Environmental issues with salmon
Determining how environmental stressors and climate change will affect these fisheries is challenging due to their lives split between fresh and saltwater.
A recent 2009 study looked at 59 years of catch and escapement data of Bristol Bay sockeye to determine age and size at maturity trends attributable to the selectivity of commercial gillnet harvests.
[7] With more competition for prey and space in the ocean, the period of maturation in saltwater before salmon reach sexual spawning age grows.
Reduced retention of the nutrients brought by the returning adult salmon in stream pools has lowered population numbers.
[9] Other environmental factors, such as light intensity, water flow, or change in temperature, dramatically affects salmon during their migration season.
[10] Modern farming methods and various sources of pollution have resulted in loss of invertebrate diversity and population density in rivers, thus reducing food availability.
When the water temperature increases the thermal requirements for the three species (Atlantic Salmon, Brown Trout, and Arctic Charr) are a necessity because if any other problems occur it can be predicted/anticipated by those of the biodiversity in the freshwater ecosystems (2).
The long term affects from climate change produce more selection pressures in different parts of salmon's life such as Juvenile growth, development rates, thermal tolerance, and disease resistance.
Salmon fishery stocks are still abundant, and catches have been on the rise in recent decades, after the state of Alaska initiated limitations in 1972.
In Canada, returning Skeena River wild salmon support commercial, subsistence and recreational fisheries, as well as the area's diverse wildlife on the coast and around communities hundreds of miles inland in the watershed.
Out of 435 wild stocks of salmon and steelhead, only 187 of them were classified as healthy; 113 had an unknown status, 1 was extinct, 12 were in critical condition and 122 were experiencing depressed populations from a study from 1997.
During these twenty—five years the fishermen of each State have naturally tried to take all they could get, and the two legislatures have never been able to agree on joint action of any kind adequate in degree for the protection of the fisheries.
Meanwhile very few salmon reach the spawning grounds, and probably four years hence the fisheries will amount to nothing; and this comes from a struggle between the associated, or gill—net, fishermen on the one hand, and the owners of the fishing wheels up the river.The commercial salmon fisheries in California have been either severely curtailed or closed completely in recent years, due to critically low returns on the Klamath and or Sacramento Rivers, causing millions of dollars in losses to commercial fishermen.
Now Chinook (King), Atlantic, and Coho (silver) salmon are annually stocked in all Great Lakes by most bordering states and provinces.
Introduced and sustaining populations of Pacific salmon are found in New Zealand, Chile, Argentina, and the Falkland Islands.
Native Atlantic salmon populations outside of North America are found in much of coastal Europe, as well as Greenland, Iceland, the Faroe Islands, and the northwestern part of Russia.
[24] Several governments and nongovernmental organizations (NGOs) are sharing in research and habitat restoration efforts to relieve this situation.
Results overall show estuary problems exist for some rivers, but issues involving feeding grounds at sea are impacting populations as well.
[26] The Puget Sound Partnership is currently working to implement policy change at the local level to alter the fate of salmon.
This recovery plan was developed by Shared Strategy, a grassroots collaborative effort to protect and restore salmon runs across Puget Sound.
In order to ensure the future of Pacific Northwest salmon, the Partnership continues to encourage Stormwater & Low Impact Development, and advocates the "Puget Sound Starts Here" public education program.
