Planet over Profit

Ok so I lied, I thought it might be good to talk about salmon farming at this point but as I wrote the post I realized I could write a whole series on that topic so I am going to save it until I finish this string.

You may recall a few posts back that I said aquaculture can have a bright future in our world so long as the right combination of species, location, and scale is discovered. When aquaculture operates in the wrong location its activities can alter or impact the ecosystem in a negative way. From my experience, there is no better example of this than shrimp farming and its removal of mangrove forests to construct farms (I will cover all the issues with shrimp farming extensively in the future).

Mangrove forests are arguably one of the most important ecosystems on the planet as they protect coastlines from the effects of storms and tsunami’s, provide excellent habitat for many coastal marine species, and support the economies of local communities. During the shrimp farming boom of the late 1980’s and early 1990’s, the price of shrimp was so high that farms were being developed as fast as possible to take advantage of the market. Farmers believed that growing shrimp in mangrove areas would work well due to its proximity to the sea and the fact that shrimp grew in the mangrove forests naturally. As a result aquaculture became a significant factor in the deforestation of mangroves in tropical countries, in some cases accounting for at least 1/3 of the removal of mangroves. The negative effect on mangrove forests was further exacerbated when high nutrient water that was sometimes loaded with chemicals used to control disease was discharged into the mangroves after the shrimp were harvested.

This effect has been a major black eye for the shrimp farming industry and it has been seen in  almost every country where shrimp farms operate near mangrove forests.

This picture was taken in Thailand and it shows a farm built right in a mangrove forest. What you are seeing in the pumping station that pumps water into the farms. You can be sure that the area where the farm is built was formerly a mangrove forest.

To challenge the idea that farming a native species is better, consider the example of farming Atlantic salmon in British Columbia which was began in the early 1980’s. Atlantic salmon were preferred for farming over Pacific’s because of the existing husbandry knowledge, success of farming Atlantic’s in Europe, and the challenges (e.g. aggressiveness) associated with domesticating local species such as Chinook salmon.

As I mentioned, the introduction of exotic species is the 2^nd leading cause of species extinction worldwide. When I heard that the salmon farming industry was based on an exotic species it made absolutely no sense to me given the passionate lectures I had witnessed from ecology professors on this topic. I couldn’t believe that the Canadian government would allow this to happen, but it made good sense economically so the Canadian environment was put at risk by short sighted government managers.

The government denied that there would be any problem with farming Atlantic salmon stating publicly “don’t worry they won’t escape”. Atlantic salmon were soon found to be escaping and the government said “they won’t survive”. Atlantic started showing up in the catches of fisherman as far away as Alaska (where salmon farming is banned) and were observed in rivers near the farms (I have seen Atlantic salmon swimming in rivers myself on the west coast of Vancouver Island). Next the government said “they will not spawn in the wild.” Juvenile Atlantic salmon were observed in 3 rivers in BC. Finally, the government said “they won’t establish a self sustaining population”. So far there is no evidence that Atlantic salmon are establishing a population in BC, however one wonders how long it could take when there continues to be a supply of healthy adult Atlantic salmon escaping and entering rivers where other escaped Atlantic salmon are present. It is important to note that just because a species is exotic does not mean it will establish a population and have an impact. But it does appear that Atlantic salmon are being encouraged to establish a population in BC despite the risk.

So after reading the above you are probably saying to yourself that this is proves that farming native species is better but consider that there is no evidence that Atlantic salmon have established self sustaining populations in areas they have been introduced. On the contrary there is evidence that escaped Atlantic’s can interbreed with wild Atlantic’s and reduce the health of the wild population in the areas where they coexist (e.g. Europe). Although I am not aware of any literature that demonstrates the same effect when farmed Pacific salmon interbreed with wild Pacific salmon the literature suggests that there may be a greater risk in farming Pacific salmon in British Columbia.

With the above noted, this may lead one to question logic of farming salmon in British Columbia or anywhere for that matter. That will be the topic of the next post.

This past week I was travelling in eastern Thailand touring shrimp farms for our improvement projects. As we drove by the white structure in the picture below, my thai colleagues pointed and said “bird condo”.

Bird nest farm near Trat, Thailand

Its actually a very specialized farm for the the Edible-nest Swiftlet (Aerodramus fuciphagus), which is a small bird of the swift family found in Thailand and other parts of South east Asia. The interesting thing is that its nest is made of solidified saliva!! These bird farms are set up to encourage the birds to nest and the nests are harvested. The set up for these farms is highly specialized right down to the specific type of wood required for construction.

