Lobster Hatchery
Shellfish Hatchery Systems Ltd.
The Aquahive release system
Throughout the evolution of lobster hatcheries dating back to the 1950’s, it has always been a problem to release the juvenile lobsters into a natural habitat. Deploying them by divers, although effective, was cost prohibitive and generally involved growing the juvenile lobsters in the hatchery for several months until they achieved a large size. A later development was to use a delivery system that involved a tank on the deck of a boat connected to a diver on the sea-bed by a tube. As the lobsters flowed down the tube the diver could remain on the sea-bed and direct the juvenile lobsters into areas that looked appropriate for young lobsters to hide. Although this method was faster than a diver placing lobsters on the sea-bed, it also proved to be expensive and it is now thought that it may have had an immediate predation rate of over 50%. One video recorded in Canada by 2 divers following this release method showed small fish consuming the vast majority of the juvenile lobsters released.
There is another release method that has been used, that is as above but without the divers to direct the lobsters into suitable areas of habitat. There are no records of survival rates available from this release method.
In 2002 the Orkney Lobster Hatchery started using a release method that positioned the juvenile lobsters directly on the sea-bed with a protective layer of paper between them that dissolved and allowed the lobsters direct access to the sea-bed substrate. This idea was developed using an Aquahive tray and an Aquahive skeleton tray.
The Aquahive trays can be taken directly from the Aquahive cylinder containing juvenile lobsters. The Aquahive tray then becomes the holding cells in the developed release system. A secondary skeleton tray, developed by Shellfish Hatchery Systems Ltd, and a perforated sheet of paper are used to close the cells during deployment. A weight is then added to overcome buoyancy. The skeleton tray that sandwiches the perforated paper helps to produce drag, and the weight ensures that the deployment system always lands on the sea-bed in the correct orientation, even if deployed in water less than 3 metres deep.
Unlike any traditional system, the juvenile lobsters are positioned on a perforated soft paper membrane a few millimetres above the substrate. The juvenile lobsters will leave their cells by enlarging or cutting between perforations, directly emerging into a more secure habitat. The juvenile lobsters will leave the cells at different rates, allowing them to move outward through the substrate rather than above. Tank trials of this release method have shown that lobsters will only exit the trays if habitat is available. On sea-release trials Shellfish Hatchery Systems Ltd observed that the lobsters exited the trays during the hours of darkness taking between 24 and 120 hours depending on the available substrate.
The Aquahive release system can be deployed individually or several release systems can be connected together in a string with weights and buoys at each end of the string. The Aquahive trays are currently being used in Norwegian hatcheries, in Canada, Orkney and at the National Lobster Hatchery in Padstow.
