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Narwhals (Monodon monoceros Linnaeus, 1758) summering on northern Baffin Island are experiencing increases in vessel traffic related to an iron-ore mine operated by Baffinland Iron Mines Corporation; how this increase in vessel traffic may impact narwhal is currently unknown. Cortisol is a stress response hormone and a stress indicator in marine mammals. This study evaluated cortisol levels in narwhal blubber sampled during subsistence harvests prior to project-related vessel traffic (2000–2006), during project-related vessel traffic (2013–2019), and during a high-stress entrapment event that occurred in 2015. There was a significant increase in cortisol levels from pre- (0.81 ± 0.45 ng/g (±SE)) to during (1.81 ± 0.48 ng/g (±SE)) project-related vessel traffic (over 100% higher), and both were significantly lower than cortisol levels from animals sampled during an entrapment event (10.52 ± 0.59 ng/g (±SE)). Increased vessel traffic, changing ice conditions, altered Arctic food webs, increased predation pressure from killer whales, and cumulative impacts from these sources likely all contribute to increased stress levels for narwhals. Thus, there is a need for continued monitoring of stress responses (i.e., cortisol levels) and other health indicators in narwhals to understand how individual fitness and the population will be impacted over time.

To investigate the milk fatty acid composition of female Steller sea lions (Eumetopias jubatus (Schreber, 1776)) between and within maternal states (i.e., perinatal or foraging), milk samples were collected in 2010 and 2011 via gastric intubation from Steller sea lion pups on a small rookery in the central Gulf of Alaska. Maternal states of lactating females were determined upon reuniting with their sampled pups via remotely operated video cameras on the rookery. Milk fatty acid composition between Steller sea lion maternal states was significantly different, and thus can be utilized to distinguish between perinatal and foraging Steller sea lions of the same geographic region in the absence of direct observation. However, milk fatty acid composition remained relatively constant within perinatal Steller sea lions, suggesting steady mobilization of fatty acids from blubber to milk, and within foraging Steller sea lions, implying females forage on similar prey species within several days after their perinatal period. Differences in milk fatty acid composition between maternal states, including differences in the relative percentages of polyunsaturated fatty acids, may have important implications for growth and development of offspring.

Beluga whales (Delphinapterus leucas) are facing profound changes in their habitat, with impacts expected at the individual and population level. Detecting and monitoring exposure and response to environmental stressors is necessary for beluga conservation and management of human activities. Cortisol has proven as a useful tool to assess stress on wildlife. Cortisol was measured in three blubber layers and plasma in subsistence-hunted beluga whales from the summers of 2007 to 2010 using an HPLC/MS/MS. We assessed the effect of biological and biochemical factors. Cortisol ranged from undetectable to 17.8 ng/g in blubber and 2.5 to 61.2 ng/mL in plasma. Concentrations were highest in the inner blubber layer likely reflecting circulating levels. All tissues were significantly higher in 2008 for reasons that remain unclear. Cortisol levels were on par with resting levels in captive belugas. Best fit models for cortisol revealed age to be an important determinant along with length and blubber thickness. Lack o...

Lactating New Zealand (NZ) sea lions (Phocarctos hookeri) exhibit different foraging patterns during their foraging trips, with benthic divers spending more energy at sea than mesopelagic conspecifics. We compared blubber fatty acids (FAs) of 14 benthic and 12 mesopelagic females captured at the Auckland Islands, NZ subantarctic, in late January 2000 using an analysis of similarities (ANOSIM). FA profiles between foraging types were significantly different (global R = 0.30, p = 0.001), suggesting a different use in prey resources. We then compared the diet predictions by quantitative FA signature analysis (QFASA) by using a prey FA library available in the region. Overall, diet predictions were significantly distinct between benthic and mesopelagic females (global R = 0.17, p = 0.022), although the diets consisted of the same prey but in different contributions. The results suggest benthic females do not compensate their higher foraging costs by feeding on prey with higher energy densities. Foraging areas of benthic females are not exploited by the trawling fishery; therefore, the benthic tactic might be a trade-off between a higher foraging cost and less resource competition.

Serum thyroid hormone (TH) concentrations have been used alone or with other measurements to assess health status or effects of toxicant exposure in marine mammals. Histological sections from thyroid glands of the bowhead whale ( Balaena mysticetus L., 1758) were examined in conjunction with serological TH analyses. Serum was assayed for total and free triiodothyronine and total and free thyroxine via radioimmunoassay. Histomorphology of thyroid tissue was assessed by light microscopy and the utilization of an epithelial-follicular index (EFI). Age, sex, or season did not significantly affect serum TH levels. However, TH concentrations in pregnant or lactating females were found to be significantly lower than in the other sex and reproductive groups investigated. The EFI and epithelial height (EH) were greater in spring subadult and adult whales compared with those that were landed in the fall. No correlation was found between serum TH concentrations and serum, blubber, or liver levels of select polychlorinated biphenyl metabolites and organochlorine congeners examined. Low variability in concentrations of the serum THs across age, season, and sex and reproductive groups supports the existence of strong homeostatic mechanisms for maintaining TH concentrations in these presumably healthy animals. Departures from these ranges may indicate a disturbance in these regulatory mechanisms and may be a useful indication of toxicity or other health disorders.

