Fishing, aquaculture and the environment

Back in the 80’s and early 90’s I was an avid amateur fisherman and also spent quite a few years in commercial fisheries. I worked in all sorts of areas – oyster farming, trawling, seining, scallop dredging, trapping, sharking, hand lining, set lining, drop lining and long lining; so I was able to get a pretty good handle on the environmental issues involved – unfortunately as someone contributing to the damage.

While pursuits that involved hooks weren’t so bad environmentally speaking – I won’t get into the cruelty aspects in this article – anything involving nets and dredges were quite horrifying in terms of wiping out stocks and damage to marine ecosystems. 

In some areas where I worked, nets had been dragged up and down the same stretches for decades, eventually turning the ocean floor into a barren wasteland.

Nets are indiscriminate, not only capable of wiping out entire populations of fish, but also capturing huge quantities of non-target species at times, depending on the method used and the target species involved. 

The amount of “junk” fish and other marine creatures we used to toss over the side was truly tragic. While targeting has improved these days and more is being done to make use of incidental by-catch; there’s still a lot of carnage. Nets can also be caught on the bottom or be otherwise lost and continue to “ghost fish” for many years, killing not only fish, but other marine creatures such as whales, dolphins and turtles.

The fishing industry has become a great deal more environmentally conscious since my fishing days; but with demand for seafood booming, there’s simply not enough wild stocks to cater to it in a sustainable way.

Aquaculture – the answer?

While aquaculture has been carried out in China for thousands of years, it’s only in more recent times that aquaculture has become widely adopted in other countries. 

Aquaculture is cultivation of seafood (or fresh water species) under controlled conditions; such as ponds and pools onshore or offshore pens. According to the September 7 2009 online edition of the Proceedings of the National Academy of Sciences (PNAS), aquaculture will supply half of the total fish and shellfish for human consumption this year. That’s quite an achievement and means tens of millions of tons will be produced during 2009.

When you look at the prices of seafood, some types have skyrocketed, but others such as shrimp (called prawns in Australia) have actually dropped in price dramatically. I remember back in the 80’s prawns costing around 20 bucks a kilo (around USD $9 a pound). They were really a luxury food. Nowadays, even after nearly three decades of general inflation, they are cheaper – thanks to aquaculture.

The increase of aquaculture activities has certainly taken a lot of pressure off wild stocks; but not enough to stop many species being threatened and the destruction of marine habitats goes on.

So, the answer is more aquaculture?

For sure, aquaculture has great promise. However, while aquaculture is generally viewed as being “green” – there are some associated problems mainly confined to crustacean and some fish farming that actually contribute to the decimation of wild species and have other negative impacts on aquatic environments.


All those hungry fish need to be fed something; and often their feed is based on other fish. According to an article on Science Daily, around 20 million metric tons of wild fish were harvested for the production of fishmeal in 2006 – and it can take up to 5 pounds of wild fish to produce 1 pound of farmed salmon.

Research is continuing in tweaking fishmeal mixes to reduce pressure on feed stocks without heavily impacting on desired weight gain. There’s also species such as carp that are vegetarian – so farm-raised vegetarian fish are generally considered more environmentally friendly as they can be fed predominantly plant based foods

Antibiotics and chemicals

Antibiotics and other chemicals added to feed and to control growths in pens have caused some concern, not just in terms of wider aquatic environment impact, but also on human consumption; particularly in regions where governmental controls are lax. 

Habitat destruction

Fish farms can take up huge amounts of space in sensitive environments, both on land, in natural waterways and at sea. Again, more a problem in countries with weak environmental regulations; however, products of these farms do wind up on our plates too.

Algae blooms

Fish poop and fishmeal is full of all sorts of nutrients. When the fish defecate or the feed goes uneaten, the excess nutrients can feed algae. This isn’t so much a problem in open waters where fish populations are balanced, but in a fish farm, population concentrations are very high. The food and poop waste can cause a nutrient overload and consequently a bloom of algae. When the algae die and decompose, oxygen in the water downstream/down-current can be decreased through bacterial activity and that lack of oxygen can kill fish and other creatures in the area. 


When I was a kid, if you went to a seafood store, mostly what was being sold was fish caught within our own waters. Nowadays, the displays are chock full of fish from other countries; prawns (shrimp) in particular. They are frozen or deep chilled overseas and then make the long journey to our shores. This adds to food mile impact in terms of emissions and other resource use. This issue isn’t confined to aquaculture, but also wild fisheries.

What to do?

In reading these sorts of articles, you might be asking yourself, “Geez, I can’t eat meat because it’s bad for the environment and now I can’t eat fish for the same reasons?!?!” 

That’s not the point I’m trying to make. 

We’ve become so disconnected from our food and its impact on the environment. Most of us have little idea of what goes on with it before it hits our plate. This article, as with similar articles I publish, is to raise awareness of some of the issues associated with our food choices and as a starting point for further research; so people have the tools to make the choices that are right for them. 

As I mention in a lot of my articles, it’s not just the ingredients of a product or how it’s made/raised – but how much of it we consume. Many people are now reducing meat consumption for environmental reasons, sometimes replacing it with huge quantities of chicken or fish.

So what’s better for the environment – a pound of beef, a pound of chicken or a pound of fish? As mentioned in my article on the carbon footprint of food, it’s yet another case of “it depends” as so many factors are involved. And yes, a vegetarian or vegan diet probably has the least impact, and there are plenty of good mock meat products around now; but that’s not what this article is about.

What does remain very relevant and a very important “take-home” point is that if we’re consuming a lot of something under the false impression that it’s more environmentally friendly than what it actually is; then we may not be achieving our desired goal of minimizing our environmental impact. 

We need to apply pressure to the companies that feed us to ensure our food has the least negative impact on the ecosystem as possible – everything from rearing/growing, to harvest, transport and packaging – and how we deal with the waste, including the waste from our own bodies. More of us need to return to growing our own food too; even if it’s just a fraction of our consumption.

When it comes to green living and food choices, the old saying of “everything in moderation” definitely applies. It’s certainly something I continue to struggle with on a daily basis.