Incidental mortality of seabirds caused by longline fisheries in the south-western Atlantic Ocean has been assessed only with reference to the number of birds caught, not taking into account how the ...configuration of the gear affects mortality. We provide the first direct estimates of the impact on seabirds of the semi-pelagic fishing gear used in the Argentine Kingclip
Genypterus blacodes fishery. The gear included weights and buoys, sequentially spaced along the lines, which enabled fishing to occur at different depths. During a fishing trip onboard the F/V
Argenova XII in the austral summer of 2005, 74 birds were captured, comprising 56 White-chinned petrels
Procellaria aequinoctialis and 18 Black-browed albatrosses
Thalassarche melanophrys. More than half of the hooked birds were caught in the first third of the lines being set, and almost all White-chinned petrels (96%) and Black-browed albatrosses (83%) were caught within 30
m (i.e. 24 hooks) of buoys. The floats used in semi-pelagic longlines are likely to decrease the sinking rates of baited hooks near them, buoying up the lines near the surface and increasing the likelihood of seabird interactions. Although we lack information on the distribution of captured fish along these longlines, the most feasible methods to reduce seabird bycatch in the Argentine semi-pelagic longline fishery would be (1) to deploy lines without hooks near line floats (the removal of 24 hooks either side of each float should substantially reduce seabird interactions with gear) or (2) to use long snoods between the mainline and the floats, allowing the baited hooks to quickly sink beyond the reach of seabirds.
We analyzed the effect of the shrimp fishery on Magellanic Penguins (Spheniscus magellanicus) in two ways: (1) we determined whether penguins were incidentally killed and the magnitude of incidental ...take, and (2) estimated the overlap between penguin diet and fish by-catch of the shrimp fishery (total capture excluding shrimp and seabirds). We worked with the fishing fleet operating at Golfo San Jorge with onboard observers over 200 days in 1995-1997, sampling fishery by-catch and entangled birds. Penguins were affected during the austral summer. Estimations of mortality rates showed 0.33% of the breeding population at Golfo San Jorge is incidentally killed by the shrimp fishery every summer. By-catch in shrimp fishery nets was composed of species important as penguin prey (anchovy and hake) in higher proportions during summer. The daily by-catch of these species was higher than the total calculated daily intake for all penguins breeding in the Golfo San Jorge. This could have a significant effect on birds. We recommend that an observer program be implemented to monitor seabird mortality and that fishing gear should be improved to reduce the indirect effect of the fish by-catch on penguins.
The breeding distribution of the Kelp Gull Larus dominicanus in coastal Argentina ranged along over 3600 km of coastline, from Claromeco, southern Buenos Aires (38 degree 45'S, 59 degree 28'W) to ...Bahia Ushuaia, Tierra del Fuego (54 degree 51'S, 68 degree 16'W). A total of 105 breeding colonies was identified at 55 localities. Median colony size was 184 pairs, ranging from two to 12 260 breeding pairs. Total population size for the Argentine coast, considering only the 94 colonies for which the number of breeding pairs is available (89% of total sites), was estimated as 74 360 breeding pairs. Most colonies were on islands (81.9%). A total of 40 Kelp Gull colonies was located within coastal protected areas, representing over 60% of total population size. All Kelp Gull colonies for which we had size estimations for more than one season or for which previous information was available (n = 7) showed an increase in numbers of breeding pairs. Available information suggest that Kelp Gulls are feeding generalists taking advantage of artificial food sources resulting from human activities such as refuse tips, sewage outfalls, slaughter houses, and fisheries bycatch. As a result of their concentration close to cities, Kelp Gulls may result in hazards to aircraft and threats to human health. The opportunistic feeding habits and flexibility in nesting requirements of the Kelp Gull make this widely distributed and abundant species a probable key factor in the structuring of seabird assemblages and a problem to other coastal wildlife if populations continue to increase. Similarly, threats to human populations are likely to increase under current Kelp Gull population trends. Management and research requirements are presented.
In diving seabirds, sexual dimorphism in size often results in sex-related differences of foraging patterns. Previous research on Magellanic penguins, conducted during the breeding season, failed to ...reveal consistent differences between the sexes on foraging behavior, despite sexual dimorphism. In this paper, we tested the hypothesis that male and female Magellanic penguins differ in diet and foraging patterns during the non-breeding period when the constraints imposed by chick rearing activities vanish. We used stable isotope ratios of carbon and nitrogen in feather and bone to characterize the diet and foraging patterns of male and female penguins in the South Atlantic at the beginning of the 2009-2010 and 2010-2011 post-breeding seasons (feathers) and over several consecutive breeding and migratory seasons (bone). The mean δ^sup 13^C and δ^sup 15^N values of feathers showed no differences between the sexes in any of the three regions considered or in the diet composition between the sexes from identical breeding regions; however, Bayesian ellipses showed a higher isotopic niche width in males at the beginning of the post-breeding season. Stable isotope ratios in bone revealed the enrichment of males with δ^sup 13^C compared with females across the three regions considered. Furthermore, the Bayesian ellipses were larger for males and encompassed those of females in two of the three regions analyzed. These results suggest a differential use of winter resources between the sexes, with males typically showing a larger diversity of foraging/migratory strategies. The results also show that dietary differences between male and female Magellanic penguins may occur once the constraints imposed by chick rearing activities cease at the beginning of the post-breeding season. PUBLICATION ABSTRACT
In diving seabirds, sexual dimorphism in size often results in sex-related differences of foraging patterns. Previous research on Magellanic penguins, conducted during the breeding season, failed to ...reveal consistent differences between the sexes on foraging behavior, despite sexual dimorphism. In this paper, we tested the hypothesis that male and female Magellanic penguins differ in diet and foraging patterns during the non-breeding period when the constraints imposed by chick rearing activities vanish. We used stable isotope ratios of carbon and nitrogen in feather and bone to characterize the diet and foraging patterns of male and female penguins in the South Atlantic at the beginning of the 2009-2010 and 2010-2011 post-breeding seasons (feathers) and over several consecutive breeding and migratory seasons (bone). The mean delta super(13)C and delta super(15)N values of feathers showed no differences between the sexes in any of the three regions considered or in the diet composition between the sexes from identical breeding regions; however, Bayesian ellipses showed a higher isotopic niche width in males at the beginning of the post-breeding season. Stable isotope ratios in bone revealed the enrichment of males with delta super(13)C compared with females across the three regions considered. Furthermore, the Bayesian ellipses were larger for males and encompassed those of females in two of the three regions analyzed. These results suggest a differential use of winter resources between the sexes, with males typically showing a larger diversity of foraging/migratory strategies. The results also show that dietary differences between male and female Magellanic penguins may occur once the constraints imposed by chick rearing activities cease at the beginning of the post-breeding season.