Sex differences in foraging behaviour have been attributed to size dimorphism, niche divergence, and sex-specific fitness-maximizing strategies. Although sex differences in diving behaviour of marine carnivores are thought to result in sex differences in diet, this is not known for any species over temporal scales relevant to life-history characteristics. We examined blubber fatty acid (FA) profiles of gray seals, Halichoerus grypus (Fabricius, 1791), a sexually size-dimorphic species in which sex differences in foraging behaviour have been observed. FA profiles reflect prey consumed over a period of weeks or months. FA profiles of adult males and females varied significantly by season but there was a season by sex interaction, indicating that seasonal changes in diet differed by sex. FA profiles of adults also varied interannually, with a significant sex by year interaction. Interannual variability may have been a response to changes in ocean-bottom temperatures affecting prey availability or changes in prey abundance. Adult FA profiles differed from those of 6-month-old juveniles; however, there was no evidence of sex differences in the diet of younger animals. Our results indicate that sex differences in the foraging behaviour of adults are reflected in differences in diet at multiple temporal scales.

Odontocete blubber has been shown to be variable in composition and can be separated into strata visually, histologically, and biochemically. The purpose of this study was to examine fatty acid composition of bottlenose dolphin (Tursiops truncatus (Montagu, 1821)) blubber, and determine if differences exist between body sites, reproductive states, and (or) seasons. The influence of these variables on blubber composition could aid in the creation of a model that would use fatty acid signature analysis to evaluate diet in free-ranging populations. Blubber samples were obtained from freshly dead animals along the Texas and Louisiana coastlines. Samples from nine body sites were analyzed to investigate site variability, and from one site to evaluate differences due to season, reproductive state, and blubber layer. All body sites of animals sampled in the winter were statistically indistinguishable, indicating that biopsy samples could be obtained from any location on the animal for fatty acid analysis during this season; however, three distinct blubber layers were identifiable, and reproductive states were significantly different in terms of fatty acid composition. Seasonal differences in fatty acid composition were also highly significant for all one-site inner blubber layer samples. Ultimately, the differences in fatty acid composition could have resulted from dietary or physiological factors and need to be examined further.

Analyses of fatty acid constituents in a sample of bowhead whale (Balaena mysticetus) blubber were conducted using a method that has not been applied before to studies of lipids in marine mammals. It involves creation and analysis of nitrogen (picolinyl) ester derivatives of the fatty acids followed by combined gas chromatography – mass spectrometry for verification of structures. Use of this approach allowed the structural confirmation of 45 different fatty acids in the blubber sample. The traditional method of methyl ester derivatization of fatty acids followed by gas chromatography – mass spectrometry analyses provides more component characterization than analyses by gas chromatography – flame ionization detection, but not enough to effectively differentiate double bond isomers or branched compounds. Although the novel approach is time intensive, we recommend that it be employed for studies where the precise identification and confirmation of fatty acids is important.

Vitamin A is a nutrient essential to all mammals for growth and development, as well as for the maintenance of reproductive, endocrine, and immune systems. Environmental contaminant-related disruption of vitamin A has been observed in many wildlife species and can therefore be used as a biomarker of toxic effects. However, the natural processes regulating vitamin A uptake, storage, and distribution among compartments are poorly understood in marine mammals. In this study, 20 young healthy harbour seals (Phoca vitulina) were captured to establish a compartment-based model providing a foundation for a mechanistic understanding of vitamin A physiology and disruption. Vitamin A (retinol, retinyl palmitate, and (or) retinoic acid) was quantified in blood plasma and in biopsy samples of liver, blubber, and skin. Although the highest concentrations of vitamin A were found in liver, blubber represents a more important storage depot, with an estimated 66% of the total retinoid content of the compartments measured. We suggest that vitamin A physiology in the precocious harbour seal has evolved to deal with high vitamin A availability during a short nursing period and to sustain growth during the postweaning fast. Positive correlations in vitamin A concentrations among liver, blubber, and skin support the use of less invasive biopsy sampling of just blubber or skin, which can provide physiologically relevant information in biomarker studies of free-ranging marine mammals.

Discussion 2223 The composition of blubber of marine mammals has been the goal of a large number of investigations during the last 70–80 years (Ackman and Lamothe 1989). Differences in the fatty acid composition have been detected among different species of seals and whales, even among different populations within species and between pups and adults. It is the prevailing assumption that these differences are caused by differences in diets. The continuing development of analytical equipment has increased the sensitivity and resolution of the analyses, allowing detection and quantification of 70 or more fatty acids in samples of blubber, or any other tissue, from marine animals. With such complex mixtures, evaluation of the data calls for a multivariate approach where the information contained in all fatty acids is retrieved simultaneously (Kaufman 1992). Nevertheless, in the vast number of published investigations on lipids, univariate methods, e.g., Student’s t test, have been, and still are, the predominant way of data han

Seventy-eight harbour porpoises, Phocoena phocoena (33 females, 45 males), were obtained in summer (June-September) as incidental by-catch from the cod fishery in the Gulf of St. Lawrence and examined for the presence of cranial sinus nematodes. Stenurus minor (Kühn, 1829) Baylis and Daubney, 1925 were present in the cranial sinuses of all adult porpoises (>1 year old, N = 66, mean intensity = 2362, range = 87-8920) and absent in all young of the year (

