| 1. |
- Andersson, Magnus, et al.
(författare)
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Fiskbestånd och miljö i hav och sötvatten : Resurs- och miljööversikt 2012
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detta är den nionde utgåvan av den samlade översikten över fisk- och kräftdjursbeståndens status i våra vatten. Kunskap om fiskbestånden och miljön är en förutsättning för att utnyttjandet av fiskresurserna skall bli bärkraftigt. För svenska vattenområden beskrivs miljöutvecklingen i ett ekosystemsperspektiv, dels för att tydliggöra fiskens ekologiska roll och beskriva yttre miljöfaktorer som påverkar fiskbestånden, dels för att belysa fiskets effekter på miljön.Fiskbestånd och miljö i hav och sötvatten är utarbetad av Sveriges lantbruksuniversitet (SLU), Institutionen för akvatiska resurser (SLU Aqua), på uppdrag av Havs- och vattenmyndigheten. Rapporten sammanfattar utveckling och beståndsstatus för de kommersiellt viktigaste fisk- och kräftdjursarterna i våra vatten. Bedömningar och förvaltningsråd är baserade på Internationella Havsforskningsrådets (ICES) rådgivning, SLU Aquas nationella och regionala provfiskedata, samt yrkesfiskets rapportering.
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| 2. |
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| 3. |
- Westerberg, Håkan, et al.
(författare)
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Properties of odour plumes from natural baits
- 2011
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Ingår i: Fisheries Research. - : Elsevier BV. - 0165-7836. ; 110:3, s. 459-464
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Tidskriftsartikel (refereegranskat)abstract
- The formation of an odour trail can be broken down into a chain of events: first, the emission of the attractant from the bait, second, a turbulent mixing into the immediate surroundings and third, a downstream advection and dispersion of the attractant by the current flowing past the bait. In this work, a simple analysis of the physical processes governing the first two stages shows that the release of attractant will decline as the inverse of the square root of time. The decline curve will be similar for all solid natural baits within a realistic size range during normal soak times. Experiments were performed to measure typical diffusion constants of odour substances in fish tissue and it is shown that due to the low diffusivity just a thin surface layer will release its content of odour substances during a fishing operation using pieces of fish as bait. Moreover, the initial concentration of attractant when a plume is formed will be independent of the size of a solid bait and only depend on the ratio of the surface area to the cross-section area of the bait. To increase the maximum concentration of odour substance in the plume and utilize a given amount of bait optimally, a solid bait should be cut into smaller pieces. The effect of current speed on the initial odour concentration in the plume is strong. Due to speed variations during the soak time the effectiveness of the attraction will vary in time. To extend the analysis and develop models for optimization of the range of the olfactory signal from a bait it is necessary to know both the concentration of the attractant in the bait and the target species detection threshold. When such data become available it will be possible to estimate the range of attraction of baits under different environmental conditions.
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| 5. |
- Westerberg, Håkan, et al.
(författare)
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Stock assessment of eels in the Baltic: reconciling survey estimates to achieve quantitative analysis
- 2016
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 73, s. 75-83
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Tidskriftsartikel (refereegranskat)abstract
- The data from two scientific surveys, where eel is part of the catch, have been studied to assess trends in recruitment and escapement to and from the Baltic. Abundance of juvenile eel was monitored in the Sound, between Sweden and Denmark, from 1992 to 2002. The total natural recruitment of new eels was estimated under the assumption that the number of juvenile eels observed in the surveys represented an accumulation of eels migrating into the Baltic. To assess the total recruitment, the stocking by imported glass eels, or transplanted juveniles from outside the Baltic, was added. Fish larvae monitoring at a nuclear power plant in the Kattegat gave an index of glass eel abundance which was well correlated with glass eel monitoring in the Sound. This was used to extrapolate the recruitment time-series to the full period from 1981 to the present. The main conclusions from the analysis were: (i) the recruitment to the Baltic region, including the contribution from stocking, has declined by 95% between 1981 and 2012. (ii) The stocking of glass eel and bootlace eel has been of the same order of magnitude as natural recruitment, averaging 25-30% of the total supply of glass eel to the Baltic, with a decreasing trend with time. (iii) The total landings in the Baltic countries have ranged from 5 to 15% of the estimated survival without anthropogenic mortality. This proportion has been stable and independent of a large decrease in potential escapement.
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| 6. |
- Ansell, Anders, et al.
(författare)
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Kap 14 - Hållfasthet
- 2021
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Ingår i: Betonghandbok Material – Del II. - Stockholm : AB Svensk Byggtjänst. ; , s. 27-188
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Bokkapitel (populärvet., debatt m.m.)
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| 7. |
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| 8. |
- Brehmer, Yvonne, et al.
(författare)
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Neural correlates of training-related working-memory gains in old age
- 2011
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 58:4, s. 1110-1120
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Tidskriftsartikel (refereegranskat)abstract
- Working memory (WM) functioning declines in old age. Due to its impact on many higher-order cognitive functions, investigating whether training can modify WM performance has recently been of great interest. We examined the relationship between behavioral performance and neural activity following five weeks of intensive WM training in 23 healthy older adults (M = 63.7 years). 12 participants received adaptive training (i.e. individually adjusted task difficulty to bring individuals to their performance maximum), whereas the others served as active controls (i.e. fixed low-level practice). Brain activity was measured before and after training, using fMRI, while subjects performed a WM task under two difficulty conditions. Although there were no training-related changes in WM during scanning, neocortical brain activity decreased post training and these decreases were larger in the adaptive training group than in the controls under high WM load. This pattern suggests intervention-related increases in neural efficiency. Further, there were disproportionate gains in the adaptive training group in trained as well as in non-trained (i.e. attention, episodic memory) tasks assessed outside the scanner, indicating the efficacy of the training regimen. Critically, the degree of training-related changes in brain activity (i.e. neocortical decreases and subcortical increases) was related to the maximum gain score achieved during the intervention period. This relationship suggests that the decreased activity, but also specific activity increases, observed were functionally relevant.
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| 9. |
- Bruckmeier, Karl, 1952, et al.
(författare)
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Findings from the case studies in the Baltic Sea reconciliation in practice : The seal conflict and its mitigation in Sweden and Finland
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This chapter presents the results of case studies on human wildlife conflicts conducted in Sweden and Finland. In both cases the model conflict is between the conservation of the grey seal (Halichoerus grypus) and small-scale coastal fishing. The cases are presented together because of the many similarities and the close interaction of the stakeholders in the seal management. Some of the similarities are, in fact, commonalities, the most important of them being the shared grey seal population and the existence of joint protection programmes (from HELCOM and EU) for the grey seal. The characteristics of the conflict between grey seal protection and fishery can be shown by way of systematic comparison between the two countries and model regions as done here. Thus one can also better see what can be learned from the comparison of the cases and use the knowledge gained for suggestions for the further management of the conflict. In future, additional conflict mitigation measurements to those currently practiced will be required. The main messages from both case studies in the Baltic Sea are formulated with regard to the significance of coastal fishery (as resource manager, not only resource user), with regard to single conflict mitigation measures, such as seal hunting and technical solutions to the conflict, and with regard to a combination of measures and overall approaches to conflict management, all of which converge to the conclusion that it is much more that can be learned from the management of the seal conflict than the resolution of that specific conflict: one by one the lessons learned turn out to be steps of a more encompassing strategy of sustainable resource management in the coastal zone.
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