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75-462: Standing 538 ft (164 m) high, Trinity Dam forms Trinity Lake – California's third largest reservoir, with a capacity of more than 2,400,000 acre-feet (3,000,000  dam ). The dam includes a hydroelectric plant, and also provides flood control to the Trinity and Klamath river basins. Below the dam is Lewiston Lake , formed by a second dam, which diverts water through a 10.7 mile tunnel to

150-501: A common ancestor . The Eocene salmon's fossil from British Columbia provides evidence that the divergence between Pacific and Atlantic salmon had not yet occurred 40 million years ago. Both the fossil record and analysis of mitochondrial DNA suggest the divergence occurred 10 to 20 million years ago during the Miocene . This independent evidence from DNA analysis and the fossil record indicate that salmon divergence occurred long before

225-443: A capacity of 24,000 cu ft/s (680 m/s), and the service spillway, a morning-glory (bell-mouth) design, can take 22,400 cu ft/s (630 m/s) of water. The dam's auxiliary spillway has a capacity of 2,250 cu ft/s (64 m/s). Trinity Lake can hold up to 2,447,650 acre-feet (3,019,130  dam ) at full pool, and encompasses up to 17,722 acres (7,172 ha) of water. Trinity Powerplant, located at

300-442: A few species of salmon remain in fresh water throughout their life cycle, the majority are anadromous and migrate to the ocean for maturation: in these species, smolts spend a portion of their out-migration time in brackish water, where their body chemistry becomes accustomed to osmoregulation in the ocean. This body chemistry change is hormone-driven, causing physiological adjustments in the function of osmoregulatory organs such as

375-473: A fish returns after just one year's sea feeding, it is called a grilse in Canada, Britain, and Ireland. Grilse may be present at spawning, and go unnoticed by large males, releasing their own sperm on the eggs. Prior to spawning, depending on the species , salmon undergo changes. They may grow a hump, develop canine-like teeth, or develop a kype (a pronounced curvature of the jaws in male salmon). All change from

450-569: A high demand for wild forage fish . As a predator, salmon require large nutritional intakes of protein , and farmed salmon consume more fish than they generate as a final product. On a dry weight basis, 2–4 kg of wild-caught fish are needed to produce one kilogram of salmon. As the salmon farming industry expands, it requires more forage fish for feed, at a time when 75% of the world's monitored fisheries are already near to or have exceeded their maximum sustainable yield . The industrial-scale extraction of wild forage fish for salmon farming affects

525-532: A lot of work on Henneguya salminicola was done by scientists at the Pacific Biological Station in Nanaimo in the mid-1980s, in particular, an overview report which states, "the fish that have the longest fresh water residence time as juveniles have the most noticeable infections. Hence in order of prevalence , coho are most infected followed by sockeye, chinook, chum and pink. As well, the report says, at

600-412: A technically demanding kind of sport fishing , not necessarily intuitive for beginning fishermen. A conflict exists between commercial fishermen and recreational fishermen for the right to salmon stock resources . Commercial fishing in estuaries and coastal areas is often restricted so enough salmon can return to their natal rivers where they can spawn and be available for sport fishing. On parts of

675-836: Is a major contributor to the world production of farmed finfish, representing about US$ 10 billion annually. Other commonly cultured fish species include tilapia , catfish , sea bass , carp and bream . Salmon farming is significant in Chile , Norway , Scotland , Canada and the Faroe Islands ; it is the source for most salmon consumed in the United States and Europe. Atlantic salmon are also, in very small volumes, farmed in Russia and Tasmania , Australia. Salmon are carnivorous , and need to be fed meals produced from catching other wild forage fish and other marine organisms. Salmon farming leads to

750-680: Is derived from Middle English : samoun , samon and saumon , which in turn are from Anglo-Norman : saumon , from Old French : saumon , and from Latin : salmō (which in turn might have originated from salire , meaning "to leap". ). The unpronounced "l" absent from Middle English was later added as a Latinisation to make the word closer to its Latin root. The term salmon has mostly displaced its now dialectal synonym lax , in turn from Middle English : lax , from Old English : leax , from Proto-Germanic : * lahsaz from Proto-Indo-European : *lakso- . The seven commercially important species of salmon occur in two genera of

