This paper reviews some specific studies of cetacean life history energetics over the past 20–30 y that include one of the largest species, the baleen fin whale, Balaenoptera physalus, the medium-sized odontocete long-finned pilot whale, Globicephala melas, and one of the smallest marine odontocetes, the harbour porpoise, Phocoena phocoena. Attention is drawn to the decrease in longevity with size and the differences in biological parameters that reflect this and affect life history strategy and energy utilization. Data from the past whaling industry in Iceland for fin whales, the Faroese ‘grindedrap’ for pilot whales, and by-catches as well as some live captive studies for harbour porpoise have been used. The studies demonstrate how information can be gathered to compile energy budgets for individuals, relying on carcase measurement and analysis, dietary investigations, biochemical analyses of tissues, and general life history studies including reproduction; as well as from monitoring living animals. The individual examples presented show how food energy storage in the form of fat can be variously important in insulation in the smallest species to controlling reproductive efficiency in large migratory species. The paper concludes by noting that an understanding of energy use in the individual can be an important input in multi-species ecosystem modelling.

The “stock” is the fundamental population unit of legally mandated conservation efforts, yet its formal definition in the scientific literature and in two U.S. conservation acts is varied and so general that attempts to apply it in practice are arbitrary. Because choice of stocks deserving management protection is sometimes politically contentious, improvement of the working definition is important. A key element should be the degree to which a population can be considered an evolutionarily significant unit. We propose that a hierarchial classification scheme be applied to stock designations. Category I populations, having the highest probability of being evolutionarily significant units, are characterized by a discontinuous genetic divergence pattern where locally adapted and closely related genome assemblages are separated from others geographically and by significant genetic distances. Category II populations are similarly characterized by significant genetic diversity, but with weak geographic partitioning. Category III populations are the converse of II, having little genetic differentiation between assemblages that are clearly separate and likely to be reproductively isolated. Category IV assemblages have the lowest probability of being evolutionarily significant units and are characterized by extensive gene flow and no subdivision by extrinsic barriers. In addition to phylogeographic designation, the following information is used in the classification, as indicated by single‐letter abbreviations: distribution (a), population response (b), phenotypic (c), and genotypic (d) information. Included are evidence both for and against designating population as a separate stock. In the designation “Type II a/bc,” for example, information to the right of the solidus would be evidence for “lumping,” to the left would be for “splitting.” Missing letter abbreviations would signify lack of reliable data. Note that phylogeographic designation depends on the results of selection operating to produce a locally adapted genome (indicated by differences in demographic, phenotypic, and genotypic measures) and on gene flow (indicated by differences in distribution or by movement data). Hierarchial stock categorization allows resource managers to direct limited resources to the populations most deserving of protection, that is, the populations that are most likely to be evolutionarily significant units. Using this comprehensive classification of stock allows preliminary, conservative splitting of assemblages where data are lacking without the danger that these divisions will become entrenched as biological dogma.

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.

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Tissues from fin (Balaenoptera physalus) and sei (Balaenoptera borealis) whales taken off the coast of Southwest Iceland in July–August in 1978 and 1981 were analysed for percent lipid, protein, and ash contents. The tail region of the whales, especially the dorsal area, constituted the main area of lipid storage in both blubber and muscle. No significant differences (p > 0.05, ANOVA) were evident between reproductive classes, except that adult females appear to store more lipid in the tail muscles than other classes. Most sei whale tissues contained more lipid than those of fin whales, but the differences may be explained by variations in seasonal feeding and fattening. Seasonal variations and differences between reproductive classes were evident from girth and blubber thickness. Juvenile males were thinnest and adult females were thickest.

A review of historical harbour porpoise catches in Danish waters, together with current distribution, are provided. Most information on distribution is derived from historical catch data with a total of about 100,000 animals taken in Little Belt alone and 40,000 from Isefjord area during the 19 th century. Recent sightings surveys and tagging indicate extensive movements of animals within and between Inner Danish Waters and the Skagerrak / North Sea. Biological information is reviewed for the region, drawing on directed catches, bycatches and strandings from a database comprising nearly 1,900 records from 1834 through 1998. Diet, parasites, pollutants, biological parameters (age and reproduction) and body condition are reported, focusing mainly on the period 1996-98 when comprehensive data were collected. In 1980s samples, gadoids were the most important prey items (found in 62% of stomachs) followed by clupeoids (35%), gobiids (30%), and ammodytids (30%). Some dietary differences were observed between North Sea and Inner Danish waters. Pollutant analyses indicated a decline in sumDDT concentrations yet an increase in sumPCB and HCH levels in Danish porpoises, with comparatively higher levels here than in Baltic and Norwegian waters. Heavy metal concentrations appear higher than in Baltic porpoises. Biological parameters indicate a longevity of up to 23 years in both sexes but with fewer than 5% living beyond 12 years. Sexual maturity occurred at slightly over age 3 years in both females and males, with corresponding lengths of about 135 cm in males and 143 cm in females. The data indicate a size range at birth of 65 -75 cm (weight 4.5 -6.7 kg), with a minimum of 60 cm and 3.4 kg, and a likely gestation time of 10 months. Conception most likely occurs during August, with peak births in June.

Williams, R., Vikingsson, G. A., Gislason, A., Lockyer, C., New, L., Thomas, L., and Hammond, P. S. 2013. Evidence for density-dependent changes in body condition and pregnancy rate of North Atlantic fin whales over four decades of varying environmental conditions. – ICES Journal of Marine Science, 70: 1273–1280. A central theme in ecology is the search for pattern in the response of a species to changing environmental conditions. Natural resource management and endangered species conservation require an understanding of density-dependent and density-independent factors that regulate populations. Marine mammal populations are expected to express density dependence in the same way as terrestrial mammals, but logistical difficulties in data acquisition for many large whale species have hindered attempts to identify population-regulation mechanisms. We explored relationships between body condition (inferred from patterns in blubber thickness) and per capita prey abundance, and between pregnancy rate and body condition in North Atlantic fin whales as environmental conditions and population size varied between 1967 and 2010. Blubber thickness in both males and females declined at low per capita prey availability, and in breeding-age females, pregnancy rate declined at low blubber thickness, demonstrating a density-dependent response of pregnancy to prey limitation mediated through body condition. To the best of our knowledge, this is the first time a quantitative relationship among per capita prey abundance, body condition, and pregnancy rate has been documented for whales. As long-lived predators, marine mammals can act as indicators of the state of marine ecosystems. Improving our understanding of the relationships that link prey, body condition, and population parameters such as pregnancy rate and survival will become increasingly useful as these systems are affected by natural and anthropogenic change. Quantifying linkages among prey, fitness and vital rates will improve our ability to predict population consequences of subtle, sublethal impacts of ocean noise and other anthropogenic stressors.