The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Report of the scientific committee.

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Dolphins, Whales and Porpoises Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans

Consistent evaluation and new recommendations for action are required of protective measures to address threats that were unrecognised or non-existent until recently. Global warming, noise pollution and reduced availability of prey are now of great concern. The all too familiar threats of accidental killing in fishing gear and exposure to toxic chemicals remain almost intractable. This Action Plan reviews threats and offers possible solutions. It also contains a thorough review of the status of species and a list of 57 recommended research projects and education initiatives

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Dolphins, whales and porpoises : 2002-2010 conservation action plan for the world's cetaceans

Since the 1970s the role of fishery bycatch as a factor reducing, or limiting the recov- ery of, marine mammal populations has been increasingly recognized. The proceedings of a 1990 International Whaling Commission symposium and workshop summarized fishery and bycatch data by region, fishery, and species, and estimated the significance of the 'impacts' of bycatch in passive gear on all cetacean species and subspecies or geographically defined populations. A global review of pinniped bycatch in 1991 concluded that incidental mortality in passive gear had contributed to declines of several species and populations. Here we update the information on cetacean gillnet bycatch, assess bycatch data on marine mammals other than cetaceans (i.e. pin- nipeds, sirenians, and 2 otter species), determine where important data gaps exist, and identify species and populations known or likely to be at high risk from bycatch in gillnets. We found that at least 75% of odontocete species, 64% of mysticetes, 66% of pinnipeds, and all sirenians and marine mustelids have been recorded as gillnet bycatch over the past 20-plus years. Cetacean bycatch information in some areas has improved, facilitating our ability to identify species and populations at high risk, although major gaps remain. Understanding of the scale of pinniped and sirenian bycatch has also improved, but this bycatch remains poorly documented, especially at the population level. This study reveals how little is known about marine mammal bycatch in gillnets in much of the world. Even as other significant threats to marine mammals have become better documented and understood, bycatch remains a critical issue demanding urgent attention if there is to be any hope of preventing further losses of marine mammal diversity and abundance, and of protecting, or restoring, ecological health.

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Marine mammal bycatch in gillnet and other entangling net fisheries, 1990 to 2011

To clarify population structure of finless porpoises (Neophocaena phocaenoides) in Japan, we examined mitochondrial DNA sequences of 174 animals. All individuals except for a female were collected in 5 geographically discrete coastal waters where Japanese porpoises are mainly distributed: Sendai Bay-Tokyo Bay, Ise-Mikawa Bays, Inland Sea-Hibiki Nada, Omura Bay, and Ariake Sound-Tachibana Bay. We analyzed 345 base pairs of the control region for all animals and detected 10 haplotypes. Two of those were shared by animals from > 1 area, whereas the other 8 were each found only in 1 area. The most common haplotype in Ise-Mikawa Bays and Ariake Sound-Tachibana Bay was not found at other locations. Analysis of the frequency distribution of haplotypes quantified genetic differentiation, and measurements of gene flow indicated limited dispersal of animals among locations. We conclude that finless porpoises in each of the 5 locations belong to distinct populations.

Population Structure of Finless Porpoises (Neophocaena Phocaenoides) in Coastal Waters of Japan Based on Mitochondrial DNA Sequences

To clarify phylogenetic relationships of Bryde's whales, we examined the nucleotide sequence of the mitochondrial control region and cytochrome b gene in 33 animals: 12 from offshore waters of the western North Pacific, five from off the Solomon Islands, and 16 from the East China Sea and coastal waters of Kochi in southwestern Japan. For reference purposes, homologous sequences from four Balaenoptera species including four Bryde's whales collected in the eastern Indian Ocean were added. We found whales from the three sampling areas to be genetically distinct. The control region sequences suggested that the whales from the three areas separate at higher than the populational level from one another. The cytochrome b data indicated that genetic differences between whales off the Solomon Islands and animals in the other two areas are equivalent to values found among recognized Balaenoptera species, although such a relationship was not observed between the other two areas. We conclude that whales in the East China Sea and coastal waters of Kochi separate from Bryde's whales in offshore waters of the western North Pacific at higher than the populational level but lower than the specific level (i. e., at the subspecific level) and that whales off the Solomon Islands do not belong genetically to the Bryde's whale as previously recognized.

Phylogenetic relationships of bryde's whales in the western north pacific and adjacent waters inferred from mitochondrial dna sequences1

Development, sexual dimorphism, and individual variation were examined in the skeleton of the finless porpoise in the coastal waters of western Kyushu, Japan. Skulls ceased growing by 4 yr. Postcranial skeletons ceased increasing in size at an age older than 11 yr. The finless porpoise was estimated to attain cranial maturity by 4 yr and physical maturity at 14–23 yr. Sexual dimorphism was not detectable in most of the cranial characters but was detected in more than half of the postcranial characters. Females tended to show larger values of postcranial characters. The shape of the pelvic bone was obviously different between males and females. Thus, a discriminant function was proposed to determine sex using measurements of this bone. Individual variation was greatest in the feeding apparatus such as length of the rostrum, and least in the braincase.

DEVELOPMENT, SEXUAL DIMORPHISM, and INDIVIDUAL VARIATION IN THE SKELETON OF THE FINLESS PORPOISE, NEOPHOCAENA PHOCAENOIDES, IN THE COASTAL WATERS OF WESTERN KYUSHU, JAPAN

Geographic variation in the skull morphology of the finless porpoise was studied with special refer ence to identifying local populations in Japanese waters. Twenty-five skull characters were measured for 146 specimens. These specimens were divided into five samples on the basis of available distribution al information: 1) from Sendai Bay to Tokyo Bay, 2) Ise Bay and Mikawa Bay, 3) Inland Sea and the ad jacent waters, 4) Omura Bay, 5) Ariake Sound and Tachibana Bay. Morphological differences were ex amined by the analysis of covariance and canonical discriminant analysis. The skull morphology varied among the samples. The porpoises in Ise Bay and Mikawa Bay possessed rather narrow skulls. There was no evidence that skull morphology was more similar between geographically close areas. Such geo graphic variation suggests that porpoises in each area rarely intermingle. We considered that there are at least five local populations in Japanese waters.

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Hideyoshi Yoshida

Papers

Population Structure of Finless Porpoises (Neophocaena Phocaenoides) in Coastal Waters of Japan Based on Mitochondrial DNA Sequences

Phylogenetic relationships of bryde's whales in the western north pacific and adjacent waters inferred from mitochondrial dna sequences1

DEVELOPMENT, SEXUAL DIMORPHISM, and INDIVIDUAL VARIATION IN THE SKELETON OF THE FINLESS PORPOISE, NEOPHOCAENA PHOCAENOIDES, IN THE COASTAL WATERS OF WESTERN KYUSHU, JAPAN

Geographic Variation in the Skull Morphology of the Finless Porpoise Neophocaena Phocaenoides in Japanese Waters

A questionnaire survey on the distribution of the finless porpoise, neophocaena phocaenoides, in japanese waters