825-441: Is quite high (perhaps as high as 40 to 50%). To lay her roe , the female salmon uses her tail (caudal fin), to create a low-pressure zone, lifting gravel to be swept downstream, excavating a shallow depression, called a redd. The redd may sometimes contain 5,000 eggs covering 2.8 m (30 sq ft). The eggs usually range from orange to red. One or more males approach the female in her redd, depositing sperm, or milt, over

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900-448: Is sent to other water customers that live throughout the State. This is important because this requires the help of two dams just to move water from the reservoir to the customers that require water for either Agriculture or Urban uses. With 145 miles (233 km) of shoreline, Trinity Lake is a popular summer destination for Northern California residents. Since 1965, the lake has been part of

975-624: Is serviced by three marinas: Trinity Alps Marina located on the southern end in view of the Dam; Cedar Stock marina on the Stuart Fork arm on the west end of the lake; and Trinity Center marina at the northern end of the main arm of the lake. Most of the marinas rent houseboats to vacationers year round. Trinity Lake is located northwest of Redding , off of Highway 299 north-northeast of the Gold Rush mining town of Weaverville . The Alpine scenery surrounding

1050-946: Is strictly a fish parasite that cannot live in or affect warm blooded animals, including man". According to Klaus Schallie, Molluscan Shellfish Program Specialist with the Canadian Food Inspection Agency , " Henneguya salminicola is found in southern B.C. also and in all species of salmon. I have previously examined smoked chum salmon sides that were riddled with cysts and some sockeye runs in Barkley Sound (southern B.C., west coast of Vancouver Island ) are noted for their high incidence of infestation." Sea lice , particularly Lepeophtheirus salmonis and various Caligus species, including C. clemensi and C. rogercresseyi , can cause deadly infestations of both farm-grown and wild salmon. Sea lice are ectoparasites which feed on mucus, blood, and skin, and migrate and latch onto

1125-481: Is the common name for several commercially important species of euryhaline ray-finned fish from the genera Salmo and Oncorhynchus of the family Salmonidae , native to tributaries of the North Atlantic ( Salmo ) and North Pacific ( Oncorhynchus ) basins. Other closely related fish in the same family include trout , char , grayling , whitefish , lenok and taimen , all coldwater fish of

1200-476: Is under development in Alaska . There, the young salmon are released into the ocean far from any wild salmon streams. When it is time for them to spawn, they return to where they were released, where fishermen can catch them. An alternative method to hatcheries is to use spawning channels. These are artificial streams , usually parallel to an existing stream, with concrete or rip-rap sides and gravel bottoms. Water from

1275-458: The Central Valley with water for irrigation and produces hydroelectric power. This lake is known for its many small arms, glassy inlets, and good water-skiing conditions. After the death in office of California United States Senator Clair Engle in 1964, the lake was renamed after him. The name change never received wide popularity and the name was returned to the original name. The lake

1350-610: The Cook Inlet Aquaculture Association , as a way to increase salmon populations in situations where they have declined due to overharvesting , construction of dams and habitat destruction or fragmentation . Negative consequences to this sort of population manipulation include genetic "dilution" of the wild stocks. Many jurisdictions are now beginning to discourage supplemental fish planting in favour of harvest controls, and habitat improvement and protection. A variant method of fish stocking , called ocean ranching,

1425-484: The Japanese word for trout. On the other hand, the steelhead and sea trout , the anadromous forms of rainbow trout and brown trout respectively, are from the same genera as salmon and live identical migratory lives, but neither is termed "salmon" . The extinct Eosalmo driftwoodensis , the oldest known Salmoninae fish in the fossil record , helps scientists figure how the different species of salmon diverged from

1500-518: The Pacific Northwest and Alaska , salmon are keystone species . The migration of salmon represent a massive retrograde nutrient transfer, rich in nitrogen , sulfur , carbon and phosphorus , from the ocean to the inland freshwater ecosystems . Predation by piscivorous land animals (such as ospreys , bears and otters ) along the journey serve to transfer the nutrients from the water to land, and decomposition of salmon carcass benefits

1575-456: The Pacific coast of Canada , the louse-induced mortality of pink salmon in some regions is commonly over 80%. The risk of injury caused by underwater pile driving has been studied by Dr. Halvorsen and her co-workers. The study concluded that the fish are at risk of injury if the cumulative sound exposure level exceeds 210 dB relative to 1 μPa s. As can be seen from the production chart at

