Salmon have been a staple part of diets of Europeans for centuries. This is partially due to the fact that the habitat of Atlantic Salmon spreads throughout most of the European coast, as far south as Spain. It has been fished throughout these areas since Paleolithic times (CCC, 2012). The importance of this fish can be recognized by the fact that regulations to protect salmon stocks have existed since at least 1030 AD (CCC,2012). The overall decline of salmon populations was first noticed 1215 AD, when nets across rivers (particularly the river Thames) stopped Salmon from returning to their natural spawning grounds. This caused the number of spawning salmon declined significantly (CCC,2012). With industrialization and the development of modernized fishing technology, Salmon species continued to decline. The introduction of meat preservation methods in the form of canning and icing increased Salmon demand worldwide and drove down the Atlantic populations (CCC, 2012). This decline was consistent until the 1960’s when the stocks of many of the European Atlantic Salmon collapsed due to overconsumption, and a variety of other factors (Winsor et al. ,2012). Atlantic Salmon are now extent from 84% of the rivers in North America that they were once found in (Veterinary Medicine Advisory Committee,2015). These steep downward trends are not only isolated to the North American Continent, as populations have also significantly fallen in the Europe as well.
As shown by the figure above, populations of Atlantic Salmon have declined significantly since the 1970’s. This is true particularly in the North Atlantic (Baltic Sea) populations, where the prefishery abundance has declined over 50%. While not as severe, the overall populations of Atlantic salmon have declined significantly.
Pacific salmon are of the family Oncorhynchus. In this family there are of 7 salmon species, 5 of which are found in North America. Pacific Salmon fishing in the North America’s began
likely 9000 years ago (Lichatowich & Lichatowich, 2001). The first style of fishing methods normally involved using dip nets (pictured left), and catching salmon as they returned from the the sea to spawn. At first, salmon was not highly significant in the diets of North American natives but as time went on many communities became reliant on salmon as a staple food sources. It has been documented that some communities had more 90% of their food remains comprised of salmon, demonstrating its extreme importance in some areas (Lichatowich & Lichatowich, 2001). The importance of Salmon can also be documented in its appearance in indigenous art throughout it history as a food.
Salmon played an integral role in the development of culture and economies throughout the western part of the united states. By drying or smoking salmon, a stable year round protein source was achievable. This stable protein source allowed for larger populations and improved the overall quality of life in these areas, as people had a stable source of food. This helped lead to diversification of economies and cultural development. (Lichatowich & Lichatowich, 2001).
Salmon have been extensively fished for many years by native peoples living of the west coast, but with the influence of industrialization and westward movement fishing practices became much more targeted and efficient. In the 1860’s canning operations were developed throughout the coastlines of the western North American Continent (Longo et al., 2014). These canneries allowed Pacific salmon to be shipped further and consumed by more people, increasing the demand. In late 1890s, the fish wheel was introduced, a highly effective method of fishing that could catch 20,000 pounds of salmon in a day (Longo et al., 2014). In addition to this new method, gillnets (a contraption that would catch the gills of passing salmon) were used to catch vast numbers of salmon as they returned to their streams (Longo et al.,2014). These methods caused entire fisheries of salmon to collapse, as no salmon were able to return to spawn. The return of spawners of all Pacific salmon dropped steadily until the the 1920’s, stagnating until another collapse in the 1970s that continued to the 1990s. Today, only 16% of Salmon populations in the Pacific Northwest are considered to be stable (Longo et al., 2014).
Threats to Salmon today:
Salmon face many threats in today’s world. The most pressing of these include, loss of genetic variation and habitat degradation. Salmon rely on pristine environments in order to be able to grow and return to spawn. After spending time in the oceans, it is imperative that they be able to return to their original streams to spawn. If they are unable to return due to damming or habitat destruction they will not spawn and will die without contributing to the next generation. This caused a great deal of problems with damming in both the Atlantic and Pacific regions. In the Columbia river basin, one of the most heavily dammed watersheds in the world, and estimated 1/3 of salmon habitat is blocked off completely (Longo et al., 2014). Not only this, but logging efforts, climate change and overall habitat degradation has vastly decreased the quality of the Salmon environments worldwide. Logging is a major issue for Salmon, and has been since commercial logging began. In the early to mid 19th century habitat degradation as a result of damming and logging contributed significantly to the decline of salmon populations in the New England area (Veterinary Advisory Committee, 2015). Logging causes an increase in water temperature, lower water quality, and disrupts to overall natural environment of the stream. The effects cause the loss of Salmon fry and lower population numbers overall. In addition to the direct threat of habitat degradation, climate change is a also concern for wild Salmon. Lower snowpack levels mean lower flows for Salmon that return to spawn in the spring and fall, and mean that less spawning habitat is available for spawning and hatching fry (Battin, 2007). Increased water temperature, as a result of climate change, is also a major issue, and could result in the loss of significant amounts of spawning habitat (Battin, 2007).
When populations of Salmon were first threatened, hatchery fish, or fish that were raised in hatcheries then released to streams were introduced. In both the Atlantic and Pacific a vast number of Salmon are produced in hatcheries and then released into the wild. In the Pacific Northwest they are more hatchery raised salmon than wild stocks of salmon (Longo et al., 2014). Hatchery fish were introduced originally to serve as a supplement to the loss of wild stocks. The introduction of hatchery fish brought with it its own host of problems. Not only do the hatchery salmon endanger the genetic variation of salmon that allows them to be resilient to many different factors; including disease and environmental threats, but it also causes density problems that increase wild fish mortality (Levin, 2001). Increases in wild fish mortality is caused by the vast number of hatchery fish that are released at similar times which causes a massive influx of population into the oceans. This increases ocean based mortality due to the limitations in the resources with such high stock density (Levin, 2001). This means that stock fish are a main contributor to higher levels of wild fish mortality at sea.
Overall salmon have many threats that they face that have helped to cause steed declines in the number of spawning salmon, and the overall populations of wild stocks of salmon worldwide. The problems of salmon are complex and there have been many attempts to continue to have enough salmon to satisfy the growing demands of the world populations. One example of this includes the farming of Atlantic salmon currently taking place in Chile, a special focus on this issue can be found here.
Biography of Sarah Smith-Tripp
Sarah Smith-Tripp is a first-year at Wellesley College. She enjoys biology and environmental studies. She hopes to major in biology and minor in public health and society. She is on crew, a member of Wellesley Environmental Defense, and Regeneration (a farming co-op). In her free time, she enjoys climbing mountains, swimming in cold streams, and going on adventures.
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