‘Data Deficient’ but potentially threatened: first biological observations on the poorly known quagga catshark (Halaelurus quagga)

Abstract

Context

The quagga catshark (Halaelurus quagga) is a small-sized (~370-mm total length), deep-water catshark (Family: Pentanchidae), assessed as Data Deficient on the IUCN Red List.

Aim

We aimed to bridge critical knowledge gaps on aspects of the life history and exploitation of H. quagga to make a meaningful Red List assessment, and develop management plans.

Methods

Specimens landed as bycatch in three harbours along the Laccadive Sea coast of south-western India were examined to gather the first information on exploited length classes and aspects of reproductive biology.

Key results

Halaelurus quagga had a female-dominated sex ratio, a positively allometric growth in females, and isometric growth in males. Mature H. quagga males ranged between 294 and 336 mm, and females between 315 and 370 mm, with pregnant females carrying two, three or four egg cases with embryos in each uterus.

Conclusions

This study provides the first information on the biology and exploitation of H. quagga, showing that the species is landed (and discarded) as bycatch in trawl fisheries, with the catches comprising a significant amount of reproductively active individuals.

Implications

The intense deep-sea bottom-trawling off south-western India is a major threat to H. quagga, and, if left unmanaged, could likely trigger a threatened category on the IUCN Red List.