| 1. |
- Christensen-Dalsgaard, Signe, et al.
(författare)
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What’s the catch with lumpsuckers? A North Atlantic study of seabird bycatch in lumpsucker gillnet fisheries
- 2019
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 240
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Tidskriftsartikel (refereegranskat)abstract
- Worldwide, incidental bycatch in fisheries is a conservation threat to many seabird species. Although knowledge on bycatch of seabirds has increased in the last decade, most stems from longline fisheries and the impacts of coastal gillnet fisheries are poorly understood. Gillnet fishing for North Atlantic lumpsucker (Cyclopterus lumpus) is one such fishery. We collated and synthesized the available information on seabird bycatch in lumpsucker gillnet fisheries across the entire geographical range to estimate and infer the magnitude of their impact on the affected seabird populations. Most birds killed were diving ducks, cormorants and auks, and each year locally high numbers of seabirds were taken as bycatch. We found large differences in bycatch rates among countries. The estimated mean bycatch in Iceland was 2.43 birds/trip, while the estimates in Norway was 0.44 and 0.39 birds/trip, respectively. The large disparities between estimates might reflect large spatial differences in bycatch rates, but could partly also arise due to distinctions in data recorded by onboard inspectors (Iceland), self-administered registration (Norway) and direct observations by cameras (Denmark). We show that lumpsucker gillnet fisheries might pose a significant risk to some populations of diving seabirds. However, a distinct data deficiency on seabird bycatch in terms of spatio-temporal coverage and the age and origins of the birds killed, limited our abilities to fully assess the extent and population consequences of the bycatch. Our results highlight the need for a joint effort among countries to standardize monitoring methods to better document the impact of these fisheries on seabirds.
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| 2. |
- Evans, Thomas J., et al.
(författare)
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Foraging behaviour of common murres in the Baltic Sea, recorded by simultaneous attachment of GPS and time-depth recorder devices
- 2013
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 475, s. 277-
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Tidskriftsartikel (refereegranskat)abstract
- Global positioning system and time-depth recorders were deployed in combination to investigate the foraging behaviour of common murres Uria aalge breeding at Stora Karlso Island, Baltic Sea, during the chick-rearing period. In the pre-breeding period the main prey species of murres, sprat Sprattus sprattus, is targeted by commercial fisheries, likely reducing prey availability during the breeding season. Foraging trips typically consisted of a short flight followed by a period sitting on the sea surface (0.39 +/- 0.48 h), followed by several (5.3 +/- 3.8) diving bouts interspersed by flights and water surface activity. Following the final diving bout, murres returned directly to the colony. Overnight foraging trips lasted longer than daytime trips, and that result corresponded with greater diving activity and reduced dive depths around dawn and dusk, likely times of high prey accessibility. High outward flight groundspeeds (20.0 +/- 2.8 m s(-1)) were aided by tailwinds, and lower inward flight groundspeeds (15.1 +/- 2.5 m s(-1)) were impeded by headwinds. Flights following the wind direction may reflect a strategy to reduce crosswind drift. Foraging intensity was lower than reported by most other studies of murres, suggesting more abundant or aggregated prey.
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| 3. |
- Griffiths, Jennifer R., et al.
(författare)
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The importance of benthic-pelagic coupling for marine ecosystem functioning in a changing world
- 2017
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 23:6, s. 2179-2196
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Forskningsöversikt (refereegranskat)abstract
- Benthic-pelagic coupling is manifested as the exchange of energy, mass, or nutrients between benthic and pelagic habitats. It plays a prominent role in aquatic ecosystems, and it is crucial to functions from nutrient cycling to energy transfer in food webs. Coastal and estuarine ecosystem structure and function are strongly affected by anthropogenic pressures; however, there are large gaps in our understanding of the responses of inorganic nutrient and organic matter fluxes between benthic habitats and the water column. We illustrate the varied nature of physical and biological benthic-pelagic coupling processes and their potential sensitivity to three anthropogenic pressures - climate change, nutrient loading, and fishing - using the Baltic Sea as a case study and summarize current knowledge on the exchange of inorganic nutrients and organic material between habitats. Traditionally measured benthic-pelagic coupling processes (e.g., nutrient exchange and sedimentation of organic material) are to some extent quantifiable, but the magnitude and variability of biological processes are rarely assessed, preventing quantitative comparisons. Changing oxygen conditions will continue to have widespread effects on the processes that govern inorganic and organic matter exchange among habitats while climate change and nutrient load reductions may have large effects on organic matter sedimentation. Many biological processes (predation, bioturbation) are expected to be sensitive to anthropogenic drivers, but the outcomes for ecosystem function are largely unknown. We emphasize how improved empirical and experimental understanding of benthic-pelagic coupling processes and their variability are necessary to inform models that can quantify the feedbacks among processes and ecosystem responses to a changing world.
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| 4. |
- Hentati-Sundberg, Jonas, 1983-, et al.
(författare)
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The Karlsö Murre Lab methodology can stimulate innovative seabird research
- 2012
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Ingår i: Marine Ornithology. - 1018-3337 .- 2074-1235. ; 40, s. 11-16
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Tidskriftsartikel (refereegranskat)abstract
- Studies of seabirds have contributed substantially to theoretical and applied ecology, but practical limitations in the field and lack of knowledge of the life history of studied birds often constitute significant hurdles to progress in research. In the middle of the largest seabird colony in the Baltic Sea, on the island of Stora Karlsö, we have built an artificial breeding site for Common Murres Uria aalge. The Karlsö Murre Lab enables high-resolution studies with minimal disturbance of the breeding birds. It became operational, with the first recruitment of breeding murres, in 2009. Building materials and location were chosen to minimize environmental impact. The lab was constructed to allow future outfitting with a range of high-technology devices. Since most of the fledged chicks in the subcolony have been ringed over the last 10 years, this will enable recruitment and studies using advanced technology of birds with known life history. Hence, we will be able to perform seabird studies with a resolution that is impossible in a strictly natural environment. Better knowledge of links between seabirds and their environment facilitates the use of seabirds as indicators, which in turn can improve marine ecosystem-based management.
