It has long been recognised that fish are attracted to old wrecks, debris and other man-made structures such as offshore gas and oil platforms. Offering static surfaces that drifting marine life can cling onto, they provide refuge and shelter for the phyto- and zoo-plankton. Over time these artificial reefs begin to exhibit the same characteristics as natural reefs of rock and coral. A food chain develops that, in turn, serves to attract the larger pelagic species of fish.
In 1775, Japanese fishermen – aware of the commercial possibilities of being able to predict those sites where fish could be readily harvested – created artificial marine life habitats of bamboo and sticks weighted down by sandbags. These were placed in up to 60-metres of water in otherwise barren sea-floor deserts and, after a short space of time, began to attract fish in large numbers.
As a concept, the establishment of artificial reefs has continued to find favour with certain sections of the marine farming industries: the oyster farming and pearl fishing sectors have employed them successfully for years, while line fishermen (usually amateurs and limited in the size of their catch), are drawn to such wreck sites.
But as a commercially viable project to increase fish numbers for harvesting, the sinking of hulks or the establishment of other types of Fish Attracting Devices has met with limited success. While all fishermen recognise the catch potential of wrecks the gains are minimal when compared with the risk of tearing, snagging or losing an expensive net that catches on the structure.
As a broad generalisation it’s divers – and the dive tourism industry – that has benefited most from the establishment of artificial reefs; desolate areas that previously had little to commend them as dive locations have suddenly acquired an underwater attraction worth visiting.
In Australia there have, over the years, been many successful attempts, employing a variety of materials, to establish artificial fish habitats. Old car tyres have proved particularly suitable as has the use of derelict cars. Even small vessels have been used to good effect in creating man-made reefs.
The majority of these have been modest affairs sited in comparatively shallow waters away from the commercial fishing grounds. Usually the initiative of nearby dive clubs whose members volunteer their time and labour to build them, the purpose of such reefs has been to add a feature benefit to local dive sites.
Periodically vessels whose useful life had come to an end – and for whom there were no buyers – were scuttled. While it was appreciated that these hulks would become artificial reefs serving to attract marine life, the main reason was one of simple economics in the question of how best to dispose of them
Very few wrecks have been purposefully sunk in Australia as a means of improving commercial fish stocks. During the late 1970’s through to the early 1980’s a number of vessels, including the Sydney Harbour Ferry, ‘Dee Why’ and the ‘Meggol’, (formerly HMS Wexford and HMAS Doomba), were scuttled in 50 plus metres of water off of Long Reef – a notable promontory on Sydney’s northern beaches – with the aim of establishing an artificial reef that would enhance the opportunities available to both recreational and commercial fishermen.
While the wrecks did attract fish in greater varieties and numbers, there was no firm evidence to suggest that the establishment of the reef had significantly improved on – or helped create larger – fish populations. (One argument suggests that artificial reefs only act as a focal point for fish already in the area, while another view suggests that juveniles seeking shelter in the wreck are able to grow to maturity and therefore boost total stock numbers.)
In recent years Australia, like many other countries around the world, has come to appreciate the need for proper environmental safeguards. It’s no longer possible to go out and establish an artificial reef just anywhere. While each of the States have their own policies in place regarding wreck sinking the procedures that must be followed are similar.
Permission must first be sought from a number of Government Departments and a site selected that will have the least impact on the existing marine environment. And before the final approval for any sinking is given, rigid guidelines govern the stripping and cleaning of all materials that might have an adverse impact on the marine environment.
Despite these rigorous procedures a number of bodies have draft policies in place to establish more artificial reefs around Australia’s coastline. Mostly intended as recreational diving or fishing attractions, the major problem in doing so is one of cost. To buy a suitable vessel is an expensive exercise in itself. But add the additional costs necessary to meet the environmental criteria imposed by the EPA and it can be prohibitive.
The above article was first published in Nekton Magazine in Feb 1998