Grey Seal Pups Research Articles

Polybrominated diphenyl ethers and selected organochlorine chemicals in grey seals ( Halichoerus grypus) in the North Sea

Blubber samples from grey seal ( Halichoerus grypus) pups were collected in 1998 through to 2000. Twenty four newly weaned pups were sampled in November 1998, 13 of which were re-sampled during their first year of life, between March and December 1999, and an additional 48 and 25 samples (new cohorts) were obtained in 1999 (November–December) and 2000 (May–September) respectively. ∑PBDE concentrations (sum of Di-HxBDEs) ranged from 45 to 1500 ng/g lipid, with a geometric mean of 290 ng/g lipid. BDE 47 dominated the congener profile, followed by BDEs 100, 99, 153 and 154. ∑PCB concentrations (sum of 41 congeners) ranged from 100 to 93 000 ng/g lipid, with a geometric mean of 4600 ng/g lipid, with CB congeners 153, 138 and 180 making up 84% of the total PCB concentrations. The predominant OC pesticides were p, p′-DDE (geometric mean = 860 ng/g lipid, range = 160–3800 ng/g lipid) and p, p′-DDT (geometric mean = 120 ng/g lipid, range = 30–670 ng/g lipid). No significant differences were found between males and females, probably due to the young age of the animals. Significant decreases ( P < 0.01 for PBDEs and P < 0.05 for PCBs/OCs) were observed between newly weaned seals in 1998 and 1999, but not for the majority of juveniles in 1999 and 2000. Significant differences ( P < 0.01) were also found between the different seasons in 1999 newly weaned and juvenile seals, reflecting changes in blubber mass.

Seroprevalence of Toxoplasma gondii in Canadian pinnipeds.

Sera (n = 328) collected from phocids (1995-97) from the east coast of Canada, including harp seals (Phoca groenlandica), hooded seals (Cystophora cristata), grey seals (Halichoerus grypus), and harbor seals (Phoca vitulina), were diluted 1:25, 1:50, and 1:500 and tested by a modified agglutination test for antibodies to Toxoplasma gondii. Titers equal to or greater than 1:25 were considered evidence of exposure. Grey seal (11/122, 9%), harbor seal (3/34, 9%), and hooded seal (1/60, 2%) had titers of 1:25 and 1:50. Harp seals (n = 112) were seronegative. Probable maternal antibody transfer was observed in one harbor and one grey seal pup at 10 and 14 day of age, respectively. Transmission of T gondii in the marine environment is not understood. The discovery of T. gondii in marine mammals might indicate natural infections unknown because of lack of study or might indicate recent contamination of the marine environment from the terrestrial environment by natural or anthropogenic activities.

PHONING HOME‐A NEW GSM MOBILE PHONE TELEMETRY SYSTEM TO COLLECT MARK‐RECAPTURE DATA

AbstractWe describe and evaluate a new telemetry system based on GSM (Global System for Mobile Communications) mobile phone technology that may provide mark‐recapture data for single year survivorship studies. These phone‐tags automatically attempt to send an SMS text message once every two days. The successful receipt of a text message ashore constitutes a resighting event within the coastal zone of GSM coverage. Haul‐out data and coastal location data are incorporated into the messages. Data are presented for a three‐month period (January‐March) following tag deployment on 59 gray seal (Halichoerus grypus) pups at the Isle of May (Scotland). An average of 15.5, 4.1, and 8.2 seals succeeded in registering within each three‐day period in January, February, and March, respectively. Tags registered with a wide geographical range of GSM radio cells on the Scottish and English east coasts, and also from Norway and Germany. Haulout records covering 54% of the animals' time were received. With future modifications to the tags, this figure should approach 100%. The median delay to network registration was 9.6 sec from a seal in the sea (not hauled out). These data show that GSM mobile phone telemetry is a useful technique to obtain haul‐out and mark‐recapture data.

Polychlorinated biphenyls and organochlorine pesticides in Baltic and Atlantic gray seal (Halichoerus grypus) pups.

