Helen Scales

Space Rockets Save Fish

Mike is a great fisherman. One of the best. So he thinks anyway, and today perhaps he might be right. The slack line pulls tight. His forehead beading with sweat, Mike struggles to reel in his prize. Held aloft, scales glittering and shining in the Florida sunshine, the specimen is a fine one.

A few thousand kilometres to the southeast a small grimy outboard

engine trails behind it a convulsive belch as the small volcanic

island of St Lucia grows distant on the horizon. Peter sits at the

tiller while his son Elijah hauls in an algae-encrusted rope. Up

from the deep emerges a large trap that's been lurking on the coral

reef overnight, waiting for unsuspecting fish to blunder in. Big,

colourful snappers, grunts and parrotfish twitch and jump around

in the bottom of the little boat. The catch is a fine one.

Fish stocks the world-over are suffering from too many people hunting

too few fish. Marine parks and "no-take" reserves have

been used for decades to protect fish that are left. Many studies

have shown that banning fishing in a particular area leads to a

boost in the number and size of fish inside the reserve. But, until

now, there has been little proof that marine reserves may also benefit

nearby fishing grounds.

A team of researchers led by Dr Callum Roberts of the University

of York, UK, are investigating two marine reserves that are proving

to help both fish and fishermen.

The fish that Mike caught was probably born in Banana Creek Reserve,

a large area of estuary near the Cape Canaveral that in 1962 was

closed to the public to protect the Kennedy Space Centre.

Sports fishermen are understandably competitive about who holds

current world records for the biggest fish caught. As a result there

are well-documented reports of the number of world record-breaking

fish caught near the marine reserve at Cape Canaveral. Dr Roberts

and his team scrutinised records spanning forty years and found

that several years after the reserve was created there was a dramatic

boost in the number of trophy fish that were being caught in the

region compared to the whole of Florida. The waters around the reserve

"have become a honey pot site for catching spectacular fish,"

says Dr Roberts.

Fish inside marine parks find a safe haven from the arsenal of

fishing hooks, lines and nets they might otherwise encounter. They

can live for longer and grow bigger than fish outside a reserve.

The fish in this study, such as the spotted sea trout, make immense

underwater journeys during their lifetime. Some of the fish that

grow fat and healthy inside a reserve eventually wander across the

watery reserve boundaries and meet the hook of a soon-to-be champion

fisherman. Fish migration from marine reserves can supply nearby

fisheries with potentially prize-winning fish. Prize winning in

Florida, but elsewhere those are meal-winning fish.

Back in St Lucia, a series of small coral reef reserves was created

in 1995 to try and rescue the threatened fish stocks on which many

fishermen, like Peter and Elijah, rely for their food and livelihoods.

Fishing is still allowed in areas of reef nestled amongst the network

of park areas, but initially the fishermen were worse off than before.

"The fish catch was of low value due to too much fishing in

too small an area," says Dr Roberts.

This problem didn't last too long. The research team carried out

underwater counts of fish size and numbers. They have shown that

after three years there was three times the number of fish inside

the reserve and twice as many outside compared to before the park

was set up. Dr Roberts' team also monitored the fish being caught

by fishermen. Since the reserve was created, fish catches have increased

in total weight by between 43% and 90%.

As well as the migration of long-distance swimmers out of marine

reserves, another mechanism is at work to boost fish stocks outside

protected areas. Bigger fish make more eggs than smaller fish. So

the bigger fish inside the reserves produce lots of eggs. Fish eggs

and the tiny larvae they hatch into may drift out of reserves on

ocean currents into areas where they "seed" nearby fisheries,

like a farmer scatters seed over his land.

So, whether a marine reserve is set up to protect space rockets

or with the specific aim of preserving fish stocks it seems that

fishermen of all shapes and sizes can truly benefit. Hopefully this,

and other studies, will provide enough evidence to persuade governments

and fishing authorities to create more and more marine reserves

in the race to protect this precious and ever-threatened resource.

- October 2004

About the Author

Helen is a marine biologist at the University of Cambridge