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1650-504: The Quaternary glaciation began the cycle of glacial advance and retreat. There are several other species of fish which are colloquially called "salmon" but are not true salmon. Of those listed below, the Danube salmon or huchen is a large freshwater salmonid closely related (from the same subfamily) to the seven species of salmon above, but others are fishes of unrelated orders , given

1725-654: The Salmo and Oncorhynchus genera also contain a number of trout species informally referred to as salmon. Within Salmo , the Adriatic salmon ( Salmo obtusirostris ) and Black Sea salmon ( Salmo labrax ) have both been named as salmon in English , although they fall outside the generally recognized seven salmon species. The masu salmon ( Oncorhynchus masou ) is actually considered a trout ("cherry trout") in Japan , with masu actually being

1800-637: The Trinity Dam and located in Trinity County, California , United States. The dam was built by the U.S. Bureau of Reclamation . The lake's capacity is 2,447,650  acre⋅ft (3,019.13  GL ), making it one of the largest reservoirs in California . The lake's surface is at 2,370 ft (720 m) above MSL. Trinity Lake captures and stores water for the Central Valley Project , which provides

1875-585: The Yurok and Hupa (Hoopa). Both tribes have reservation lands in the area. Trinity Lake is less used by vacationers than the lower Lake Shasta due in part to the lengthy winding road up from the valley floor. Typical drive time from Redding (Interstate 5) to the lake is about 90 minutes along a winding mountain road. This makes it a destination spot for fishing and water sports. Popular fishing includes that of smallmouth and largemouth bass , catfish , kokanee , rainbow and brown trout . Fish remain ample, despite

1950-497: The forest ecosystem . In the case of Pacific salmon , most (if not all) of the salmon that survive to reach the headwater spawning grounds will die after laying eggs and their dead bodies sink to cover the gravel beds, with the nutrients released from the biodegradation of their corpses providing a significant boost to these otherwise biomass -poor shallow streams. Grizzly bears function as ecosystem engineers , capturing salmon and carrying them into adjacent dry land to eat

2025-524: The myrtle zone . These dams can be overtopped at high tide and hold water at low tide. This provides refuges for juvenile salmon so they do not have to swim into large channels where they are subject to predation by larger fish. It has been discovered that rivers which have seen a decline or disappearance of anadromous lampreys , loss of the lampreys also affects the salmon in a negative way. Like salmon, anadromous lampreys stop feeding and die after spawning, and their decomposing bodies release nutrients into

2100-590: The otolith (annuli), analogous to the growth rings visible in a tree trunk. Freshwater growth shows as densely crowded rings, sea growth as widely spaced rings; spawning is marked by significant erosion as body mass is converted into eggs and milt. Freshwater streams and estuaries provide important habitat for many salmon species. They feed on terrestrial and aquatic insects , amphipods , and other crustaceans while young, and primarily on other fish when older. Eggs are laid in deeper water with larger gravel and need cool water and good water flow (to supply oxygen) to

2175-610: The subarctic and cooler temperate regions with some sporadic endorheic populations in Central Asia . Salmon are typically anadromous : they hatch in the shallow gravel beds of freshwater headstreams and spend their juvenile years in rivers , lakes and freshwater wetlands , migrate to the ocean as adults and live like sea fish , then return to their freshwater birthplace to reproduce . However, populations of several species are restricted to fresh waters (i.e. landlocked) throughout their lives. Folklore has it that

2250-826: The subfamily Salmoninae . The genus Salmo contains the Atlantic salmon , found in both sides of the North Atlantic , as well as more than 40 other species commonly named as trout . The genus Oncorhynchus contains 12 recognised species which occur naturally only in the North Pacific, six of which are known as Pacific salmon while the remainder are considered trout. Outside their native habitats, Chinook salmon have been successfully introduced in New Zealand and Patagonia , while coho , sockeye and Atlantic salmon have been established in Patagonia, as well.     Both

2325-546: The Central Valley Project came to fruition in 1961 with the completion of Trinity Dam. The lake was renamed Clair Engle Lake from 1964 to 1997. It was eventually renamed Trinity Lake. The lake was completely filled with water from the Trinity River by 1963 and is the third largest lake in California with 145 miles (233 km) of shoreline. The area is the ancestral lands of several Native American tribes, most notably

