Mangrove red snapper (river snapper)

Mangrove red snapper (river snapper) facts

Also called

River snapper, rock salmon or river roman in South Africa; mangrove jack in Australia; also mangrove snapper, red snapper and red bream.

Family

Lutjanidae, the snappers.

Native range

The tropical Indo-West Pacific: from the Red Sea and Persian Gulf down the East African coast to South Africa — estuaries as far south as Gqeberha (Port Elizabeth) — and east to Samoa and the Line Islands, north to the Ryukyus and south to Australia. It has reached the eastern Mediterranean through the Suez Canal but is not established there.

Habitat

Juveniles and young adults live in mangrove estuaries, tidal creeks and the lower reaches of rivers, among rocks and mangrove roots, where they tolerate very low salinity. Adults move out to coral and rocky reefs down to 80–120 m (260–400 ft).

Water temperature

Tropical to subtropical. AquaMaps puts its preferred surface water at about 23–29°C (74–85°F); FishBase gives a range of 16–30°C.

Size

Most adults 40–80 cm (16–31 in); the largest measured about 150 cm (59 in).

Record

IGFA all-tackle world record: 11.62 kg (25 lb 9 oz), Takuya Kano, Ashizuri Misaki, Kochi, Japan, 3 May 2006. South African records are heavier: 14.1 kg (31 lb) on shore tackle and 16.6 kg (36 lb 10 oz) by spearfishing.

Lifespan

Long-lived: aged to 31 years in Papua New Guinea and up to 39 years off eastern Australia.

What it eats

Mostly at night: mullet and other baitfish ambushed from under ledges and mangrove roots in estuaries; on reefs, small fish, crabs and crayfish.

Spawning

At sea on offshore reefs — off northern KwaZulu-Natal and Mozambique, it is thought, in South African waters — in the southern spring and summer, October to March in Queensland, and through the year nearer the equator. Spawning peaks around the full moon. In Queensland males mature at about 47 cm and females at 53 cm fork length.

Young fish

Thirty to fifty days after hatching, juveniles of 2–5 cm move into mangrove estuaries and the lower reaches of freshwater streams. They carry about eight pale bars on the sides and two blue lines across the cheek.

Teeth and mouth

Prominent canine teeth at the front of both jaws, for seizing prey — and fingers.

Look-alikes

Two-spot red snapper (red bass, Lutjanus bohar) of the reefs is darker, with a deep groove from the nostril to the eye and scale rows that rise obliquely from the lateral line; it is a well-known carrier of ciguatera. The river snapper’s scale rows on the back run more or less parallel to the lateral line.

Eating

Excellent: firm, sweet, white flesh, and a valuable market and farmed fish in Asia. In South Africa it is a no-sale species. Ciguatera has been reported.

Status

Least Concern on the IUCN Red List (2015). In South Africa catch rates in the Kosi Bay fisheries fell between the 1980s and 1990s, and the loss of estuary habitat in KwaZulu-Natal is thought to have hit it hard.