Fatty acid signature analysis is based on the principle that unique arrays of fatty acids within groups of organisms can be transferred, largely unaltered, up the marine food chain and thus may be an indicator of diet composition. We applied fatty acid signature analysis to milks collected from Antarctic fur seals (Arctocephalus gazella) at South Georgia in 1990–1991, during the perinatal period (N = 19) and subsequently during early (N = 11), mid (N = 11), and late (N = 8) foraging trips. In lactating otariid females, milk fatty acids secreted during the perinatal fast are derived largely from blubber mobilization and thus are influenced by dietary history prior to parturition. Conversely, milk fatty acids secreted during foraging trips are derived primarily from immediate dietary intake. The fatty acid signature of perinatal milks was significantly different from that of all other milks, suggesting differences in the prepartum diet when females are away from the breeding grounds. At the onset of foraging periods, the fatty acid composition of milks' changed dramatically to reflect a diet composed mainly of krill. However, during late foraging periods, milk fatty acids again changed from those of early and mid foraging, and suggested a predominance of teleost fish in the diet. These findings were consistent with independent assessments of diet by faecal analysis and indicate the potential value of fatty acid signature analysis in studying foraging ecology in free-ranging pinnipeds.

We examined blubber distribution in 50 mature harp seals (Phoca groenlandica) from the St. Lawrence River estuary, Canada, between December 1988 and April 1989. Blubber was thickest and most variable dorsally, becoming gradually thinner through the neck region and around the foreflippers. Blubber thickness relative to body radius was greatest dorsally at positions from 40 to 70% of standard length (measured back from the snout) and in the posterior region; it varied less topographically than blubber thickness alone, thereby increasing the insulating effectiveness of blubber stores. The largest sexual and seasonal differences in blubber were at the sites with the greatest relative blubber thicknesses. Pregnant females (winter) had thicker blubber than males (winter) or postpartum females (April) at corresponding body sites. Pregnant females had significantly thinner blubber ventrally in the abdominal region than at corresponding lateral positions, whereas males and postpartum females had a more uniform distribution. Blubber mass was highly correlated with estimated blubber volume (R2 = 0.9967, p 2 = 0.7847, p −3. We discuss the pattern of blubber distribution in harp seals with respect to the multiple functions of energy demands, thermal insulation, streamlining, and mobility.

Using chemical analysis we measured the composition of 26 harp seals (Phoca groenlandica) representing both sexes, aged between 3 months and 30 years, and encompassing a wide range of body conditions. Predictive relationships between total body water and total body fat contents, total body protein content, and gross energy were calculated. These equations allow accurate estimation of harp seal body composition provided total body water content and body mass are known. Using these data we compared the accuracy of three existing equations that have been used to predict body fat content of other species. We found that in adult harp seals, lean body mass has a relatively stable hydration of 70% but the hydration of blubber varied with body condition. Lipid content, and thus energy density of blubber, increased with increasing body condition.

We evaluated organochlorine contaminant concentrations and burdens in blubber samples from 50 harp seals (Phoca groenlandica) obtained from the estuary and northern Gulf of St. Lawrence and Hudson Strait, Canada, between December 1988 and December 1989. The concentration and burden of PCBs increased significantly during the winter months for males occupying the St. Lawrence estuary. The potential for rapid accumulation of contaminants in the estuary was also observed among females: nine postpartum females (1 month after weaning) had higher organochlorine levels than prepartum females from the same location. The lowest observed contaminant concentrations and burdens were in seals from Hudson Strait in autumn. In winter specimens, males had DDT and PCB concentrations about 4 and 2 times as great, respectively, as females of similar age distribution and collection date. Congeners with IUPAC Nos. 138 and 153 accounted for more than 50% of total identifiable PCBs, which is consistent with their prevalence in other marine biota. The concentration of PCBs has declined and the percent p,p′-DDE of total DDT has increased between 1982 and the present study. Unlike the beluga whale (Delphinapterus leucas), harp seals occupy the more polluted waters of the estuary only seasonally, and this may account for their lower residue concentrations.

We evaluated body condition in 315 harp seals (Phoca groenlandica) obtained between 1988 and 1991. Total percent lipid of blubber did not vary between the five body sites and three depths sampled. In nine winter specimens, blubber, carcass, viscera, and skin contributed 89.5, 8.7, 0.9, and 0.9% of total body lipid. Pregnant females in winter had higher percent lipid in muscle than males, but no difference was observed in percent lipid in liver or blubber or in liver mass. Those females obtained 1 mo postpartum had the highest percent lipid in muscle and liver, the heaviest livers, but the lowest blubber lipid content. Sculp mass (skin with attached blubber) increased from autumn through late winter, with pregnant females having heavier sculps than males in winter. Both sculp and core mass varied on a seasonal and annual basis in males and females. Blubber was most variable dorsally between 40 and 70% of length, measured from the snout, and thickest at 50%, coincident with the position of maximum girth. Blubber thickness measured over the sternum was significantly less variable than at the 50% dorsal position. The direct measurements of body component masses may be necessary to detect subtle differences in body condition.