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2400-468: The North American West Coast salmon sport fishing has completely replaced inshore commercial salmon fishing. In most cases, the commercial value of a salmon sold as seafood can be several times less than the value attributed to the same fish caught by a sport fisherman. This is "a powerful economic argument for allocating stock resources preferentially to sport fishing". Salmon aquaculture

2475-558: The Pacific Ocean, the second host releases a stage infective to salmon. The parasite is then carried in the salmon until the next spawning cycle. The myxosporean parasite that causes whirling disease in trout has a similar life cycle. However, as opposed to whirling disease, the Henneguya infestation does not appear to cause disease in the host salmon—even heavily infected fish tend to return to spawn successfully. According to Dr. Kieser,

2550-608: The Sacramento Valley. In response to the Great Depression and drought conditions in California during the early 20th century, the United States Congress passed the 1935 Rivers and Harbors Act , which authorized the Central Valley Project (CVP) – a system of dams and canals to provide a stable supply of irrigation water to California's Central Valley . Among the project works was a 1942 proposal to divert water from

2625-566: The Trinity River in northwestern California to augment water supplies in the CVP service area, known as the Trinity River Division. However, the state dropped the Trinity River project from the CVP in 1945. Six years later, however, the U.S. Bureau of Reclamation (USBR), which was responsible for the construction and operations of most CVP facilities, revived the division, which comprised a system of four dams and two tunnels to capture and store

2700-679: The Trinity Unit of the Whiskeytown-Shasta-Trinity National Recreation Area . The lake has been developed with boat ramps and marinas, most of which are concentrated in the Stuart Fork arm in the southwest and around the resort town of Trinity Center near the north end of the reservoir. Trinity Lake Trinity Lake , previously called Clair Engle Lake , is a reservoir on the Trinity River formed by

2775-800: The USBR built the Trinity River Fish Hatchery. The hatchery is operated by the California Department of Fish and Game and has a capacity of 40 million eggs. In 1992, Congress passed the Central Valley Project Improvement Act, which established a minimum annual release of 340,000 acre-feet (420,000  dam ) into the lower Trinity River. Also, below the Trinity Dam, is the Lewiston Dam (California) in which that water

2850-417: The United States. As the reservoir filled, it submerged the pioneer towns of Trinity Center, Stringtown and Minersville as well as parts of a historic Northern California stagecoach route. The reservoir was originally named Clair Engle Lake after Clair Engle , a United States senator and major proponent of the CVP. This name was unpopular among local residents, many of whom had watched their homes inundated by

2925-432: The adjacent stream is piped into the top of the channel, sometimes via a header pond, to settle out sediment. Spawning success is often much better in channels than in adjacent streams due to the control of floods, which in some years can wash out the natural redds. Because of the lack of floods, spawning channels must sometimes be cleaned out to remove accumulated sediment. The same floods that destroy natural redds also clean

3000-478: The base of the dam, has two Francis turbines with a capacity of 140 megawatts (MW) combined, uprated from an original capacity of 100 MW. The plant generates an average of 358.97 million kilowatt hours (kWh) and has a low capacity factor , which means it operates mainly on a peaking basis. Trinity Dam forms an impassable barrier for migrating salmon in the Trinity River, but along with other division facilities has also had adverse impacts on salmon habitat in

3075-608: The common name "salmon" simply due to similar shapes, behaviors and niches occupied: Salmon eggs are laid in freshwater streams typically at high latitudes. The eggs hatch into alevin or sac fry. The fry quickly develop into parr with camouflaging vertical stripes. The parr stay for six months to three years in their natal stream before becoming smolts, which are distinguished by their bright, silvery colour with scales that are easily rubbed off. Only 10% of all salmon eggs are estimated to survive to this stage. The smolt body chemistry changes, allowing them to live in salt water. While

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3150-430: The developing embryos. Mortality of salmon in the early life stages is usually high due to natural predation and human-induced changes in habitat, such as siltation, high water temperatures, low oxygen concentration, loss of stream cover, and reductions in river flow. Estuaries and their associated wetlands provide vital nursery areas for the salmon prior to their departure to the open ocean. Wetlands not only help buffer

3225-472: The elimination of beavers from large parts of the river system, salmon runs plummeted, even in the absence of many of the factors usually associated with the demise of salmon runs. Salmon recruitment can be affected by beavers' dams because dams can: Beaver dams are able to nurture salmon juveniles in estuarine tidal marshes where the salinity is less than 10 ppm. Beavers build small dams of generally less than 60 cm (2 ft) high in channels in

