- Visit your local fish shop (or fish section of the supermarket) and identify two types of seafood on sale that have been cultivated using aquaculture. Take photographs to document your presence at the shop/supermarket, and showing the two seafood products. Add the photos to your blog, along with a brief description of how the product is cultivated (and if possible, where).
I chose Atlantic salmon and Rainbow Trout.
Atlantic salmon: Are cultivated in a “sea cage” Brood stock – which are the salmon that are selected for breeding are chosen when they are close to sexual maturity. Once they reach sexual maturity they are striped (their roe and milt) meaning that their eggs are fertilized under very controlled conditions. These eggs are placed into hatching trays, once hatched the baby salmon or alevins are moved to tanks and kept in conditions that closely resemble natural habitat (low temperature and dark). Eventually the alevins are ready to feed and move into another tank that provides them with a food supply and various types of water circulation, again to resemble natural habitat. The fish are then slowly adapted to salt water and are able to continue to grow. At this stage the salmon can be moved into sea cages or pens in the ocean.
Rainbow Trout: Rainbow trout will not spawn naturally within an aquaculture system and so their eggs need to be artificially spawned. The eggs are taken from high quality brood fish once they reach a fully mature age. Eggs are removed from the females and milt is collected from males. Milt from multiple males is mixed together and exposed to the egg. These fertilized eggs are kept in darkness until an eye is visible through the shell of the egg. Once the eye stage is reached the fry are placed in hatching jars until they have fully hatched. The fry are reared in concrete or fibreglass tanks that are circular in shape to enable an even water flow. They are fed in these tanks and once they reach 8-10cm in size they are moved to outdoor facilities.
- Compared and contrasted the environmental impacts of different aquaculture methods, and the types of species they are suitable for producing?
Net Pens/cages: –
- Water can carry pollutants into the enclosure. Contamination from wild fish (disease). Farmed fish can escape potentially interbreeding and prey on native species or transfer disease.
- Can be farmed in land based enclosures or areas where there isn’t a native fish species present to avoid this from happening.
- The use of mussels or oysters to act as a barrier between the enclosure and wild in case of escapes.
- Constructed next to natural water systems. Water pumped from this source.
- Waste, escapee shrimp and other pollution may escape and may contaminate the outside water systems.
- To stop this from occurring farmers recycle the water from the ponds and treat the water themselves to prevent polluting the nearby water source or having shrimp escape.
Recirculating systems: –
- Land based tanks.
- Used to farm salmon
- Wasted transported through treatment systems, and recycled avoids it leaking or contaminating outside water sources.
- Can be built in a number of different places allowing for no damage to natural habitats.
- Minimal pollution.
- Juvenile shellfish are introduced from hatcheries to avoid depletion of wild populations.
- Also prevents damage to habitats.
- Minimal impacts to wild fish stock
Suspended culture: –
- Minimal damage to habitats or fish stock.
- Possible implications in regards to interbreeding with wild fish stock causing a treat to their viability. (When multiple hatchery raised fish are released at one time.)
- In your blog, write about trends in Australian aquaculture production and income over time.
- In regards to income from 1992 till now aquaculture income has generally continued to increase with a slight exception in 2000 – 2004 ($950 – $750 million) where it had a slight decrease from previous years. Between 2005 – 2011 the aquaculture income appears to be relatively stable with only a slight decrease in 2008-2009 at $900 million.
- In regards to production from 1992 until now the production of aquaculture has continued to steadily increase throughout the years with only minor decreases in 2002 and 2004 (430 and 490 tonnes respectively).
- In your blog, identify which aquaculture methods (outlined in the previous section) are utilized by each of the oyster, barramundi and Atlantic salmon farmers, whether each is a monoculture or polyculture industry, and what the environmental costs and benefits are of the methods used.
Oyster farming : –
- Methods: Bags/rack, are used to farm oysters. It’s a monoculture industry. Costs: The populations are situated within a single area. Possibility of escapees. The environmental costs are minimal.
Benefits: Farmed are less susceptible to diseases such as QX. Natural resources used to feed and maintain oysters.
- Recirculating systems are used to farm barramundi.
It’s a monoculture industry.
Costs: The fish are imported. In order to farm these fish lots of water is required.
Benefits: Waste waster is treated via a specialized filter system, which recycles waste water – used to water vegetable gardens. It also provides a sustainable method of obtaining seafood ad it does not affect wild fish stocks.
- Net Pens/cages and recirculating systems.
It’s a monoculture industry.
Costs: Waste and pollution can cause contamination. Diseases transferred from wild fish that get too close. Damage to sets can cause issues in regards to interbreeding, escaping and diseases.
Benefits: Provides a sustainable source of seafood. Does not affect wild population fish stocks.
- In your blog, discuss whether at its current growth rate, aquaculture will keep pace with global human population growth, and what the impacts of expanding aquaculture industries will be.
At this current time the world’s population is only going to increase. (est 9.6 billion people by 2050 which is quite an increase on todays population of 7.2 billion). If the aquaculture industry continues to grow at its current rate it wont have a problem keeping up with the expansion of the human population however it may cause some serious side effects. Such as:
- The requirement of more wild fish to be used as feed.
- The increased production of waste materials and
- The increased need for location. – More areas to have fish farms and the resources needs to run them.
Ways to decrease loss of habitat and resources include
- Using other sources of feed such as farmed marine microbes and other organic feed replacements instead of fish produced feed. – CSIRO developed method.
- Rules to implement how waste is disposed of – recycled and treated through specialized filter systems that re use the waste water or use it for environmentally friendly alternatives such as watering gardens etc.