Sustainable Seafood | Seasonality and Farmed Fish

Welcome back to my sustainable seafood guide, which aims to bring clarity to the ins and outs of making more environmentally conscious choices if you choose to eat seafood. I decided to start this series as despite three years training as a marine biologist, I still wasn’t sure whether I should even be eating fish at all, or sticking to my vegetarian diet in order to help the planet. In the last article within this series, I discussed some of the nutritional points that makes seafood a popular choice in many healthy diets, and why you might want to eat it. Since that post, I finished my month of  exclusively vegetarian food options in Spain, to a US field trip where we were taking scientific surveys and retaining samples, with the option of a seafood cookout at the end. It was a case of one extreme to another, but I found it really interesting to be in an environment where fishing is very much a way of life.

Sustainable seafood

For the purpose of clarification, sustainable seafood is fish, molluscs or crustaceans that have been wild caught or farmed in a way that is considered to not negatively impact the long term health of the species, or have negative knock-on effects on dependant species or the ocean. A fishery is “A unit determined by an authority or other entity that is engaged in raising and/or harvesting (wild caught) fish”. A fishery is a little hard to define as it’s based around a population that is constantly changing. However if you think of it as roughly one large population of interacting shoals or individuals based in one general area then you’re about there.

When looking for making more sustainable choices, the two main British authorities are the Marine Stewardship Council (MSC) and the Marine Conservation Society (MCS). The MSC sets the standard for sustainable fishing in the UK and hires independent experts to assess fisheries. If you see the blue MSC ecolabel on a fish, then you know that it can be traced back to a fishery certified to MSC’s standards. The MCS is an organisation best known for setting up marine protected areas, works with fishermen and industry to implement more sustainable practices and aims to help educate the public on helping marine environments. You may also know MCS through their organised beach cleans and for setting up the Good Fish Guide. Seeing the MSC blue ecolabel is a pretty good guarantee about the sustainability of the fish, and some won’t buy fish without that label. However, you can also use MCS’s Good Fish Guide to help you there isn’t a label. Some supermarkets will also mark where the fish on offer was caught, which you can double check against the guide.

Do I need to worry about sustainability changing season-to-season?

In theory, no. When a sustainable fishing quota is set, advising scientists determine the amount of fish that can be removed from the population over the course of a year. This figure must allow the remaining population numbers to be maintained and wider ecosystem effects must be considered. So as long as under the quota of fish is being caught, it shouldn’t matter when or where they are caught. That being said, early on in the year, many fish species have just spawned so are carrying roe (eggs) and have lost a lot of body fat so would taste bad and affect the next generation of fish. So currently, the  MCS recommends avoiding eating fish during these times. A guide illustrating spawning times can be found here. Fishermen will know not to, or will be prevented from, fishing around spawning grounds so as not to damage the habitat of young fish.

Many fish are considered to be at their best in terms of taste in early autumn, as they have built up reserves over summer. But again, herring caught in September is no more or less sustainable than in May. It is also worth noting that this only applies to fresh fish, as frozen or tinned can take a longer period of time to reach your shelves. 

Farmed Salmon: Sustainable or Not?

Most UK-sourced salmon comes from farms in Scottish waters. However, there has recently been a lot of public backlash around farmed fish, with images of deformed-looking fish and tales of disease outbreak reaching mainstream media. It paints a worrying image. Environmentally, farmed fish should be the better choice. Energetically and ecologically, it is more efficient as far less individuals are lost to predation, so less energy (i.e. all the calories that a fish has consumed and used in their entire life, including the calories locked up in the fish itself) is lost. Not to mention the added benefit of reducing pressure on wild stocks of fish, many of whom have seen severe population declines. Domestication of farmed salmon by selective breeding has produced less aggressive individuals with smaller heads and body cavities than in wild populations. 

Farming is moving to greener solutions fortunately. Cleaning fish such as wrasse are being added to cages to keep salmon healthy, and fishmeal is being supplemented with omega-3 rich seaweeds.

A new certification, the Aquaculture Stewardship Council (ASC) puts in place strict standards, including the banning of constant use of antibiotics in non-diseased fish (a preventative measure against disease that is potentially speeding up the rate of antibiotic resistance). However, some feel as though ASC’s standards are not strict enough. Even with selective breeding, salmon aren’t adapted to such high population densities, and so it could be argued that we should be focusing on eating other farmed species, such as Charr. Farmed salmon may have contributed towards passing disease onto wild populations. 

Salmon farming is continually improving and moving towards more ethical and environmentally sound practices. A well-known example is the RSPCA’s Freedom Food certification. This adheres to five principles: freedom to express normal behaviour, and to be free from distress; hunger and thirst; discomfort; and pain, injury and disease. 

 Use of other species that like to be in high densities such as charr might be better. As salmon farmers look for greener solutions to things like salmon lice we have to take care that we don’t generate other fisheries for cleaner fish such as wrasse, and wild fishing of the latter is a new and problematic issue. 

Today’s Takeaway

In summary, seasonality shouldn’t be an issue in making sustainable choices, but using a guide to advise you on spawning seasons will make shopping for fresh fish easier. Farmed salmon (and other species) relieves pressure on wild stocks, but has ethical concerns and contributes to disease risk. Look for ASC, RSPCA or similar certifications when buying farmed salmon.

I hope this guide helped! In the next and final instalment, I’ll be discussing climate change and how sustainable seafood that isn’t just fish can be. A huge thanks to Prof. Michel Kaiser and Dr. Claire Szostek for their expertise and help in the writing of this series. Photo by Sami Hamill.