Australian blackspot shark

Lore & Background

The Australian blackspot shark is a small inshore shark with two dorsal fins, triangular pectoral fins, paired pelvic fins, an anal fin, and a heterocercal caudal fin. Its second dorsal fin has a dark to black tip, while all other fins are plain—a key distinction from other species in the blackspot complex, which have dusky or black tips on more than just the second dorsal fin. The shark is overall pale brown, fading to gray after death, with almost white ventral surfaces for countershading camouflage. Its upper teeth have oblique cusps with smooth-edged cusplets on one side, and its lower teeth are narrow and upright with smooth-edged cusplets.

These sharks are believed to reproduce every year, with no known seasonal restrictions for reproduction. They are viviparous, supporting offspring with a yolk-sac placenta. Litter size averages 2 pups, ranging from 1 to 3. There is no direct evidence of diet, but it is most likely composed of small fish, cephalopods, and crustaceans. The sharks are believed to live for 6.5–7 years.

The geographic range is believed to be inshore waters around northern Australia, from Shark Bay in Western Australia to K'gari in Queensland, and also in Papua New Guinea. They occupy the continental shelf from the surface to a depth of 123 m. Geographic range is another distinguishing characteristic; its close relative C. dussumieri is distributed more in the Indo-Pacific region.

Reader's Guide

The Australian blackspot shark is notable primarily for its cryptic nature and recent taxonomic clarification. Because it was only distinguished from the whitecheek shark and the blackspot shark in 2012, much of the existing literature predates this reclassification and groups it with those species. This means that historical data on its biology, distribution, and threats may be conflated with other species. The shark's main threat is bycatch, particularly from prawn trawl fisheries, where caught individuals are sold for meat and fins. Bycatch reduction devices can limit the number of larger individuals affected, but they are not used in all fisheries and do not guarantee the sharks will not end up as bycatch. The IUCN considers this species to be of least concern as of July 23, 2018. Its significance lies in being a distinct member of the blackspot complex, with fin coloration and geographic range serving as key distinguishing features. The lack of direct dietary evidence and the uncertainty around its gestation period highlight how little is known about this inshore shark, underscoring the need for further study now that its taxonomic identity is established.

Did You Know?

• The Australian blackspot shark was reclassified as a distinct species from the whitecheek shark and blackspot shark in 2012.
• Litter size averages 2 pups, ranging from 1 to 3, and the sharks are believed to live 6.5–7 years.