What the Experts Say
Recreational divers groups have and continue to promoted the sinking of derelict ships as artificial reefs at sites throughout Georgia Strait.
On the surface, an artificial reef sounds like a good idea. So what’s the problem?
Scientists have been studying artificial reefs since the 1970’s. While they agree that these reefs have an effect, they do not agree that the effect is beneficial nor on the economic benefits.
In 2010, the Basel Action Network released a report which highlighted the economic case against sinking artificial reefs. Simply put, it makes more financial sense to recycle the ship that strip and sink it.
In a Bellingham Herald article (December 1992) entitled “Biologists doubt fake-reef benefit” two scientists from Washington State were quoted
Bill Summers, an oceanography professor at Western Washington University, said: “Reefs attract sea creatures, but don’t necessarily cause an increase in living matter. And there may be some environmental harm.”
He did not advocate sinking large amounts of human junk, including ships, in the ocean.
“Reefs attract sea creatures, but don’t necessarily cause an increase in living matter. And there may be some environmental harm.”
Steve Quinnell, a fish biologist at Washington State Dept. of Fisheries, said Washington would not use a ship to improve fisheries; state officials consider rock and concrete reefs more productive and favor a more natural design. (He admitted that a ship is more exciting for a diver.)
Dr. James Bohnsack, a Florida fisheries scientist, has said: “…little direct scientific evidence exists to properly guide building efforts and show long-term beneficial or detrimental impacts”, and that he is “concerned about the current US practice of relaying on “materials of convenience” [ie. old ships], especially considering that Japan has rejected this approach and has spent over $100 million annually since 1976 for reef construction and research. He has expressed worry that “the enthusiasm for artificial reefs could draw attention away from possibly more beneficial fishery management actions such as enhancing or preserving existing estuaries and other natural habitats.”
(From “The Rediscovery of the Free Lunch and Spontaneous Generation: Is Artificial Reef Construction Out of Control?”, American Institute of Fishery Research Biologists Briefs, 1987.)
“the enthusiasm for artificial reefs could draw attention away from possibly more beneficial fishery management actions such as enhancing or preserving existing estuaries and other natural habitats.”
Raymond M. Buckley, from the Washington Dept of Fisheries, is not opposed to artificial reefs per se, but wants them only built by fisheries experts. He says that “all too often artificial reef programs have depended on voluntary community involvement with donated labor and surplus materials of opportunity”, and the “[fishery enhancement] objectives have to be far beyond the overused and self-serving desire to “improve fishing”: they must address the species to be enhanced, the fisheries that will benefit, and the potential for adverse impact”. He says “it is irresponsible to continue to allow marine habitat alterations that do not have high potential to produce the desired enhancement without causing offsetting impacts.”
Jeffrey Polovina (Bulletin of Marine Science vol. 44 No. 2 1989) opposed AR’s, saying that they actually decrease fish stocks by promoting concentrations of fish, which makes catching them easier and hence leads to overfishing.
Artificial reef proposals have been rejected in California for environmental considerations and potential liability concerns.
The Japanese have worked with pre-fabricated reefs, and say that dumping scrap metal is not effective. They conclude that to be successful, an artificial reef needs instead to be designed for the specific location, considering factors such as:
- number of chambers
- chamber size
- optimum reef size
- design
- substrate
- depth vs. distance offshore
- spatial arrangement/configuration
- materials
They are using plastic and cement, but not scrap metal. They recommend any artificial reef be 600-1000 metres away from natural reefs so as not to draw species away.
To be successful, artificial reefs must be very specific, and you need to consider what species you want to enhance.
A reading of the literature shows that the majority of successful artificial reefs have several common characteristics:
- they are specifically designed for the purpose
- they are placed on relatively flat seabeds where there was previously little or no fish habitat
- they have a depth of 80 – 120 feet (too deep for most divers)
- they are in a location where strong ocean currents provide good water exchange
- Any artificial reef – even a bad one – will act as a fish aggregating device, but only the good ones improve upon nature by creating something nature hasn’t provided.
In BC waters, nature has already filled the bill nicely. Artificial reefs made of old ships and other cast-off materials are therefore unnecessary – and may even harm the environment by replacing existing natural habitats with less effective artificial ones. At the very least, we are altering marine habitat by sinking ships – somewhat akin to gathering a bunch of old wreck cars in the midst of a forest or grassland. This would create habitat for certain species (eg. rats), but would definitely alter the natural ecology.