Understanding how seafood is sourced

​

Seafood differs from other food categories because there is more variation between species.

​

The main differences usually come down to:

• whether the seafood is wild-caught or farm-raised

• the type of species

• what the animal eats

• the quality of the water environment

• how the fish is handled and processed after harvest

​

Wild-caught seafood comes from natural waters, where the environment and diet are less controlled but more natural. Farm-raised seafood comes from managed systems, where feed, stocking density, and water quality play a much larger role.

​

Shellfish such as oysters, mussels, and clams are different from fish. They are typically filter feeders, meaning they draw nutrients directly from the surrounding water rather than being fed formulated diets. Because of this, both wild and farmed shellfish are more directly influenced by water conditions than feed inputs.

​

This is why seafood quality is not defined by a single label. It depends on the sourcing system, the species, and how the product was handled.

 

How to think about seafood choices

​

When comparing seafood, it helps to look at three things together:

• sourcing system

• species

• accumulation over time

​

Smaller fish lower on the food chain tend to accumulate less over time than larger predatory fish. This is why species like sardines and anchovies are different from fish like tuna or swordfish.

​

For farm-raised seafood, feed quality, stocking density, and water conditions become more important. Some systems are more carefully managed than others, but this is not always visible from the label alone.

​

Shellfish reflect the environment they are grown in more directly than most fish. Water quality plays a larger role than feed, and they are typically consumed whole, which means they can contain what is present in that environment. Microplastics have also been found across many types of seafood, particularly in shellfish.

Looking at these factors together gives a clearer understanding of how the seafood was sourced.

 

Common labels explained

​

Wild-Caught
Seafood harvested from natural waters rather than raised in farming systems. Quality still varies depending on species, region, and handling practices.

 

Farm-Raised
Seafood raised in controlled systems such as ponds, tanks, or ocean pens. Feed, water quality, and stocking density can differ significantly by operation.

 

Sustainably Sourced
Typically refers to environmental or fishery management practices, not necessarily feed quality, farming conditions, or accumulation.

 

Low Mercury
Generally refers to smaller species lower on the food chain, such as sardines, anchovies, and some types of mackerel.

 

Higher Mercury Species
Larger predatory fish such as tuna and swordfish tend to accumulate more over time due to their position in the food chain.