Hatcheries: Solution or Threat

Though there are conservation projects that take the effort to assess the different facets of overfished salmon populations before conducting appropriate conservation plans, the sheer number of unsustainable salmon populations has caused an immediate response of instilling hatcheries from those who are involved in the salmon business to promote the abundance of these commercially-valuable fish. 

Salmon hatcheries are owned spaces where salmon are bred and raised to a certain age and then released to increase the number of salmon stocks (9). This process aims to provide a high survival rate of eggs to fry. The procedure involves harvesting eggs from females and sperm from males into a container, and then mixing the two to have fertilized eggs (5). Then, these bred salmon are released into open waters. This is because salmon are anadromous fish. Anadromous fish have a life history pattern where they are spawned in freshwater tributaries. Then they migrate to and spend time in oceanic waters until they become mature adults and return to freshwater tributaries to spawn. Therefore, the bred salmon are released once they are a certain age to grow in marine waters.  

The YouTube video below: Trip to Salmon Hatchery Fall 2006 from JulieLeung shows how hatcheries run (5). Because salmon have a natural life history pattern of spawning once and dying once they have spawned, the killing of the mature adult salmon to harvest the eggs and sperm has no adverse effect on salmon populations.

So replenishing the declining salmon numbers with hatcheries seem to be a solution because the total numbers of salmon seem to be maintained.  However, a greater issue is underlying this "solution" to preserve the endangered salmon populations.  The underlying issue is the potential genetic loss that can come about from hatcheries.

Hatcheries have a great potential in being a detriment to salmon populations and we do not know the extent of the risk or damage hatcheries can cause.  Although hatcheries provide higher egg-fry survival rates (which is a benefit because habitat degradation reduces egg-fry survival rate), they prevent salmon from being born and raised in natural environments. This can induce loss in genetic diversity not only from inbreeding, but also from the unnatural environmental conditions of the hatcheries causing a natural selection for those who have better qualities to stand the unnatural conditions (9).  By raising salmon in unnatural conditions and then releasing them to natural conditions can cause a negative impact on wild salmon populations, as the bred salmon mate with wild salmon. Furthermore, potential overcrowded salmon in hatcheries increase their susceptibility to an epidemic (4), which can also cause adverse effects on wild salmon through interaction.

Because it seems as though the numbers of salmon are maintained from hatcheries, the potential genetic loss can be overlooked.  However, we must focus on preserving the genetic diversity of these species, especially that of wild salmon for effective conservation. Studies have shown that the increase of bred salmon causes a decrease in wild salmon populations (6,7). The increase of bred salmon raises the total number of salmon, which allows to fishers to fish at high rates. Since both wild and hatchery-raised salmon are in open marine waters in their adult phase, there is a risk of wild salmon to be continued to be overfished, or even at even higher rates, and this possible consequence has been observed (6,7).