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Auteur BORDIER, C.; SARAUX, C.; VIBLANC, V.A.; GACHOT-NEVEU, H.; BEAUGEY, M.; LE MAHO, Y.; LE BOHEC, C.
Titre Inter-Annual Variability of Fledgling Sex Ratio in King Penguins Type Article scientifique
Année (down) 2014 Publication Revue Abrégée Plos One
Volume 9 Numéro 12 Pages 1-17
Mots-Clés
Résumé As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (20002009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1:1 equilibrium upon first breeding attempts, as would be expected from Fisher's classic theory of offspring sex-ratio variation.
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ISSN 1932-6203 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1126
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Auteur Garavelli, L.; Kaplan, D.; Colas, F.; Stotz, W.; Yannicelli, B.; Lett, C.
Titre Identifying appropriate spatial scales for marine conservation and management using a larval dispersal model : the case of Concholepas concholepas (loco) in Chile Type Article scientifique
Année (down) 2014 Publication Revue Abrégée Progress in Oceanography
Volume 124 Numéro Pages 42-53
Mots-Clés
Résumé Along the coast of Chile, fisheries targeting the marine gastropod Concholepas concholepas, commonly named “loco”, were highly valuable until the end of the 80s when catches declined significantly. Since the late 90s, a management plan based on territorial-user-rights areas has been implemented, with limited effect on stock recovery. More effective loco conservation and management is impeded by lack of information regarding connectivity via larval dispersal between these individually-managed areas. To develop a regional view of loco connectivity, we integrate loco life history information into a biophysical, individual-based larval dispersal model. This model is used to evaluate scales of loco connectivity and seasonality in connectivity patterns, as well as to partition the coast into largely disconnected subpopulations using a recently developed connectivity-matrix clustering algorithm. We find mean dispersal distances ranging from 170 to 220 km depending on release depth of larvae and planktonic larval duration. Settlement success levels depend quantitatively on the physical and biological processes included in the model, but connectivity patterns remain qualitatively similar. Model estimates of settlement success peak for larval release dates in late austral autumn, consistent with field results and with favorable conditions for larval coastal retention due to weak upwelling during austral autumn. Despite the relatively homogeneous Chilean coastline, distinct subpopulations with minimal connectivity between them are readily identifiable. Barriers to connectivity that are robust to changes in model configuration exist at 23 degrees S and 29 degrees S latitudes. These zones are all associated with important headlands and embayments of the Chilean coast.
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Volume de collection Numéro de collection Edition
ISSN 0079-6611 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 359
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Auteur HANEL, R.; STEPPUTTIS, D.; BONHOMMEAU, S.; CASTONGUAY, M.; SCHABER, M.; WYSUJACK, K.; VOBACH, M.; MILLER, M.J.
Titre Low larval abundance in the Sargasso Sea: new evidence about reduced recruitment of the Atlantic eels Type Article scientifique
Année (down) 2014 Publication Revue Abrégée Naturwissenschaften
Volume 101 Numéro 12 Pages 1041-1054
Mots-Clés Anguillidae; Anguilliformes; Eel larvae; Population declines; spawning area
Résumé The European eel Anguilla anguilla has shown decreased recruitment in recent decades. Despite increasing efforts to establish species recovery measures, it is unclear if the decline was caused by reduced numbers of reproductive-stage silver eels reaching the spawning area, low early larval survival, or increased larval mortality during migration to recruitment areas. To determine if larval abundances in the spawning area significantly changed over the past three decades, a plankton trawl sampling survey for anguillid leptocephali was conducted in March and April 2011 in the spawning area of the European eel that was designed to directly compare to collections made in the same way in 1983 and 1985. The catch rates of most anguilliform leptocephali were lower in 2011, possibly because of the slightly smaller plankton trawl used, but the relative abundances of European eel and American eel, Anguilla rostrata, leptocephali were much lower in 2011 than in 1983 and 1985 when compared to catches of other common leptocephali. The leptocephali assemblage was the same in 2011 as in previous years, but small larvae of mesopelagic snipe eels, Nemichthys scolopaceus, which spawn sympatrically with anguillid eels, were less abundant. Temperature fronts in the spawning area were also poorly defined compared to previous years. Although the causes for low anguillid larval abundances in 2011 are unclear, the fact that there are presently fewer European and American eel larvae in the spawning area than during previous time periods indicates that decreased larval abundance and lower eventual recruitment begin within the spawning area.
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Langue Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0028-1042 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1127
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Auteur Grande, M.; Murua, H.; Zudaire, I.; Goni, N.; Bodin, N.
Titre Reproductive timing and reproductive capacity of the Skipjack Tuna (Katsuwonus pelamis) in the western Indian Ocean Type Article scientifique
Année (down) 2014 Publication Revue Abrégée Fisheries Research
Volume 156 Numéro Pages 14-22
Mots-Clés Condition; Gonadosomatic index; Oocyte; Reproductive capacity; Spawning season
Résumé We studied the sexual maturity, batch fecundity and spawning season of the Skipjack Tuna Katsuwonus pelamis. Generalized additive modelling was applied to assess the effect of demographic features on ovary growth. During 2009 and 2010, 673 females were caught on board a purse-seine fishing vessel in the western Indian Ocean. Fish were classified into different reproductive phases and this information was used to determine the size at maturity (L-50), the timing of spawning and the batch fecundity (n = 51). The size at maturity (L-50) for females was estimated to be 39.9 cm. The mean relative batch fecundity was 140 +/- 64 eggs g(-1) of fish. Spawning occurs during the monsoons and inter-monsoon seasons with peaks in the reproductive activity during the North-east and South-west monsoon events. Demographic differences were detected in the reproductive timing of the population and a large investment in gamete production was observed in fish with high hepatic condition and in their first spawning year.
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ISSN 0165-7836 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 360
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Auteur LE MAHO, Y.; WHITTINGTON, J.D.; HANUISE, N.; PEREIRA, L.; BOUREAU, M.; BRUCKER, M.; CHATELAIN, N.; COURTECUISSE, J.; CRENNER, F.; FRIESS, B.; GROSBELLET, E.; KERNALEGUEN, L.; OLIVER, F.; SARAUX, C.; VETTER, N.; VIBLANC, V.A.; THIERRY, B.; TREMBLAY, P.; GROSCOLAS, R.; LE BOHEC, C.
Titre Rovers minimize human disturbance in research on wild animals Type Article scientifique
Année (down) 2014 Publication Revue Abrégée Nature Methods
Volume 11 Numéro 12 Pages 1242-1244
Mots-Clés
Résumé Investigating wild animals while minimizing human disturbance remains an important methodological challenge. When approached by a remote-operated vehicle (rover) which can be equipped to make radio-frequency identifications, wild penguins had significantly lower and shorter stress responses (determined by heart rate and behavior) than when approached by humans. Upon immobilization, the rover-unlike humans-did not disorganize colony structure, and stress rapidly ceased. Thus, rovers can reduce human disturbance of wild animals and the resulting scientific bias.
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Volume de collection Numéro de collection Edition
ISSN 1548-7091 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1128
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