Length of lactation, pup growth rate, and female weight loss in ringed seals (Phoca hispida) were estimated using cross-sectional data from the Canadian and Norwegian Arctic. At birth the pups had a standard length of 63.4 cm (SE = 1.3, N = 11) and weighed 5.4 kg (SE = 0.4, N = 6). Weaning occurred approximately 39 d (range 36–41 d) after birth at an estimated length of 88.4 cm (SE = 0.65, N = 96) and an estimated weight of 22.1 kg, resulting in an increase in length of 0.64 cm∙d−1 and a weight change of 0.43 kg∙d−1. Regression of female weight on the number of days after the nominal date of birth for each region indicated that the postpartum female weighed 81.2 kg and lost 0.64 kg∙d−1 (95% CI = ±0.20). During lactation, female weight declined by an estimated 32%, with much of the loss occurring from the blubber. Analyses of stomachs indicated that ringed seals supplemented stored energy reserves by feeding during lactation.

Hooded and harbor seals are unique among true seals (family Phocidae) in that the lanugo (fetal pelage) is typically shed in utero. Shedding had occurred in all newborn hooded seals examined off the Labrador coast (n = 62) and in 94% of newborn harbor seals on Sable Island, Nova Scotia (n = 110), although in one-fifth of the latter the molt was incomplete. In hooded seals the shed hair in the amniotic sac was organized into tightly woven disks, whereas in harbor seals the shed hair formed a loose mat with no evident structure. We examined hair masses in the intestines of pups of both species but could find no evidence that the intestines were involved in hair disk formation. We argue that fetal shedding, like prenatal blubber deposition, is an adaptation enabling newborn pups to enter cold water without adverse consequences. This ability allows the use of pupping substrates that are unstable or regularly inundated with water.

I examined the body condition of 220 harbour porpoises (Phocoena phocoena) killed incidentally in commercial fishing operations in the Bay of Fundy between July and September, 1985–1988. Condition was assessed using a direct measure (blubber mass) and two indirect measures (blubber thickness and girth). To compare condition among porpoises of different sizes, each measure was regressed against an appropriate measure of body size, and the residuals of these regressions were used as indices of condition. Mean residuals of blubber mass varied significantly among both reproductive classes and sampling years. Calves and nonlactating mature females had greater mean residual values for blubber mass than immature porpoises and mature males; lactating females possessed intermediate levels. Porpoises sampled in 1987 had greater mean residual blubber mass than porpoises sampled in other years. Although the residuals of girth and blubber thickness demonstrated similar trends to those of blubber mass, they were poorly correlated with the residuals of blubber mass and are not robust indices of condition in harbour porpoises.

We have investigated the relationships between percent blubber content and xiphostemal blubber thickness or girth-to-length ratios in ringed seal (Phoca hispida), harp seal (Phoca groeniandica), and grey seal (Halichoerus grypus). The blubber content was significantly correlated with blubber depths and girth-to-length ratios in all three species, in addition, we have developed an estimator for percent blubber content (the LMD-index) based on standard length (L, in meters), body mass (M, in kilograms), and on blubber thickness (d, in meters) measured at a defined position dorsally. From these variables the percent blubber content (B%) can be estimated by the expression B% = 4.44 + 5693 [Formula: see text], with a standard error of the estimate of three percentage units. This index also gave reasonable estimates for blubber content in three harbour seals (Phoca vitulina) and eight bearded seals (Erignatus harbatus).

Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) from the Svalbard Islands are described. The blubber content of adult females decreased from a high of about 50% at the beginning of the pupping season in March–April to a low of 31% during moulting in June. In adult males, the blubber content decreased from 41% in March to 29% in June. By estimating an individual seal's body mass by 1 April from its standard body length, we calculated an average daily loss of body mass of 160 g/day in adult females and 100 g/day in adult males from the start of lactation to the middle of moulting. The blubber content of sexually immature seals was less in June and July than in April, but the seasonal changes were smaller than in adult seals. We found no evidence of significant changes in core mass in adult seals, and suggest that the seasonal body mass changes are mostly due to changes in body fat content.

Postmortem temperature regimes were measured in 11 minke whales, Balaenoptera acutorostrata, at tissue depths varying from 1.5 (in the blubber) to 30 cm, at two different sites on the whales' sides, one in the flipper region (site A) and one in the dorsal fin region (site B). Body temperatures of instantaneously killed whales were assumed to represent those of living animals. Core body temperatures were 35.0 °C at site A and 35.6 °C at site B. Core body temperature and the size of the thermal core were affected by blubber thickness and the time between harpoon strike and death, but were not influenced by duration of pursuit prior to harpooning. Both intra- and inter-specific comparisons reveal that the thickness of the blubber layer is important for the maintenance of thermal gradients and, thereby, for heat conservation.

