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Sustainable management of lakes requires us to overcome ecological, economic, and social challenges. These challenges can be addressed by focusing on achieving ecological improvement within a multifaceted, co‐beneficial context. In‐lake restoration measures may promote more rapid ecosystem responses than is feasible with catchment measures alone, even if multiple interventions are needed. In particular, we identify restoration methods that support the overarching societal target of a circular economy through the use of nutrients, sediments, or biomass that are removed from a lake, in agriculture, as food, or for biogas production. In this emerging field of sustainable restoration techniques, we show examples, discuss benefits and pitfalls, and flag areas for further research and development. Each lake should be assessed individually to ensure that restoration approaches will effectively address lake‐specific problems, do not harm the target lake or downstream ecosystems, are cost‐effective, promote delivery of valuable ecosystem services, minimize conflicts in public interests, and eliminate the necessity for repeated interventions. Achieving optimal, sustainable results from lake restoration relies on multidisciplinary research and close interactions between environmental, social, political, and economic sectors.

Er der forskelle mellem landsdele og en mulig tilbagegang?

Overlevelsen og trivslen for genudsatte fisk afhænger af, om fisken bliver behandlet skånsomt i forbindelse med fangst og håndtering - DTU Aqua har samlet en række anbefalinger til skånsomt catch and release-lystfiskeri.

Fangstjournalen er gået ind i sit ottende leveår og vi præsenterer her nogle nøgletal for 2023

Fangstjournalen er omdrejningspunkt for en undersøgelse der skal skabe større viden om, hvad der kommer ud af de mange tusinde ørrede, der bliver udsat i Danmark hvert år.

En undersøgelse blandt danske lystfiskere viser, at fiskeri ved kysten er det absolut mest populære, og at laksefisk oftest er målet for fisketuren.

Large reductions in fish biomass are common both as a method of managing lake ecosystems by fish removals (biomanipulation), and as naturally occurring fish kills. To further understand how fish reductions change feeding patterns of fish we studied the diets of small-medium sized roach (Rutilus rutilus) and European perch (Perca fluviatilis) on a monthly basis using gut-content analysis during an 18-month period before and following a whole lake fish removal in a eutrophic shallow lake. Further, we performed in-depth analyses of zoobenthos communities of the profundal and littoral zones, as well as analyzing the zooplankton community in the littoral and pelagic part of the lake to estimate abundance and biomass of potential diet items. We found that, in general, there was a trend towards increased zoobenthivory in both species and among all sized fish after the fish removal, regardless of prior diet preference. Reduced piscivory among larger perch (>150 mm), and reduced zooplanktivory among smaller perch and roach (

It is well recognized that COVID-19 lockdowns impacted human interactions with natural ecosystems. One example is recreational fishing, which, in developed countries, involves approximately 10% of people. Fishing licence sales and observations at angling locations suggest that recreational fishing effort increased substantially during lockdowns. However, the extent and duration of this increase remain largely unknown. We used four years (2018-2021) of high-resolution data from a personal fish-finder device to explore the impact of COVID-19 lockdowns on angling effort in four European countries. We show that relative device use and angling effort increased 1.2-3.8-fold during March-May 2020 and generally remained elevated even at the end of 2021. Fishing during the first lockdown also became more frequent on weekdays. Statistical models explained 50-70% of the variation, suggesting that device use and angling effort were relatively consistent and predictable through space and time. Our study demonstrates that recreational fishing behaviour can change substantially and rapidly in response to societal shifts, with profound ecological, human well-being and economic implications. We also show the potential of angler devices and smartphone applications for high-resolution fishing effort analysis and encourage more extensive science and industry collaborations to take advantage of this information.

Maj måneder er højsæson for lystfiskeri efter fladfisk

Hornfiskebarometeret i Fangstjournalens app er netop blevet opdateret med nyt layout og det viser, at sæsonen er i fuld gang.

Laksefiskeriet i de jyske åer er i fuld gang.

