Artificial reefs, created by deliberately sunk ships and other structures, may not be all that they’re cracked up to be, according to two American academics.
One, Prof William Lindberg, who specialises in fisheries science at the University of Florida, has said that artificial reefs may actually hinder rather than improve levels of marine life in the surrounding area.
His logic is that fish populations can be drawn to an artificial reef – and then be destroyed by fishermen who are drawn to the same place.
“You can use them [artificial reefs] as a tool for economies. You may be able to use them as a tool for ecological benefits, but you can’t necessarily do both simultaneously with the same reef,” he told the Herald Tribune.
The way around such a problem is for fishing bans or restrictions to be put in place. These do exist for some ships sunk as reefs and diving attractions; apart from anything else, masses of fishing hooks and masses of visiting divers do not mix well.
However, another less easily solved problem is that of a shortage of food that can occur on artificial reefs for, say, grouper and snappers.
A study five years ago by Lindberg and other scientists found that grouper that chose the safety and shelter of an artificial reef were significantly lighter than those living in less sheltered but more nutritious areas.
Likening an artificial reef to a city, Lindberg said: “You can have a city of several million people, but you better have some farmland out thereproducing food for them.”
Another expert, Prof James Cowan, who specialises in oceanography and coastal science at Louisiana State University, agreed.
A number of studies dating back over some 25 years had shown that some fish species need to travel to find their primary food source if they are to grow and reach adulthood, he said.
Cowan also mentioned that reefs are often placed where people want them, rather than where is best for regional marine life. Sometimes, a reef is created in an area that “would be, in nature, the nursery habitat”.
As a result, adult fish can end up living among and competing with juveniles, and more predators are drawn to the nursery area, further threatening the young.