In China, birds nest soup is considered to be a delicacy (like Shark fin soup) and the market for birds nest made of saliva is very lucrative. My thai colleagues told me that the saliva sells for $2,000 – 3,000/ kg.

I don’t know if there are impacts from these types of farms and would love to know more about it. Given that is a native species, the only impact I can think of is effects (food web competition, pollution, etc) from a larger than normal population.  I only saw one or two of these structures in the area of was travelling so perhaps that’s not an issue of concern at least in this area. If I am able to find the time to learn more I will post again about this topic.  Comments welcome!

Another key factor affecting the impact of aquaculture is whether or not it is a native species. A native or endemic species is one that is naturally part of the ecosystem whereas an invasive or exotic species has been deliberately or accidently introduced into the ecosystem by humans. There are all sorts of reasons for these introductions from the control of pests, the pet trade, or the desire to recreate a familiar environment. The method of introduction can range from intentional release, larvae hitchhiking in the ballast water of ocean going tankers, or many other unforeseen methods. Regardless of the why or how, the bottom line is that exotic species have been found to be the second leading cause of species extinction worldwide (habitat destruction is #1) and thus a serious conservation concern.

Aquaculture has also been found to be a major vector for the introduction of exotic species around the world. This is because if the culture of a species is successful (economically) in one area of the world, then it makes sense to aquaculturists and entrepreneurs to attempt to farm it in another area that has similar growing conditions (e.g. temperature, water quality, etc). This makes sense given the significant amount of work involved in the culture of species including experimentation with feeding schedules and ingredients, breeding strategies, and general animal husbandry techniques. This information is generally species specific and you can understand why they don’t consider the invasiveness of a species before they farm it a given area. This is actually something that governments need to regulate and control carefully but that has yet to happen with a few exceptions (e.g. Australia).

As a general rule, I would suggest that farming a native species is preferable to farming a non-native species given the conservation concerns associated with the introduction of exotic species. To offer, let’s consider Yellowtail farming (Seriola rivioliana) off the coast of Hawaii. This native species is one that is not fished due to the presence of a toxin that prevents humans from consuming it. The toxin enters the fish during its larval phase of its development but given that this phase happens on land for aquaculture the toxin is not a problem for farmed yellowtail. The lack of fishing also lessens the potential impacts of escapes and disease transfer (typically issues of concern associated with finfish in open net pens) because when wild populations are healthy they are able to resist negative influences much better. In my view, from a species perspective this is the ideal situation.

In the next post, I will give you an example that challenges the idea that farming a native species is better.

So as stated in the previous post, aquaculture has the potential to be a sustainable method of food production depending on the combination of species, location, and scale. In this post, let’s explore what factors make a species “right” for aquaculture from an ecological sustainability perspective?

We first need to consider the realities of a food web or the trophic levels of an ecosystem. The basic idea is that the higher an animal is positioned in the food web the more energy it takes to grow that animal. Ecology tells us that 90% of the energy is lost for every level that you go up the food web (or higher trophic levels). To visualize this, think of an African Savannah with abundant grasses and insects, the wildebeest and zebra are abundant but not as abundant as the grasses and insects, and the lions and leopards even less abundant than the wildebeest and zebra. Each level of a food web is limited by how much energy there is available and therefore the number of animals decreases as you go higher.

If we apply this idea to aquaculture we see that it takes a lot of energy to farm an animal that is at the top of the food web (e.g. tuna or salmon) and much less to farm something that is closer to the bottom (e.g. seaweed or shellfish). Consider that as a general rule, impact is correlated with the amount of inputs (e.g. feed, chemicals, etc) that are used in aquaculture production because the more inputs you require the more likely that it is that you will have an impact. With this in mind, it’s easy to see why salmon and tuna can have far greater impacts than shellfish or seaweed farms. They simply require more energy or inputs for production. Therefore, a general conclusion is that the lower an animal is on the food web the less likely its production will have a significant impact on the environment. This is the first important factor that makes a species a good or bad candidate for aquaculture. Exceptions of course can happen when the scale and location of production is not appropriately considered (we will explore that in future posts).

While the position of the animal in the food web is only one factor predicting the environmental impact. In the next few posts we will explore a few more reasons.