3300-821: The estuary from silt and pollutants, but also provide important feeding and hiding areas. Salmon not killed by other means show greatly accelerated deterioration ( phenoptosis , or "programmed aging") at the end of their lives. Their bodies rapidly deteriorate right after they spawn as a result of the release of massive amounts of corticosteroids . Salmon are mid- level carnivores whose diet change according to their life stage. Salmon fry predominantly feed upon zooplanktons until they reach fingerling sizes, when they start to consume more aquatic invertebrates such as insect larvae , micro crustaceans and worms . As juveniles (parrs), they become more predatory and actively prey upon aquatic insects , small crustaceans, tadpoles and small bait fishes . They are also known to breach

3375-432: The fish return to the exact stream where they themselves hatched to spawn , and tracking studies have shown this to be mostly true. A portion of a returning salmon run may stray and spawn in different freshwater systems; the percent of straying depends on the species of salmon. Homing behavior has been shown to depend on olfactory memory . Salmon are important food fish and are intensively farmed in many parts of

3450-443: The fish. There they deposit nutrient-rich urine and feces and partially eaten carcasses. Bears preparing for hibernation tend to preferentially consume the more nutrient- and energy -rich salmon roes and brain over the actual flesh , and are estimated to discard up to half the salmon they've harvested uneaten on the forest floor, in densities that can reach 4,000 kg (8,800 lb) per hectare, providing as much as 24% of

3525-520: The flow of the Trinity and transport it to the Sacramento River , generating a net surplus of hydroelectric power along the way. Trinity Dam was to be the main storage feature of the division, providing a stable flow to the Lewiston Dam , the diversion point for Trinity River waters into the Central Valley. Construction at Trinity Dam began on June 4, 1956 with preliminary excavation and the river

3600-566: The gills, which leads to large increases in their ability to secrete salt. Hormones involved in increasing salinity tolerance include insulin-like growth factor I , cortisol , and thyroid hormones , which permits the fish to endure the transition from a freshwater environment to the ocean. The salmon spend about one to five years (depending on the species) in the open ocean, where they gradually become sexually mature. The adult salmon then return primarily to their natal streams to spawn. Atlantic salmon spend between one and four years at sea. When

3675-642: The lake makes up the Trinity Alps. The Alps were formed in the late Jurassic Period by volcanic activity in the form of ultramafic and granitic plutons (igneous rock formed from super-heated magma cooling under the surface of the earth), and tectonic activity (the super continent of Pangaea was beginning to pull apart into two separate super-sized continents) and glaciation during frigid climate periods known as ice ages (land surface modified by action of glaciers). The last remaining glaciers are on Thompson’s peak, at more than 9,000 feet (2,700 m). The lake bed

3750-547: The lake remain strong. Black bears are common, so proper precautions must be taken to secure campsites, throw away garbage and store food safely. Additional wildlife includes bobcats , mountain lions and many different bird species. The lake contains land-locked populations of kokanee salmon and king salmon, along with more typical California lake species such as largemouth and smallmouth bass, rainbow trout and catfish. Salmon all other members of Salmoninae Salmon ( / ˈ s æ m ən / ; pl. : salmon)

3825-488: The lake, visitors enjoy hiking and camping in the pristine wilderness of the Trinity Alps and the Shasta-Trinity National Forest. There has been a dramatic decline in various fish species in the river since the dams were built and the lake created. Spawning steelhead , Chinook and Coho Salmon populations have all been affected by their loss of spawning ground. However, wildlife populations surrounding

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3900-681: The left, the global capture reported by different countries to the FAO of commercial wild salmon has remained fairly steady since 1990 at about one million tonnes per year. This is in contrast to farmed salmon (below) which has increased in the same period from about 0.6 million tonnes to well over two million tonnes. Nearly all captured wild salmon are Pacific salmon . The capture of wild Atlantic salmon has always been relatively small, and has declined steadily since 1990. In 2011 only 2,500 tonnes were reported. In contrast, about half of all farmed salmon are Atlantic salmon. Recreational salmon fishing can be

