How Do We Know If Fish Farming Is Sustainable?

This is the last article in my series on aquaculture. Many times in this small series, I’ve argued that the expansion of fish farming is both good and necessary. And, just as many times, I’ve said that this expansion needs to be sustainable. Sustainable is a problematic word. It means so many things to many people that it may actually mean nothing to anybody. For myself the short, and admittedly rather vague, definition I use is that sustainable means practicing now in ways that do not preclude the opportunity for others to practice in the future. Others, however, have undertaken much more rigorous efforts to define sustainable aquaculture in particular. They have also taken the steps to recognize those who adhere to their sustainability vision. In this article I describe some of the work of those who define sustainable aquaculture and what it means.

In the search for new practices to increase the sustainability of fish farming, how do we decide what is important to do?

Many organizations seek to address this question.  While they differ importantly in details, they operate similarly.  Each establishes standards they believe will foster sustainable aquaculture.  Auditors then assess performance against the standards and award a ranking or a certification to those who meet the the organization’s standards.

A foundational assumption for certifications is that achieving their standards means we obtain our seafood with lower environmental and social impacts.  Any certification’s usefulness  depends broadly on two things.  One is the quality of its standards. They must be relevant, unambiguous and objectively measurable. By these criteria, the quality of standards varies alarmingly amongst the existing systems.  Relevance is particularly lacking.  For instance, in one comparison of three certification schemes, the authors concluded “However, in very few cases did farms actually fail for detected known poor performance, but generally for inadequate paperwork or monitoring”.  The heart of certification must certainly be about performance on the water; that may be pretty difficult to discern for most of us as seafood consumers.

A second central consideration to a certification scheme’s relevance is that there must be a causal link between standards and desired outcomes.  Amongst the many certification programs there is tremendous variability in how, or even whether, this link is made. In part this is because aquaculture standards are generally designed to prevent local ecosystem deterioration rather than to achieve well defined environmental improvements.  The difference is non-trivial. The logic here is that when knowledgeable experts design sensical standards, the consequence of implementing  those standards is environmental benefit.    This is a reasonable postulate but it begs to be tested. Assessing outcomes will help lend confidence to existing standards, show the need for new ones and help to discard those that are unattached to benefit.

Furthermore, clear statements about outcomes reinforce the mission of the certifiers, namely, to enact change on the water.  The audience for certifications is certainly the fish farmer but it is also consumers.     Directing consumers’ choices at the seafood counter feeds directly back to farmers meeting their business goals directly-improved aquacultural practices lead to better business performance of a farm.

If changing consumer behavior is a target of certification (and I contend it must be) then certifiers must speak directly and effectively to them.

Here’s an example of what I mean.  There is no doubt, it is important that redox potentials on the ocean floor must not become highly negative due to waste organic material produced by a farm.

But, and this is just a guess on my part, it may very well be that you don’t enhance the sales of Fish X by saying the benthic redox potential below certified Farm X is +75 mV whereas other uncertified farms in the area have redox potentials below -200 mV.  However, a message that scallops (or lobsters or crabs or seaweed or coral) flourish below Farm X because of the environmental stewardship that undergirds Farm X practices might alter a purchase decision.  Try these two out on your neighbors and let me know which resonates better.

In the comments section, I would love to hear your thoughts on how environmental NGOs, retailers, chefs, farmers and others could talk about the sustainability of our seafood in useful ways.  Please, take 2 minutes to jot me a note.  If there are enough responses, I’ll collect them and write a short article summarizing your thoughts.

Seafood is the most complicated and obtuse item in the grocery store. Certifications are a large part of the complexity that faces (annoys?) consumers. Thankfully there are some aggregators of certifications and I list a couple below. They look across the spectrum of certifications and compile lists of fish they deem sustainable when viewed at arms length rather than through the parochial lens of a given certifier. As well, I have listed for you some of the more well known certifying groups.


Both of these organizations synthesize many different inputs to advise on fish sustainability




Aquaculture Stewardship Council[1]

Home page


Global Aquaculture Alliance

Home page


Global GAP

Home page


Food and Agriculture Organization of the United Nations



Monterey Bay Aquarium Seafood Watch

Home page

[1] A disclosure-I am a member of the Board of Directors of the Aquaculture Stewardship Council

  1. ive left comments for you on the AISP LinkedIn page. You have missed off many certification groups. Importantly FAO are NOT certifiers and organisations like ‘Friends of the Sea’ report they are the largest certifier. Do some sums and add up what the costs of certification are then try and ascertain the benefits of certification in dollar terms. There has to be a better way!!!

    • Inger Melander
    • March 17, 2016

    Dear Scott,
    Thank you investera again for an interesting early morning read. I do however miss WWF’s Sustainable Seafood Guides on your list below rankings.
    Inger Melander
    WWF Sweden

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