Thursday, August 07, 2008

Is the trout sword a double-edged one?

- Charles King (For The Highlands News - published Friday, 07 August 2008)


All emotions aside, what exactly are the implications – both to the trout industry and the environment - if brown and rainbow trout were reclassified as invasive, or even listed as prohibited species?

The Sunday Times reported that draft regulations promulgated a year ago to control foreign species and prevent or minimise the harm they wreak on the environment (as part of the National Environmental Management Biodiversity Act) are about to be signed into law.

They report that if this were to happen, the country's multimillion-rand trout industry could collapse because it would be illegal for anyone to either farm trout or fish for the species.

The Biodiversity Act wants to see native species protected, which will mean that aquaculturists would need to acquire expensive permits, and fishermen would be required to kill any trout they caught.

According to the report Etienne Hinrichsen, chairman of the Aquaculture Association of Southern Africa, is calling for trout to be exempted from the regulations.

"If trout were having a major biodiversity impact, then we wouldn't really have a leg to stand on — but this is not so," he said.

But is it really not so?

Globally invasive species have been highlighted as one of the major pressures on native biodiversity.

Rainbow trout (Oncorhynchus mykiss), one of the most widely introduced fish species in the world is a highly valued sport fish. But internationally concerns have been raised about its effect on native fish and invertebrates through predation and competition.

Brown trout (Salmo trutta) has been introduced around the world for aquaculture and stocked for sport fisheries. But it's guilty of reducing native fish populations, especially other salmonids, through predation, displacement and also food competition. It's also one of the "world's 100 worst" invaders.

Invasive species are also known to be a major driver of global changes in freshwater community structure and ecosystem function. But until recently ecologists haven't been able to forecast (even possibly prevent) the introduction, spread and impact of species likely to cause net financial or environmental harm.

Has anyone counted the cost and impact of these freshwater invasive species on our natural habitats and national biodiversity?

On the other hand, the only estimate I could find in a relatively short time as to the value of Rainbow trout alone to the economy, was that in 2002 it was the most important South African aquaculture product. A total of 1 800 tons worth R44m was produced.

That sounds like a lot of created jobs to me. (Or is it a fat cat, elitist industry where very little wealth trickles down?)

The good news is that there appears to be a middle ground. Research is being conducted around the concept of zoning rivers or sections thereof so as to be able to conserve threatened species as well as to manage established alien species that have a high socio-economic value.

All emotions aside, we need to ask questions and examine facts. Despite the size of our human egos and our illusions of grandeur, we're immensely fragile and merely custodians of 'our' land.

 Poet Carl Sandburg from his astounding 1918 poem "Wilderness":

I am the keeper of zoo: I say yes and no:

I sing and kill and work...

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1 comment:

Shane said...

Sandburg's words are like cold water to one's face! Shocking but so true. The smooth running of 'our' eco-systems are ultimately in our hands as custodians thereof, and we must very carefully weigh up the consequences and the effects of our thoughts turned actions on nature. Thanks for this!