Case study – Northland’s portable biosecurity treatment facility
A large floating dock to treat hull bio-fouling has been built for the Northland Regional Council. A vessel can be brought into the dock and the gate is raised behind it enclosing all the seawater and preventing any marine pests escaping. The dock is 16 metres long and 5.5 metres wide with a three metre draft. It can accommodate a variety of vessel shapes, including many launch and small barge designs as well as yachts with a deep keel.
If a vessel hull is carrying a marine pest then the dock can be used to contain and treat the hull of the vessel before it spreads any further. Testing has been completed on the floating dock over the last year, which indicates that the dock can be a very effective and quick way of managing vessels which have hull fouling.
A marine pest treatment was recently undertaken in Auckland using the floating dock. A team of biosecurity staff from Northland Regional Council and NIWA scientists treated the hull of a vessel that was infested with the Mediterranean fanworm Sabella using the portable treatment facility. Aquaria trials have indicated that Sabella are very susceptible to chlorine over a short exposure time, chlorine is known to disperses well in salt water and this treatment is quick and easier to administer once the vessel is enclosed within the dock. A resource consent was obtained to add chlorine to the water in the dock which was then left overnight to kill the Sabella (and other fouling). The treatment appeared to work very well and during the course of the day scientists were able to collect data regarding the survival of Sabella on the hull.
Most vessel owners are aware that clean hulls and fresh antifoul prevent marine pests from establishing and that slipping, cleaning and antifouling vessels on a regular basis will prevent marine pest transfer. However, in some remote harbours where slipping and cleaning facilities are not available (such as Whangaroa) the treatment dock can provide a safeguard which can be used in emergencies to treat an infected hull without moving the boat to another habour where facilities are available.
Northland now has two portable treatment facilities which have proven to be particularly useful in instances where there are no other facilities to slip a vessel, such as remote locations, bays or harbours that have no supporting infrastructure. This facility is expected to become a regular tool for dealing with biofouling on (smaller) vessels arriving in Northland ports and marinas from elsewhere in New Zealand and overseas.
Last updated at 2:11PM on February 25, 2015