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

A goblin shark, Mitsukurina owstoni,was captured by deepwater shark longline targeting squaloid sharks off Palabuhanratu, West Java, Indonesia at about 200 m depth. Morphological measurements were taken and compared to other records from Australia, New Zealand and Japan. This new recordfrom Indonesian waters extends the distribution of this species in the Indian Ocean.


INTRODUCTION
The goblin shark Mitsukurina owstoni, is a peculiar deepwater shark from the Order Lamniformes.This species is the only member of the Family Mitsukurinidae and characterized by: an elongated and blade-like snout, anal fin much larger than dorsal fins, no precaudal pit, and caudal fin without a ventral lobe (Compagno 2001;Compagno et al., 2005).The name "goblin" was given due to its unusual appearance when its mouth is protruded (Nakaya et al., 2016).This species is also known as a living fossil due to its close relation to the extinct Mesozoic shark of the genus Scapanorhynchus (Hussakof, 1909).
The M. owstoni specimen was initially identified by the long, flat and blade like snout, protrusible jaws and had its soft and flabby body.The body remained soft after fixation in formalin.This species was described based on a young male specimen collected in near Yokohama, Japan (Jordan, 1898).Prior to 1985, only 33 specimens of M. owstoni had been recorded worldwide, with 23 of them from Japan and the remainder from South Africa, Europe, Guiana and Australia (Stevens and Paxton, 1985).In recent decades, it has been reported from New Zealand (Duffy, 1997), the eastern North Pacific (Ugoretz and Seigel, 1999), the Gulf of Mexico (Parsons et al., 2002), Colombia (Grijalba-Bendeck andAcevedo, 2009), Atlantic Ocean (Prokofiev and Kukuev, 2009), western South Atlantic (Rincon et al., 2012) and western North Atlantic (Driggers III et al., 2014).
Many of the known specimens of M. owstoni were found with the mouth in the protruded position and once preserved, the jaw can often not be retracted into the normal position (Hussakof, 1909;D'Aubrey, 1969;Glover, 1976;Stevens and Paxton 1985;Parsons et al., 2002).Based on thischaracter, Hussakof (1909) describing four specimens of goblin shark as a new species, Scapanorhynchus jordani.Subsequently authors considered S. jordani as junior synonym of M. owstoni (Compagno, 1984;2001;Stevens and Paxton, 1985;Ebert, 2013).
Mitsukurina owstoni is a poorly known shark due to its occurrence in deepwater habitats as a bottom-dwelling and possibly semioceanic shark (Compagno, 1984;2001).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 Mar. Res. Indonesia Vol.42, No.2, 2017: 65-72 and Shao 2009; Prokofiev and Kukuev, 2009), but it has been taken, rarely, in water as shallow as 40 m (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).In the Indian Ocean, this species has been recorded from South Africa, Mozambique, Australia and New Zealand (Stevens and Paxton, 1985;Duffy, 1997;Ebert, 2013).This paper details the first record of this species in Indonesian waters.

MATERIALS AND METHODS
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 0.1mm.
All measurements were expressed in percentage of total length (TL).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.Description:

Mitsukurina owstoni
The snout long, ~5.5% TL when the mouth protruded and 10.2% in the normal position (snout to upper lip).Eyes small, eye diameter less than 1% TL.Mouth width 6.5% TL and its length 5.7% TL.First gill slit height 3.7% TL while the fifth gill slit 3.1% TL.First dorsal fin origin slightly posterior to the pectoral fin origin.First and second dorsal fins subequal in size.First dorsal fin base slightly larger than second dorsalfin base, i.e. 6.1 vs. 5.0% TL respectively.Pelvic fins slightly larger than first dorsal fin, its length about 9.8% TL.Anal fin longer than dorsal fins, its The tooth count of this female specimen is (16-16) / (14-14).The anterior teeth are large, long, narrow shaped and hooked (Figure 2).There is a gap between the third and the fourth tooth rows in the upper jaw.Lateral teeth have erect cusps and gradually decrease in size towards the mouth corner.The posterior teeth are much smaller and flattened than anterior and lateral teeth.
The skin has small and rough denticles.Colouration was pinkish when in fresh condition, light brown once preserved.

