Age Dynamics

Kongens Lyngby, Denmark

Age Dynamics

Kongens Lyngby, Denmark
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Hoydal K.S.,Norwegian University of Science and Technology | Hoydal K.S.,Environment Agency | Letcher R.J.,Carleton University | Blair D.A.D.,Carleton University | And 3 more authors.
Science of the Total Environment | Year: 2015

Concentrations of PCBs, organochlorine pesticides (OCPs), brominated flame retardants and a suite of relevant metabolites of these POPs, in all 175 different compounds, were determined in liver and plasma of traditionally hunted pilot whales (n. = 14 males and n. = 13 females of different age groups) from the Faroe Islands. The main objectives of this study were to determine differences in the presence and concentrations of the compounds in the liver and plasma, how they depend on developmental stage (calves, sub adults, and adult females), and to assess maternal transfer of the compounds to suckling calves. Generally, the lipid weight (lw) concentrations of quantified POPs in the liver and plasma of pilot whales were positively correlated, and lw concentrations of most POPs did not differ between these matrices. However, concentrations of some individual POPs differed significantly (p. <. 0.05) between plasma and liver; CB-153 (p. = 0.044), CB-174 (p. = 0.027) and BDE-47 (p. = 0.017) were higher in plasma than in liver, whereas p,p'-DDE (p. = 0.004) and HCB (p. <. 0.001) were higher in liver than in plasma. POP concentrations differed between age/gender groups with lower levels in adult females than in juveniles. The relative distribution of compounds also differed between the age groups, due to the influence of the maternal transfer of the compounds. The results indicated that larger, more hydrophobic POPs were transferred to the offspring less efficiently than smaller or less lipid soluble compounds. Very low levels of both OH- and/or MeSO2-PCB and PBDE metabolites were found in all age groups, with no significant (p>0.05) differences between the groups, strongly suggesting a very low metabolic capacity for their formation in pilot whales. The lack of difference in the metabolite concentrations between the age groups also indicates less maternal transfer of these contaminant groups compared to the precursor compounds. © 2015 Elsevier B.V.


PubMed | Carleton University, Environment Agency, Norwegian University of Science and Technology and Age Dynamics
Type: | Journal: The Science of the total environment | Year: 2015

Concentrations of PCBs, organochlorine pesticides (OCPs), brominated flame retardants and a suite of relevant metabolites of these POPs, in all 175 different compounds, were determined in liver and plasma of traditionally hunted pilot whales (n=14 males and n=13 females of different age groups) from the Faroe Islands. The main objectives of this study were to determine differences in the presence and concentrations of the compounds in the liver and plasma, how they depend on developmental stage (calves, sub adults, and adult females), and to assess maternal transfer of the compounds to suckling calves. Generally, the lipid weight (lw) concentrations of quantified POPs in the liver and plasma of pilot whales were positively correlated, and lw concentrations of most POPs did not differ between these matrices. However, concentrations of some individual POPs differed significantly (p<0.05) between plasma and liver; CB-153 (p=0.044), CB-174 (p=0.027) and BDE-47 (p=0.017) were higher in plasma than in liver, whereas p,p-DDE (p=0.004) and HCB (p<0.001) were higher in liver than in plasma. POP concentrations differed between age/gender groups with lower levels in adult females than in juveniles. The relative distribution of compounds also differed between the age groups, due to the influence of the maternal transfer of the compounds. The results indicated that larger, more hydrophobic POPs were transferred to the offspring less efficiently than smaller or less lipid soluble compounds. Very low levels of both OH- and/or MeSO2-PCB and PBDE metabolites were found in all age groups, with no significant (p>0.05) differences between the groups, strongly suggesting a very low metabolic capacity for their formation in pilot whales. The lack of difference in the metabolite concentrations between the age groups also indicates less maternal transfer of these contaminant groups compared to the precursor compounds.


Galatius A.,University of Aarhus | Bossi R.,University of Aarhus | Sonne C.,University of Aarhus | Riget F.F.,University of Aarhus | And 4 more authors.
Environmental Science and Pollution Research | Year: 2013

Profiles of seven compounds of perfluoro-alkyl substances (PFASs) were compared among three species of top predators from the Danish North Sea: the white-beaked dolphin (Lagenorhynchus albirostris), the harbor porpoise (Phocoena phocoena), and the harbor seal (Phoca vitulina). The seals had higher total burdens (757.8 ng g-1 ww) than the dolphins (439.9 ng g-1 ww) and the porpoises (355.8 ng g-1 ww), probably a reflection of feeding closer to the shore and thus contamination sources. The most striking difference among the species was the relative contribution of perfluorooctanesulfonamide (PFOSA) to the profiles; the seals (0.1 %) had much lower levels than porpoises (8.3 %) and dolphins (26.0 %). In combination with the values obtained from the literature, this result indicates that Carnivora species including Pinnipedia have a much higher capacity of transforming PFOSA to perfluorooctane sulfonic acid (PFOS) than cetacean species. Another notable difference among the species was that the two smaller species (seals and porpoises) with supposedly higher metabolic rates had lower concentrations of the perfluorinated carboxylic acids, which are generally more easily excreted than perfluorinated sulfonamides. Species-specific characteristics should be recognized when PFAS contamination in marine mammals is investigated, for example, several previous studies of PFASs in cetaceans have not quantified PFOSA. © 2013 Springer-Verlag Berlin Heidelberg.


