Brown guitarfish, yellow guitarfish.
Long, pointed snout with
elongated rostral cartilage forming a slightly extended rostral tip.
Pectoral fin posterior margins
convex. Body behind pectoral fins tapers into a thick tail topped by two well
developed dorsal fins of roughly equal size. Caudal fin triangular with
indistinct lower lobe. Dorsal color
yellowish brown with a mottled pattern of symmetrical, darker blotches. Ventrum
pale. Rear border of spiracles have two visible folds.
Another form of R.schlegelii exists that has a significantly shorter snout. This
may be a case of sexual dimorphism or it could represent a completely separate
Listed as occurring at depths from
80-240m but this species is occasionally sighted by recreational divers much
shallower than 40m around southern Honshu, Japan. On sandy bottoms
often adjacent to rocky reefs.
and distribution: Restricted to the Northwest Pacific Ocean. Further study
is needed to determine which of the two forms of R.schlegelii occur in which
regions. It appears that the long-snouted form is centered around Japan and
likely occurs off the coast of China, Korea and Taiwan.
on or partially buries in sand when not foraging for food.
Guitarfishes are ovoviviparous (yolk
After absorbing all of the yolk,
embryos suckle from tiny club shaped villi (projections) that
provide nutrients for the young as they develop.
IUCN Red List Status: The brown guitarfish (Rhinobatos schlegelii) has
not yet been evaluated by the IUCN largely due to the confusion over the species
complex and the extent of its range.
However, it is susceptible to capture in a variety of fishing gear including
trawl, gillnet and line fisheries and rhinobatids are highly valued for their
fins. Historical fishing pressure has been relatively intensive across its known
range, although increases in fuel prices have reportedly led to some decrease in
recent years off Japan. Other Rhinobatos species have proved vulnerable to
population depletion as a result of their limiting life-history characteristics
and serious declines have been reported in similar species where they are
heavily fished. Consequently, the brown guitarfish may prove to be threatened
when these taxanomic issues are resolved.
Ito, Chiba Prefecture, Japan.
species: The brown guitarfish
needs to be reviewed to establish how many species actually exist.
There appears to be a long snout and short snout species in Japan and what is
likely another similar species in the Philippines.
to divers: Generally easy to approach with careful slow movements. May
slowly move away or bolt upon very close
This guitarfish is occasionally encountered in Chiba and Izu; two peninsulas on
the south side of Honshu, Japan.
In Chiba. There are a number of dive shops operating in the region. One
recommended operator is Bommie Dive Center in Ito, Chiba Prefecture.