Bliver der hjemtaget flere kyst-havørreder end tidligere?

Foreningerne AROS, Hadsten Lystfiskeriforening og Berringbro og Omegns Sportsfiskerforening samarbejder nu med Fangstjournalen om indsamling af data omkring lystfiskernes fisketure. Foreningerne får derved mere viden om deres fiskevand og de tilhørende fiskebestande.

Fangstjournalen fungerer nu som platofrm for indrapportering i alle 8 sammenslutninger, der organiserer laksefiskeriet i de vestvendte vandløb.

Fangstjournalens tidsserier om fiskeri og fangster er vigtige, hvis man i fremtiden vil have mulighed for, at kunne dokumentere ændringer i fiskebestandene.

Denne rapport omfatter resultaterne af tre delprojekter, der blev gennemført med støtte fra European Maritime and Fisheries Fund (EMFF) i perioden 2019-2022. Projektet omhandler arterne ål (Anguilla anguilla) og havørred (Salmo trutta). For åls vedkommende forsøges der at svare på spørgsmål vedrørende udvandringen af blankål fra Østersøen og risikoen for at blive fanget i det danske fiskeri. For havørred ønskes viden om omfanget af skarvprædation på unge ørreder på kysten samt viden om omfanget af såkaldt Catch and Release (C&R) lystfiskeri på havørreder på kysten, og hvordan C&R påvirker fiskene efter genudsætning. Udvandring og fangst af blankål i dansk farvand blev undersøgt i fællesskab med øvrige forskningsinstitutioner i Østersøområdet via et samarbejde, som blev indledt i 2019. Nærværende rapport omhandler de af EMFF-finansierede mærkninger, hvor blankål mærket af DTU Aqua og svenske SLU Aqua i 2019, kan anvendes til at estimere fiskeritrykket på blankål i danske farvande. I alt 248 ål blev mærket med elektroniske (akustik) mærker på hhv. Yxlö (103 ål), Svartö (72 ål) og Utlängän (73 ål) langs den svenske Østersøkyst i august-oktober 2019. Det elektroniske mærke udsender et unikt, kodet signal hvert minut, som kan registreres af hydrofoner. Ved at opstille hydrofoner, som kan monitere bundgarnsfiskeriers fangster af elektronisk mærkede ål og samtidig opstille rækker (arrays) af hydrofoner på tværs af Lillebælt, Storebælt og Øresund, kunne det registreres, hvor mange mærkede ål der hhv. fangedes af de overvågede bundgarnsfiskerier eller lykkedes med at vandre ud af Østersøen. Af de 103 mærkede ål fra Yxlö, som er det nordligste udsætningspunkt, blev ganske få (8 stk.) individer registreret på hydrofonerne i Øresund eller Bælterne, og derfor vil disse ål ikke indgå i analyserne. I alt 84 individer (58%) af de 145 øvrige mærkede ål trak ud af Østersøen, og 82 (98%) af disse vandrede ud af Østersøen gennem Øresund. Det tog i gennems

Sea trout (anadromous brown trout, Salmo trutta L.) is a popular recreational angling target species in the Baltic Sea region and beyond. Across countries, a substantial part of angled sea trout is released after capture either due to management regulations or due to voluntary decisions by the anglers. However, information about post-release impacts of catch and release (C&R) on survival and growth in saline waters is largely missing. We used a flow-through seawater raceway (4–10 °C) to investigate impacts on survival and growth of angled and released sea trout (< 40 cm) up to 29 days post release. Bleeding was common among angled sea trout, but differed between angling treatments, i.e., lure fishing with treble hook (size 4), lure fishing with single hook (size 1/0) and fly fishing with single hook (size 12). However, no mortality and no significant differences in growth were found after a 26–29 days monitoring period among a control group and the three treatment groups, but a small subset (6%) of the angled fish caught on lure had unhealed/infected hooking wounds at the end of the experiment. The results infer that adverse effects of C&R on coastal sea trout due to high post-release mortality or reduced growth can be limited and may not pose a significant problem for sea trout stocks. Nevertheless, further studies are required to corroborate these results under more natural field conditions and at higher water temperatures. In addition, further studies on long-term sublethal impacts of C&R on sea trout are needed.

