2019
  PDF

Improvement of the biological advice for Common Sole in Danish waters

År: 2019

This projected was originally applied for in 2016 under the program Fiskeri, natur og miljø EHFF. The project was granted from 01-04-2016 to 05-08-2018, and extended to 31-12-2018 (in an application from 14-12-2017).
The scope of the project was to improve the biological advice on soles in Skagerrak, Kattegat, the Belts and Western Baltic. Sole is a small but very valuable fish important to fisheries. Therefore, the stock assessment on sole is important for the commercial fisheries. In the autumn of 2015, a benchmark for the sole stock in the Danish waters was carried out improving the precision of biomass estimates and estimates of fisheries pressure. Based on this revised assessment, it also became clear that knowledge on spawning areas and areas for juvenile sole is sparse and may introduce a potential error in the assessment. Furthermore, regional differences in growth rates and mortality are not well-known. In order to minimize these potential errors, this project was set up to include analyses of extended surveys, new initiatives to collaborate directly with the fishermen as well as include results of using new fishing gear technology. The intention was to improve not only stock assessment but also improve the basis for the fisheries management.
The report presented in this document is a direct outcome of the project documenting the achieved goals. The results are to be included in the on-going ICES working group on sole (WGBFAS) and be used in the forthcoming benchmark process.
Original languageEnglish
Place of PublicationKgl. Lyngby
PublisherTechnical University of Denmark (DTU)
Number of pages122
ISBN (Electronic)978-87-7481-259-3
Publication statusPublished - 2019
SeriesDTU Aqua Report
Number337-2019
ISSN1395-8216

 

Environmental influences of life history strategies in partial anadromous brown trout (Salmo trutta, Salmonidae)

År: 2019

Environmental influences of life history strategies in partial anadromous brown trout (Salmo trutta, Salmonidae)

Nevoux, M., Finstad, B., Davidsen, J. G., Finlay, R., Josset, Q., Poole, R., Höjesjö, J., Aarestrup, K., Persson, L., Tolvanen, O. & Jonsson, B., 2019, (Accepted/In press) In : Fish and Fisheries. 32 p.

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review

This paper reviews the life history of brown trout and factors influencing decisions to migrate. Decisions that maximize fitness appear dependent on size at age. In partly anadromous populations, individuals that attain maturity at the parr stage typically become freshwater resident. For individual fish, the life history is not genetically fixed and can be modified by the previous growth history and energetic state in early life. This phenotypic plasticity may be influenced by epigenetic modifications of the genome. Thus, factors influencing survival and growth determine life-history decisions. These are intra- and interspecific competition, feeding and shelter opportunities in freshwater and salt water, temperature in alternative habitats and flow conditions in running water. Male trout exhibit alternative mating strategies and can spawn as a subordinate sneaker or a dominant competitor. Females do not exhibit alternative mating behaviour. The relationship between growth, size and reproductive success differs between sexes in that females exhibit a higher tendency to migrate than males. Southern populations are sensitive to global warming. In addition, fisheries, aquaculture with increased spreading of salmon lice, introduction of new species, weirs and river regulation, poor water quality and coastal developments all threaten trout populations. The paper summarizes life-history data from six populations across Europe and ends by presenting new research questions and directions for future research.
Original languageEnglish
JournalFish and Fisheries
Number of pages32
ISSN1467-2960
DOIs
Publication statusAccepted/In press - 2019

  PDF

Working Group on Technology Integration for Fishery-Dependent Data (WGTIFD)

År: 2019

Working Group on Technology Integration for Fishery-Dependent Data (WGTIFD)

Alger, B., Borges, L., Allegaert, W., Bryan, J., Bach, P., Barkai, A., Goienetxe, O. E., Fraga, A., González, Ó., Hager, M., Holah, H., Kavanaugh, J., Keaton, J., Kilburn, R., Linden, D., McAfee, B., McElderry, H., McGuire, C., McHale, B., Nuevo, M., Oesterwind, D., Schreiber Plet-Hansen, K., Rossi, N., Wallace, F., Wealti, M., Wilson, K., Garcia, E., Quincoces, I., Hetherington, S. & Cowan, B. J., 2019, Copenhagen: International Council for the Exploration of the Sea (ICES). 34 p. (ICES Scientific Report; No. 1, Vol. 46).

Research output: Book/ReportReport – Annual report year: 2019Research

The Working Group on Technology Integration for Fishery-Dependent Data (WGTIFD) met in Copenhagen, Denmark, 7-9 May 2019 for its first meeting in its three-year multi-annual cycle. WGTIFD has diverse membership including technology service providers, academic and governmental marine institutions, and non-profit environmental organizations, across a wide range of EU, US, and Canadian fisheries. The WGTIFD’s primary objective is to examine the electronic tools and applications that are used to support fisheries-dependent data collection, both on shore and at sea, including electronic reporting, electronic monitoring, positional data systems, and observer data collection. The primary objectives of the first meeting were to inventory and review the various national fisheries dependent hardware and software applications and approaches (ToR A); define and agree on consistent vocabulary on electronic technologies (ToR B); and report on developments in machine learning and computer vision technologies and their applications in fisheries dependent data collection (ToR E). The working group was able to develop a common vocabulary of terms that can be used within the ICES community, and conducted a survey of WGTIFD participants on their experience in implementing technology for monitoring and reporting programs, and their views on strategies and incentives to engage stakeholders. This Year 1 report provides a fairly robust assessment on the available electronic technologies and how they’re being used in fisheries around the world, the successes and challenges with implementing these tools, and some of the existing applications for using machine learning for processing data in fisheries. WGTIFD also started to examine the risks and benefits of different technologies (ToR C), but does not make a full assessment or recommendation at this time. The same can be said for how to integrate data from technologies (ToR D). These topics will be examined in Year 2 and will be fully reported at the end of the multi-annual cycle.

