Aquaculture 101: Part 1
At the recent Chefs for Oceans talk on aquaculture, organized by Ocean Wise Executive Chef Ned Bell, I presented a primer on farmed seafood. This event was geared towards chefs wanting to know more about the seafood options available on the Canadian market. But from the great feedback I received, I realized that this conversation about farmed seafood is sorely lacking. So without further ado, here’s what I shared about farmed seafood at Chefs for Oceans.
Global Seafood Production for Human Consumption
More than half of all seafood that humans consume globally is farmed. Only 47% comes from the wild. Wild fisheries cannot significantly increase production without becoming unsustainable, so aquaculture has been stepping in to meet demand.
Ocean Wise’s Recommendations
How does Ocean Wise make recommendations on farmed fish?
The Ocean Wise Seafood program bases recommendations on scientific reports published by the Seafood Watch program based out of the Monterey Bay Aquarium.
Each fish is scored on ten different criteria that measures the impact of seafood farms on the environment. Fish must score at least 5.5 out of 10 to be recommended by Ocean Wise. Seafood Watch considers scores 3.33-6.66 as yellow, i.e. a “good alternative.” Ocean Wise has no yellow category. Seafood either meets our line of 5.5/10 and is recommended, or it does not.
Shrimp is the most popular seafood item with North Americans consuming 1.8 kilos per person each year. The majority is farmed in traditional ponds in Asia. These are unsustainable seafood choices, given that the ponds are located in areas of historically deforested mangrove forests, which are critical ecosystems. A serious concern is chemical usage, as antibiotics that are highly or critically important to human health, are used in these ponds which are in contact with natural water bodies. Overuse of these antibiotics can lead to the development of antibiotic resistance which is a leading global issue. Fortunately, if you like shrimp, you can choose ones raised in silvofisheries.
The shrimp grow in mangrove forests that farmers are required to maintain. They are kept in uncrowded conditions to keep them healthy, which means that antibiotics are not used. They also feed from the mangrove forest, making fish feed unnecessary. This relieves pressure on wild fish stocks, as they do not need to be converted into feed to nourish the shrimp.
Most people know that bluefin tunas are highly unsustainable. But what about farmed tuna?
Unfortunately farmed bluefin tuna are no better than wild-caught. Most tuna farms are not true farms, as they capture wild juveniles and fatten them in the farms before sale. This reliance on wild bluefin tuna populations does not alleviate any fishing pressure on them.
One farm in Japan has successfully bred bluefin tunas in captivity. However, bluefin tunas are top predators, which means that they need to consume enormous amounts of wild fish. The amount of fish feed they require is unsustainable. The equivalent of a bluefin tuna farm on land would be a lion farm meant for human consumption, since the latter is also endangered, a top predator, and would require large amounts of meat to feed.
One commonly consumed seafood item is eel, also known as unagi.
Few people know that virtually all commercially available eel species are at least threatened, with some being critically endangered.
Like tuna farms, eel aquaculture relies on wild juvenile populations that are fattened in captivity. This practice has decimated many global populations. Fortunately, some Ocean Wise sushi partners are now replacing eel with sustainable sablefish. Look for this alternative.
Branzino and Hamachi
Branzino is a name given to European sea bass or sea bream. Both species are raised in the Mediterranean. Antibiotic usage is a main concern as any chemicals used can flow straight into the ocean.
Hamachi is also known as amberjack and is raised in Japan. This seafood item has several issues including the use of antibiotics that are important to human health, problems with disease on the farms, the use of wild juveniles that are fattened, and 2.7 to 4.5 kilos of fish feed required to produce half a kilo of hamachi.
Although we are most familiar with salmon as a species being raised in open-net pens, branzino and hamachi are also raised this way.
As an alternative to hamachi, a related species is known as kanpachi and grows in submersible net pens in Hawaii. These pens are submersed up to 60 metres deep and are strictly monitored to prevent any habitat impacts. No antibiotics are used and the fish are native to Hawaii, meaning that any escapes will not compete with the wild population. Kanpachi need one kilo of wild fish for every half kilo produced.
Farmed shellfish like oysters, mussels, and clams are all sustainable superstars. Known as zero-input farming, these species require no feed since they filter algae from the surrounding water, and no chemicals. It is sometimes argued that shellfish can be more sustainable than vegetables, as even vegetables require cleared land space to grow, freshwater and sometimes chemicals.
Raising seafood inland is becoming increasingly popular as an alternative to open-net pens. Also known as RAS for “recirculating aquaculture system”, waste water from the tanks is treated before being recirculated through the farm.
This minimizes the effect of effluent on the environment. The land-raised species have little to no chance of escaping and interacting with wild fish.There is also no opportunity for disease or parasite interactions. Antibiotics are rarely used since these fish are raised in optimal and controlled conditions.
More seafood is raised on land than you may think: Arctic char, sturgeon, Atlantic salmon, coho salmon, rainbow trout, whiteleg shrimp, and tilapia are all species cultured this way in Canada.
All these species, both unsustainable and sustainable, are commonly found on Canadian menus or in supermarkets. If you want to choose the sustainable alternative, look for the Ocean Wise logo! Stay tuned for part 2 of this series where I address salmon.
Claire Li is an Ocean Wise Seafood Account Representative.