Japanese flying squid

Japanese Flying Squid
Todarodes pacificus (dorsal view)
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Coleoidea
Order:	Teuthida
Family:	Ommastrephidae
Genus:	Todarodes
Species:	T. pacificus
Binomial name
Todarodes pacificus (Steenstrup, 1880)
Subspecies
T. p. pacificus (Steenstrup, 1880) T. p. pusillus Dunning, 1988
Synonyms
Ommastrephes pacificus Steenstrup, 1880 Ommastrephes sloani pacificus Sasaki, 1929 Todarodes sloanei pacificus (Steenstrup, 1880)

The Japanese Flying Squid or Japanese Common Squid, Todarodes pacificus, is a squid of the family Ommastrephidae. This animal lives in the northern Pacific Ocean, in the area surrounding Japan, up the full coast of China up to Russia, then spreading across the Bering Straight over towards the lower coast of Alaska and the coast of Canada. They tend to cluster around the central region of Vietnam.

Description

Ventral view of Todarodes pacificus

One of the eight arms

One of the two tentacular clubs

Adult squid have several distinguishing features. The mantle encloses the visceral mass of the squid, and has two fins, which are not the primary method of propulsion. Instead, the squid has a siphon: a muscle which takes in water from one side, and pushes it out the other side: jet propulsion. The squid has eight arms and two tentacles with suction cups along the backs. In between the arms sits the mouth, or beak. Inside the mouth is a tooth-tongue-like appendage called the radula. Squid have ink sacs, which they use as a defense mechanism against possible predators. Squid also have three hearts.

The age of a squid can be determined on the basis of its growth rings, or statoliths, when additions are appended daily to the balance organs in the back of the squid’s head. This species of squid can weigh up to 0.5 kg. Mantle length in females can go up to 50 cm; males are smaller.

Habitat

The Japanese squid can live anywhere from 5° to 27°C, and tend to inhabit the upper layers of the ocean. They are short lived, only surviving about a year.

Around 25 different species of squid swim in the Vietnam locale alone.

Life cycle

Within this year of life, the squid mature from larvae form, feed and grow, migrate, and at the end of their lives, congregate at the mating grounds, where they reproduce. Three subpopulations have been identified in Japanese waters. “The main group spawns in winter in the East China Sea, the second in autumn, west of Kyushu, and the third, minor group in spring/summer in the Sea of Japan as well as off northeastern Japan.”

"Their migration moves North then South, tending to follow the surface currents. The squid tend to travel in large schools of more or less uniform size [meaning] that it is often possible to follow the growth of cohorts from recruitment to spawning, although the earliest part of the life history is generally more difficult to study because the larvae are always pelagic and some are rarely caught".

Squid generally only live one year because as soon as they reproduce, they die. Males mature first, and “transfer their spermatophores on the still immature females.” Then, on the continuing journey south, the females “mature and spawn 300 to 4,000 small, elliptical or semi-spherical eggs.” The squid migrate together, and lay all their eggs in the same area where they were born. The eggs hatch into larvae after only 102–113 hours (somewhere around five days), depending on the water temperature.

Diet

Squid are difficult to study individually in the lab, because “the animals appear to become stressed by isolation,” However, it is believed that the planktonic larvae feed on phytoplankton and zooplankton until they grow large enough to begin feeding on fish. When the squid matures more, it will eat mainly fish and crustaceans, however, it will also resort to cannibalism, especially when trapped in nets together.

"Flying"

Flying squid have been observed to cover distances as long as 50 meters above the surface of the water, presumably to avoid predators or save energy as they migrate across vast expanses of ocean, uniquely utilizing jet-propelled aerial locomotion.

Predators

Many vertebrate predators depend heavily on squid, which is second only to krill as a food source in the Southern Ocean. Animals such as the grey-headed albatross and the sperm whale (the largest of the toothed whales) feed almost entirely on squid. Other predators include dolphins, seals, baleen whales, and rays.

In a study done by Sakuri in 1993, Todarodes pacificus was studied in the lab. The following data was found.

Temperature (C)	Relative Growth Rate (% per day)	intake (body mass/day)	Food
16	.06	30%	Fish

Study done by Sakuri. Lab results are not synonymous with what you would find in the wild. The squid are able to grow and reproduce much better in a lab setting.

Fishery

Major players in the fishing of the Japanese flying squid are mainly Japan (with the highest usage and catch in tons), the Republic of Korea (with the second greatest catch), and a relatively new player: China. Production and consumption of the Japanese flying squid is highest in Japan. Within all countries where it is being fished, the squid is also exported to many other countries for consumption, the United States being a top importer. Japan is the largest consumer and exporter of the Japanese flying squid. This is due to the country’s impressive consumption of seafood and sushi. Other countries use the Japanese flying squid for use in sushi as well.

The fishing season for the Japanese flying squid is all year round, but the largest and most popular seasons are from January to March, and again from June to September. Gear used to catch the Japanese flying squid is mainly line and hook, lift nets, and gill nets, the most popular method being hook and line used in jigging.

Current data on the Japanese flying squid shows that throughout the years, the rate of capture has been fairly consistent, with one major fluctuation in the late 70s to early 90s.

Current data shows that the Japanese flying squid is a sustainable fishery. This is due to their short life spans, and the fact that fishermen tend to try to catch the squid after it has spawned and before its imminent death. The fishing techniques used, mainly the hook and line methods used coupled with fishing at night to attract the squid, seem to allow for minimal by-catch. Other systems like gill nets are usually less specific in what they catch, although some technological advances have involved larger openings to allow smaller animals to pass through.