Organochlorine pollutants (OCs), such as polychlorinated biphenyls (PCBs), DDT, chlordanes (CHLs), hexachlorobenzene (HCB) and hexachlorocyclohexanes (HCHs) were determined in blubber biopsies from free-ranging Baltic and Atlantic gray seal (Halichoerus grypus) pups. Well-fed pups from the Baltic Sea had concentrations of DDT, PCBs, and HCHs that were 2 to 10 times higher than in corresponding pups from populations in the Atlantic Ocean. The OC pattern in the Baltic seals differed significantly from that of their Atlantic relatives, reflecting the predominance of regional point source inputs into the Baltic Sea and long-range atmospheric inputs into the Atlantic Ocean. The differences in the pattern of the compounds also indicated an enhanced metabolism of the more metabolizable compounds in the more contaminated Baltic seals. Surprisingly, the proportions of the high chlorinated and low-volatile PCB congeners (> 6 Cl atoms) were comparable or lower in the Baltic pups as compared to the Atlantic pups. This difference might be due to Baltic seals occupying a lower trophic level than Atlantic seals and/or to the eutrophication situation in the Baltic Sea, which causes sedimentation of these PCB congeners. Significantly higher OC concentrations were found in starved and/or abandoned Baltic pups as compared to well-fed pups. The most contaminated Baltic seal pups in the present study had PCB concentrations that are comparable or higher than those reported to impair the immune systems and vitamin A dynamics in phocids.

Polybrominated diphenyl ethers (PBDEs) in grey seals during their first year of life—are they thyroid hormone endocrine disrupters?

Blubber biopsy and blood samples were collected from weaned grey seal pups and juveniles in 1998 and 1999. The relationship between the concentration of total PDBEs in the blubber and the circulating concentrations of serum proteins, minerals and thyroid hormones was investigated. Fifty-four post-weaned pups were sampled and 55 first year juveniles, of which 13 were recaptured post-weaned pups. The median concentration of total PBDEs in the pups’ blubber was 170 and 460 ng g −1 in the first-year animals. Total blubber PBDEs contributed significantly to the prediction of circulating thyroid hormone concentrations, after controlling for age and condition. Cholesterol and albumin concentrations were also positively related to blubber PBDEs. The results of this study suggest a link between thyroid hormones and exposure to PBDEs in grey seals during their first year of life. Such an association is not alone sufficient evidence for a cause and effect relationship, however it is in accordance with the hypothesis that these compounds are endocrine disrupters in grey seal pups.

Negative relationship between PCBs and plasma retinol in low-contaminated free-ranging gray seal pups ( Halichoerus grypus)

Polychlorinated biphenyls (PCBs) have been shown to affect retinol (vitamin A) homeostasis in adult as well as neonatal seals. The aim of the present study was to examine the relationships between plasma (PL)-retinol status and PCB concentrations in different blood compartments (blood cells (BCs), PL, and whole blood (WB)) of free-ranging neonatal gray seals ( Halichoerus grypus) and to identify which PCB congeners may be responsible for the PL-retinol-depressing effects of PCBs. PL-retinol concentrations correlated positively with body mass and negatively with ΣPCB (lipid-weight basis, lw) in WB and ΣPCBlw in BCs. ΣPCBlw in WB was the parameter that best described the variation in PL-retinol concentration ( r 2=0.455, n=20, P=0.0007). Furthermore, PL-retinol concentrations correlated with nine of the 15 detected PCB congeners. It is possible that there is an equilibration between the concentrations of metabolizable congeners and their metabolites and that the retinol-depressing effect of PCBs in neonatal gray seals is caused by PCB-OH metabolites that interfere with the formation of PL transport complexes that transport retinol in PL and increase renal excretion of retinol. This suggestion is in accordance with previous mechanistic explanations of the retinol-depressing effect of PCB in rodents.

The effect of total immunoglobulin levels, mass and condition on the first‐year survival of Grey Seal pups

Summary1. A joint live‐recapture/live‐resighting/dead‐recovery mark–recapture model was used to investigate the effect of serum gammaglobulin (IgG) levels, sex, mass and condition (mass/length as a surrogate for total body fat) at weaning on the probability of survival from weaning to age 1, in Grey Seal (Halichoerus grypus Fabricius 1791) pups born at two different breeding colonies (Isle of May and Farne Islands) in two different years (1997 and 1998).2. It was found that increased mass or condition at weaning had a positive effect on the first year survival of Grey Seal pups born at both colonies. Males had a lower probability of survival than females.3. Higher postweaning circulating IgG concentrations also decreased the probability of survival. It is not known if those pups with high IgG were individuals with naturally higher circulating concentrations or because titres were elevated due to antigenic challenge.