DISCUSSION
The shark was caught by deepwater shark longline boat, targeting squalids and centrophorids, operating off Citireum beach, Palabuhanratu in about 200 m depth.
The goblin shark Mitsukurina owstoni (Mitsukurinidae) has a wide, but patchy distribution in all temperate and tropical seas including the Indian Ocean (Compagno, 2001;Ebert, 2013).The specimen collected from off Palabuhanratu, West Java, however, is the first record of the occurrence of this species in tropical Indian Ocean region.
The Indonesian specimen was a juvenile female based on its size.Duffy (1997) found specimens not protruded (Duffy, 1997;Yano et al., 2007;Lee and Shao, 2009;Rincon et al., 2012).The first method has a weakness due to the position of the jaws may vary among specimens.The position of the jaws is usually loose when firstly captured and then remain fixed in certain position after being preserved.Nakaya et al., (2016) examined the function and movements of the jaws of M. owstoni based on the living specimens captured from Japan and recording their feeding behaviour.They found that M. owstoni has the ability to open their mouth widely and rapidly protrude the jaws forward as their feeding behaviour to get the prey.This ability is considered as the fastest and greatest jaw protrusion among sharks.
As a deepwater shark which has a flabby body, M. owstoni is considered to be a slow swimmer (Ebert, 2013).The rapid and extensive jaw protrusion may be to counterbalance for its lack of ability for fast and strong swimming to pursue its prey.The jaw protrusion will provide it with the opportunity to expand the accessible distance to the prey and enable it to capture the faster swimming prey (Nakaya et al., 2016).
Mitsukurina owstoni is considered to be a very rare shark species and is rarely caught in deep sea fisheries.Even though there were many reports and number of specimens gathered from Japan waters, the catch number of this species have been relatively small, only one or two individuals per record (Yano et al., 2007).Due to its rarity in the fisheries and its widespread but sporadic distribution in the Atlantic, Pacific and Indian Oceans, the conservation status of the goblin shark is categorized as Least Concern based on the IUCN Red List (Duffy et al., 2004).However, the intensive deepwater shark fishery targeting for the liver oil in certain area may influence its population stability in the future.

ACKNOWLEDGEMENT
The author thank to Agus from Palabuhanratu who collected the specimen and gave valuable information on the fishery.I also thank to Mohammad Adrim and Priyo Agustono of the Research Centre for Oceanography -LIPI for their assistances in preserving the specimen, and Dr. William White of CSIRO Hobart for reviewing the manuscript. of 1260 and 1280 mm TL had umbilical scars and categorized them as juveniles.A 1380 mm TL male specimen collected from equatorial East Atlantic (Prokovief and Kukuev, 2009) was also reported as a juvenile.The record of the largest adult size of M. owstoni was 3840 mm TL, collected from South Australia as a fully mature male (Stevens and Paxton, 1985).The size at maturity of this species is uncertain, but possibly at about 2600 to 3800 mm TL for males and over 4000 mm TL for females.Size at birth is unknown but the smallest free swimming individual was an 817 mm male (Ebert, 2013).
In general, the Indonesian specimen has similar morphology to specimens collected from Japan, Australia and New Zealand based on its morphometric measurements.However, the measurements taken suggest it has a shorter pectoral-fin base, longer pectoral-fin anterior margins, and having a shorter second dorsal-fin compared to specimens from Australia and New Zealand (Stevens and Paxton, 1985;Duffy, 1997), while specimens from Japan have wider ranging values for those characters (Stevens and Paxton 1985;Yano et al., 2007).The available Japanese data had a shorter anal-caudal space and more slender body by having a slightly shorter head, abdomen and caudal peduncle height (see Table 1).This data suggests some intraspecific differences in some characters, possibly also influenced by potential differences in measurement morphology between studies.Yano et al., (2007) examined 148 specimens of M. owstoni to investigate the morphology of this species and found that the variation of the body proportions was up to 8%.The soft and flabby body of this species may influence to the variation.
Most records of this species are of specimens with protruded jaws (Stevens and Paxton, 1985;Parsons et al., 2002;Grijalba-Bendeck and Acevedo, 2009;Driggers III et al., 2014).More than 86% of M. owstoni captured during the study in Japan had the upper jaw at least slightly protruding (Yano et al., 2007).This protrusible jaw issue made some authors had different ways to measure the length of snout.Some authors previously determined the snout length by measuring between the tip of the snout to actual position of the upper jaw (Jordan 1898;Bass et al., 1975, Stevens andPaxton, 1985), but others used the measurement between the tip of the snout to the upper lip with an assumption that the jaws are Jordan, 1898 Mitsukurina owstoni Jordan 1898:200, Pls.11-12 (type locality: Misaki, Sagami Sea, Japan); Stevens & Paxton 1985:40, Figure 1 (off Sydney); Duffy 1997 (east coast of New Zealand); Parsons et al., 2002: 190, Figure 1 (Gulf of Mexico); Yano et al., 2007 (Tokyo Submarine Canyon); Rincon

Table 1 .
Proportional dimensions of Mitsukurina owstoni from Indonesia, comparing to specimens from Australia, New Zealand and Japan (presented as percentage of total length)