Trophic links as vectors of pathogens and contaminants

19th Annual Conference of the European Cetacean Society and associated workshop, April 2-7, 2005, La Rochelle, FranceIn marine mammals, feeding represents the main route of entry for persistent organic pollutants and toxic elements, as well as most internal parasites and many pathogenic micro-organismsN

The stranding anomaly as population indicator: the case of Harbour Porpoise <i>Phocoena phocoena</i> in North-Western Europe

Ecological indicators for monitoring strategies are expected to combine three major characteristics: ecological significance, statistical credibility, and cost-effectiveness. Strategies based on stranding networks rank highly in cost-effectiveness, but their ecological significance and statistical credibility are disputed. Our present goal is to improve the value of stranding data as population indicator as part of monitoring strategies by constructing the spatial and temporal null hypothesis for strandings. The null hypothesis is defined as: small cetacean distribution and mortality are uniform in space and constant in time. We used a drift model to map stranding probabilities and predict stranding patterns of cetacean carcasses under H-0 across the North Sea, the Channel and the Bay of Biscay, for the period 1990-2009. As the most common cetacean occurring in this area, we chose the harbour porpoise <i>Phocoena phocoena</i> for our modelling. The difference between these strandings expected under H-0 and observed strandings is defined as the stranding anomaly. It constituted the stranding data series corrected for drift conditions. Seasonal decomposition of stranding anomaly suggested that drift conditions did not explain observed seasonal variations of porpoise strandings. Long-term stranding anomalies increased first in the southern North Sea, the Channel and Bay of Biscay coasts, and finally the eastern North Sea. The hypothesis of changes in porpoise distribution was consistent with local visual surveys, mostly SCANS surveys (1994 and 2005). This new indicator could be applied to cetacean populations across the world and more widely to marine megafauna

Japan’s whaling is unscientific

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Marine habitat use by grey seals in Brittany: application to the Marine National Park of the Iroise Sea

The grey seal Halichoerus grypus is a key species living in the planned Marine National Park of the Iroise Sea, at the western point of Brittany. A telemetry study was set up in order to track movements and behaviour at sea of six grey seals, for a better understanding of the foraging behaviour of the species in Brittany. The use of Satellite Relay Data Loggers (SRDL, Sea Mammal Research Unit, UK) showed extensive individual variability in movements at sea and foraging strategies. All seals used distinct foraging areas; some of them travelled long distances at sea for feeding while others foraged in coastal habitats. Dive forms and depths suggested that the seals can forage during different types of trips at sea, including in the vicinity of their haul-out sites. However their potential foraging areas are widely dispersed and greatly exceed the limits of the planned protected area. The impact of the predation of the seals on fish resources within the Marine National Park is therefore expected to be limited. We suggest that fish resources as well as interactions between seals and fisheries should be managed at a broader scale.</p

Grey seat diet at the southern limit of its European distribution: combining dietary analyses and fatty acid profiles

The north-east Atlantic grey seal, Halichoerus grypus, is widely distributed along the European coastline from northern Russia to France, with the core population centred around Scotland. To date, very little is known of the diet of the species at the southern margin of the species range. However, because grey seal numbers have been increasing over the last few decades in France, the issue of their potential interactions with coastal fisheries is frequently raised. The diet of grey seal in the Molene Archipelago was investigated by combining scat, stomach content and fatty acid analyses, since all three approaches have complementary potentials to reveal feeding habits of a predator. A total of 145 scats mostly of moulting adult males, 14 stomach contents of yearlings and 14 blubber samples from animals of all ages were analysed following standard methodologies. Scats revealed a diet mainly constituted of 50.6% by mass (M) of wrasse, Libridae (mostly Labrus bergylta), 20.7%M conger eel, Conger conger, and 11.9%M sea bass, Dicentrarchus labrax. Stomach contents were made up of 52.3%M cuttlefish, Sepia officinalis, 9.5%M sole, Solea solea, and 9.4%M conger eel. All these prey are different from the diet observed in core areas. Fatty acid analysis from the blubber confirmed that the diet differed between the Molene Archipelago and one of the Scottish breeding sites. It also showed that most of the inter-individual variability was explained by variation in seal body masses, which could be linked to behavioural ontogeny of foraging strategies. Most of he prey species indentified in the food of the grey seal in Brittany are also targeted by professional and/or recreational fisheries in the area; additionally, several prey size-ranges also partly overlap with marketed size-ranges for several species

Assessment of Argos location accuracy from satellite tags deployed on captive gray seals

The Argos satellite system is commonly used to track and relay behavioral data from marine mammals, but their underwater habit results in a high proportion of locations of non-guaranteed accuracy (location classes (LC) 0, A, and B). The accuracy of these locations is poorly, documented in marine mammals. We assessed the accuracy of all LCs on four juvenile gray seals fitted with Argos satellite relay data loggers and held in captivity in an outdoor tank for a total of 61 seal-days, Four hundred and twenty-six locations were obtained from seals in captivity, and their latitude and longitude error was assessed before and after filtering, following McConnell et al. (1992). There was significantly more error in longitude than latitude in all LCs except LC A. The ratio of the standard deviations of longitude: latitude ranged from 1.77 (LC 3) to 2.58 (LC 1). Filtering had very little effect on errors in LCs 3-1, but in the remaining LCs filtering resulted in error reductions ranging from 8% to 63%. In LCs 0, A, and B, error reduction was greater in the 95th percentile errors, especially in longitude. The averages of the latitude and longitude 68th percentile errors and those predicted by Argos (in brackets) were 226 (150), 372 (350), and 757 (1000) in for LCs 3, 2, and I respectively. Both latitude and longitude errors of LCs &gt; 0 were normally distributed. Both filtered and unfiltered LC A locations were of a similar accuracy to LC 1 locations, and considerably better than LC 0 locations.</p

Status and conservation of the grey seal, <em>Halich</em>œ<em>rus grypus</em>, in France

We investigated the status of the grey seal in the Molene archipelago. western Brittany. where a Marine, National Park is planned. We combined regular censuses, photo-identification and satellite telemetry to investigate trends in grey seal abundance, site fidelity, individual movements and haulout site use. Individual movements and seasonal variations in abundance suggest that the seals used the Molene, archipelago alternatively with other haulout sites of the South-west British Isles during their annual cycle, Nine out of 16 seals fitted with Satellite Relay Data Loggers (SRDLs) moved to the Isles of Scilly. English Cornwall, Wales or the Channel islands. On average the seals spent 85% of their time Near Haulout, 56.8% of which in the Mol ne archipelago. Overall the seals spent 66% of their tracking time within the boundaries of the Marine National Park. From 1997 to 2000 in the Molene archipelago. we observed a peak in number during the moulting season (mean = 49.8 seals) and a lower abundance during the breeding season (mean = 38.3 seals). The sex ratio was strongly skewed towards males during the moult (between 3.1 and 5.3-1), and was close to 1: 1 during the summer. Inter-annual site fidelity outside the breeding season was very high, varying from 70% to 95% or identified seals. suggesting that the observed movements constitute rotations rather than random dispersion, From 1991/1994 to 1997/2000. the mean number of seals counted at haulout sites increased by 7%, close to the rates of increase observed in the core population of the British Isles at the same period. The Marine National Park may be too restricted for the overall conservation of the population but management plans should be aimed at preserving the characteristics of the habitat for the grey seal. (c) 2005 Elsevier Ltd. All rights reserved.</p