Some aspects of the biology of the goblin shark, Mitsukurina owstoni, collected from the Tokyo Submarine Canyon and adjacent waters, Japan

Abstract

A total of 148 specimens of Mitsukurina owstoni were examined for morphology, distribution, stomach contents, and reproductive condition. Sixty-nine males (81.7-208.5 cm in total length, TL) and 56 females (92.8-196.1 cm TL) were collected with bottom gillnets along a steep slope of the Tokyo Submarine Canyon (100-350 m depth) from May 1995 to October 1996. In addition, data were obtained from 23 specimens of M. owstoni collected from Sagami Bay, Suruga Bay, and the Enshu-nada Sea from 1972 to 2001. Japanese catch records already published (from 1898) plus those in the present study were from the Pacifi c coast of Japan, from Choshi to the Kii Peninsula. The main fi shing season for M. owstoni by bottom gillnet fi shing in the Tokyo Submarine Canyon was October to April, at depths of 200-245 m. No specimens examined were sexually mature, including the largest male (208.5 cm TL) and female (196.1 cm TL) recorded. Of 110 stomachs from specimens from the Tokyo Submarine Canyon, 32 (29.1%) were empty. The remainder variously included teleost fi shes, squids, decapods, isopods, digested food, and human refuse. Teleost fi shes (Macrouridae sp. and Stomiidae spp.), an isopod (Cymothoidae), and decapods (Pasiphaea sinensis and Sergia sp.) were the only identifi able prey, the indication being that teleosts (all size ranges) were of primary importance as prey for M. owstoni.

Rediscovery of Chirostylus dolichopus Ortmann, 1892 (Crustacea: Decapoda: Anomura: Chirostylidae) from its type locality, Boso Peninsula, Japan, with description of the colouration in life

“…2a). The steep slope is situated at eastern margin of the Tokyo Submarine Canyon, and reaches about 200 m depth over narrow horizontal distance (about 3 km) (see Yano et al, 2007). At the diving sites around Uki-shima Islet, divers have observed nine other individuals referable to C. dolichopus during June to August of 2015, some living on colonies of fanlike gorgonaceans (Jiro Uochi, personal communication).…”

NOTES ON THE RECORD OF GOBLIN SHARK (Mitsukurina owstoni Jordan, 1898) FROM INDONESIA

“…These proportions were then compared to other available data for M. owstoni from Australia, New Zealand and Japan (Stevens and Paxton 1985;Duffy 1997;Yano et al 2007) in order to determine whether there were any differences in morphology among those locations.…”

“…Methods of measurements, body terminology and general biological data were taken according to the methods of Stevens and Paxton (1985) and Yano et al (2007). Tooth counts were made using calculation following Yano et al (2007) as follows: (total number in left side upper jaw) -(total number in right side upper jaw) / (total number in left side lower jaw) -(total number in right side lower jaw).Weight and all measurements were taken using a digital balance and measuring tape for large measurements and calipers for the smaller measurements to the nearest 0.1 mm.…”

“…Pelvic fins slightly larger than first dorsal fin, its length about 9.8% TL. Anal fin longer than dorsal fins, Stevens & Paxton (1985) 2) Duffy (1997) 3) Stevens & Paxton (1985); Yano et al (2007 its base length 8.6% TL and its height 3.4 % TL. The upper caudal margin subequal to distance from snout to first dorsal-fin origin.…”

“…Most records were taken between 100 and 1200 m depth (Stevens and Paxton 1985;Stewart and Clark 1988;Duffy 1997;Parsons et al, 2002;Yano et al 2007;Lee and Shao 2009;Prokofiev and Kukuev 2009), but it has been taken, rarely, in water as shallow as 40m (Ebert 2013). This species is occasionally caught in deepwater bottom gillnet and longline fisheries operating on the outer continental shelves and slopes (Parsons et al, 2002;Yano et al, 2007). M. owstoni has a patchy distribution in all major ocean basins (Compagno et al, 2005).…”