Stomach contents of 81 harbor porpoises (Phocoena phocoena (L.)) collected from eastern Canadian coastal waters during 1969–1972 were examined. A total of 454 free otoliths and 54 undigested specimens representing a minimum of 281 fish, consisting of nine species in seven families, were recovered from the copious semidigested fish remains found in 52 of the stomachs. Clupea harengus (herring), Gadus morhua (cod), and Scomber scombrus (mackerel) otoliths accounted for more than 78% of the total. Osmerus mordax (smelt), Pollachius virens (pollock), Merluccius bilinearis (silver hake), Sebastes marinus (redfish), and Macrozoarces americanus (ocean pout) otoliths were also identified. Squid (Illex sp.), hagfish (Myxine glutinosa), and polychaetes (Nereis sp.) were identified in a few stomachs. Fifteen of the stomachs examined were empty or contained only fluid. Examination of the stomachs of the 16 smallest animals indicated that weaning occurred at body lengths of 100–104 cm.

The morphological and cytological characteristics of the stomach of the harbor porpoise (Phocoena phocoena (L.)) are described from dissections and histological preparations. The stomach consists of the following three compartments: forestomach, with keratinized stratified squamous epithelium and well-developed muscularis externa; main stomach, with rugose mucosa containing mucous, parietal, and zymogenic cells; and pyloric stomach, with typical pyloric glands. The opening from the fore-stomach to the main stomach is located near the esophageal opening. A sphincter is not present, but the opening is surrounded by several epithelial folds. The main stomach is joined to the pyloric stomach by a narrow connecting channel possessing pyloric glands. The gross and microscopic characteristics of the compartments are interpreted in relation to function.

The axial and pectoral musculature of the harbour porpoise (Phocoena phocoena (L.)) is described, using standardized nomenclature, from dissections of 12 specimens of mixed age and sex. The axial musculature consists of two main groups, epaxial and hypaxial, which can be further subdivided: the epaxials include the spinalis, longissimus, and lateral branch of the iliocostalis lumborum, with an extensive system of tendons that insert on the vertebrae of the peduncle and flukes; the hypaxialis and the lateral branch of the hypaxialis, with fewer associated tendons, but these are also inserted on the vertebrae of the peduncle and flukes. Fifteen muscles in the pectoral region, which control position of the flippers, are described. Visual observations and film analysis of the complex locomotory and manoeuvering movements of wild harbour porpoises are used to suggest functions for the described muscles.

No abstract

Six harbor porpoises captured in herring weirs between September 1973 and September 1974 on the southern coast of New Brunswick were tagged and released. The three smallest animals were given visible dorsal fin tags, and the three larger specimens radiotelemetric packages attached to their dorsal fins. These animals were tracked using an ADFS-210 receiver coupled with a fixed-loop array on a 6.7-m mast antenna. Good signals were received at distances of up to 16 km using frequencies in the 26–28 MHz region. Most tracking problems resulted from interference from citizen-band operations and "skip" at certain times of the day and night. The transmitters appeared to cause little or no disruption of normal behavior in the larger animals. Intermittent contact was maintained for 2, 3, and 11 days respectively before the animals moved out of range. A total of 76 h, 29 min actual radiotracking time was recorded. Some tentative estimates of distances travelled per unit time, average swimming speeds, and apparent time spent foraging and feeding are tabulated.