Carcharhinus tjutjot
A requiem shark once confused with the whitecheek shark.
The Indonesian whaler shark (Carcharhinus tjutjot) is a requiem shark from the family Carcharhinidae. For a long time, it was mistaken for the whitecheek shark (C. dussumieri). This species is economically important in both commercial and small-scale fisheries across the Indo-Pacific, but because it is frequently taken as bycatch, the IUCN lists it as vulnerable.
Taxonomy was clarified in 2012 when researchers distinguished it from C. dussumieri using traits like vertebral counts, fin shapes, and fin color. Confusion also arose with the blackspot shark (C. sealei), especially because both have black markings on the second dorsal fin. Genetic sampling eventually helped separate the two, though some physical similarities remain.
In appearance, the Indonesian whaler shark has a black mark on its second dorsal fin, a fairly long snout, and an upright, triangular first dorsal fin. Its upper front teeth are slanted and flanked by jagged, knife-like cusplets. Males reach full maturity at about 100 cm, females at 92 cm, and first maturity occurs around 76 cm. Newborns measure 34–38 cm.
This highly migratory species lives in the western Pacific, from Indonesia and Taiwan to Borneo. It does not occur in Australia or New Guinea, and its presence west of the Indo-Malay Peninsula is unconfirmed. It inhabits demersal inshore waters from the surface down to 170 meters. Genetic studies reveal two distinct populations in the eastern Indian Ocean, suggesting a limited migration range within the Indian Ocean or South China Sea.
The IUCN lists the Indonesian whaler shark as vulnerable. Off the Malaysian Peninsula and Borneo, most landed sharks are juveniles, many at or below birth size. Because nursery areas overlap with fishing grounds, the species faces a high extinction risk. Small individuals are commonly caught as bycatch by long-range fisheries, and even when finless, they are sold for human consumption.
Quick Facts
- Taxon
- Carcharhinus tjutjot
Facts from the source article.
Lore & Background
The Indonesian whaler shark was initially thought to be C. dussumieri, but was identified as a distinct species in 2012 by morphological characteristics such as vertebral counts, dorsal and pectoral fin shape, and fin colouration. Its divergence has characterized shark populations within the tropical Indo-West Pacific. Morphological ambiguities and similarities to the blackspot shark (C. sealei) complicated its identification across the region, with distinctions arising in genetic sampling, though certain characteristics like black markings on the second dorsal fin remained hard to distinguish.
The Indonesian whaler shark is often confused with C. sealei due to similarities in morphologies. It can be identified by a black marking in the second dorsal fin, a relatively long snout, and an erect triangular first dorsal fin. Its upper anterior teeth are slanted, with jagged, knife-like cusplets flanking them. It ranges in size from 76 cm at first maturity to about 100 cm for males and 92 cm for females when fully mature, with size at birth around 34–38 cm.
C. tjutjot is a highly migratory species commonly found in the western Pacific, ranging from Indonesia and Taiwan to Borneo. It is not found in Australia or New Guinea and is not confirmed to live west of the Indo-Malay Peninsula. It prefers demersal inshore habitats from the surface to 170 meters. Molecular genetic analysis has shown the presence of two distinct population groups in the eastern Indian Ocean, suggesting a restricted migration range in the Indian Ocean or the South China Sea.
Reader's Guide
The Indonesian whaler shark holds significance as a key economic group in global fisheries, including commercial and small-scale fisheries within the Indo-Pacific region. Its common spawning and nursery areas overlap with commercial fishing grounds, and it is often caught as bycatch, which has caused it to be listed as a vulnerable species on the IUCN Red List. Studies have shown that sharks landed on the Malaysian Peninsula and coast of Borneo Island are mainly juvenile, with size and maturity ranging from less than or at birth. Due to the overlap in nursery and common fishing grounds, the species is near facing threat from extinction. Small sharks are commonly caught as bycatch by long-range fisheries, sometimes without fins as they are marketable for human consumption. Its legacy is tied to the challenges of species identification and the conservation pressures faced by requiem sharks in the Indo-Pacific region.
Did You Know?
- The Indonesian whaler shark was thought to be a junior synonym of the whitecheek shark until recently.
- It was identified as a distinct species in 2012 based on morphological characteristics.
- Its size at birth is around 34–38 cm.
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