The Landlocked Salmon you will use are very similar to the Atlantic Salmon. In fact, they are just varieties of the same species (Salmo salar).
Prior to the last ice age all of the members of this species returned to the sea after completing their early development in freshwater. In the sea growth to the adult phase of the life cycle occurred. Then the adults returned to freshwater streams to spawn, thus completing the life cycle. This is the anadromous life cycle (breed in fresh water/adult in salt water).
During the last glacial period the weight of the ice cap depressed the surface of the earth in the northern hemisphere. Salt water welled up the valley of what is now the St Lawrence River and into what are now the Great Lakes, Lake Champlain, and other lakes. The Atlantic Salmon extended its range into these new salt water lakes.
When the ice began to melt the weight on the earth's surface was reduced and the earth's surface rebounded. The rising land created barriers so the salt water could no longer circulate into these lakes and they became freshwater lakes.
Young Atlantic Salmon which had been living in the streams above these lakes when they were salt water were stuck. As they matured and began their journey toward the salt water, they encountered these barriers that prevented their return to the ocean. It was probably a very difficult time for these salmon and probably most of them did not survive.
The few that did became the ancestors of today's Landlocked Salmon. These salmon complete their early development in freshwater streams, then move into lakes where they grow to adults. The adults then return to freshwater streams to spawn, again completing the life cycle. This is the freshwater life cycle.
This split occurred only a few thousand years ago. Not many genetic changes have occurred in that time and the two types of salmon are still almost identical except for the accident of where they happen to live. The two are still considered to be members of the same species even though they do not interbreed in nature.
The material in your handouts which refers to the Atlantic Salmon is valid for the Landlocked Salmon. EXCEPT - The Landlocked Salmon do not return to the sea as young adults (smolt), only to a lake. (They still undergo the same physiological changes to prepare for life in salt water, they just never get there.) The only changes you will need to make will be the logical ones that refer specifically to:
| Atlantic Salmon | Landlocked Salmon | ||||