Despite the widespread use of stock enhancements to improve fisheries across the world, there is a lack of robust knowledge under which conditions fish stocking provides additive effects rather than merely replacing a fraction of natural recruitment. Fully controlled and replicated studies at the level of entire ecosystems are needed to provide answers. Properly monitored experimental releases also allow testing mechanisms of density- and size-dependent population regulation. In this study, the population-level outcome of stocking juvenile pike (Esox lucius L.) in naturally reproducing lentic stocks was investigated. We used a replicated before-after-control-impact design in 15 experimental lakes involving two stocking densities and unstocked controls. Releasing age-0 pike failed to generate additive effects at the age-2 cohort. As expected from theory, we observed density-dependent mortality and differential survival of wild and stocked pike. Stocked and wild fishes showed contrasting responses in terms of growth to variation in predator density, competitor density and the forage base, suggesting both subpopulations differed in their response to stocking-induced changes in population traits (e.g., density). Despite the lack of additive effects caused by stocking, a fraction of the stocked individuals established in the stock-enhanced cohort, indicating that replacement of wild recruits by stocked conspecifics had occurred. Depending on the origin of the stocking material, pike stocking thus has the potential for genetic hybridization, while not necessarily benefiting fisheries catch. We conclude that whenever a natural pike population exists, stocking juvenile pike will not produce additive effects in lakes and that enhanced pike populations will be strongly regulated by size- and density-dependent juvenile mortality and less by density-dependent growth.

Formålet med denne rapport er at lave en opsamling af viden, der belyser de dyrevelfærdsmæssige konsekvenser af catch and release (herefter kaldet C&R) i forbindelse med lystfiskeri. Genudsætning af fisk foregår i de fleste typer af fiskerier, herunder bl.a. kommercielt fiskeri, fritidsfiskeri med redskaber som ruser og garn og lystfiskeri med stang og snøre. Betegnelsen C&R anvendes generelt i forbindelse med lystfiskeri, hvor fangsten genudsættes. Det er udelukkende denne type af fiskeri, der behandles i denne rapport. Overordnet kan der være flere årsager til at fisk genudsættes, herunder lovmæssige, i) fisken opfylder ikke målkravet (den kan f.eks. være under målet og skal derfor genudsættes), ii) arten er fredet (pga. fredningstid eller kvoten er opbrugt) eller frivillige hvor iii) fiskeren, af forskellige årsager, ønsker at genudsætte fisken, selvom det lovmæssigt er tilladt at hjembringe den1,2. Parametrene sult, ubehag, frygt, sygdom/skade samt udtryk af normal adfærd anvendes ofte til at beskrive dyrevelfærd3. Hvorvidt fisk føler ubehag og frygt debatteres fortsat4–9, bl.a. fordi der er et vist kognitivt element involveret i dette, og det er således ikke noget, der os bekendt er undersøgt i forbindelse med C&R. Flere studier måler på stressfaktorer, og det er antageligvis disse undersøgelser, der kommer tættest på en estimering af ubehag og frygt. Sult er ligeledes en vanskelig parameter at måle på fisk, men da de fleste fiskearter vokser hele livet, er det et godt alternativ at måle på væksten. Flere undersøgelser kigger således på, om C&R påvirker fiskenes vækst. Den skade, der evt. påføres fisken i forbindelse med C&R kan både komme fra krogen (fysisk skade), fighten (fysiologisk udmatning) og håndteringen (både fysisk skade og fysiologisk effekt). Er denne skade tilstrækkelig alvorlig, kan fisken dø. Da overlevelse er relativt let målbar, fokuserer mange C&R-studier på d