Sustainability and dams

[Kerry]

Are dams etc classed as sustainable fisheries ???

Cheers, Kerry.

[Fitzy]

Tough one Kerry. I don't think they are in the normal sence of the term "sustainable", however with the fish stocking programs running in a "put, grow & take" system, they are sustainable if the fish keep getting replaced on a regular basis.

Cheers,

Fitzy..

[lordy]

Tough one Kerry. I don't think they are in the normal sence of the term "sustainable", however with the fish stocking programs running in a "put, grow & take" system, they are sustainable if the fish keep getting replaced on a regular basis.

Fitzy..

I say they are sustainable. Plenty of agriculture is classed as sustainable and it involves the same thing. Take from one end and replace from the other. We plant orchards and harvest fruit etc. So long as fish keep being restocked its sustainable for as long as we want. If its over exploited it won't be damaged since its not stocked by natural recruitment, it'll just need more fish to kick start it again. The only way it can be unsustainable is if there is a build up of toxic fish waste. More nutrients (grown fish) are removed than are added to the system (fingerlings) so the fishing stocking part isn't affecting nutrient loads. All the stocked fish's nutrients are cycled withing from the lake itselft, unlike farmed fish in which additional nutrients are introduced as feed.

[Vern_Veitch]

I do not know of any dams that have not reduced the downstream productivity of our native fisheries and buggered up habitat. That said, we cannot live without dams to supply our drinking water and we may as well make the most of them. Stocking to create a put and take fishery is certainly a worthy secondary use of a dam that is necessary for human consumption. If it is well managed then that particular aspect of the dam is sustainable.
I won't get into the argument about the downside of dams built purely for agriculture other than to say that we are yet to get it right. Anyone who doubts should look at the salinity issues in the Murray-Darling that are just a repeat of what has happened in most other arid areas of the world for the last 10 000 years when we have tried to make them greener.
We are slow learners but it has destroyed past civilisations and we keep trying.
Vern

[lordy]

Vern thats too true. I'd taken it solely from the point of view that the dams where there so lets use them. The is no doubt they are bad for the rivers though. But dams aren't going away so we might as well exploit them for our benefit, especially if it doesn't increase the damage, and stocking and fishing dams certainly doesn't increase the damage if done properly, and that means that the stocked species are logical additions that are ecologically sound.

[Fitzy]

Getting pretty much right off the main topic (but anyway).
The issue of Sustainability is a very big one in regard to our stocked & un stocked impoundments, Weirs & barrages in Qld.
If the commercial sector is ever able to get thier foot in the door (and they try all the time) then the issue will be a very big one. One there's a dollar involved in anything it them becomes a "resource". Once that happens, said commercial sector can lobby DPI for sustainable quotas etc. This is even more alarming if you think that if one of these applications to "harvest" noxious/pest/translocated fish is ever successful. We could well see bag limits imposed upon pest fish species to protect the "resource". Much the same as trout are protected by closed season in the southerly climes.

There is also the temptation for one or two carp or tilapia to "accidentally" slip into more & more lakes, rivers, weirs etc etc. Then the good old commercial netter will come to the rescue again. Not in a bid to rid these fish, but primarily to make a buck.
Human nature really. I'd be tempted if I was a gill netter on MacIntyre brook to move a few carp up above the dam wall into Coolmunda.

anyway, I'm getting right off the topic now.

fitz

[Kerry]

Fitzy, you mention weirs and barrages which as far as I'm aware there are only 2 barrages in Qld (or the country for that matter ???).

Wonder why there isn't more barrages than dams? The sustainability issue may still be similar but one would think the down stream habitat and water flow issues wouldn't be as badly affected ???

Cheers, Kerry.