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Entries in Environment (2)

Friday
Jan242014

Fruit vs Fish to drought-proof our farms

 

Australian aquaculture company Aquanue says that citrus growers should consider growing fish instead of fruit.

According to Aquanue’s Managing Director, Gareth Lott, land-based aquaculture is more productive than citrus farming by many orders of magnitude.

Aquanue has reviewed data from Primary Industries and Regions SA (PIRSA), the South Australian Research and Development Institute (SARDI), Horticulture Australia, and other sources, and suggests that farming fish in its tank-based system could generate returns per hectare more than 800x the average citrus farm. 

“According to the PIRSA Fresh Citrus Report September 2005 (data based on estimates made by PIRSA in consultation with growers), a conventional citrus farm in the Riverland generates $17,870 revenue per hectare.  A facility occupying a hectare using our system to grow high-value fish for the Chinese market could generate as much as $15,000,000 revenue each year – 839 times the average citrus return form the same amount of land.” according to Lott.

“Our system is a far more efficient user of precious water resources as well” Lott continues. “SARDI data tells us that it can take between 4 and 8 megalitres of water to produce a ton of citrus.  So let’s use 6 megalitres as an average.  That means it takes 6,000 litres of water to produce a kilogram of citrus.  We can produce a kilogram of fish and only consume 70 litres - even as little as 50 litres if the building is properly designed.  That is 0.8% to 1.2% of the water required to produce the same amount of fruit”.

Similar comparisons with other food production sectors show even more attractive numbers.  CSIRO Land and Water scientists revealed the following water requirements:

To produce 1kg of

Water required (litres)

Compared with Aquanue process (approximate)

oven dry wheat grain

715-750

12x

Maize

540-630

10x

Soybeans

1,650-2,200

30x-40x

Paddy Rice

1,550

30x

Beef

50,000-100,000

1,000x – 2,000x

Clean Wool

170,000

2,880x

“Fish can now be farmed on land, in tank systems that use very advanced filtration processes, with much less risk than traditional farming.  Given the growing demand from China, and the pressures faced by our water supply in this country, perhaps it is time to pull up the trees and sell off the cattle” Lott suggests. 

Thursday
Aug112011

Twenty coral reef fishes threatened with extinction

In 2006 a panel of twenty experts from 10 countries convened at a conservation summit to assess the status of groupers worldwide.  Their conclusions included a dire warning that Twenty species of grouper, a globally important group of 162 coral reef food fishes, are threatened with extinction unless management or conservation measures are introduced.

The ground-breaking workshop at the Department of Ecology and Biodiversity of the University of Hong Kong was the first systematic assessment of the commercially important species, said Dr. Yvonne Sadovy, Chair of the IUCN Grouper and Wrasse Specialist Group and Associate Professor at HKU.

“The results are worrying and highlight the urgent need for fishery management, more effective marine protected areas (MPAs), and more sustainable eating habits for consumers of these fishes,” said Sadovy, who organized the workshop.

Groupers are the basis of the multi-million dollar live reef fish market of the sea food trade centred in Hong Kong, where consumers can pay up to US$100 per kg for this delicacy.  

Groupers are also the most valuable commercial fishes in the fresh fish markets of the tropics and sub-tropics.

The fishing grounds shifted rapidly in response to increasing demand in the 1990s. Reefs near Hong Kong, China were quickly depleted and sources of capture now extend well into both the Pacific and Indian oceans, broadly the Indo-Pacific region.

The major issues facing the trade are

  • overfishing and consequent depletion of resources that are in many cases used in other subsistence or commercial fisheries;
  • destruction of coral and mortality of nontarget fish when using cyanide solution in some places;
  • fishing the spawning aggregations of some target fish, causing depletion of reproductive fish;
  • the contribution of reef fish aquaculture, which is still largely dependent on grow-out of wild-caught fish, to depletion of the target fish stocks —and the extensive use of wild fish as fish feed;
  • the wastage of nontarget fish—many are killed during fishing operations but not eaten, while many fish that could be used as food in local communities are caught to feed LRFF during grow-out—and because of deaths of target fish before reaching the market;
  • social issues resulting mostly from conflicts and corruption regarding prices and access to fish, and from injuries and deaths from diving; and
  • the inclusion of threathened species in the trade.
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