Many technologies in fisheries are relatively new, compared with traditional data collection programs, and the working group itself is new, making it difficult to determine the reach and impact of the Year 1 report. However, technology-based programs appear to be developing and expanding rapidly, and interest in future work of the group is growing too, so it is expected that the findings will have greater impact over time. Additionally, the intial work was intentional for developing a baseline of tools and vocabulary, and it is expected that work in Year 2 on exploring trade-offs of technologies and how the data is used, will be of more interest and to a wider audience. WGTIFD will be meeting in Galway, Ireland May 11-15, 2020 to expand their work.
Original languageEnglish
Place of PublicationCopenhagen
PublisherInternational Council for the Exploration of the Sea (ICES)
Number of pages34
DOIs
Publication statusPublished - 2019
SeriesICES Scientific Report
Number1
Volume46
ISSN2618-1371

Bibliographical note

ICES Scientific Report

 

From endangered to sustainable: Multi‐faceted management in rivers and coasts improves Atlantic salmon (Salmo salar) populations in Denmark

År: 2019

From endangered to sustainable: Multi‐faceted management in rivers and coasts improves Atlantic salmon (Salmo salar) populations in Denmark

Koed, A., Birnie-Gauvin, K., Sivebæk, F. & Aarestrup, K., 2019, (Accepted/In press) In : Fisheries Management and Ecology. 13 p.

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review

The status of Atlantic salmon, Salmo salar L., over the last decades has been of concern across its entire distribution area. Its anadromous nature exposes the species to human pressures in both freshwater and marine environments, and over long periods, thus exacerbating its decline. Given its value within the food industry, the recreational angling community as well as culturally, the status of Atlantic salmon is regarded as a matter of national and international conservation interest, providing great incentive for its management. The literature currently lacks specific examples of successful and unsuccessful management strategies and practices for Atlantic salmon populations at a broader scale. To address this, the present article describes how the multi‐faceted management approach taken for Danish Atlantic salmon, which included changes in legislation, stocking practices, habitat restoration, population genetics and barrier removals, successfully rehabilitated salmon populations in four major Danish rivers. Specific recommendations are provided for the successful management of Atlantic salmon elsewhere.
Original languageEnglish
JournalFisheries Management and Ecology
Number of pages13
ISSN0969-997X
DOIs
Publication statusAccepted/In press - 2019

 

Modelling the spatio-temporal bycatch dynamics in an estuarine small-scale shrimp trawl fishery

År: 2019

Modelling the spatio-temporal bycatch dynamics in an estuarine small-scale shrimp trawl fishery

Rezende, G. A., Rufener, M. C., Ortega, I., Ruas, V. M. & Dumont, L. F. C., 2019, In : Fisheries Research. 219, 105336.

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review

The Patos Lagoon estuary in Southern Brazil is an important nursery ground for many commercially important fish and invertebrate species, with shrimp fisheries sustaining most of the surrounding small-scale fishermen. Although they are illegal, trawl gears are widely used by small-scale fishermen in order to catch shrimp. Shrimp trawl fisheries in tropical waters have high bycatch rates and cause a variety of problems, spanning from conflicts with other fisheries to changes in ecosystem trophic dynamics. A better understanding of the factors driving the bycatch process is therefore needed to establish reliable management measures. Here we used hierarchical Bayesian spatio-temporal models (HBSMs) to describe the bycatch of a small-scale shrimp trawl fishery in the Patos Lagoon estuary relative to a set of environmental and spatio-temporal predictors. Two different models were used to estimate bycatch trends: an effort-based method (BPUE) and a ratio-based method (BR, bycatch rate). A third model was used to evaluate the dynamics of shrimp catch per unit of effort (CPUE) as this measure is equally important to describe the underlying bycatch process. Overall, the bycatch consisted of 61 species of which 45 have market value. The mean bycatch rate was 86.2% for the entire period, which represents 6 kg of bycatch for every 1 kg of shrimp caught. Although the contribution of environmental variables differed among the models, the yearly spatial effect was identified as a common that explained bycatch dynamics. Moreover, the predictive maps revealed consistent hot and cold-spots from year-to-year, which varied in intensity for BR, BPUE and CPUE, and, therefore, represent a valuable benchmark for stakeholders and managers.

Original languageEnglish
Article number105336
JournalFisheries Research
Volume219
ISSN0165-7836
DOIs
Publication statusPublished - 2019