Dynamics of vitamin A in grey seal (Halichoerus grypus) mothers and pups throughout lactation

Vitamin A concentrations were measured in milk and serum of grey seal (Halichoerus grypus) mothers and in the serum of their pups sampled 2–6 times between parturition and weaning on the Isle of May, Scotland, in 1998 and 2000. Changes in serum vitamin A concentration were also followed in pups during the postweaning fast. During their 18-day lactation period, fasting mothers produced a milk very rich in vitamin A. Concentrations of 6.3 ± 1.6 and 10.1 ± 4.5 mg/kg (mean ± SD) were measured in colostrum (day 0) and in milk at late lactation ([Formula: see text]11 days), respectively. Surprisingly, the vitamin A concentration increased at late lactation, even when it was expressed per unit of milk lipids. The vitamin A concentration in mothers' serum was 329 ± 65 μg/L at day 0. The concentration dropped at day 3 (228 ± 21 μg/L serum), but increased to 400 ± 121 μg/L serum at late lactation. At birth, the serum vitamin A concentration of pups (111 ± 5 μg/L) was much lower than that of their mothers, revealing limited placental transfer. The vitamin A concentration in pup serum then increased throughout lactation to 499 ± 96 μg/L at the end of the nursing period. At that time, the pups' serum was more concentrated than the mothers' serum, reflecting the great vitamin A ingestion. After weaning, serum vitamin A concentrations of pups dropped over several days and then stabilized at 336 ± 45 μg/L.

Vitamin E status and the dynamics of its transfer between mother and pup during lactation in grey seals (Halichoerus grypus)

Concentrations of vitamin E, a powerful antioxidant, were measured in milk and serum of 18 grey seal (Halichoerus grypus) mothers and in the serum of their pups sampled up to 6 times between parturition and weaning on the Isle of May, Scotland, in 1998 and 2000. The vitamin E concentration in colostrum (89.4 ± 22.5 mg/kg milk; mean ± SD) was 4.5 times greater than that in later milk (20.9 ± 5.0 mg/kg milk). It then remained constant until the end of lactation. The decline in concentration of vitamin E in grey seal milk corresponded to a drop in the vitamin E concentration in mothers' serum between parturition (14.0 ± 4.8 mg/L serum) and the second half of the lactation period during which the serum vitamin E concentration remained stable (9.6 ± 3.2 mg/L serum). Circulating vitamin E concentrations varied significantly among mothers but there was no relationship with mother's age. Despite these differences between mothers, individuals produced milk with very similar vitamin E concentrations. The vitamin E concentration in grey seal pups' serum was low at birth (lowest concentration 3.1 mg/L serum) but increased sharply to a peak around days 1–3 (31.2 ± 5.2 mg/L serum). It then fell, before stabilizing until the end of lactation (21.1 ± 4.5 mg/L serum), reflecting the changes reported in the milk.

Factors affecting first‐year survival in grey seals and their implications for life history strategy

Abstract In order to estimate the effect of weaning mass and body condition on the post‐weaning survival of grey seal pups from the Isle of May, Scotland in 1998 during their first year of life, a simultaneous analysis of live resighting and dead recovery mark–recapture data was used. A new type of tag was employed which allowed individuals to be identified when resighted alive (Hall, Moss &amp; McConnell 2000) as well as when found dead. The probability of post‐weaning survival to age 1 increased with body condition at weaning and differed between the sexes. Regardless of pup condition and time of year, the odds of survival for female pups over a 2‐month interval was estimated to be 3·37 (SE = 1·30) times higher than for males. Regardless of sex, a 1 standard deviation increase in pup condition was estimated to increase the odds of survival by a factor of 1·422 (SE = 0·226). For a male pup in average condition (0·41 kg cm−1) the estimated annual survival after adjusting for tag‐loss was 0·193 (SE = 0·084); for a female pup in average condition (0·39 kg cm−1) it was 0·617 (SE = 0·155). The effect of condition at weaning on survival was significantly greater for male pups than for females. This implies that high quality females should invest more heavily in their male pups because the marginal return, in terms of increased reproductive value, from any additional expenditure is twice that for females. Male pups in our sample were significantly heavier at weaning and in better condition than female pups. However, this does not provide conclusive support for our predictions, because we could not control for the effects of maternal size on weaned mass.

Distribution, demographics and survivorship of grey seal pups (Halichoerus grypus) rehabilitated in southwest England

