Izak Catshark - Biology and Ecology

Biology and Ecology

Compared to other deep-sea sharks, the Izak catshark has a large heart suggestive of a relatively active lifestyle. It is a generalist that feeds on a wide variety of bony fishes, crustaceans, and cephalopods; larger sharks consume proportionately more crustaceans and fewer fishes. At least some part of its recorded diet probably represents scavenging from fishery discards, given the presence of fast-moving, pelagic species that the shark is unlikely to have captured live. Polychaete worms, hydrozoans, gastropods, and hagfish eggs may also be occasionally ingested. This species often has nematode and flatworm parasites in its stomach.

The Izak catshark is oviparous and reproduction proceeds throughout the year without seasonal patterns. Mature females have a single functional ovary and two functional oviducts; a single egg matures within each oviduct at a time. Each egg is contained within a purse-shaped capsule 3.6–4.3 cm (1.4–1.7 in) long and 1.2–1.5 cm (0.47–0.59 in) across. The capsule is light brown with long tendrils at the four corners that likely serve to anchor it to rocks; its surface has a velvet-like texture and bears lengthwise striations. The rate of egg laying is unknown but thought to be high, based on this shark's resilience to fishing pressure. The preponderance of females and juveniles at shallower depths may indicate that such waters serve as nursery areas. The young hatch at under 11 cm (4.3 in) long. Males and females mature sexually at 45–50 cm (18–20 in) and 40–45 cm (16–18 in) long respectively.