Frie A.K.,Norwegian Institute of Marine Research | Fagerheim K.-A.,Norwegian Institute of Marine Research | Hammill M.O.,Maurice Lamontagne Institute | Kapel F.O.,Greenland Institute of Natural Resources | And 4 more authors.
ICES Journal of Marine Science | Year: 2011

Blind readings of known-age samples are the ultimate quality control method for age estimates based on hard tissues. Unfortunately, this is often not feasible for many species because of the scarcity of known-age samples. Based on a unique collection of known-age teeth of harp seals (age range: 1-18 years), ageing errors were evaluated in relation to true age, reader experience, sex, and tooth format (images vs. originals). Bias was estimated by linear models fitted to deviations from true age, and precision was estimated as their residual standard error. Image-based blind readings of 98 tooth sections by 14 readers, representing different levels of experience, generally showed high accuracy and precision up to a seal age of ∼8 years, followed by an increasingly negative bias and increased variance. Separate analyses were therefore conducted for young seals (1-7 years) and older seals. For young seals, moderate associations were found between reader experience and levels of bias, precision, and proportions of correct readings. For older seals, only precision levels showed a significant association with reader experience. Minor effects of sex and tooth format are unlikely to affect these main patterns. Observed errors, even for highly experienced readers, may affect important age-related parameters, emphasizing the importance of known-age calibration of the output from all readers. © 2011 International Council for the Exploration of the Sea.


Heide-Jorgensen M.P.,Greenland Institute of Natural Resources | Iversen M.,Greenland Institute of Natural Resources | Nielsen N.H.,Greenland Institute of Natural Resources | Lockyer C.,Age Dynamics | And 3 more authors.
Ecology and Evolution | Year: 2011

The effects of climate change on marine ecosystems and in particular on marine top predators are difficult to assess due to, among other things, spatial variability, and lack of clear delineation of marine habitats. The banks of West Greenland are located in a climate sensitive area and are likely to elicit pronounced responses to oceanographic changes in the North Atlantic. The recent increase in sea temperatures on the banks ofWest Greenland has had cascading effects on sea ice coverage, residency of top predators, and abundance of important prey species like Atlantic cod (Gadus morhua). Here, we report on the response of one of the top predators in West Greenland; the harbour porpoise (Phocoena phocoena). The porpoises depend on locating high densities of prey species with high nutritive value and they have apparently responded to the general warming on the banks ofWest Greenland by longer residence times, increased consumption of Atlantic cod resulting in improved body condition in the form of larger fat deposits in blubber, compared to the situation during a cold period in the 1990s. This is one of the few examples of a measurable effect of climate change on a marine mammal population.© 2011 The Authors.


Best P.B.,University of Pretoria | Meyer M.A.,Oceans and Coasts | Lockyer C.,Age Dynamics
African Journal of Marine Science | Year: 2010

The distribution, seasonality and schooling behaviour of killer whales Orcinus orca in South African waters have been investigated from 785 records compiled between 1963 and 2009, and their size, morphometrics, growth, reproduction, food and feeding behaviour described from the examination of 54 individuals, 36 of which were landed at the Durban whaling station between 1971 and 1975. Qualitatively, the species appears to be more frequently encountered offshore, where it forms small schools of generally less than six animals. Seasonality of occurrence is not marked, although circumstantial evidence indicates that some individuals migrate from higher latitudes. Males reach 8.81 m and females 7.9 m, with 16.2% of males exceeding the size of the largest female. Stomach content and observational data suggest that the species can be characterised locally as an opportunistic predator of megavertebrates, rather than as the fish-feeding ecotype previously described. A stranded adult male with extreme tooth wear that was 1.5-2 m shorter than other males of equivalent age may be representative of a separate 'offshore' ecotype. Apparent differences between features of the population's life history and those of resident killer whales in the north-eastern Pacific might be attributed to either uncertainties in age determination using dentinal growth layer groups or sampling bias. The basis for the suggestion that killer whales in South African waters should be reclassified as Vulnerable (rather than Data Deficient) is challenged. © NISC (Pty) Ltd.


