Sicklefin weasel shark

7/5/2020

Hemigaleus microstoma picture by Randall, J.E.

We recently talked about the straight tooth weasel shark, but today The Fins United Initiative is talking about the sicklefin weasel shark (Hemigaleus microstoma)!

But wait- it doesn’t stop there. It was previously considered to be an animal also found in Australian waters, but those “down under” individuals were recently described as a new species, Hemigaleus australiensis (White et al. 2005). So where exactly is the range for this critter? The Indian Ocean and the northwest and western central Pacific Ocean. Think around India, Sri Lanka, Myanmar, Thailand, Malaysia, Indonesia, Philippines, China, Taiwan and possibly the Red Sea. It is also suggested by the IUCN that the specimens from the Red Sea need to be re-examined. Overall, it seems to not be particularly common throughout its range.

Known from specimens caught on the insular and continental shelves, it has been observed in shallow waters to depths of at least 170 meters (m). Here they feast on almost exclusively on cephalopods! A small shark, it only gets up to 1.14 m in total length (TL); males are known to reach maturity at about 75 cm TL while females mature from 75-78 cm TL. Litter sizes for the sicklefin weasel shark don’t get bigger than 4 individuals that are born at about 47 cm TL. The latest research shows that the females may undergo two pregnancies per year, having gestation period of less than six months!

The IUCN has assessed them as Vulnerable (VU) due to them being caught in inshore and offshore artisanal fisheries throughout its range.