Observations of Free-Swimming Porpoises and Whale Schools and Studies of the Chemistry of Head Oil in Porpoises.
Status rept. 1 Jul 71-30 Sep 71,
OCEANIC INST WAIMANALO HAWAII
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The report covers the period of July 1, 1971 through September 30, 1971, and is concerned with the progress of studies on the Hawaiian spinner porpoise, Stenella cf. longirostris. The islands of Kauai and Niihau were selected as the first to be surveyed on the basis that they are the most distant from the island of Hawaii and therefore the least likely to be influenced by animal migration from Hawaii. Both yielded very high density figures for spinner schools. The most remarkable finding at these two islands is the close proximity of the individual schools to one another. This increased population density must reflect a corresponding increase in food organisms from a nearby deep scattering layer, since previous studies indicate that this is the sole food source for the Hawaiian spinner. Studies on the molecular structures of triacylglycerols from acoustic tissues revealed that a very limited number of isomeric forms are present, a finding quite unexpected in such a highly evolved animal. Gas-liquid chromatographic analysis of the intact structures indicated that less than 22 isomers are present in the major fraction 80 of the melon triacylglycerols. Moreover, the studies demonstrated that diisovaleroyl-isopentadecanoylglycerol is an important structure in the lipids of acoustic tissues.