Sustainable aquaculture takes one step forward, two steps back.
17 February 2004 PETER ALDHOUS
Fish farms are in danger of losing any ground they may have gained over the past few years to becoming a sustainable industry, according to Rebecca Goldburg, a senior scientist with Environmental Defense in New York.
While aquaculture is proving less wasteful now than in the late 1990s, it is using up more resources than ever before. And recent US policies could be set to make things worse. Environmental Defense is concerned about the sustainability of aquaculture primarily because farmed fish are frequently fed on meal made from wild-caught fish. In 2000, Goldburg co-authored a paper revealing that 1.9 kilograms of wild fish were on average required to produce every 1 kg of fish farmed in 1997 <http://www.nature.com/nsu/040216/040...tml#b1#b1>1.
Goldburg has now recalculated these figures with more recent data, and has come up with some good news. In 2001, each kilo of farmed fish consumed only 1.36 kg of wild-caught fish. This increase in efficiency is due in large part to an expansion of freshwater aquaculture in China, says Goldburg. Fish farmers there tend to raise carp or tilapia, which are vegetarians, and so don't consume any wild fish stocks. Efforts are also being made to coax carnivorous fish, such as salmon, into eating feed based on vegetable protein <http://www.nature.com/nsu/040216/040...tml#b2#b2>2. "They're going to have to figure out how to use less fishmeal in the long run," says Claude Boyd, an expert on aquaculture at Auburn University in Alabama.
But it's not all good news. The expansion of aquaculture has meant that the total catch going towards fish food has continued to increase, from 10 million tonnes in 1997 to 12 million tonnes in 2001. As aquaculture continues to boom, it will exact a growing toll on species such as sardines and herring, Goldburg says. The situation could be made worse by a new policy from the US National Oceanic and Atmospheric Administration (NOAA), which aims to promote offshore farming of species such as red snapper and cod. By growing these fish in cages held almost 5 kilometres off the coast, NOAA wants to expand the worth of the US aquaculture industry from $1 billion to $5 billion per year. The problem is that these fish are carnivores, which could reverse the trend to use feed containing a lower proportion of fishmeal. "An explosion in growing carnivorous fish can easily override these efficiency gains," says Goldburg.
References
Naylor, R. L. et al. Effect of aquaculture on world fish supplies. Nature, 405, 1017 - 1024, doi:10.1038/35016500 (2000). <http://www.nature.com/doifinder/10.1...;Article|
Powell, K.. Fish farming: eat your veg. Nature, 426, 378 - 379, doi:10.1038/426378a (2003). <http://www.nature.com/doifinder/10.1...;Article|
© Nature News Service / Macmillan Magazines Ltd 2004
Hi Joe
Have missed the informitive info that you post, it all makes a good read, some i agree with , some i dont, but i also have a problem with applying fertilizer to the land (washing into the oceans) just to feed farmed fish. I think we need farmed fish, but not a the detriment of any other species or land mass
just my thoughts
cheers
blaze
Well this fact that it takes more kg of wild fish to produce less kg's of farmed fish isn't really something new, just something that many conveniently forget but then really convienient probably isn't a good term at all as many apparently don't realize this fact, full stop.
Fish farms really do nothing to reduce the commercial catch and in fact probably increase it but on a much larger scale and in areas where it's generally out of sight and out of mind.
Dabbling in nature for the $$ result, and yes just what the country needs is for $$'s and carp to become one.
Cheers, Kerry.
Hi Blaze. thanks
the posts have only justed to come back through. Have had some good feed back from people. some agree , some don't. I am the same with some that i post. Cant hurt being informed either way.
cheers
Joe
Its a lot like farming tigers for meat and feeding them on beef cattle.
But then again for the people making the money from the farming its easy because its not there problem, its ours.
Cheers Kev
Thanks Joe.
if they need wild fish meal they can get a billion tonnes of carp out of our southern waters that would be a positive step
Read somewhere that NSW fisheries have been trialling fingerlings (snapper and mulloway) releasing them into botany bay, and are having great success. Cant see why it cant be the go eleswhere. Using less resources to feed em.
cheers
Joe.
Most of the fish they use to make fishmeal are the crappy bait fish in abundance. Its not like they are catching snapper and grinding them up to make pellets for trout. Keeping that in mind they still need to catch these fish at a sustainable level. Have they considered using left over fish frames to make the meal, how much of a dint would this make in 12 million tonnes of fish. I read something about them using restaurant scraps to make pellets for red claws. I personally don't like the idea of eating farmed fish, I'd much rather eat something caught fresh (i'm not much of a trout person but farm trout taste pretty c grade). The stocking idea Jaybee metioned sounded good, and it also sweetens the deal for us recreational fishers.
Jeremy
Hi Jeremy
there is also another report on the web where pilchards have been wiped out in sth east asia to feed the farms in norway, if this food chain disappears what is left ? so the fishmeal isnt crappy fish, even Sth Africia are reporting the big run of pillies that ppl can scoop up in buckets isnt happening like it use to.
cheers
Joe
Thought I read somewhere that they are trying to add things like soy to the pellets for feeding farmed fish to provide some of the protien requirements and reduce the amount of fish meal required.
The ratio of fish killed to fish produced certainly needs to get down to at least 1 to 1 and eventually lower. Otherwise you are just robbing Peter to pay Paul.
Cheers
Jeff
true about the bait fish to feed fish if they could get it down to a 1-1 ratio or lower (by useing fish frames) i can see the futrue of farmed fish defintly help take some presure of wild stock but what i read about captuvie breeding and restocking may also be another way to do it but lets hope they think of the fishes life too and don't do what they have done with the bass in some areas and under cooked the fish (mixed the eggs and milk with wrong salt content) i know there is alot of bass in empoundments and restocked rivers with birth defects
Originally Posted by jaybee
??? ??? ??? ???
How about all the anti biotics farmed fish need to be fed to keep healthy, how is that going to affect us in the long run, not to mention the high density housing so to speak. all those fish caged in one area, doing the same thing day in and day out, so much for pristine waters.
cheers
joe.
The use of antibiotics is a problem for all types of animal raising. They practically pump it into sheep, cattle and chickens breed for slaughter because the compact conditions are filled with disease and it also acts to a certain extent as a growth steriod. The chickens that you buy at shopping centres are 3 months old when they are slaughtered, we've kept meat chickens and it took us 5 or 6 months to get them that big. The problem with agricultural use of antibiotics is it breeds out weak strains of bacteria leaving only the hardier resistant one's known as super bugs. The original Penicillin strain is know practically useless thanks to this. Looking at this in fishing terms i suppose it means that naturally occuring fish not treated by antibiotics are going to take the full blow from these hardier bugs.
Jeremy.
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