3975-458: The longer the fish remain in fresh water, and they then deteriorate further after they spawn, when they are known as kelts. In all species of Pacific salmon, the mature individuals die within a few days or weeks of spawning, a trait known as semelparity . Between 2 and 4% of Atlantic salmon kelts survive to spawn again, all females. However, even in those species of salmon that may survive to spawn more than once ( iteroparity ), postspawning mortality

4050-474: The lower reaches of the river. Within ten years of the dam's completion, more than three-quarters of Trinity River water was being diverted to the Central Valley each year, and the little flow left in the river was warm, shallow and less suitable for spawning salmon. In addition, the dam blocks the Trinity River's annual floods and sediment loads, leading to degradation in the gravel bars that are vital for salmon habitat. In response to declining salmon populations,

4125-500: The negative impact that the dams have had on spawning ground in part due to the Trinity River Fish Hatchery, located just below Lewiston Dam . The California Office of Environmental Health Hazard Assessment (OEHHA) has developed a safe eating advisory for fish caught in Trinity Lake based on levels of mercury or PCBs found in local species. House boating, speed boating, and waterskiing are also popular lake activities. Surrounding

4200-446: The parasitic infection into a number of cysts that contain milky fluid. This fluid is an accumulation of a large number of parasites. Henneguya and other parasites in the myxosporean group have complex life cycles, where the salmon is one of two hosts. The fish releases the spores after spawning. In the Henneguya case, the spores enter a second host, most likely an invertebrate, in the spawning stream. When juvenile salmon migrate to

4275-517: The preferred prey of seals and sea lions, which can eat 30 lampreys to every salmon, allowing more adult salmon to enter the rivers to spawn without being eaten by the marine mammals. According to Canadian biologist Dorothy Kieser, the myxozoan parasite Henneguya salminicola is commonly found in the flesh of salmonids. It has been recorded in the field samples of salmon returning to the Haida Gwaii Islands . The fish responds by walling off

4350-408: The problems of rising costs for buying hatchery fish feed . Yet another attractive alternative is the increased use of seaweed . Seaweed provides essential minerals and vitamins for growing organisms. It offers the advantage of providing natural amounts of dietary fiber and having a lower glycemic load than grain-based fish meal . In the best-case scenario, widespread use of seaweed could yield

4425-466: The regular streams. Spawning channels preserve the natural selection of natural streams, as there is no benefit, as in hatcheries, to use prophylactic chemicals to control diseases. Farm-raised salmon are fed the carotenoids astaxanthin and canthaxanthin to match their flesh colour to wild salmon to improve their marketability. Wild salmon get these carotenoids , primarily astaxanthin, from eating shellfish and krill . One proposed alternative to

4500-449: The rising waters. By 1995, it had been renamed Trinity Lake. Trinity Dam is an earth and rock-filled dam composed mainly of river gravel and local rock, rising 538 ft (164 m) from its foundations and 440 ft (130 m) above the riverbed. The dam's crest is 2,450 ft (750 m) long and 2,395 ft (730 m) above sea level. High water releases are controlled by three different sets of gates. The outlet works have

4575-407: The roe. The female then covers the eggs by disturbing the gravel at the upstream edge of the depression before moving on to make another redd. The female may make as many as seven redds before her supply of eggs is exhausted. Each year, the fish experiences a period of rapid growth, often in summer, and one of slower growth, normally in winter. This results in ring formation around an earbone called

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4650-503: The salmon population. This system is referred to as ranching . It was very common in countries such as Sweden, before the Norwegians developed salmon farming, but is seldom done by private companies. As anyone may catch the salmon when they return to spawn, a company is limited in benefiting financially from their investment. Because of this, the ranching method has mainly been used by various public authorities and non-profit groups, such as

4725-421: The silvery blue of a fresh-run fish from the sea to a darker colour. Salmon can make amazing journeys, sometimes moving hundreds of miles upstream against strong currents and rapids to reproduce. Chinook and sockeye salmon from central Idaho, for example, travel over 1,400 km (900 mi) and climb nearly 2,100 m (7,000 ft) from the Pacific Ocean as they return to spawn. Condition tends to deteriorate

4800-546: The skin of wild salmon during free-swimming, planktonic nauplii and copepodid larval stages, which can persist for several days. Large numbers of highly populated, open-net salmon farms can create exceptionally large concentrations of sea lice; when exposed in river estuaries containing large numbers of open-net farms, many young wild salmon are infected, and do not survive as a result. Adult salmon may survive otherwise critical numbers of sea lice, but small, thin-skinned juvenile salmon migrating to sea are highly vulnerable. On