Cent quatre vingt huit jeunes phoques gris vivants, originaires des cotes de Cornouailles, du Devon, du Dorset et des iles Scilly, ont ete presentes pour rehabilitation au Sanctuaire national des phoques, a Gweek, en Cornouailles, entre aout 1992 et fevrier 1998. Il y avait nettement plus de mâles que de femelles (p < 0,05). Pres d'un quart de ces jeunes etaient presevres, et l'epoque precoce de l'annee ou ils etaient presentes correspondait a l'avance de la saison de reproduction du phoque gris dans le sud-ouest de l'Angleterre. Soixante-neuf pour cent des jeunes ont ete presentes entre octobre et decembre, quand la mer etait difficile, ce qui en est probablement responsable. Plus de la moitie des jeunes presevres ont ete trouves dans les sites de reproduction connus, mais le type de repartition des jeunes sevres a ete vraisemblablement complique par la dispersion de jeunes nes localement et par l'arrivee de jeunes d'autres populations. Cent cinquante deux jeunes phoques gris ont pu retourner a la vie sauvage au cours des six annees de la periode d'etudes, avec ceux qui ne devaient pas survivre de leurs traumatismes, causes de mortalite la plus frequente. Il est difficile de tirer des conclusions sur l'impact du programme de rehabilitation sur les populations fragmentees, des phoques gris de la region, sans tester un monitoring apres le lâcher. Des suggestions en/vue d'ameliorations sont esquissees.

Mother–pup vocal recognition in the grey seal (Halichoerus grypus) of Sable Island, Nova Scotia, Canada

AbstractParental recognition of offspring would be expected to evolve among densely populated species in which parental investment is large, and separations of the mother–pup pair are frequent. Although otariids present a well‐developed system of mutual vocal recognition, evidence in phocids is weak. Furthermore, allo‐suckling is prevalent in some species and may reflect confusion over the identity of pups. The vocalizations of grey seal Halichoerus grypus pups have been found to be stereotyped and individually distinctive on the Isle of May, Scotland. However, playback experiments showed that mothers fail to discriminate between the vocalizations of their pup and a non‐filial pup. Moreover, widespread allo‐suckling was observed. In contrast, grey seals on Sable Island, Nova Scotia, a population reproductively isolated from that of the Isle of May, show very little allo‐suckling. This may reflect the presence of a recognition system that does not seem to be present on the Isle of May. During the 1999 breeding season on Sable Island, vocalizations of grey seal pups were recorded and playback experiments carried out to determine whether female grey seals respond differently to the playback of vocalizations of their own pup, a familiar pup and an unfamiliar pup. Grey seal mothers were found to make significantly more head turns and body movements towards the loudspeaker during the playback of their own pup call than during the playback of a familiar or unfamiliar pup call. In addition, there was no evidence of an effect of pup age. This suggests that female grey seals can discriminate between pup calls using the stereotyped and individually distinctive vocalizations of their pup, and that different selective pressures may be in operation between the Sable Island and Isle of May colonies.

Conditions in grey seal pups (Halichoerus grypus) presented for rehabilitation

A survey was carried out on the condition of 188 live grey seal (Halichoerus grypus) pups presented for rehabilitation from the coasts of south-west England between 1992 and 1998. The...

Treatment of lesions of osteomyelitis in the hind flippers of six grey seals (Halichoerus grypus)

Six rescued grey seal (Halichoerus grypus) pups had traumatic injuries to their hind flippers; three had osteomyelitis without fractures, one had a single fracture and associated osteomyelitis, and two had...

Where have all the fathers gone? An extensive microsatellite analysis of paternity in the grey seal (Halichoerus grypus).

Microsatellites were used to conduct an extensive analysis of paternity of grey seals from two Scottish breeding colonies at North Rona (n = 1189) and the Isle of May (n = 694), spanning more than a decade. A maximum of 46% of pups at North Rona and 29% of pups at the Isle of May could be allocated a father, even though the majority of candidate males for specific study sites within each colony were believed to have been sampled. Based on the paternities which could be assigned, both colonies showed evidence of reproductive skew, apparently due to the presence of approximately five males who were exceptionally successful. Some males were assigned paternities at least 10 years before, and colleagues 10 years after, being sampled, implying a reproductive lifespan of at least 10 years, and there are indications that the real maximum lies in the range 15-20 years. Male grey seals appear to have at least two breeding strategies they can adopt. On land, some males benefit from a traditionally polygynous system. However, between 50 and 70% of grey seal pups born at a particular colony are not fathered by males who are likely to be sampled by us, implying that these males seldom venture ashore here. We conclude that aquatic mating may play a much larger role in the grey seal than has previously been thought.

