Jasus Tristani

''Jasus paulensis'', also commonly known as the St Paul rock lobster, is a species of spiny lobster found in the waters around Saint Paul Island in the southern Indian Ocean and around Tristan da Cunha in the southern Atlantic Ocean. At one time the rock lobsters on Tristan da Cunha were believed to be a separate species known as the Tristan rock lobster (''Jasus tristani''), but the use of mitochondrial DNA sequencing has shown them to be identical. Some authorities, for example the International Union for Conservation of Nature, retain them as separate species. The Tristan rock lobster features on the coat of arms and the flag of Tristan da Cunha.

Description

Males of this species grow to a total length of about with a carapace length of while females may attain a total length of . Like other rock lobsters, it lacks chelae (claws) on its front pair of walking legs. The carapace is armoured with large flat spines, about as wide as they are long, mixed with small spines. The first few abdominal segments are sculptured with fine transverse grooves at the front of each segment with a smoother area behind.

Distribution and habitat

Although this spiny lobster was originally known only from St Paul and neighbouring New Amsterdam Islands in the southern Indian Ocean, more recently it has been discovered on other seamounts on the Southwest Indian Ridge, so its range is rather larger than originally thought. A previously recognised species ''Jasus tristani'', found around Tristan da Cunha in the southern Atlantic Ocean, has now been synonymised with ''J. paulensis''. This is an uncommon species throughout its range and is usually found at depths between but occasionally down to about . It is found on rocks and among kelp.

Ecology

''Jasus paulensis'' is nocturnal. It feeds on seaweeds and scavenges on dead animal material. The eggs are laid from May onwards and the female incubates them under her tail for several months.

Fishery

Early visitors to St Paul found that it was possible to catch a lobster by hand in shallow water in the crater lake bay, take it to a nearby submarine hot spring, and cook it, without ever removing it from the water. In 1928, a large-scale fishery and cannery for the spiny lobster using lobster pots was set up on St Paul, but the company went bankrupt three years later, stranding seven people on the island and leading to a tragedy known as " Les Oubliés de Saint-Paul" (the forgotten ones of Saint-Paul). In the next two decades, there were several, largely unsuccessful, attempts to harvest the lobsters using factory ships. In the period 1950 to 1956, the spiny lobsters were harvested by the French company Sapmer with about 260 tonnes of lobster tails being processed annually (equivalent to about 800 tonnes of whole lobster). This company still operates factory vessels equipped with deep-freeze facilities in the area.

Before 1950, the rock lobster on the Tristan da Cunha archipelago was only fished for local consumption. Since then, companies such as the South Atlantic Islands Development Corporation have exploited it. Production peaked in the 1970s, with over 800  tonnes being collected in some years, but the industry has since waned, with less than 400 t being caught most years since 1992. The fishery became MSC-certified in 2011, and the current TAC total still stands at about 400 tonnes annually. Since 1996 it has been harvested by Ovenstone Agencies in a partnership with the Island Govt scheduled to last at least until 2026.

References

{{Taxonbar, from=Q6493529

Achelata
Edible crustaceans
Crustaceans of the Atlantic Ocean
Fauna of Tristan da Cunha
Fauna of Gough Island
Crustaceans described in 1862
ÃŽle Amsterdam