Gaskin et al.: Phocoena phocoena in the coastal waters of northern Japan 



441 



Barlow and Hanan (1990), Hohn and Brownell (1990), 

 Dalheim et al. (1991), Forney and Barlow (1991), Rosel 

 and Haygood ( 1991) and Stacey et al. ( 1990). 



The life history of the harbor porpoise has been well 

 studied in the North Atlantic and northeastern Pa- 

 cific, but little is published about the distribution, move- 

 ments and life history of the species in the waters of 

 Japan and adjacent regions of eastern Russia. Jones 

 (1984) recorded 10 specimens taken incidentally in 

 salmon nets from 1978 to 1981 near the eastern 

 Aleutians and one male at 57°N some 700 miles east 

 of central Kamchatka. Miyashita and Doroshenko 

 (1990), and Miyashita and Berzin (1991) reported a 

 few recent summer sightings of harbor porpoises in 

 the northeastern and northwestern Sea of Okhotsk 

 and between southeastern Sakhalin and the southern 

 Kurile Islands. Earlier, Nishiwaki (1966) concluded that 

 the harbor porpoise was less common off Japan than 

 in North American waters. Ohsumi (1972), however, 

 regarded it as common around northern Japan, in- 

 cluding the northern Pacific coast of Honshu, and 

 Hokkaido; Hawley (1960) noted it was taken inciden- 

 tally in the herring fishery in this region. Some catches 

 of harbor porpoise have been reported (Table 1) in Japa- 

 nese coastal fisheries statistics provided to the Inter- 

 national Whaling Commission ( 1984, 1985, 1986, 1987, 

 1988, 1989, 1990) and by Miyazaki (1983), but 

 identifications in the catch statistics are not always 



Table 1 



Summary of reported catches of harbor porpoises in Japanese waters, taken from domestic 

 fisheries statistics incorporated in national progress reports on cetacean research (IWC 

 1984-1990). 



'Specific identification particularly doubtful. Because of the level of uncertainty about iden- 

 tifications of animals taken in the hand harpoon fishery, the totals reported for each year 

 should be cited with caution. We also note the following known omissions: 1983: 1 more 

 from Hokkaido gill nets; 1984: 2 more from northern Honshu pound nets; 1985: 21 more 

 from Hokkaido gill nets and pound nets. These are not included in the body of the table to 

 avoid potential confusion with the officially reported statistical data. 



reliable and could include some Dall's porpoises 4 . 

 Miyazaki et al. (1987) made preliminary comparisons 

 of growth and skull morphology of Japanese porpoises 

 with samples from the North Atlantic and northeast- 

 ern Pacific. Recently Amano and Miyazaki ( 1992 1 re- 

 peated the analyses of skull morphology with larger 

 samples and compared their results with those of Yurick 

 and Gaskin (1987), using more sophisticated analysis 

 than Miyazaki et al. (1987). 



The harbor porpoise is now considered to be seri- 

 ously threatened in several parts of the world, for ex- 

 ample in the Baltic Sea, Black Sea, and Bay of Fundy — 

 Gulf of Maine, where indirect and direct catches (Hohn 

 and Peltier, 1990) may have contributed to dramatic 

 declines in numbers in recent years (IWC, 1984; Read 

 and Gaskin, 1990; Gaskin, 1992). Given the high fishing 

 effort involving gill nets and trap nets in Japanese 

 coastal waters (Tobayama et al., 1991) and the dearth 

 of data for the harbor porpoise population in this re- 

 gion, any new information is useful. A systematic as- 

 sessment of the status of the species around Japan 

 would be desirable. 



The objective of the present study was to increase 

 the data base for harbor porpoise in Japanese waters. 

 We collected new material; examined and measured 

 harbor porpoises in Oceanaria; and verified documented 

 but unpublished captures and stranding records from 

 museums, fisheries institutions and other agencies in 

 Japan. We tabulate data from 

 45 new specimens, together 

 with the 15 originally exam- 

 ined by Miyazaki et al. ( 1987). 

 We present for the first time, 

 the apparent changes in sea- 

 sonal distribution of the har- 

 bor porpoise in the waters of 

 Japan and adjacent regions. 

 We combine and re-analyze 

 the new data in conjunction 

 with those published by Mi- 

 yazaki et al. (1987) to improve 

 insights into the life history 

 of harbor porpoise in the re- 

 gion. We reinforce the length- 

 age relationships reported by 

 Miyazaki and his colleagues 

 and estimate the length at 

 birth, and probable season of 

 parturition of harbor porpoises 

 in northern Japanese waters. 



4 Toshio Kasuya, Far Seas Fisheries 

 Research Laboratory, Shimizu. 

 Shizuoka, Japan, pers. commun. 

 1985. 



