442 



Fishery Bulletin 9 1 (3), 1993 



Materials and methods 



We re-examined the 15 harbor porpoise specimens in 

 the collection at the National Science Museum in To- 

 kyo, and obtained data on 45 new specimens, bringing 

 the total sample size to 60. One of us (A.K.) encour- 

 aged local fishing companies and the Oceanaria in 

 Hokkaido and northern Honshu to collect, sex, mea- 

 sure and preserve specimens or designated samples 

 (e.g., teeth, testes, ovaries, and pieces of blubber) of 

 Phocoena phocoena, killed in fishing gear from 1983 

 onwards. This program yielded 12 animals, mostly from 

 gill nets. In April and May of 1985 and 1986, the au- 

 thors arranged frequent inspections of the floating 

 pound nets operated by the Nomura Fishing Company 

 of Usujiri, Hokkaido, which are set to catch tuna, squid, 

 and salmon, depending on the season. Salmon are the 

 target species during April and May. From these nets 

 we collected another 16 specimens: 11 in 1985 and five 

 in 1986. During the same period we were invited to 

 the three Oceanaria which held captive harbor por- 

 poises, Otaru Aquarium in western Hokkaido, 

 Asamushi Aquarium in Aomori, northern Honshu and 

 Sunshine City Aquarium in Tokyo. We obtained mea- 

 surements and body weights of 14 live or frozen speci- 

 mens in these facilities. Additional confirmed records 

 of three more stranded specimens, presently with few 

 data, were obtained by A.K. through telephone conver- 

 sations, and descriptions, from Noshiro (February 1987, 

 sex unrecorded), Niigata (February 1989, (?) and 

 Nishiyama (March 1987, sex unrecorded) (Fig. 1). All 

 measurements of porpoises were made to the nearest 

 0.5 cm and weights to the nearest 0.1kg. 



Causes of entrapment were known in almost all cases 

 (Tables 1 and 2). Ages are now known for 28 animals, 

 14 males and 14 females, of which ages of 6 males and 

 9 females were determined by Miyazaki et al. (1987). 

 Age determinations of newly acquired specimens were 

 made from thin longitudinal sections of dentine ac- 

 cording to the methods of Gaskin and Blair (1977). 

 Ages of the National Science Museum specimens were 

 estimated from decalcified sections by Miyazaki et al. 

 ( 1987), based on both dentine and cementum layers in 

 each specimen. 



The reproductive status of males was determined by 

 using the criteria of Gaskin et al. (1984): 1) Immature, 

 ie. single testis volume much less than 90 cc; and 

 2) Mature but inactive, ie. single testis volume greater 

 than 90 cc but with no seminal fluid present in the 

 seminiferous tubules or epididymis. No mature males 

 were taken with testes in an active state. 



Female porpoises were classified as mature if one or 

 more corpora albicantia or a corpus luteum were 

 present, or immature if none could be found, again 

 according to Gaskin et al. ( 1984). 



r \ fifSWakkanai 



44N 



Nemuro 



40 N 



36N 



144°E 



Figure 1 



Localities of confirmed harbor porpoise records in Japan, as fisted in 

 Tables 2 and 3. 



A few collections of stomach contents were obtained 

 from the porpoises killed in fishing gear and were pre- 

 served in 70% ethyl alcohol. 



All materials obtained during this study have been 

 lodged at Hokkaido University (Hakodate campus) and 

 the National Science Museum, Tokyo. 



Results 



Japanese localities used in the text are shown in Fig- 

 ure 1. Location, date of capture, lengths, body weights, 

 age and reproductive condition are given in Table 1 for 

 males and Table 2 for females. Specimens previously 

 examined by Miyazaki et al. (1987) are clearly distin- 

 guishable by the National Science Museum collection 

 prefix (M-) 5 . 



r 'One male, M2490 from Nemuro. was not used by Miyazaki et al. 

 (1987). 



