Good afternoon everyone. Before I begin, let me introduce you to the fish on my slide. It is a bluefin tuna, one of the most overfished fish in the sea. Today, we will discuss a possible solution to saving the bluefin tuna from extinction – fish farming.
Today, I will talk in brief about the following things: How the overfishing crisis came about, is fish farming the solution to our woes, potential dangers of conventional methods of fish farming, and how we could make fish farming safe and environmental.
Not only is our world population growing, the proportion that is affluent is increasing as well. The newly rich from rapidly developing countries such as China are partaking in foods that were once considered a luxury, such as maguro or tuna sushi. These trends have led to an increasing demand for fish.
To meet demand,fishermen employ more and more efficient methods of catching fish, such as trawling. Because we have begun to remove fish faster than the sea can replenish it, many fish stocks have become overfished.
This has led to fisheries collapse. Here is prime example: the Atlantic cod stocks crashed in 1992 and have barely recovered since.
Is fish farming the way to go? Just as industrial poultry and cattle farming have allowed us to meet our diet of chicken, pork, and beef without causing extinction of their animals, fish farms could lessen the stress on our oceans and prevent fisheries collapse.
Fish Farms like this one in Hong Kong.
But could we be trading one problem for more serious problems?
Certainly, fish farming is nothing new historically; fish culture has been dated back to China in the 1100 BC. Nevertheless, it is only in the past half-century that we have seen an explosion in the aquaculture industry to meet our increasing consumption of fish. Statistically, it looks like we have kept wild capture on a fairly constant rate, which should be good news for the oceans, right?
But this sudden expansion of the fish farming industry should worry us, as any possible impacts on the environment are now of a bigger nature. Fish farming comes with many potential problems, some of a possibly irreversible nature. Do we go ahead and play with nature, and reap the possible consequences, like these two scientists here, or should we be more cautious about it? It might be wise to consider the precautionary principle here.
Before I inform you of the problems, it would be good to know the various broad categories of fish farming methods. They can be open water, meaning they interact with the greater marine ecosystem in some way, or closed water, which usually refers to inland ponds or tanks. They can also be intensive, or extensive. Intensive methods are more common because they maximize yield, which is what every farmer wants. There are also other alternatives, which I will cover at the end. The dangers of fish farming lie in Open Water and Intensive fish farming.
So firstly, what are the problems with open water fish farming?http://alexandramorton.typepad.com/alexandra_morton/2012/10/no-one-can-understand-why.html
This diagram sums it up. The crux of the problem is that the fish farm internal system is able to interact directly with the larger marine ecosystem, without any control. Any waste from the fish farm enters the sea directly, without treatment as you would with wastewater runoff from industries on land. Things added for the fish tend to end up in the sea. Fish farms are also an incubator for disease and pathogens, which are passed on to wild fish which congregate near the fish farms. It is also inevitable that fish escape from fish farms, and if these fish are foreign or genetically modified, it can pose trouble to local fish.
These comics show the toxicity that fish farm wastes tend to have. If you’ve ever kept an aquarium, you know how dirty the water can get without a filter. This is worse – the mixture contains excrement, medicines, and fertilisers.
Fertilisers are usually added to increase primary production of the fish farm – in the case of extensive farming – and they often run off into the sea (click)
Leading to eutrophication.
Farmed fish are often squeezed into tight spaces, and they rub off each other, causing skin damage and infectious disease and parasites to spread easily. That is why many farmed fish sometimes have lesions.Caliguslouse feeding on young sockeye salmon. http://alexandramorton.typepad.com/photos/fish_farms/caligus-louse-damage.html
The escape of farmed fish also pose a problem for local fish species. Look at the size of that GM fish, they are bigger and stronger than the normal-sized fish, and they may deprive local fish of their prey. It is also a problem if foreign species are introduced; these invasive species may be more aggressive and take over the ecosystem as well. The balance within a marine ecosystem may be upset with the death of local fish, leading to secondary repercussions, for example the over-multiplication of undesirable species. For these various reasons, open water farming has too many potential dangers.
Now, we move on to the problems of intensive farming. It all lies in fish feed. What is wrong with fish feed, you might ask? Trace the source of fish feed and often, it comes from wild fish itself.
If that is the case, then the intuitive logic that every fish farmed is every sea fish saved is erroneous. Instead, the burden is just as great, if not greater than before. That is because our appetite for fish is often for top predators such as cod, tuna, salmon, red snapper, barramundi, swordfish, trout – sounds like your typical Fish and Co. menu, doesn’t it? Their impact on the marine biomass is a hundred times more than herbivorous fish like tilapia. If our fish feed is made from marine fish, it thus does not make fish farming of these top predators any more sustainable than fishing them.
Are there better alternatives to the current status quo? These alternatives could help us avoid the risks associated with fish farming by taking precautions – such as fish farming on land and creating self-sustainable fish farming ecosystems.
One option is Integrated Multi-Trophic agriculture. It is a modernized form of agriculture, where more than one kind of marine organism is reared. By taking the effort to rear marine organisms from different trophic levels, you diversify your yield while at the same time maximizing the existing primary production of the habitat.
Aquaponics are yet another way to avoid the problems associated with fish farming. Combining aquaculture with hydroponics, it allows fish wastes to be used to grow plants. The plant bed act as a filtration system for the water. As a result, you get healthier fish, plants to sell, and a waste removal system.http://en.wikipedia.org/wiki/File:Aquaponics_with_catfish.jpg
Fish farming are certainly problematic for our environment, perhaps all it needs is a tweaking of current methods in order to ensure sustainability. The precautionary principle exhorts us to take the precautionary approach to avoid environmental degradation. It is thus important that we consider these more sustainable methods of fish farming, instead of letting unsustainable practices continue. With luck, fish farming might be able to save the bluefin tuna after all.Any questions?
The Perils of Fish Farming
FISH FARMING The right solution to
WHAT I WILL BE SHARING TODAY
1. The Overfishing Crisis
2. The Solution: Fish Farming – or is it?
3. The Dangers of Conventional Fish Farming
4. Making Fish Farming Safe and Environmental
The Precautionary Principle
“In order to protect the environment, the
precautionary approach shall be widely
applied by States according to their
capabilities. Where there are threats of
serious or irreversible damage, lack of full
scientific certainty shall not be used as a
reason for postponing cost-effective
measures to prevent environmental
- Principle 15 of the Rio Declaration
DIFFERENTIATING FISH FARMING
• Open Water
•Along rivers, lakes, seas,
•Ultimately lead to the ocean
• Closed Water
•Ponds, tanks, closed lakes
•Food from external sources
•Food from sources inherent to
• Other Methods?
non-native species Antibiotics,
Fish Meal and Fish Oil
New diseases and parasites
introduced to the environment
Fish Sewage: Uneaten food, waste
products, diseases and pathogens
GM Fish and non-native
species that escape
compete with native fish
• Modernised form of
• Rearing marine organisms
from different trophic levels,
• Salmon (carnivorous)
• Carp, Oysters
• Seaweed (autotrophs)
Plants utilize water filled with
nitrogen-rich fish waste for
their own growth, purifying
the water for the fish in the
Aquaponics with catfish