The Difference Between Atlantic and Landlocked Salmon

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Question: What’s the difference between an Atlantic salmon and a landlocked salmon?

Wil O., Stoneham, MA

Answer: From a taxonomic perspective, there is actually no major difference between Atlantics and landlocks, which are sometimes called “landlocked Atlantic salmon.” They are the same species, although there are some genetic differences. (The species name for Atlantic salmon is Salmo salar, whereas landlocked salmon is Salmo salar sebago.) The relationship of the two is similar to that of rainbow trout and steelhead (both Oncorhynchus mykiss), in which life history and behavior, rather than genetics, distinguish the two.

In the U.S., landlocks were originally found in just four Maine lake systems—Sebago, Green, Sebec, and Grand. Although many people believe that landlocks are “glaciomarine relicts,” trapped by rising land and dropping sea levels some 10,000 years ago, more recent evidence suggests that certain Atlantic salmon simply stopped going to the ocean. This view is supported by the fact that all four original lakes offered access to the ocean before they were dammed. Scientists do admit that they have no explanation for why some fish would decide to become “voluntarily landlocked.”

Native landlock populations are also found in Canada and Scandinavia, and they’ve been stocked all over the world—not surprising since “salar” is Latin for “leaper,” and one of the distinguishing characteristics of the landlocked salmon is its tendency to go airborne as soon as it feels a hook. More than 175 lakes and 44 rivers in Maine are listed as prime “landlock” fisheries, and you can even find them in the mountains of Argentina.

Landlocks don’t grow as large as their sea-run cousins, generally running between 12 and 20 inches, although much larger specimens can be found in big lakes. The IGFA all-tackle world record, from a lake in Sweden, is 23 pounds 11 ounces, and the largest landlock taken with a fly rod, in Labrador, weighed in at 7-1/2 pounds.