In diving seabirds, sexual dimorphism in size often results in sex-related differences of foraging patterns. Previous research on Magellanic penguins, conducted during the breeding season, failed to ...reveal consistent differences between the sexes on foraging behavior, despite sexual dimorphism. In this paper, we tested the hypothesis that male and female Magellanic penguins differ in diet and foraging patterns during the non-breeding period when the constraints imposed by chick rearing activities vanish. We used stable isotope ratios of carbon and nitrogen in feather and bone to characterize the diet and foraging patterns of male and female penguins in the South Atlantic at the beginning of the 2009-2010 and 2010-2011 post-breeding seasons (feathers) and over several consecutive breeding and migratory seasons (bone). The mean δ.sup.13C and δ.sup.15N values of feathers showed no differences between the sexes in any of the three regions considered or in the diet composition between the sexes from identical breeding regions; however, Bayesian ellipses showed a higher isotopic niche width in males at the beginning of the post-breeding season. Stable isotope ratios in bone revealed the enrichment of males with δ.sup.13C compared with females across the three regions considered. Furthermore, the Bayesian ellipses were larger for males and encompassed those of females in two of the three regions analyzed. These results suggest a differential use of winter resources between the sexes, with males typically showing a larger diversity of foraging/migratory strategies. The results also show that dietary differences between male and female Magellanic penguins may occur once the constraints imposed by chick rearing activities cease at the beginning of the post-breeding season.
The LHCb experiment is preparing for a major upgrade in 2018–2019. One of the key components in the upgrade is a new silicon tracker situated upstream of the analysis magnet of the experiment. The ...Upstream Tracker (UT) will consist of four planes of silicon strip detectors, with each plane covering an area of about 2m2. An important consideration of these detectors is their performance after they have been exposed to a large radiation dose. In this paper we present test beam results of pre-prototype n-in-p and p-in-n sensors that have been irradiated with fluences up to 4.0×1014neq/cm2.
The plasticity of masticatory muscles was studied by comparing rats that were wearing a protrusive appliance and were kept on a liquid diet with two control groups: (1) pair-fed rats and (2) rats ...that had free access to ordinary pelleted food. The animals were 45 days old at the beginning of the experiment and were studied for a period of 20 days. Three jaw muscles with different functions were examined: masseter, temporalis, and digastric. Muscle fiber composition was determined (1) by fiber counting after staining with four monoclonal antibodies, which were able to recognize the four major myosin heavy chain (MHC) isoforms and therefore four fiber types (I, IIA, IIX, IIB) and (2) by electrophoresis on 6% polyacrylamide gels. The comparison between free-diet rats and pair-fed rats showed that the change from a hard pelleted diet to a liquid diet caused a shift in fiber type and MHC distribution, characterized by an increase of IIB MHC in temporalis and digastric muscles but not in the masseter muscle. The comparison between pair-fed rats and rats wearing appliances showed on the contrary a decrease in IIB MHC and an increase in IIA and IIX MHC. The results support the conclusions that (1) rat jaw muscles can quickly adapt to functional demand changing their fiber type composition, (2) the changes appear restricted inside the fast fiber population, and (3) fiber-type changes caused by dietary variation are not less than those caused by orthodontic intervention and must be taken into account to assess the effect of the appliance correctly.
In diving seabirds, sexual dimorphism in size often results in sex-related differences of foraging patterns. Previous research on Magellanic penguins, conducted during the breeding season, failed to ...reveal consistent differences between the sexes on foraging behavior, despite sexual dimorphism. In this paper, we tested the hypothesis that male and female Magellanic penguins differ in diet and foraging patterns during the non-breeding period when the constraints imposed by chick rearing activities vanish. We used stable isotope ratios of carbon and nitrogen in feather and bone to characterize the diet and foraging patterns of male and female penguins in the South Atlantic at the beginning of the 2009–2010 and 2010–2011 post-breeding seasons (feathers) and over several consecutive breeding and migratory seasons (bone). The mean δ¹³C and δ¹⁵N values of feathers showed no differences between the sexes in any of the three regions considered or in the diet composition between the sexes from identical breeding regions; however, Bayesian ellipses showed a higher isotopic niche width in males at the beginning of the post-breeding season. Stable isotope ratios in bone revealed the enrichment of males with δ¹³C compared with females across the three regions considered. Furthermore, the Bayesian ellipses were larger for males and encompassed those of females in two of the three regions analyzed. These results suggest a differential use of winter resources between the sexes, with males typically showing a larger diversity of foraging/migratory strategies. The results also show that dietary differences between male and female Magellanic penguins may occur once the constraints imposed by chick rearing activities cease at the beginning of the post-breeding season.
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