| 71. |
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| 72. |
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| 73. |
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| 74. |
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| 75. |
- Palm, Stefan, et al.
(författare)
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Workshop on Baltic salmon management plan (WKBaltSalMP)
- 2020
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Rapport (refereegranskat)abstract
- This report contains the output of the International Council for the Exploration of the Seas (ICES) workshop on evaluating a draft Baltic salmon management plan (WKBaltSalMP). The main aim was to provide scientifically based responses to a special request received from the European Commission (EC). The process included two meetings attended by scientific experts, national managers and stakeholder representatives. As requested, information on river size and estimated potential productivity was compiled and updated following consultation with national experts within ICES WGBAST (Baltic Salmon and Trout Assessment Working Group). Existing and alternative reference points for assessment of stock status and fishing opportunities were also examined. The group concluded that the currently used targets (50% and 75% of the potential smolt production capacity, PSPC) are inconsistent with the overall objective in the draft plan of achieving maximum sustainable yield (MSY). As a precautionary reference point Rlim was evaluated, defined as the lowest level of smolt production from which the stock would be expected to recover to its specific MSY-level (RMSY) in one salmon generation, if all fishing was completely closed. Simulations developed specifically for the workshop allowed evaluation of requested recovery rates of individual wild salmon stocks under alternative commercial fishing scenarios. The simulations examined commercial harvest rates ranging from 0 to 0.9 (encompassing rates that gives maximum yield in the commercial sea fisheries, located between 0.2 and 0.3; Figure 5.1.1), with additional values examined below 0.1 to better illustrate impacts on less productive river stocks. Neither the EC request nor the draft multiannual plan specify criteria for when (i.e. with what probability) a target has been reached. Therefore, stock-specific tables with simulation-based probabilities of smolt production being above alternative targets for each fishing scenario are presented. These analyses only included river stocks currently assessed analytically by ICES. For remaining stocks, such river specific probabilities could not be determined. For river stocks not assessed analytically, correlative analyses between total estimated sea survival and recruitment over generations were performed. These results indicate that sea survival seem to play an important role in the development also for these stocks, similar to for those currently included in the ICES model. A simplified stable-state population dynamics model was constructed to study trade-offs between mixed (sea) and stock-specific (river) fisheries in terms of achievable catches and proportions of stocks above/below reference points. This analysis illustrated that when the mixed fishery harvest rate is low all river stocks can achieve MSY, whereas when this harvest rate increases, smaller (less resilient) stocks fall below this target. That some smaller stocks fall below MSY (or even goes towards extinction) does not make a noticeable difference to the total yield. Hence, there exists an inbuilt conflict between overall production aims and protection of weak stocks that can only be resolved if mixed-stock sea fisheries for Baltic salmon are kept at a low level. The report also contains requested comments on the draft management plan. The workshop identified that the draft has a strict focus on commercial sea fisheries, although the relative importance of recreational fisheries for Baltic salmon has increased significantly over time. The current two management units for EU commercial fisheries (subdivisions 22 to 31 and Subdivision 32) are further maintained in the draft, whereas evidence has accumulated that salmon are migrating between these areas more than previously recognized. The draft finally does not address management of hatchery-reared Baltic salmon more than marginally, despite large ongoing releases for various purposes in most countries.
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| 76. |
- Palm, V., et al.
(författare)
-
Single-molecule linewidths of terrylene in incommensurate biphenyl: Thermocycling and time-resolved experiments
- 2007
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Ingår i: Journal of Luminescence. - : Elsevier BV. - 0022-2313. ; 127:1, s. 218-223
-
Tidskriftsartikel (refereegranskat)abstract
- The purely electronic linewidth delta of terrylene impurity molecules in monocrystalline biphenyl is studied at temperatures T between 1.7 and 3.5 K using the technique of single-molecule spectroscopy (SMS). Based on the data obtained, individual molecules appear to have their own law of delta(T) dependence; further, hysteresis effects have been observed in thermocycling experiments. The single-molecule (SM) lines investigated quickly broaden and vanish at temperatures between 3 and 3.5 K and reappear after the sample is cooled down again. At T approximate to 2 K, a slow process of spectral diffusion (SD) was observed on timescales longer than 10s. To learn about the role of faster SD processes, the technique of intensity time-frequency correlation (ITFC) SMS was applied to a stable SM line after it had been broadened by 75% as a result of a thermocycling experiment. At 2 and 2.3 K, no significant line broadening could be revealed on timescales between 0.16 ms and 10s. (C) 2007 Elsevier B.V. All rights reserved.
