Planet over Profit

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.