Atlantic Salmon

The Atlantic Salmon: How Does This Fish Make its Way onto Our Dinner Plates?

The Atlantic salmon (Salmo salar) is a species of fish that is highly prized by many diners around the world. Their pink-hued meat, flavorful oil, and nutrient content make this sea-run species a popular addition to any plate. But what goes into making an Atlantic salmon and how does it make its way on to our dinner plates? Let’s take a closer look.

Spawning and Early Life Cycle

An adult Atlantic salmon begins its life in the coastal estuaries of the Atlantic Ocean, typically returning to the rivers where it was born. With some exceptions, adults generally migrate from the open ocean to freshwater rivers in the late summer and live there until the following spring when they begin spawning. Here, adults form large schools and females deposit their eggs in the gravel beds.

The newly laid eggs are in a very immature state and unable to hatch on their own. Young salmon, known as alevin, emerge when the egg absorbs enough water and its embryonic membranes dissolve. Up to 300 fertilized eggs never hatch and are used by other salmon as a food source.

Typically in the spring, once they reach a length of 5 to 7 centimeters, alevin will swim out of the gravel bed and enter the currents of the river itself to begin their juvenile stage. At this point, the salmon have a life expectancy of up to three years and will develop the ability to feed on crustaceans, fish fry and other food sources.

Smoltification

When the young salmon reach late summer, they enter the next stage of their life cycle—known as smoltification. This is the process in which the salmon undergo both physiological and behavioral changes to survive in the ocean environment. During smoltification, the salmon’s body slows and adjusts to the changing temperature and salinity levels of the ocean.

The changing pH and ion concentrations in the ocean also cause their gills to swell and increase their oxygen extraction capabilities. Additionally, their pigment cells darken, providing them with better camouflage from predators in their new environment. Further, their digestive systems adapt to their new diet of plankton, small shrimp and other marine food sources.

Atlantic Salmon in the Open Ocean

Once smoltified, salmon are equipped to inhabit the open ocean. During this period of two years, the salmon will remain in a state of migration, moving to a number of different locations in search of food. Additionally, they will increase in size, sometimes reaching lengths of up to 1 meter and weights of 8-12 kilograms.

This new size and powerful swimming capabilities allows the salmon to predate on a variety of fish, such as sand eels, capelin and other juvenile fish, as well as smaller crustaceans. By keeping the size of the salmon that are fed on by the salmon in check, their population numbers can remain stable in their environment and support a wide variety of other species, including larger, predatory fishes.

Feline to Farming

After spending a few years in the ocean, the salmon will journey back to their birth location and precondition themselves for reproduction as they feed on smaller, more agile prey. At this point, they are referred to as returning adults—or kelts.

Unfortunately, the survival rate of fins to plate is quite low, as they are vulnerable to natural predators, such as seals and sharks, as well as fishing activities. Those that do make it to the river can find their path blocked by fishermen or natural obstacles, such as dams. The combination of these factors can unfortunately mean that only 1% of the salmon that depart for the ocean will return as adults.

As such, a large portion of Atlantic salmon consumed by humans is farmed. Farmed salmon is produced in large, floating net pens located in fjords and other coastal waters. Salmon in these pens are carefully monitored to ensure their health and are provided with a uniformly balanced diet in their enclosed facility.

From Egg to Plate

Now that Atlantic salmon have made their way on to our dinner plates, let’s review the journey this fish takes from egg to plate. Starting with spawning and the early life cycle, alevin will eventually make their way from the gravel beds to the open ocean and reach lengths of up to one meter. During this time they will develop the ability to feed on smaller, more agile prey and grow in size.

Once they reach optimal size and precondition themselves to reproduce, they will begin their journey back to the rivers of their birth. Of course, external factors—such as seals, dams and fishing activities—can have an impact on their survival rate. Those that do make their way back are often able to reproduce and lay eggs, beginning the cycle anew.

However, produce a significant portion of the salmon consumed worldwide is farmed, where they are carefully monitored, fed a balanced diet and harvested at optimal size. From egg to plate, Atlantic salmon takes quite the journey, but it is one that is worth the effort for the many who enjoy its rich flavor and welcoming color.