Salmon runs are a major event in Alaska and the Pacific North West, when these anadromous fish return to the rivers where their lives began to spawn. Once, salmon runs were common on the East coast of North America, as well. The Atlantic salmon, Salmo salar, could once be found in almost any river north of the Hudson River in New York; aggressive commercial fishing severely depleted populations of Atlantic Salmon before their closure in 1948. Today, only a handful of wild United States Atlantic Salmon can be found in rivers in Maine. Canadian and European populations of Atlantic Salmon are declining, as well, and all Atlantic salmon sold commercially comes from aquaculture.
Salmon eggs are obtained from broodstock, a population of adult fish reserved for reproduction. Once fertilized, atlantic salmon eggs are incubated at a nursery until they hatch. Newly hatched salmon, called fry, are closely monitored and given vaccinations to preserve their health as they grow into parr. At about 18 months, parr undergo considerably physiological changes that allow them to survive in salt water. At this stage they are about 5 inches long and are called smolts. Smolts are moved to floating nets in mid-April or May. Open-water pens are a practical way of maintaining Atlantic salmon stocks in salty water they need to survive, and the exchange of water in the pens with the surrounding environment removes waste and supplies oxygen-rich water for the salmon.
Though there has been considerable success in farming Atlantic Salmon, many challenges remain. In particular, salmon aquaculture may threaten wild populations and the surrounding environment through excessive nutrient loading and pollution or the transmission of diseases should any stocks escape.
This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.
Contributing Professor: Dr. Lisa Campbell
Script Author: Judson Riley
Editor: James M. Fiorendino
Featured Image from: