As the global population continues to burgeon and commercial fishing starts to hit its limits due to pressure on stocks, the importance of aquaculture is only likely to mount.

In fact, although around half of all the seafood consumed internationally already comes from fish farming, aquaculture production will need to double by 2050 if worldwide demand for this important protein source is to be met, according to the World Resources Institute.

But a key problem is that, as the industry grows, so does its impact on the environment. Major issues here include pollution as chemicals and antibiotics are pumped into the water to control disease; the interaction between farmed and wild fish, particularly in the case of salmon, and unsustainable feed sources.

In a bid to try and tackle these challenges, conservation charity the World Wide Fund for Nature (WWF) and Netherlands-based The Sustainable Trade Initiative got together in 2010 to create The Aquaculture Stewardship Council (ASC), an independent not-for profit organisation (NGO).

A sister body to the better known Marine Stewardship Council (MSC), which provides an industry certification programme to accredit sustainable wild fishing practices, the ASC's aim is to promote similar best practice within a fish farming industry that already employs a huge 16 million people worldwide.

Although it is still early days for the organisation, which has only had certified products on the market for the last 18 months or so, its aim is to boost the number of offerings carrying its logo 20-fold from 1,100 now to 20,000 within the next five years.

We speak to the ASC's chief executive and former deputy CEO at the MSC, Chris Ninnes, about what the future holds for the industry:

Q. How big is the market for ASC-labelled products today and what are your targets over the next five years?

A. Globally, certification accounts for about 1% of the total aquaculture market today. MSC, on the other hand, currently certifies about 10% of the wild fish caught globally and within five years, we believe that we should be able to match those figures.

There's still plenty of work to do, but at the end of April this year, the retail value of ASC-certified and labelled products was estimated at $230 million, a three-fold increase in 12 months. And I expect these growth rates to continue as supplies of certified products increase.

But maintaining those rates into the longer-term will also require the continued development of new markets. So our long-term strategy is to look beyond Europe and the US, which currently lead the field in ethical purchasing, as they're not big enough on their own to drive global change. That means we need a presence in middle-income and developing markets.

Q. What are you doing to try and penetrate these new markets?

A. In production terms, since launching our logo in 2012, we have close to 80 farms across the globe certified against our standards for tilapia, pangasius and salmon. These are based in countries like Indonesia, Malaysia and Mexico, but we also have certified farms in places like Australia and Norway too.

There are also about 45 other farms either awaiting the outcome of their assessment or about to engage in the audit process, including businesses specialising in shrimp, freshwater trout and bivalves, so clams, mussels, oyster and scallops. This means that we can expect certified volumes of all three species by the end of the year.

A new Aquaculture Dialogue for grouper, snapper and barramundi was also started by the WWF in 2013 and we expect it to conclude in early 2105. Other likely candidates in future are sea bass, sea bream and possibly seaweed.

But the retail market is still a work in progress. Where we are actively investing money to see what we can learn, however, is in Brazil.

The Organising Committee of the Rio 2016 Olympic and Paralympic Games has committed to only serve certified seafood sourced from the MSC or ASC, and there's been a lot of general interest among local farmers and within the market. So we'll use it as a test case for moving into other countries.

Q. How ethically-aware is the UK compared with other nations and what are you doing to up your profile here?

A. Europe leads the world in ethical purchasing, with Germany standing out due to its long history with green politics and certification approaches.

If you look at the MSC's figures though, the UK is its second biggest market in terms of value behind Germany, followed by the US. But, while the German population is bigger, the proportion of certified seafood purchased in the UK is actually much higher.

And the ASC's profile is steadily growing in the UK too. We're seeing interest at the retail level, with Sainsbury's, Lidl, Aldi and Young's all carrying our labelled products, of which there are now about 50 available.

But it's a supply and demand thing. Cod used to be just about the only thing consumed, but now salmon is the most valuable fish sold across the country, and farmed salmon is number one. So we're confident that, once we can get more supplies of certified salmon, we'll see greater uptake.

The issue is that we've not had enough products in the past for retailers to make a purchasing commitment. About half of Scottish production goes to the UK, with the rest coming from Norway and Chile. And, in the near future, we'll have various Scottish salmon farms under assessment.

In fact, the top 17 salmon farmers, which account for 70% of world production, are saying that, as part of the Global Salmon Initiative, by 2020 they want all of their products certified by us. It's a huge commitment.

Q. What about UK restaurants?

A. The food service sector tends to be more of a follower behind retail. But there is some pilot work being undertaken in the Netherlands and Germany on making it easier for these kinds of businesses to buy sustainable seafood.

There are obviously lots of controls for riskier environments such as processing, where fish is chopped up and can end up being mixed with other products.

But we're working on a simpler system for restaurants, not least because it's a fantastic educational opportunity for the public if there are a couple of lines on a menu saying 'this fish is certified and sustainable'. People are there for entertainment and so have the time to read rather than when they're in a supermarket, where it tends to be just smash-and-grab.

It's still a work in progress, but we're pretty sure that we have some committed businesses and so we're expecting to see ASC-certified seafood in European restaurants later this year.