The Use of Hatchery Technology for the Conservation of Pacific Salmon

Over the last century there has been extensive use of hatchery technology to conserve salmon stocks in the Pacific Northwest.  Hatcheries were initially used to create demographic abundance for salmon stocks impacted by anthropogenic factors such as overfishing, habitat loss, hydropower, deforestation, etc.  By the 1990’s, these efforts were so successful that many viewed them as a threat to many of the naturally reproducing stocks remaining in the Pacific Northwest.  The concerns for natural production led to the emergence of a new conservation use for hatcheries.  Hatcheries would continue to generate demographic abundance, but would now couple it with the maintenance of traits that adapted stocks to their local natural environments.  In many cases, this simply involved coupling ocean ranching technology with the sourcing of fish from their local natural spawning population and placing limits on the number of hatchery fish allowed to spawn naturally.  In more extreme cases, stocks were taken into safety-net captive rearing programs to prevent populations from winking out in years when few or no naturally produced fish returned from the sea.  These programs have built on the knowledge gained from decades of ocean ranching and have developed new techniques unique to captive rearing.  Hatchery technology, in the form of ocean ranching, has proven to be a robust tool for the mitigation of population numbers when freshwater habitat is permanently lost.  Although hatchery technology can be used to supplement weak natural populations, great care must be taken to ensure it does not impose a larger genetic risk than demographic benefit.  Captive rearing has proven to be useful in preventing the further decline of salmon stocks faced with a near certain risk of extinction.  However, it remains unclear if natural stocks taken into culture will ever regain their status as self sustaining natural populations.