Lahinch Seaworld Lobster Breeding Station
The Lobster Pond on
the left contains the broodstock of fertilised females, known as berried hens
(banded to prevent them from fighting). Female lobsters mate in the autumn, and
then carry their 20,000+ eggs on the underside of their tails, as they slowly
mature. These eggs hatch into larvae during mid to late summer.
After hatching, the
lobster larvae float to the surface of the water and tend to accumulate under
the lights. At this point we transfer the larvae to the conical bins, which
contain swirling and upwelling water. Here the planktonic, mid water stage is
stimulated, during which time the lobster larvae molt (shed there shells) four
times in order to grow. The stage four larvae (approx 1 cm in length) are
miniature replicas of the adult form. In the wild they would sink to the seabed
where they would burrow into the mud.
In captivity the
stage four larvae are transferred into individuals cells seen here to prevent
the tiny lobsters from eating each other. They are fed twice a day on a varied
diet, to mimic what they would normally have in the wild: small pieces of
mussel, crab, winkle, shrimp, prawn, mysid shrimp and sand hoppers. They are released
into the wild after approximately one year. At this stage the lobsters are
around 2-3 cm in length, and have a much better chance of growing to maturity.
Our lobster breeding station was set up
to combat some of the effects that commercial exploitation has had on lobster
populations. Lobsters are a highly prized and valuable commercial species.
Drastic overfishing for the restaurant trade, combined with lobster’s extremely
slow growth rate, has severely reduced lobster populations in many areas of
Ireland. It takes between 5 to 7 years for lobsters to reach maturity, and by
this stage they are at marketable size, so many have been caught by fishermen.
Here at
Lahinch Seaworld, we enhance our lobster breeding programme in several ways:
·
We house
male and female lobsters together to ensure egg fertilisation.
·
When any
local fishermen catch pregnant female lobsters we buy them from them to enter
into the breeding programme.
·
In addition
to rearing the larvae that our females lobsters produce, we also buy in
juvenile lobsters at various stages from other hatcheries.
The larvae
displayed here were bought in from a hatchery on the Orkney Islands this week.
We bought in juveniles at an older age (stage five) as they have a much higher
probability of survival at this age. There are no predators to reduce numbers
in our system, but the larvae do attack each other so this can limit survival.
We avoid this problem by settling them in separate calls so they cannot eat
each other.
Hatching and
growing juvenile lobsters in captivity ensures that a higher number of them
survive. In the wild it is estimated that up to 90% of juvenile lobsters die
before they become fully mature. We too have some mortalities in our breeding
programme, but we strive to ensure that each juvenile lobster gets the care and
attention it would need to survive to adulthood.