Artificial reefs, created by deliberately sunk ships
and other structures, may not be all they're cracked up
to be, according to two American academics.
William Lindberg, a professor of fisheries science at
the University of Florida, says 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 as a tool for economies," he
told the Herald Tribune. 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."
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 because, 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 five
other scientists found that the 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 there producing
food for them."
James Cowan, a professor of oceanography and
coastal science at Louisiana State University, agrees. He
says a number of studies, some dating back 25 years,
have shown that some fish species need to travel to find
their primary food source if they are to grow and reach
adulthood. He 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.
- - DIVER magazine