Diamondback squid released by trained fishermen

Fishermen trained by WWF-Pakistan released a diamondback squid in offshore waters of Ras Kachari, about 76 nautical miles west of Karachi, along the Balochistan coast earlier this week, the wildlife protection authority announced in a press release issued on Monday.

The giant squid had been entangled in the gillnet of a tuna fishing vessel skippered by Saeed Zaman. The trained fishermen, after freeing the squid from the net, carefully released it back into the sea. The squid was measured at 95 cm in length and weighed around 18 kilograms. This is the second successful release of a giant squid by fishermen this year. Earlier, in March, a 50 cm long specimen was released by WWF-Pakistan trained fishermen.

The giant diamondback squid, scientifically known as Thysanoteuthis rhombus, is an oceanic species with a cosmopolitan distribution in warm tropical and subtropical open waters of the world. It is sometimes found in the Tsushima, Kuroshio, Agulhas, Brazil Currents and the Gulf Stream, and is widely distributed in offshore waters of Pakistan.

This species propels itself slowly by gentle undulation of its long, broad, diamond-shaped fins. However, it is capable of a powerful reactive jet of short duration when it faces any threat.  In the Arabian Sea, this species is of rare occurrence as it feeds on rich and dense concentrations of mesopelagic fishes (lantern fishes).

After its release, the giant squid released a dark pigment, which is an escape mechanism of these animals. The ink creates a dark, diffuse cloud which can obscure the predator's view, allowing the cephalopod to make a rapid retreat by jetting away.  It is interesting that unlike most squids and cuttlefish, the ink released by the diamondback squid is reddish brown in colour.

This squid is also preyed upon by different species including dolphin fish, lancet fish, tuna, billfishes, sharks and marine mammals (e.g. dolphins, rough-toothed dolphin, false killer whale, and sperm whale). It is not commercially harvested for most part of its distribution including in the Arabian Sea.

However, there is an aimed fishery in some regions of its range, especially in the Sea of Japan with an annual catch of about 5,000 m. tons. This species is valued for its firm and tasty flesh, and its high commercial value makes it an important target species along the coastal waters of the Sea of Japan and around Okinawa.

Rab Nawaz, Senior Director Programmes, WWF-Pakistan pointed out that crew based observers programme in Pakistan is considered a big success as it has helped in collecting data on fish catches of tuna and tuna like species but has also provided valuable information about bycatch species. “Given its success, many regional countries are considering initiating a similar programme for their fisheries,” he said.

Muhammad Moazzam Khan, Technical Advisor (Marine Fisheries), WWF-Pakistan commended on the efforts of fishermen in releasing this bycatch species.

He informed that fishermen trained by WWF-Pakistan have released a number of species including whales, dolphins, whale sharks, mobulid rays, sunfish, sea snake, seabirds and marine turtles.  ‘The giant diamondback squid is a species of rare occurrence in Pakistan, therefore, its release by fishermen is a good omen for the fishery of Pakistan’, he added.