4875-458: The stream. Also, along with species like rainbow trout and Sacramento sucker , lampreys clean the gravel in the rivers during spawning. Their larvae, called ammocoetes, are filter feeders which contribute to the health of the waters. They are also a food source for the young salmon, and being fattier and oilier, it is assumed predators prefer them over salmon offspring, taking off some of the predation pressure on smolts. Adult lampreys are also

4950-534: The survivability of other wild predatory fish which rely on them for food. Research is ongoing into sustainable and plant-based salmon feeds. Intensive salmon farming uses open-net cages, which have low production costs. It has the drawback of allowing disease and sea lice to spread to local wild salmon stocks. Another form of salmon production, which is safer but less controllable, is to raise salmon in hatcheries until they are old enough to become independent. They are released into rivers in an attempt to increase

5025-488: The time the studies were conducted, stocks from the middle and upper reaches of large river systems in British Columbia such as Fraser , Skeena , Nass and from mainland coastal streams in the southern half of B.C., "are more likely to have a low prevalence of infection." The report also states, "It should be stressed that Henneguya , economically deleterious though it is, is harmless from the view of public health . It

5100-467: The total nitrogen available to the riparian woodlands . The foliage of spruce trees up to 500 m (1,600 ft) from a stream where grizzlies fish salmon have been found to contain nitrogen originating from the fished salmon. Beavers also function as ecosystem engineers; in the process of tree-cutting and damming , beavers alter the local ecosystems extensively. Beaver ponds can provide critical habitat for juvenile salmon . An example of this

5175-597: The use of wild-caught fish as feed for the salmon, is the use of soy -based products. This should be better for the local environment of the fish farm, but producing soy beans has a high environmental cost for the producing region. The fish omega-3 fatty acid content would be reduced compared to fish-fed salmon. Another possible alternative is a yeast-based coproduct of bioethanol production, proteinaceous fermentation biomass. Substituting such products for engineered feed can result in equal (sometimes enhanced) growth in fish. With its increasing availability, this would address

5250-417: The water to attack terrestrial insects such as grasshoppers and dragonflies , as well as consuming fish eggs (even those of other salmon). As adults, salmon behave like other mid-sized pelagic fish , eating a variety of sea creatures including smaller forage fish such as lanternfish , herrings , sand lances , mackerels and barracudina . They also eat krill , squid and polychaete worms . In

5325-568: The world, with Norway being the world's largest producer of farmed salmon, followed by Chile . They are also highly prized game fish for recreational fishing , by both freshwater and saltwater anglers . Many species of salmon have since been introduced and naturalized into non-native environments such as the Great Lakes of North America , Patagonia in South America and South Island of New Zealand . The Modern English term salmon

5400-461: Was diverted around the dam site on July 8, 1957. Work was bogged down in late 1957 when the river flooded and took out the cofferdam that protected the construction site. However, workers cleared out the dam site by the summer of 1958, and the hiatus also allowed them time to line the diversion tunnel with concrete. Rock placement began on the main structure as early as 1957, but it was not until 1959 when an 11,000 ft (3,400 m) conveyor belt

5475-506: Was incorporated, allowing much faster transport of fill to the dam site. The spillway tunnel was completed in October 1959 and the embankment was topped out in late 1960. The dam's power plant, however, was not finished until December 1963. Trinity stood as the highest earthfill dam in the world until eclipsed by the Oroville Dam , also in California, in 1968. The latter remains the tallest dam in

5550-449: Was originally a series of deep valleys in the Alps. The discovery of gold in 1848 prompted hundreds of miners to move into the area. In 1958, a plan to divert water from Trinity River to California’s Central Valley led to the construction of Trinity Dam and the creation of Trinity Lake. This project was also designed to provide hydroelectric power to the local area. The Trinity River Division of

5625-621: Was seen in the years following 1818 in the Columbia River Basin. In 1818, the British government made an agreement with the U.S. government to allow U.S. citizens access to the Columbia catchment (see Treaty of 1818 ). At the time, the Hudson's Bay Company sent word to trappers to extirpate all furbearers from the area in an effort to make the area less attractive to U.S. fur traders. In response to

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