The gross mass, mean adipocyte volume, and hexokinase and phosphofructokinase activities of blubber and internal adipose tissue were measured from fin whales (Balaenoptera physalus) caught in the North Atlantic west of Iceland. Fin whale adipocytes are smaller but more numerous than predictions from allometric equations relating adipose tissue structure to body mass, but the deviations are no greater than those of some terrestrial mammals, including humans. Significant activity of the glycolytic enzymes was measured from all adipose tissue samples except those around the eyeball; the activities of hexokinase and phosphofructokinase measured at room temperature are only slightly lower in the blubber than in the internal adipose depots. There was little evidence for metabolic correlates of the site-specific differences in the structure and chemistry of blubber. The highest capacity for glucose utilization was measured in adipose tissue from depots in the neck and the thorax, both of which may contain thermogenic tissue in neonates.

The digestive efficiency of polar bears (Ursus maritimus) feeding on their principal prey, the ringed seal (Phoca hispida) is high. Apparent digestibilities of 83.7 ± 10.3% for dietary protein, 97.3 ± 2.1% for dietary fat, and an assimilation of dietary energy of 91.7 ± 5.8% were found for the five diets. Presence of hair and bone in the diet significantly reduced the apparent digestibility of protein N. Gastrointestinal transit times were affected principally by the fat (energy) content of the diet and varied between 12.3 ± 1.9 to 38.0 ± 8.0 h. The results explain the apparent preference for seal blubber by polar bears in the arctic as well as demonstrate that any seal > 1 month of age would satisfy the bear's daily energy requirements. The limiting factors in energy intake at a given feeding are the stomach capacity of the bear and the relative proportion of blubber and meat ingested.

The distribution of blubber in ringed seals (Phoca hispida) and relationships between surface area, body mass, and linear dimensions are described. The blubber was distributed in such a way that the ratio of blubber thickness to body radius is nearly constant over the body, maximizing the available blubber for insulation. The hind part of the body has a higher thickness to radius ratio and is thus "overinsulated." During periods of mass loss, fat is lost fastest from this overinsulated region, thus reducing the negative thermal effects of the fat loss. We present formulae for calculating body surface area and an effective, or "equivalent blubber thickness," for calculations of heat loss and suggest that these formulae are independent of size and shape. By combining these equations, we arrive at a general formula for calculating a lower limit for heat loss from marine mammals. According to this formula, thermal stability can be maintained when blubber is lost if mass is simultaneously lost from the body core.

The DDE/ΣDDT (ΣDDT = DDT + DDE + DDD) ratios in the blubber of North Atlantic pinnipeds and odontocete cetaceans, as determined by several scientists and surveys, are compiled to obtain a biannual mean series. Conversion of DDT to DDE is interpreted as being due not only to the marine mammals but also to the overall detoxifying activity of the North Atlantic marine biota. The change of these ratios during the period 1964–81 is examined and a strong correlation between these ratios and time is found in both groups, which demonstrates that such an index can be tentatively used when one assesses the chronology of pollutant input into the ecosystem. An equilibrium value may be reached at the beginning of the next century when the ratio reaches a value of approximately 0.60, provided that no new inputs of contaminant into North Atlantic waters exist.

Residues of DDT group insecticides and of PCBs were measured in samples of maternal blubber, milk, and pup blubber from grey seals (Halichoerus grypus) from Sable Island, N.S. Mean ΣDDT and PCB levels in maternal blubber lipid were 14.0 and 14.5 μg/g, respectively. Concentrations of DDT and PCBs in milk lipid were approximately 60 and 30%, respectively, of those found in maternal blubber lipid, suggesting a partial barrier to passage of these residues through mammary tissue. Concentrations in pup blubber lipid were the same as, or slightly higher than, those in milk lipid.We estimated that a grey seal will lose about 30% of its total ΣDDT burden and about 15% of its PCB burden through lactation; this would be approximately balanced by its estimated annual intake of these residues from food. Thus, the observation that female seals show no increase in residue burdens with age (in contrast to males) is explained. Key words: organochlorine, DDT, DDE, PCB, seal, blubber, milk

Measurements of body girth, blubber thickness, and the lipid content of blubber, muscle, and visceral fat of Icelandic fin whales (Balaenoptera physalus) showed a consistent pattern of body fat condition for each sexual class in all years between 1977 and 1982, with pregnant and anoestrous females being fattest. There was a trend of increasing body fatness between 1977 and 1982 which is supported by data on oil production from the catch. Parallel to this was an apparent increase in food abundance and whale fecundity.

Hearts were collected from 46 harp or grey seals of various ages and sexes. After fixation in formalin, sections were cut and stained with hematoxylin-eosin, and in a limited number of cases with Oil-Red-0. Histopathological examination revealed the presence of non-specific myocarditis in two instances only and no lipid deposits. The percentage of docosenoic acid (primarily 22:1ω11) in blubber and heart muscle triglyceride, tabulated for grey seal dam-pup pairs is evidence of exposure from birth. These results indicate that the susceptibility of the rat myocardium to docosenoic acids may not be as broadly relevant in other species such as the seal, pig and man as has been proposed.

n-3 Docosapentaenoic acid (22:5n – 3) is shown to constitute as much as 6% of the total fatty acids in six sets of dam–pup blubber samples from grey seals, Halichoerus grypus. Relative to fish oils, this fatty acid is several times more plentiful in the seal fats that form an important part of Inuit diets. Consideration of intakes of ω-3 fatty acids as therapeutic agents for cardiovascular and other health disorders in man should include this quantitatively important fatty acid of seal fats.

