Rainbow Trout (Oncorhynchus mykiss or Salmo gairdneri)

Rainbow Trout (Salmo gairdneri) 


Rainbow Trout (Oncorhynchus mykiss or Salmo gairdneri) are fishes of the class Osteichthyes (Boney Fishes) found in French Hill Pond. They are of the order Salmoniformes, an important group of commercially valuable fishes. The family is Salmonidae or Trout family, which includes Salmons. The genus name, "Salmo," is Latin for Salmon. Salmo gairdneri is the original genus and species name for this fish. Recent DNA studies have shown that this fish is more closely related to the genus Oncorhynchus, Pacific salmon, spawning the new genus and species name, "Oncorhynchus mykiss."

Rainbow Trout grow to almost four feet (1.2 meters) and can weigh over 42 pounds (19 kilograms).

In the wild, Rainbow Trout spawn in freshwater streams where they live for two to four years before swimming out to sea where they live for about three years. Like other salmon, they swim upstream to their home spawning ground to deposit and fertilize eggs. But, unlike other salmon, they do not die after spawning but return to the sea. One Rainbow Trout can spawn several times. These hardy fish can be successfully introduced into landlocked freshwater. When they have no access to the sea, they spawn in the spring. Males can spawn at one year old but females take six years to mature.

The Rainbow Trout in French Hill Pond were introduced over several years with the advice and assistance of the Maine Department of Inland Fisheries and Game and the United States Department of Agriculture. Maine requires a permit to stock fish in any body of water in Maine. This permitting process includes a review of the body of water in which the fish will be introduced and the connections of that body of water with other bodies of water. Only Rainbow Trout and Brook Trout (Salvelinus fontinalis) may be introduced into French Hill Pond. Rainbow Trout are particularly hardy and stand the best chance of thriving in French Hill Pond. The photograph above shows Rainbow Trout in a plastic bag before being introduced into French Hill Pond in May 2011.

Rainbow Trout are metallic-blue to brown above and silvery white beneath with black spots on the top and sides. The landlocked variety has a red band on the sides. They have white mouths with no teeth on the back of the tongue. Their coloring is iridescent, whence the name. Trouts have two fins on their backs, a dorsal fin about midway along the back and a smaller fin, called an "adipose fin," between the dorsal fin and the tail. They have similar fins arranged along their bottoms. The anal fin of a Rainbow Trout, the bottom fin corresponding to the adipose fin, has eight to twelve rays (fin divisions).

They eat almost anything that will fit into their mouths including plant matter, insects, eggs and other fish. Rainbow Trout will feed on the surface and may even strike at food above the surface. The nearly vertical fish in the above photograph was feeding on something on the surface of the water.

The following photograph shows a Rainbow Trout in French Hill Pond. Note how the coloring blends into the background.

Rainbow Trout in French Hill Pond

Fish (Agnatha, Chondrichthyes and Osteichthyes) Fauna of French Hill Pond French Hill Pond Home Page