Wednesday, 18 January 2012

Ecological disaster as 300,000 farmed salmon lost?

Over 300,000 farmed salmon have been 'lost' by Meridian Salmon when 12 salmon cages broke loose in Shetland on Christmas Day.

A spokesman for Meridian said “It’s important to make a distinction between fish loss and fish escape. Over 300,000 adult Atlantic salmon were involved in the incident, but it remains unclear whether an escape of live farmed fish did occur or whether the fish died during the incident.”

Which means that there is a strong possibility that 300,000 farmed salmon are swimming about in the North Atlantic creating havoc in the marine ecosystem.

Why we need to be worried

When farmed salmon escape they can interact with wild salmon causing significant changes in the wild salmon stocks during ten salmon generations (about 40 years). In rivers with a high number of escaped farmed salmon it appears that the population is gradually dominated by the offspring of farmed and hybrids of salmon. Even after many decades without new escapes, it is possible that these populations will be dominated by descendants of escaped farmed fish.

Other consequences:

• Farmed fish have lower genetic variation than wild fish.

• Farmed fish hybridise with wild fish.

• The fitness of wild populations is reduced by immigration of farmed fish.

• Escaped farmed fish destroy, and compete with wild fish for spawning beds.

• The progeny of escaped farmed fish out-compete wild fish in the competition for resources in the river, both as fry and as parr.

• Farmed salmon increase the hybridisation between salmon and trout

• The size and fitness of the populations of salmon stocks will be reduced if the percentage of farmed salmon continues to be high.

Monday, 16 January 2012

Reef fish: worth more alive than dead

Despite the precarious state of our marine environment scuba diving is still one of the fastest growing sports in the world. Perhaps it is because the world's ocean is entering the end-phase of its existence that people are keen to experience a last glimpse of the underwater world.

Reef fish are some of the most sought after food fish in the world, but despite their high value as an eating fish, most are worth far more alive than dead.

People will be surprised to learn that threadfin bream (see photo) are the fish most commonly used to make Young's seafood sticks. Young's only feature a fork-tailed threadfin bream, but there are about 60 species found in the tropics, and each serve a different role in the ecosystem of a reef.

When you see a large shoal of small fish in a TV programme about tropical reefs, threadfin bream are more often than not the fish you are seeing. Without them the reef becomes a lifeless and barren desert.

The predators of the reef, the groupers, are also threatened. Coral trout and rock cod are two of the misleading names often given to groupers by fish retailers. These are the fish beloved of divers for their friendly nature and large size.

Manta rays, currently being decimated for the Chinese medicine market, are thought to be worth $1 million each over their lifetime as an attraction for divers.

Divers are some of the highest spending of all tourists and without reef fish the divers will not come.
The short-term gain from the commercial fishing of tropical and sub-tropical reefs is far outweighed by the money a healthy reef will provide in tourist revenue.

Governments must act now to give reef fish the same protection that is given to the animals in national parks. Tropical and sub-tropical reefs are the national parks of the sea and the marine life contained in them should be given the same protection.