Changes in body weight and proximate composition were monitored throughout the postweaning fast in 20 male harp seal pups. Subsequent growth after the commencement of feeding was also examined. Weaned pups lost weight at a rate of 0.43 kg/day during the 1st week of fasting, declining to 0.20 kg/day by the 10th week. During the initial 2 weeks of the fast the lean body mass accounted for 39.8% of total energy losses (14.0% from core proteins and 25.8% from core lipids). The importance of core energy reserves later diminished until, by the 6th to 8th week of the fast, blubber supplied over 90% of the total energy. Core proteins were again mobilized during the final 2 weeks of the fast. Animals which started feeding after 1 to 2 weeks of fasting gained weight at a mean rate of 0.17 kg/day; those which started after 4 weeks of fasting gained at 0.29 kg/day. The relative amounts of muscle and fat deposited appeared to vary with the time (or physiological condition) when feeding commenced.

The fatty acid composition of blubber lipid was analyzed from one example of both sexes of the four species of phocid seals inhabiting the Bering Sea: spotted seal (Phoca vitulina largha), ringed seal (P. hispida), ribbon seal (P. fasciata), and bearded seal (Erignathus barbatus). All specimens had similar fatty acid complements (10 fatty acids predominated, ranging from chain lengths of 14 to 22 carbons with zero lo six double bonds) although there were specific differences among species and between sexes. The greatest interspecific differences in blubber fatty acid composition occurred in the ringed seal and may have been due to diet.Double-bond indices (indicating degree of unsaturation) were high in all samples and higher than those calculated for Atlantic or southern hemisphere seals. Melting points of the blubber lipid ranged from −2 to −8 °C for some components; all components melted below 15 °C correlating with expected peripheral blubber temperatures of seals in cold water of the Bering Sea.

Samples of blubber, muscle, liver, and kidney of short-finned pilot whale Globicephala macrorhyncha and long-snouted dolphin Stenella (longirostris ?) from waters adjacent to St. Lucia, Lesser Antilles, were analyzed for Hg, DDT, dieldrin, and PCB. Total Hg levels were high, ranging from 1.33 to 5.36 ppm in muscle (methylated fraction 42–100%), 2.28 to 14.00 ppm in kidney (methylated fraction about 14%), and 13.00 to 157.00 ppm in liver (methylated fraction 2–17%). ΣDDT in blubber ranged from 1.25 to 7.38 ppm, dieldrin in blubber from 0.007 to 0.04 ppm, and PCB in blubber from 0.69 to 5.00 ppm. The presence of the high Hg levels is attributed largely to natural sources, as the Lesser Antilles Island Arc is a site of intense cyclic tectonic activity. There may be some contribution from atmospheric sources. Both DDT and PCB could be largely the result of atmospheric transportation from higher Atantic latitudes, although local DDT spraying programs may have contributed. Certainly the circulation pattern in the Gulf of Mexico and Caribbean appears to rule out water-borne transport from the river systems of the Gulf States of the United States.

Fin whale blubber is a heterogenous tissue containing 8.9–77.4% lipid, 3.1–33.8% protein, and 0.07–0.73% ash by wet weight. The blubber may be subdivided into three macroscopically distinct zones. The outermost zones contain up to twice the lipid content of the innermost zone adjacent to the muscle, which contains more protein. Anterior ventral blubber contains less lipid, more protein (of which 50% is collagen), and more ash than posterior dorsal blubber. Foetal blubber contains 1.2% lipid, 10.6% protein, and 0.93% ash by wet weight. Blubber lipid contains ca. 60% triacylglycerol and ca. 25–30% free fatty acid, compared with ca. 25% triacylglycerol and ca. 10% free fatty acid in foetal blubber lipid, which also contains ca. 40% phospholipid. The high free fatty acid component is certainly partly due to postmortem hydrolysis in samples analysed. Monounsaturated fatty acids comprise ca. 60% of blubber lipid; 16:0, 16:1, 18:1, 20:1, 22:1, and 22:6 predominate, similar to the dietary intake. The predominant fatty acids in the outermost and the innermost blubber zones are 22:1 and 16:0, respectively. This may have significance in energy storage and catabolic breakdown.

Measurements were made of the relation between body temperature, respiration, diving pattern, and water temperature using three adult harp seals (Phoca groenlandica). Core temperature, ventilation, gas exchange, and diving pattern were not affected by water temperature ranging from 1.8 to 28.2 °C. The basal metabolic rate of the seals in this study was not significantly different than that predicted for terrestrial mammals of equivalent size. Expired heat loss and convective heat loss from the body accounted for 16% of the heat loss and were independent of water temperature. The remaining 84% of the heat was lost from the flippers which accounted for less than 14% of the surface area. Calculations of the ratio of convective heat transfer coefficients of the blubber layer indicate that internal conduction rather than external convection governed heat loss.

