Sustainable Seafood: FAQs

5 minute read

If you've got questions about sustainable seafood, we've got the answers. Check below for the most frequently asked questions and our response to them.

What to know about buying seafood

Farmed or wild – which is best?

Simply put, neither method of producing fish is better than the other. Both have species on the Best Choice and Fish to Avoid lists, with many options in between.

Wild capture fisheries can be harmful to the seabed, and may result in unwanted bycatch, catching species like dolphins and sharks accidentally.

Aquaculture can impact the environment through pollution from chemicals, escaped fish and disease impacts.

This is all considered in the Good Fish Guide: our ratings take into account the relative sustainability and environmental impacts of all methods.

How important is it to choose seasonal fish?

Wild fish need to be allowed to grow to maturity and breed. They do this at different times of the year depending on the species and region.

However, it is difficult to apply seasonality to a lot of seafood because it is often caught and then immediately frozen. It might be sold months after being caught, and the date of the original catch can be difficult to find out.

Climate change is having some effect on breeding seasons, as temperatures and seasons change, so we could some changes in how we approach seafood seasonality in the near future. However, if you are buying local, freshly-caught seafood, it is important to check that it wasn't taken during its spawning season.

Seasonality doesn't apply to farmed seafood because they don’t breed and reproduce in the same way as wild caught fish.

What should I look for on seafood labels?

The easiest things to look for are credible eco-labels such as the Marine Stewardship Council (MSC) for wild caught seafood, or Aquaculture Stewardship Council (ASC), Soil Association or Organic for farmed seafood.

Some examples of the labels to look out for are below.

ASC Logo Landscape Soil Association Logo English EU Organic Logo GlobalG.A.P. Logo Landscape GAA BAP Logo

Seafood caught or produced to these standards is likely to be rated quite well on our Good Fish Guide and is also subject to robust traceability requirements.

It's also really important to find out what species is it, where was it caught or farmed, and how. These factors can make a big difference to sustainability and allow you to use tools like the Good Fish Guide to make an informed choice.


Unprocessed products (e.g., not tinned, breaded, or mixed with other ingredients) are legally required to have this information on pack (with the exception of the farming method).

Many brands choose to include this and additional information anyway to improve transparency and traceability.

MCS vs MSC, what's the difference?

The Marine Conservation Society (MCS) and the Marine Stewardship Council (MSC) can be easily confused! We both focus on sustainable seafood, but in different ways.

We're the Marine Conservation Society: a UK-based and -focused charity that, alongside multiple other areas of work, runs the Good Fish Guide. We also work to improve the worst performing fisheries and fish farms through engaging with government and other key stakeholders to develop better policies and legislation. We don't charge for our work on the Good Fish Guide - it's a free resource for all to use.

The Marine Stewardship Council, most recognisable by the ‘blue fish tick’ on seafood packaging, is an international non-profit organisation. MSC certification is a global sustainability standard for wild-caught seafood, and includes traceability requirements for trading certified products. In order to get the certified ‘blue fish tick’ fishers or companies need to pay for an assessment to be undertaken by a 3rd party.

We recommend choosing MSC-certified seafood, as these products are often rated well on our Good Fish Guide and are fully traceable. Around 17% of the world's fisheries by weight are now certified by the Marine Stewardship Council. Many fisheries fall outside this process, but not necessarily because they are unsustainable. The Good Fish Guide helps businesses and consumers to better understand the sustainability of fisheries and aquaculture systems that aren't certified.

If it says ‘sustainably sourced’ on a product, is it definitely ok to eat?

You might see sustainability claims like 'Responsibly Sourced' or Sustainably Sourced' on seafood packets.

These claims often relate to a voluntary sourcing code of conduct by these businesses and can be an indicator that the seafood is a good choice.

As these codes are voluntary, some businesses implement them better than others. So, in practice, there can be a wide interpretation of what is actually 'Responsibly Sourced'. It's not a fool-proof way of making the best choice.

If the labelling information is insufficient for you to make an informed choice (i.e., it doesn’t say what species is it, where was it caught or farmed, and how), ask staff or the fishmonger/waiter for more information.

If you can’t get the information you need to make an informed choice, give it a miss!

How do I know if seafood in a restaurant is sustainable?

If the restaurant has a website, that’s always a good place to start. They might have a page on where their food is sourced.

If you spot logos from the Sustainable Restaurant Association (SRA) or the Soil Association it’s usually a sign the restaurant cares about sustainability.

For specific menu options, keep an eye out for credible certification labels like MSC, ASC and organic.

You could also ask the restaurant themselves, and see if they know how and where the fish has been caught or farmed so that you can search for the rating on the Good Fish Guide.

Be wary of phrases like ‘local’, ‘fresh’, and ‘wild’, which are quite often used to imply sustainability but don’t necessarily relate to it at all.

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Ethics and welfare

Does Marine Conservation Society work on animal welfare?

Currently, welfare standards aren’t in place for wild capture fisheries, but they do exist for many farmed species such as salmon and other finfish.

These standards are set by law and in voluntary codes of practice and certifications such as RSPCA Freedom Food.

In our Good Fish Guide ratings for farmed fish, we consider requirements for animal welfare, including humane slaughter.

We recognise that good welfare practices are important and we currently defer to other organisations with the skills and experience in this field, such as Farm Animal Welfare Committee and the RSPCA.

Are there social and human welfare issues associated with seafood production?

Seafood is a hugely diverse sector. Fishing, aquaculture and seafood processing take place all over the world, involving a wide variety of cultures and regulations.

Despite this diversity, workers are entitled to be treated fairly, without having their basic human rights ignored or infringed.

Labour violations on fishing vessels are an ongoing global issue, and are often associated with Illegal, Unreported and Unregulated fishing (IUU). International treaties like the Port States Measures Agreement have been implemented to tackle IUU. They make it increasingly difficult for seafood caught by vessels operating illegally to enter the supply chain.

Organisations such as the International Labor Organisation and the Environmental Justice Foundation also carry out great work in this area.

We defer to and support the work of organisations such as these, including those defining responsible practices for aquaculture, to define and promote high social standards.

Seafood and health

What about chemicals and plastics - is it safe to eat seafood?

The NHS say that ‘a healthy, balanced diet should include at least 2 portions of fish a week, including 1 of oily fish. This is because seafood is a good source of many vitamins and minerals’ However, some seafood can contain low levels of pollutants that build up in the body. For this reason, there is specific advice for consuming certain seafood:

  • Girls, pregnant women, those that want to get pregnant one day and breastfeeding women should limit their consumption of oily fish (as well as sea bream, sea bass, turbot, halibut, rock salmon and brown crabmeat) to 2 portions a week. Everyone else should limit consumption of these to 4 portions a week.
  • Pregnant women or those trying for a baby should limit their consumption of tuna to 4 cans or 2 tuna steaks a week.
  • Vary the species of fish you are consuming, because different species have different levels of pollutants.
  • There are limits for everyone on the consumption of shark/swordfish/marlin of 1 portion a week, although children, pregnant women or women wanting to get pregnant shouldn’t consume any of these.
  • Anyone can consume unlimited amounts of white fish other than the species specifically mentioned above (sea bream, sea bass, turbot, halibut and rock salmon).

For further information, please visit the NHS website.