Fishing Lines: Underwater Tube arrives in nick of time but there's a delay on the rigs

Underground rail carriages are not the first thing that springs to mind when listing 10 Objects Doing Most for the Environment. But in America, they play a key part in repopulating the sea.

New York's Metropolitan Transportation Authority faced a problem when they upgraded their rolling stock – what to do with 1,662 old carriages? Who would want a giant, graffiti-strewn tin can?

There was no demand for the parts. The metal was worth little (the steel is low-grade). Dumps would face huge problems in disposing of them. The authority gave them to the fish.

A 44-car "train" has just been dumped into the Atlantic Ocean, 21 miles off the Maryland coast, to create an artificial reef. The 18-ton stainless steel cars, minus wheels, windows and doors, were dropped into 90 feet of water. In a few weeks the "reefs" will have attracted sealife where none existed before. In a couple of years, they will be one of the coastline's fishing hotspots.

"These reefs provide quality habitat for marine life off our coast which benefits not only the environment but also local businesses," said Rick Meehan, the mayor of Ocean City. Recreational fishermen contribute about $1 billion a year to Maryland's economy.

The state plans four more subway car reefs. Since 2001, others have been created off Delaware and New Jersey. Jeff Tinsman, Delaware's reef programme co-ordinator, said a 600-car reef increased the local fish population 400 times, and boosted the number of angling trips from 300 a year before the reef was created to 13,000.

About 95 per cent of the seabed off the US mid-Atlantic coast is bare sand. (In the North Sea, the figure's even higher.) No food or shelter there. But the reefs provide protection from predators and generate food such as mussels and shrimp that quickly colonise the structure.

In turn, small fish attract the largest predators: tuna, shark and marlin. These species have been decimated by overfishing. To avoid a repeat, the states are planning legislation to limit the number of fish that can be taken and to impose seasons when no fishing will be allowed.

Everyone is benefiting. The transport authority had to pay for environmentally hazardous materials such as PCBs and petroleum lubricants to be removed, but it offset this from the $600 a car it got from the Ocean City Reef Foundation. The reefs are expected to last for 40 years. And the fish love it.

A good lesson for the Brits here. Years ago, an Aberdeen professor proposed a scheme that was finding favour with oil companies who were stymied about what to do with their redundant oil rigs. He wanted them to be turned into reefs.

The idea was that they would be dumped off fishing towns worst hit by the decline in the industry, who would "police" their own reef. The appeal of oil rigs is that they are made of high-grade steel, which will last 100 years or more. Whatever happened to the scheme? It's about time oil companies did something for the environment.

That story appeared in the first column I wrote, 22 years ago, for a dummy issue of the paper that never got printed. It's ironic that it should come round again, because next week marks my final fishing column.