Thyroid hormones in grey seal pups ( Halichoerus grypus)

The aim of the present study was to describe the changes in thyroid hormone status in grey seal ( Halichoerus grypus) pups from birth to weaning and moulting. Plasma concentrations of total thyroxine (tT 4) were highest the first two days after birth, thereafter dropping to a lower, but stable level. This pattern may reflect a high transfer rate of maternal thyroxine prepartum, prior to parturition, or postpartum via colostrum, or it may be caused by active secretory thyrocytes in late foetal stage. Total triiodothyronine (tT 3) concentrations were lowest in neonatal pups, and increased as a function of age, indicating that deiodination of T 4 to T 3 increases as a function of age. Plasma concentrations of free thyroxine (fT 4) did not vary as a function of age. All hormone concentrations were higher than previously reported in adults, probably reflecting the important role of these hormones in regulating their high rates of metabolism and tissue synthesis and the growth of their juvenile pelage. Since polychlorinated biphenyls (PCBs) have been reported to affect plasma concentrations of thyroid hormones in seals, the information on thyroid hormone concentrations and dynamics reported in grey seal pups from a pristine Norwegian coastal environment provide valuable reference material for future studies on pups from more polluted areas.

EFFECTS OF MEAL SIZE ON OTOLITH RECOVERY FROM FECAL SAMPLES OF GRAY AND HARBOR SEAL PUPS

AbstractRecovered otoliths from pinniped feces provide valuable information on diet composition and prey size. We studied the effect of meal size on otolith recovery from the feces of one harbor and eight gray seal pups. Each of 11 experiments comprised a half‐ration meal, a period of fecal collection, a 1.5‐or double‐ration meal again followed by a period of fecal collection. A significantly lower percentage of Atlantic herring otoliths were recovered from half‐ration meals (25%± 12.5% in the harbor seal, 8.6%± 6.9% in eight gray seals) than from 1.5‐ or double‐ration meals (62.5%± 3.1 % in the harbor seal, 32.8%± 23.5% in gray seals). Meal size also significantly affected the percentage of Atlantic cod otoliths recovered from gray seal feces (65.0%± 26.3% from half ration, 98.3%± 2.9% from 1.5 ration). For both size meals, recovered cod otoliths were more significantly eroded than herring otoliths. The development of correction factors to account for the effects of digestion will need to consider the distribution of meal sizes of free‐ranging pinnipeds.

Pup production and population trends of the grey seal (Halichoerus grypus) in the Gulf of St. Lawrence

Grey seal (Halichoerus grypus) pup production of the Gulf of St. Lawrence component of the Northwest Atlantic grey seal population was determined for the 1984-1986 and 1989-1990 periods using mark-recapture methods. Pup production estimates based on recaptures from shot samples from Anticosti Island ranged from 5436 (SE = 672) to 6955 (SE = 1183) for 1984-1986. An independent estimate for 1984-1986, based on animals captured on Sable Island, was 7431 (SE = 1414) to 8633 (SE = 2827). Mark-recapture estimates of pup production for 1989 and 1990 from shot samples collected from Anticosti Island were 8825 (SE = 3164) and 9156 (SE = 2652), respectively. The estimates based on animals captured on Sable Island varied from 7295 (SE = 2118) to 8116 (SE = 846) for 1989-1990. Both the Anticosti Island and Sable Island recovery samples underestimate 1989 pup production due to hunting which removed 1612 pups from the population before they could disperse. The Gulf component of the Northwest Atlantic grey seal population is increasing at an annual rate of 7.4% (SE = 2.2).

Using mark-recapture to estimate the numbers of a migrating stage-structured population

A model is presented for the joint analysis of mark-recapture data and stage- or age-structured data that allows the population abundance, birth rates, and migration rates to be estimated in situations where standard methods may be unreliable. The model assumes that birth rates follow a continuous distribution and that migration can be described by a simple Markov process. Application of the model is illustrated using mark-recapture and stage-structured data for grey seal (Halichoerus grypus) pup production in the Gulf of St. Lawrence and resulted in estimates of 9800 and 10 500 pups produced in 1989 and 1990, respectively.

Temperature effects on the breeding distribution of grey seals (Halichoerus grypus).

The metabolic rates of six female grey seal (Halichoerus grypus) pups were measured during their postweaning fast at air temperatures between -15 degrees and 30 degrees C. The composite of their individual thermal neutral zones extended from a mean lower critical temperature of -7.1 degrees +/- 0.7 degree C to a mean upper critical temperature of 23.0 degrees +/- 0.4 degree C. Within the thermal neutral zone, mean standard metabolic rate of the fasting animals was 1,265 +/- 82 kcal d-1, or about 1.1 times the value predicted for an adult animal of similar body mass (mean mass = 40.9 +/- 1.2 kg). For those grey seal populations that reproduce during winter months in the eastern and western Atlantic and in the Baltic Sea, the lower critical temperature of fasting pups corresponds closely with the coldest mean monthly air temperature at the northern end of their breeding ranges. This observation supports the hypothesis that cold ambient air temperatures limit the northern breeding distribution of grey seals, primarily through their thermoregulatory effects on small, fasting pups before they enter the water.