Residues of the DDT group of insecticides and the polychlorinated biphenyls (PCBs) were measured in maternal blubber, milk, and blood or serum and in pup blubber and blood or serum of grey seals (Halichoerus grypus) from Sable Island, N.S. sampled in 1984 and 1985. DDT-group and PCB concentrations in blubber samples were lower in 1984 than in a sample of this population taken in the mid-1970's, but not lower than those in a sample taken in 1982. Concentrations in 1985 samples were slightly higher than those in the 1984 samples, for unknown reasons. On a lipid weight basis, residue concentrations in blood or serum were consistently about 50% of those in blubber lipid. The more highly chlorinated and therefore more lipid-soluble PCB components were transferred less efficiently from blubber to the circulatory system. Net transfer of residues from maternal blubber to maternal milk was about 70% efficient; this implies considerable degradation of circulatory lipid and resynthesis, probably to milk carbohydrates and other compounds. There was some selection against movement of especially the lower chlorinated PCB congeners from circulatory lipids into milk lipids, compared with transfer of the DDT group. Thus, a nonselective barrier exists to quantitative transfer of residues from blubber lipid to circulatory lipid, and a partially selective barrier exists against PCBs in the transfer of residues from circulatory to milk lipids; at least the latter barrier seems to involve lipid solubility.

The fatty acids of triglycerides in the hearts from two harbor seals (Phoca vitulina) and one grey seal (Halichoerus grypus) differed quantitatively in some details from those in the blubber. The 22:1 found in the heart triglycerides was about half that in the blubber triglycerides. Isomer distributions differed within 20:1 acids in the two triglycerides for both species, the higher proportion of 20:1ω11 fatty acid deposited in the heart than in the blubber indicating more active chain shortening from 22:1. The fatty acids of phospholipids of all three hearts and livers also differed quantitatively in some fatty acid details indicating organ-specific compositions. These also differed from compositions of similar lipids in terrestrial animals in their generally marine fatty acid compositions which were established for the blubbers. The grey seal (age 3 mo) showed unusual percentages of linoleic types of acids in the organ lipids and also a curious enrichment in ω7 monoethylenic acids. Dietary factors are believed to be responsible for differences between this animal and the two harbor seals (ages 10 and 23 mo).

Metabolic rates and growth rates of juvenile harp and grey seals were monitored during the postweaning period after the onset of feeding. Growth rates varied from 0.03 to 0.32 kg d−1, depending on the level of energy intake and absolute body mass of the seal. Measurements of sculp mass (blubber with attached skin), as a percentage of total mass, indicated low rates of growth in the sculp and preferential growth in the core. When feeding started there was a 1.3- to 2.3-fold increase in standard metabolic rate, which was independent of the heat increment of feeding. Metabolic requirements of feeding seals, measured by indirect calorimetry, were between 1.2 and 7.2 W kg−1 in water and between 1.2 and 6.0 W kg−1 in air, similar to average daily metabolic rates calculated from net energy intake.

Growth and organ allometry of neonatal harp seals (Phoca groenlandica) were monitored during the first 6 weeks of life from 1982 to 1984. At birth, pup mass was 9.9 ± 1.7 (1 SD) kg. After their 1st day of relatively slow growth, pups gained mass rapidly, increasing 2 kg/day throughout the remainder of the ~12-day nursing period. Two-thirds of this mass gain was accumulated as a layer of subcutaneous blubber. Pups lost mass at a rate of ~0.5 kg/day during the postweaning fast, utilizing energy stores from the viscera, muscles, and limited amounts of blubber. In neonates, liver mass fluctuated in conjunction with total body mass gain and loss. The liver of adult harp seals was large relative to terrestrial mammals of similar size, but relatively small compared with other pinnipeds. The heart of harp seals grew slowly in pups and did not lose mass during fasting, and in adults it was of similar size relative to other mammals. The spleen of neonates was large and grew quickly during nursing. Spleen mass was quite variable among postweaning animals. As would be expected for a large-sized, precocially born, relatively advanced mammalian neonate, pups are born with large brains that grow very slowly. Adult brain mass, in relation to body mass, was similar to that of other mammals.

The fatty acid composition of skin and blubber lipids was analyzed from four apparently healthy adult Pacific walrus (Odobenus rosmarus divergens) taken in the Bering Sea and one moribund walrus from the vicinity of Barrow in the northern Chukchi Sea. All specimens had similar fatty acid complements; 13 fatty acids predominated ranging from chain lengths of 14 to 22 carbons with zero to six double bonds. There were no major differences between males and females nor between the one lactating and the nonlactating female. There were specific differences from inner blubber to outer blubber and skin and between the four healthy and one moribund animal. Double-bond indices (indicating degree of unsaturation) were relatively high in all samples, which reflects the large amount of long-chain polyunsaturated acids in the skin and blubber lipids. Inner blubber lipids were more highly unsaturated than outer blubber or skin lipids similar to the patterns observed in baleen whales. Melting points of blubber lipid ranged from 2.2 to −6.8 °C for some components; all components melted below 21.5 °C. Fatty acid composition of hind flipper tissues did not differ significantly from those in the trunk skin and blubber.

DDT, PCBs, chlordane, and dieldrin levels were measured in blubber of 18 cetaceans, including humpback, sperm, dense-beaked, Atlantic, and Pacific pilot whales, and five species of dolphins. All had significant residue levels, ranging from 1.1 to 1023 ppm ΣDDT (wet weight basis), and 0.7–147 ppm PCBs. These levels are high enough to justify efforts to reduce PCB contamination of the oceans and a continued ban on widespread use of DDT.