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| 77. |
- Rogell, Björn, et al.
(författare)
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Adaptive divergence in body size overrides the effects of plasticity across natural habitats in the brown trout
- 2013
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3:7, s. 1931-1941
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of life-history traits is characterized by trade-offs between different selection pressures, as well as plasticity across environmental conditions. Yet, studies on local adaptation are often performed under artificial conditions, leaving two issues unexplored: (i) how consistent are laboratory inferred local adaptations under natural conditions and (ii) how much phenotypic variation is attributed to phenotypic plasticity and to adaptive evolution, respectively, across environmental conditions? We reared fish from six locally adapted (domesticated and wild) populations of anadromous brown trout (Salmo trutta) in one semi-natural and three natural streams and recorded a key life-history trait (body size at the end of first growth season). We found that population-specific reaction norms were close to parallel across different streams and Q(ST) was similar - and larger than F-ST - within all streams, indicating a consistency of local adaptation in body size across natural environments. The amount of variation explained by population origin exceeded the variation across stream environments, indicating that genetic effects derived from adaptive processes have a stronger effect on phenotypic variation than plasticity induced by environmental conditions. These results suggest that plasticity does not swamp the phenotypic variation, and that selection may thus be efficient in generating genetic change.
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| 78. |
- Rogell, Björn, 1979-, et al.
(författare)
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Genetic structure in peripheral populations of the natterjack toad, Bufo calamita, as revealed by AFLP
- 2010
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 11:1, s. 173-181
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Tidskriftsartikel (refereegranskat)abstract
- Decreased fitness due to loss of genetic variation is a well recognised issue in conservation biology. Along the Swedish west coast, the endangered natterjack toad (Bufo calamita) occurs on, for the species, highly unusual habitat of rocky islands. Although the toads inhabit a restricted geographical area (maximum distance between the populations is 71 km), the fragmented nature of the landscape makes the genetic properties of the populations of conservation interest. However, lack of genetic variation found using conventional methods (microsatellites) has impeded genetic studies within these peripheral populations so far. In this study we assess population structure and genetic variation among seven of these fringe populations using 105 polymorphic Amplified Fragment Length Polymorphism (AFLP) loci. We found a well-defined population structure without evidence for isolation by distance, implying restricted gene flow between populations. Additionally, the populations differed in their amount of genetic variation, emphasizing the need to monitor genetically impoverished populations for possible declines mediated by inbreeding depression and reduced adaptive potential. Conservation implications for these unique populations are discussed in the light of our results.
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| 79. |
- Rogell, Björn, et al.
(författare)
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Strong divergence in trait means but not in plasticity across hatchery and wild populations of sea-run brown trout Salmo trutta
- 2012
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 21:12, s. 2963-2976
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Tidskriftsartikel (refereegranskat)abstract
- There is ample evidence that organisms adapt to their native environment when gene flow is restricted. However, evolution of plastic responses across discrete environments is less well examined. We studied divergence in means and plasticity across wild and hatchery populations of sea-run brown trout (Salmo trutta) in a common garden experiment with two rearing environments (hatchery and a nearly natural experimental stream). Since natural and hatchery environments differ, this arrangement provides an experiment in contemporary adaptation across the two environments. A QST - FST approach was used to investigate local adaptation in survival and growth over the first summer. We found evidence for divergent selection in survival in 1 year and in body length in both years and rearing environments. In general, the hatchery populations had higher survival and larger body size in both environments. QST in body size did not differ between the rearing environments, and constitutive divergence in the means was in all cases stronger than divergence in the plastic responses. These results suggest that in this system, constitutive changes in mean trait values are more important for local adaptation than increased plasticity. In addition, ex situ rearing conditions induce changes in trait means that are adaptive in the hatchery, but potentially harmful in the wild, suggesting that hatchery rearing is likely to be a suboptimal management strategy for trout populations facing selection in the stream environment.
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| 80. |
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