wilhelm-Seelig Platz 1, D-24118 Kiel, Germany Stockholm University, Baltic Sea Centre, SE 106 91 Stockholm, Sweden *Corresponding author: tel: + 45 3588 3318; fax: + 45 3588 3333; e-mail: mee@aqua.dtu.dk.

The recruitment success of some herring stocks fluctuates strongly, and apparently, success is often already determined during the early life stages, i.e. before metamorphosis. In studying the survival of early life stages and its affecting factors, particularly those during the egg stage, it is crucial to examine the processes at the spawning sites, which often cannot be explored directly. A recent decline in the recruitment of Western Baltic spring-spawning herring (WBSSH) increases the urgency of filling the knowledge gap for this stock, especially because one bottleneck in the recruitment seems to occur before hatching. We examined the successful 20032009 spawning sites of WBSSH in the main spawning ground, the Greifswalder Bodden lagoon. Instead of using common techniques such as diving or underwater videography, which are usually unsuitable for mapping large areas, we applied a model approach. We tracked herring larvae at length 610 mm, recorded by larval surveys during MarchJune of the respective years, back to their hatching sites using a Lagrangian particle backtracking model. We compared the spawning areas identified by the model with the results of earlier field studies; however, we also analysed variations between years, larval length groups, and different applied growth models, which are needed to define hatch-dates. Although spawning sites could not be identified with high precision because of the strong diffusion in the area studied, results indicate that larvae up to 10 mm length are caught near their hatching sites. However, the location of successful spawning sites varied largely between years, with the main hatching sites situated in the Strelasund and the eastern entrance of the lagoon. This may reflect variations in spawning-site selection or quality. A better knowledge of the locations and relative importance of, and the processes occurring on, the different spawning sites will provide an important contribution to the sustainable management of this commercially valuable herring stock.