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Aqua Farming For Lobsters – Beginner’s Guide
Lobsters belong to the crustacean group and the Nephropidae family; they may be confused for crayfish; the clawed lobsters are more related to the other families of crayfishes because they almost look the same. They have long bodies with muscular tails and live in crevices or burrows on the sea floor.
Lobsters belong to the spiny lobster family; their name is derived from the tiny pointing spines that cover their body and carapace; having prominent features being the two huge antennas they use to find their way around. They have blue blood due to the presence of the blood pigment hemocyanin which contains copper rather than iron in their hemoglobin.
These crustaceans can live for over 20 years but with a possibility of living up to an estimated 45 – 50 years in the wild; and can reach a size over 5 kilograms (11 pounds), though fishers rarely retain animals over 3 kilograms (6.6 pounds).
Some Of The Lobster Terminology
- Tarspot – ‘spermatophoric mass’ is the sperm packet due to its appearance.
- Females carrying eggs are known as ‘berried’.
- Larvae are called phyllosoma because of their leaf-like shape.
- Reds are adult and non-migrating lobsters.
Marine Waters And Land Based Aqua Farming Of Lobsters
Spiny lobsters live along the coast, inhabiting shallow waters and tend to shelter in rocky reefs and corals. The small size of lobsters is abundantly available in near seashore, making fishermen to harvest them exclusively in small scale as artisanal activity and developing the continental shelf.
Most farmed shellfish are grown in traditional small-scale systems that benefit local communities and minimize the environmental impact. Utilizing simple culture technologies and minimal inputs, these systems have been used for centuries. Paradigm shift development in aquaculture conserves land, water, plant and genetic resources, is environmentally non-degrading, technologically appropriate, economically viable and socially acceptable.
Water suitable for aqua farming should have a certain degree of acidity (indicated by the water pH value and it should range between 6.7 and 8.6. The pH value range is good for growth. Spiny lobsters are caught and fattened in tanks so they can reach the desired market size of weight more than 200 grams.
The tank water volume is should be about 2 metres long, 1 metre wide and 1 metre deep; providing artificial shelter using half PVC pipes.
Catching Lobsters
The spiny lobsters are caught using bottom gillnet which is sized at 1,000 metes in length, 1.5 metes in height, 4-6 inches (10.2 – 15.2 cm) in mesh size. The netting twine is a monofilament with mesh size 6 inch (15.2 cm) and is used in separate fishing units. Boats used in fishing consist of wood while some are plastic boats made of glass-reinforced fiber. Once lobsters are caught, they are placed in gathering houses surrounded by water located on the beach.
Fattening And Growth Of Lobsters
Fattening spiny lobsters is done over a period of about 6 months being placed in cemented tanks installed with marine water on the seashore. Based on external appearance, the lobsters are separated as per their weight into the tanks; and water used in the tanks is sourced offshore from the sea water for their salinity, water temperament, pH and other parameters reflecting the ambient condition of the sea water.
The lobsters are fed finfish and shellfish at a certain percentage daily; the feedings are done in early morning giving 20% feed and in the evenings 80% feed. How to raise lobsters To avoid filamentous green algae growth in the tanks, they are covered with plastic corrugated sheeting; bearing in mind that the tanks are siphoned daily and should be cleaned thoroughly once a week.
Growth rate in the first 9 months is about 36 -61 grams per individual lobster per month; the size of growth may vary and they can weigh more. When fattening in tanks, never overcrowd lobsters in the tanks.
Lobster Species
Lobsters can be grouped into two, namely the: Clawed lobsters and Spiny or Rock lobsters. They, however, come in different species.
- Clawed lobster and Spiny or slipper lobster are marine species.
- American blue lobster
- Squat lobster – are not lobsters at all, they are closely related to the porcelain crabs, hermit crabs and more distantly, the true crabs.
- Reef or rock lobster
- Western rock lobster
Lobster Lifecycle
- Mating – lobsters mate in late winter and spring; with an attached packet of sperm to the underside of the female. The sperm remains under the female between the hind-most pair of legs until she is ready to spawn her eggs.
- Spawning – the female lobsters release their eggs, releasing sperm from the tarspot by scratching it; then eggs are fertilised as they are swept backwards from the female and become attached to the sticky ‘setae’ (fine hairs) on the ‘swimmeret’s’ beneath the tail of the female lobster. Females carrying eggs are known as ‘berried’. The eggs hatch in about four to eight weeks, depending on water temperature, and release tiny larvae into the water currents.
- Larvae – drift offshore and spend 9 – 11 months in a planktonic state while growing in a series of moults from 2mm at hatching to approximately 35 mm in the final larva stage.
- Pueruli (transparent rock lobster) – the late-stage larvae undergo a moult that totally changes their appearance. They become fully-fledged but miniature (about 25 mm long); they swim from deep waters to onshore reefs some distance of 60 km and go on without eating because their are powered by the energy reserved from their larval phase. At this stage they develop the red colouration.
- Juveniles – the pueruli that successfully return to the coast will, through a series of moults, grow to become juvenile rock lobsters, with the juveniles feeding and growing on the shallow onshore reefs for the next three or four years.
- Whites’ migration – at this point, the lobsters undergo a synchronised moult in late spring and they change their normal red shell colour to a creamy-white/pale pink. The lobsters are then known as ‘whites’, until they return to their normal red colour at the next moult a few months later.
- Once their new lighter-coloured shell has hardened, they set out on a two-pronged migration. The vast majority head west and undergo a mass migration into deeper water, where they resettle on deeper reefs; though a small percentage makes a longer migration to the north following continental shelf.