The fatty acids of phospholipids and of triglycerides from the lungs and heart of the harbor seal Phoca vitulina concolor De Kay show distinctive differences from the depot (blubber) fat. Primarily, this is due to greatly elevated levels of 20:4ω6 in the phospholipids. Although these have about the same total C20 and C22 polyethylenic acids with five and six double bonds as the depot fat, they occur in different proportions emphasizing 20:5ω3 rather than 22:6ω3. The organ triglycerides resemble the phospholipids in saturated fatty acid composition and the depot fats in monoethylenic fatty acid composition, but have remarkably low levels of 20:5ω3, 22:5ω3, and 22:6ω3 compared to the depot fat. Comparisons are made with phospholipids from the lungs of the leatherback turtle Dermochelys coriacea coriacea Linnaeus but the novel trans-6-hexadecenoic acid found in the turtle lipids could not be detected in the seal lipids.

The fatty acids of a commercial seal blubber oil have been surveyed by application of the linear log plot and separation factor procedures to the gas–liquid chromatograms of methyl esters obtained from urea complexing. These techniques, coupled with the use of two polyesters, have permitted the tentative identification of virtually all of the components. The overall composition of the seal blubber oil appears to cover the same range of fatty acids as the body oils of menhaden and herring.

From 1969 to 1971, 78 harp seals (Pagophilus groenlandicus), ranging in age from newborn to 18 years were obtained from the Gulf of St. Lawrence and the Newfoundland and Labrador coasts (Front). A further 12 seals captured in the Gulf died (in captivity) after being held for various periods of time.Total DDT and metabolites (Σ DDT) in the blubber of wild beaters and bedlamers from the Gulf were > 2 ppm, from the Front

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The food of harp seals inhabiting the northwest Atlantic consists chiefly of pelagic fish, especially capelin, Mallotus villosus, and pelagic and benthic Crustacea (Euphausiacea, Mysidacea, Amphipoda, Decapoda), with smaller quantities of benthic fish. Feeding has been observed to take place on individual items by suction, and small fish are taken tail first. Feeding is intensive in winter and (by deduction) in summer, less intensive during spring and autumn migration, and in spring during whelping and moult. A weight loss in spring due chiefly to loss in thickness of subcutaneous fat (blubber) is most intensive in adult females as a result of lactation. This loss is made up slowly in summer. The preparturient females are partly segregated in midwinter on what may be the best feeding grounds. During lactation, and immediately following it when they are again segregated from other age-sex groups, adult females tend to feed on decapod Crustacea. In spring, the only time when all age classes are in the same geographic area, there is a stratification of feeding by size of organism and by depth, from chiefly Euphausiacea taken in surface waters by the weaned young, through capelin taken probably at intermediate depths by the immature animals, to herring, cod, and other groundfish taken by the moulting adults to depths of perhaps 150–200 m. Social feeding begins at about 1 year of age with the change from Crustacea to pelagic fish. From knowledge of the rate of feeding, body weights, and reproductive rates, the ecological efficiency of harp seals (i.e. weight of annual increment of population/weight of annual food eaten) is calculated at 0.005, a low figure. Annual weights of food items eaten by the northwest Atlantic population of harp seals are roughly estimated as: all organisms, 2 × 106 metric tons; capelin, 0.5 × 106 tons; and herring, 2 × 104 tons. Predation by harp seals on capelin stocks off eastern Canada occurs only during the winter months when pack ice is present as a resting substrate, the same resource being consumed in the summer months by the great whales (Balaenopteridae).

Tissues of Beluga whales (Delphinapterus leucas) sampled from a transient herd off the Mackenzie Delta, N.W.T., contained residues of the DDT pesticide group. Muscle and liver contained p,p′-DDE and p,p′-DDT; total residue concentrations in these tissues were approximately 0.01 and 0.02 ppm fresh weight, respectively. Blubber contained p,p′-DDE, p,p′-DDT, and o,p′-DDT; total residue content was approximately 2–4 ppm fresh weight.

Fatty acid compositions were determined for total lipid (17.5% of the milk and > 95% triglycerides), 2-monoglyceride obtained by enzymatic hydrolysis of isolated triglyceride, and isolated phospholipid (~1% of total lipids). The total lipid fatty acids of the milk had a composition similar to fin whale depot fat but were enriched in hexadecanoic acid and polyunsaturated fatty acids at the expense of monoethylenic acids; correspondingly the iodine value of 136 (methyl esters) was higher than the normal range (105–120) of North Atlantic fin whale blubber oils. Over 80% of the fatty acids in the 2-position of the triglycerides were accounted for by relatively short chain fatty acids, especially hexadecanoic (54.6%), tetradecanoic (13.7%), and hexadecenoic (11.2%), so that the ester iodine value was only 48. The milk phospholipids had a fatty acid composition basically similar to that of liver phospholipids (methyl ester iodine value 120) with somewhat more polyunsaturated fatty acids and accordingly an iodine value of 144 for methyl esters.