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| 5. |
- Hentati Sundberg, Jonas, et al.
(författare)
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Övervakning av havsfåglar i Östersjön.
- 2009
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Ingår i: Havet 2009. - Stockholm : Naturvårdsverket. ; , s. 61-64
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Bokkapitel (populärvet., debatt m.m.)
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| 6. |
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| 7. |
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| 8. |
- Kadin, Martina, et al.
(författare)
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Common Guillemot Uria aalge parents adjust provisioning rates to compensate for low food quality
- 2016
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Ingår i: Ibis. - : Wiley. - 0019-1019 .- 1474-919X. ; 158:1, s. 167-178
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Tidskriftsartikel (refereegranskat)abstract
- The quantity and quality of food available within the foraging area set important constraints for chick-rearing birds, but responses to low quality are not well understood. This study explored the potential for parent birds to adjust quantity (feeding rate) and quality (energy content) in chick provisioning, by studying Common Guillemots Uria aalge on Stora Karlso, Baltic Sea, predominantly utilizing Sprat Sprattus sprattus, during conditions of high food quantity but reduced food quality. Quality is central to reproductive success in this single-prey loader. From the chick's perspective, provisioning rates should be increased to compensate for low food quality and to fulfil its growing needs with increasing age. However, the high energy cost of flying in Guillemots makes it important for parent birds to minimize commutes to feeding areas. Provisioning parameters were recorded during three dawn-to-dusk watches each breeding season from 2005 to 2013, when clupeids, presumably Sprat, constituted 98% of chick diet. Generalized additive mixed models showed that both feeding rate and size of clupeids (a proxy for energy content) varied between years and changed non-linearly with chick age, but that there was no change within breeding seasons. Chick age and year explained 36% of the variation in feeding rate but only 2% of the variation in the size of clupeids in chick diets. We conclude that parent birds tried to adjust both feeding rate and prey size, but were less successful with the latter. A strong negative correlation was found between annual feeding rates and size of clupeids, evaluated as the differences relative to the baseline year, and adjusted for the effects of chick age. Although the differences between years were small, the relationship indicates a compensation mechanism that does not seem to impact adult survival, and by which increased feeding rates can partly counteract reduced chick energy intake when food quality is low.
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| 9. |
- Kadin, Martina, et al.
(författare)
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Contrasting effects of food quality and quantity on a marine top predator
- 2012
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 444, s. 239-249
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Tidskriftsartikel (refereegranskat)abstract
- Overfishing of predatory fish has contributed to an increase in forage-fish stocks. At the same time, a rising demand for forage fish to supply fishmeal markets, in combination with climate change, has put strong pressure on these stocks, and this, in turn, has had an impact on marine top predators. We examined how inter-annual variation in food quality (sprat Sprattus sprattus weight-at-age) and quantity (sprat abundance) influenced Baltic Sea common murres Uria aalge during chick-rearing. Fledging success, i.e. survival from hatching to fledging, showed a positive relationship with food quality, but we found no effect of food quantity. We found no relationship between food quality and parental behaviour or chick feeding parameters, but a negative relationship between food quantity and trip duration. Our data indicate that there was room for parental birds to increase their effort to compensate for reduced food quality, but we found no signs of such compensation. We analysed different types of fish and seabird life-history data to separate effects of food quantity and quality on a top predator. Understanding such effects can contribute to clarifying causes and consequences for observed changes in life-history parameters and population dynamics of top predators.
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| 10. |
- Kadin, Martina, et al.
(författare)
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Linking demographic and food-web models to understand management trade-offs
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:15, s. 8587-8600
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Tidskriftsartikel (refereegranskat)abstract
- Alternatives in ecosystem-based management often differ with respect to trade-offs between ecosystem values. Ecosystem or food-web models and demographic models are typically employed to evaluate alternatives, but the approaches are rarely integrated to uncover conflicts between values. We applied multistate models to a capture-recapture dataset on common guillemots Uria aalge breeding in the Baltic Sea to identify factors influencing survival. The estimated relationships were employed together with Ecopath-with-Ecosim food-web model simulations to project guillemot survival under six future scenarios incorporating climate change. The scenarios were based on management alternatives for eutrophication and cod fisheries, issues considered top priority for regional management, but without known direct effects on the guillemot population. Our demographic models identified prey quantity (abundance and biomass of sprat Sprattus sprattus) as the main factor influencing guillemot survival. Most scenarios resulted in projections of increased survival, in the near (2016-2040) and distant (2060-2085) future. However, in the scenario of reduced nutrient input and precautionary cod fishing, guillemot survival was projected to be lower in both future periods due to lower sprat stocks. Matrix population models suggested a substantial decline of the guillemot population in the near future, 24% per 10 years, and a smaller reduction, 1.1% per 10 years, in the distant future. To date, many stakeholders and Baltic Sea governments have supported reduced nutrient input and precautionary cod fishing and implementation is underway. Negative effects on nonfocal species have previously not been uncovered, but our results show that the scenario is likely to negatively impact the guillemot population. Linking model results allowed identifying trade-offs associated with management alternatives. This information is critical to thorough evaluation by decision-makers, but not easily obtained by food-web models or demographic models in isolation. Appropriate datasets are often available, making it feasible to apply a linked approach for better-informed decisions in ecosystem-based management.
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