Coastal Aquaculture and Mariculture (2+1)

Unit 2 - Traits of important cultivable species

2.8. Lobsters
Among marine crustaceans, lobsters are the most highly priced commodity of significant interest in many countries. Supply of lobsters to domestic and international market comes mainly from the capture fisheries through intensive fishing in different parts of the world. Traditional lobster stocks are heavily over fished. Therefore aquaculture of this group in a necessity. However, aquaculture of this group is yet to take off due to very slow growth rate and difficulty in producing seed in hatcheries due to very poor survival. Presently undersized lobsters caught by fishermen are collected by the growers and cultured in suitable enclosures to marketable size through appropriate feeding schedule and water quality management. This kind of practice is called fattening. This is successfully practiced in countries like Japan, Taiwan New Zealand.
In India currently no commercial lobster fattening or culture is being undertaken. With the increase in prices for small and medium sized lobster, prospects for lobster culture in India appear to be bright. Bigger species of lobsters such as P. homarus and P. ornatus are the suitable species for culture. Following are the traits of the above species.

Spiny lobsters are heterosexual and strictly marine throughout their life. They attain maturity at the age of two and half years and reproduce in inshore waters. Breeding is continuous, each species having peaks at different times in different areas. The life cycle involves a prolonged metamorphic phase extending for several months. Fertilized eggs attach to the abdomen of the mother which is called berried female. They hatch into a flat transparent phyllosoma larvae. The pelagic larvae after a series of stages during the next 10-12 months transform in to characteristic post larvae called puerulus. The puerulus is tiny and transparent but resembles adults and settles to the bottom. It soon develops into a juvenile.

The lobsters are carnivorous and nocturnal. They feed on a wide variety of bottom dwelling organisms and decaying animal matter. The most preferred food is bivalve mollusks, polychaets and fish. Growth is relatively faster in the early stages and they attain 20 – 25 cm in the first two years, thereafter the growth rate is very slow being 2-3 cm per year. They have a life span of 7-8 years

Panulirus polyphagus
It attains a maximum body length of about 37 cm. Carapace rounded and moderately curved with spines and tubercles. Antennular plate with a single pair of anterior spines. Abdomen without groves. Body colour dull greenish. Each abdominal segment with a distinct transverse band of white colour along the posterior margin. Legs with indistinct blotches and short stripes.
It is generally associated with muddy sea bottom and found in maximum abundance along Maharashtra and Gujarat coast

Panulirus homarus
Medium sized lobster growing to about 30 cm in length. Carapace rounded with numerous spines. Antennular plate bearing two equal pairs of spines and many scattered smaller spines in between. Abdominal segments grooved transversely, grooves sometimes interrupted medially. Colour of body dark greenish to blackish. Lateral border of each abdominal segment with a white circular spot.
This species coexists with P. ornatus in the rocky coastal areas from Trivandrum to Cape Comorin, Gulf of Mannar and Madras. P. homarus is dominant in southern areas, while P. ornatus is dominant in Mandapam area.

Panulirus ornatus
The largest species under this genus, grows to about 50 cm. Carapace rounded and covered with numerous spines and tubercles. Antennular plate bearing two pairs of spines, the anterior pair being much larger than the posterior. Abdominal segment smooth, without transverse grooves. Body colour grayish brown. Each abdominal segment with a broad dark transverse band and two large white spots on either side. Legs with black and light yellow stripes.