Christensen-Dalsgaard S.N.,Norwegian Institute for Nature Research | Christensen-Dalsgaard S.N.,University of Tromsø | Aars J.,Norwegian Polar Institute | Andersen M.,Norwegian Polar Institute | And 2 more authors.
Polar Biology | Year: 2010

Validation of age estimation from tooth cementum growth layers was conducted for 32 polar bears (Ursus maritimus) of known age, by two readers. Both readers correctly estimated age for 24% of the bears, and 50-53% were within the year of correct age. The age of young animals (age 1-8) was overestimated, while ages for bears over 8 years were underestimated. Comparison between the readings of the two readers indicated that the precision was low. Further, one of the readers reread tooth slides earlier prepared and read by another age estimation laboratory. There was a large discrepancy between these readings indicating a bias in the ages estimated. We conclude that age estimation of polar bears can be difficult, particularly in populations where individuals may forage throughout the year. As tooth growth layers may deposit differently for bears from different areas, and as different laboratories may read the same slides according to different criteria, an evaluation of the methods should be conducted for all populations, based on a significant number of tooth slides, with a broad age range, from animals of known age. © 2009 Springer-Verlag.


Bloch D.,Faroese Museum of Natural History | Desportes G.,Faroese Museum of Natural History | Harvey P.,The Shetland Amenity Trust | Lockyer C.,Age Dynamics | Mikkelsen B.,Faroese Museum of Natural History
Aquatic Mammals | Year: 2012

Risso's dolphins (Grampus griseus) were taken for the first time by the opportunistic drive fishery in the Faroe Islands in two separate incidents: three in September 2009 and 21 in April 2010, with in total 16 females and eight males. Their sizes ranged from 193 to 308 cm in length and 60 to 395 kg in weight for females, and 186 to 323 cm in length and 70 to 505 kg in weight for males; the maximum weights are heavier than previously documented for this species. The smallest mature female was 277 cm long, while the youngest and also lightest mature female was 8 y old and weighed 280 kg. Sperm competition and a pro-miscuous mating system were suggested for the species based on large testicular masses. The diet was composed of cephalopods from both the water column (Todarodes and Loligo) and the ocean floor (Eledona and Todaropsis). Although both schools landed showed a mixed diet, the September school diet centred on a pelagic squid (Todarodes sagittatus), while the April school diet centred upon a benthic octopod (Eledona cirrhosa). Since August 2009, Risso's dolphins have been observed on five occasions in waters around the Faroese north of 61° 34' N, the northernmost observation situated at a latitude of 62° 23' N. Sightings of the species off Shetland occur mostly between April and September, with a peak in August and September, the observations in Faroese waters (2 in April, 1 in August, and 2 in September) falling within this period. While the species had not previously been observed in this area north of the Shetland-Faroe Channel, these observations in Faroese territorial waters indicate a likely northward extension of the known range of the species.


Fernandez-Contreras M.M.,University of Barcelona | Cardona L.,University of Barcelona | Lockyer C.H.,Age Dynamics | Aguilar A.,University of Barcelona
ICES Journal of Marine Science | Year: 2010

The numbers of short-beaked common dolphins captured annually by pairtrawlers operating off Galicia (northwestern Spain) and the operational factors influencing the bycatch were evaluated using on-board observations. Hauling time, fishing depth, and season of the year were identified as the key factors involved in the incidental capture. The dolphins were most vulnerable to trawls at night from May to September, around the continental shelf break. Most of the dolphins in the bycatch were males, and the average age was 13.4 ± 4.4 years for males and 11.5 ± 4.8 years for females. The sex ratio was male-biased owing to a few capture events involving several males each, supporting the notion that bachelor groups exist in the area. The annual bycatch in 2001 and 2002 was an estimated 394 dolphins [95 confidence interval (CI) 230-632], most taken from May to September (mean 348 dolphins, 95 CI 200-590) and just a few from October to April (mean 46 dolphins, 95 CI 0-132). This level of bycatch could be reduced significantly if trawlers were restricted to operating in water deeper than 250 m and likely avoided entirely if they were restricted to water deeper than 300 m. © 2010 International Council for the Exploration of the Sea.


Borrell A.,University of Barcelona | Vacca A.V.,University of Barcelona | Pinela A.M.,University of Barcelona | Kinze C.,Copenhagen University | And 3 more authors.
PLoS ONE | Year: 2013

In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen- isotope ratios (δ18O) in the inorganic component (hydroxyapatite), and nitrogen and carbon isotope ratios (δ15N: δ13C) in the organic component (primarily collagenous). We found significant differences between Denmark and NW Spain in δ15N and δ18O values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in δ15N, δ13C and δ 18O values in the period up to age 20, and in the ontogenetic variation of δ15N and δ18O values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted. Copyright: © 2013 Borrell et al.

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