Dolly Varden use tactile senses when spawning and to detect current. They also use chemical senses like smell and taste when hunting or eating. Schutz, Dolly Varden are opportunistic feeders whose feeding behavior and diet depends primarily on their habitat and season.
In lakes, they have been observed eating plankton when there are no smaller fish on which to prey. Adults in rivers and streams typically hunt near the faster-moving water and eat small fish or insects. Often when they are found in eddies and deeper pools, they consume crustaceans, salmonids' eggs and other small fish. They will also feed on the surface of the water, striking winged insects that fall into the water. Fly fishermen tie "flies" to mimic winged insects as lures often when fishing for Dolly Varden.
They will also consume any larvae of mayflies and midges. Northern form adult Dolly Varden make feeding sea-runs every 9 or 20 months, depending on food availability, where they may follow pink salmon Oncorhynchus gorbuscha into rivers to feed on their eggs. They primarily scavenge these eggs rather than attack them as direct predators. They mainly consume the eggs and fry that drift away downstream that would most likely not survive.
Juveniles hatch in slow-moving fresh water and initially consume the nutrients from their soft embryotic egg shell. Once they have exhausted that resource, they feed in slow-moving water, eating worms, mayfly larvae and juvenile insects that inhabit the sediment often under stones and in mud.
Often times juveniles forage very close to the bank rather than in the middle of the stream or river. Dolly Varden are prey of northern river otters Lontra canadensis.
In southeastern Alaska, during the late spring, Dolloff reported northern river otters eating hundreds of fish in a day and thousands over a six-week period. Many of these fish are Dolly Varden. Other fish in streams or rivers also can prey on juvenile Dolly Varden. They can also be prey of some birds such as white-tailed eagles Haliaeetus albicilla to the subspecies of Dolly Varden that resides in Russia and Japan.
Adult Dolly Varden avoid predation due to their dark greenish-blue camouflaged dorsal side, which matches the sediment or rocks from above. Dolloff, Dolly Varden are the apex predator of their freshwater habitats. While they are in the saltwater however they are vulnerable to bigger predators and fall into a larger food web than in freshwater. Dolly Varden are also vulnerable to many parasites. The protozoan parasites include Trichodina truttae and Tripartiella californica.
The trematode parasites include Aonurus. Brachyphallus crenatus , Buphalopsis gracilescens , Bucephalopsis ozarkii , Crepidostomum cooperi , Crepidostomim farionis , Derogenes varicus , Discocotyle salmonis , Genarches mulleri , Hemiurus levinseni , Lecithaster gibbosus , Lecithaster salmonis , Prosorhynchus crucibulum , Tetraconchus alaskensis and Tetraconchus borealis. Cestodes include Cyathocephalus truncates , Eubothrium crassum , Eubothrium salvelini , Nybeliniasurmincola , Pelichnibothrium speciosum , Phyllobothrium , Proteocephalus salmonidicola and Scolex pleuronectis.
Nematode parasites include Ascarophis malmae , Bulbodacnitis globose , Contracaecum aduncum , Contracaecum , Cucullanus laevis , Cystidicola farionis , Dacnitis truttae , Eustrongylides , Hepaticola bakeri , Metabronema canadense , Metabronema salvelini , Philonema oncorhynchi , Rhabdochona amago and Rhabdochona salvelini.
Acanthocephalan parasites include Echinorhynchus coregoni , Echinorhynchus leidyi , Neoechinorhynchus rutill , Neoechinorhynchus and Rhadinorhynchoides mijagawai. Crustacean parasites include Lepeophtheirus salmonis , Salmincola bicauliculata , Salmincola edwardsii , Salmincola falculata , Salmincola gibber , Salmincola siscowet and Salmincola smirnova.
Hoffman, Dolly Varden are one of Alaska's most sought-after game fish. There are massive tourism industries for recreational fishing in Alaska. Dolly Varden add to this industry tremendously by attracting anglers from around the world to come to Alaska to catch them. Sea-run Dolly Varden are harvested every year on their migration to the sea for food by some locals.
In the mid 's, one record states before Alaska was a state that 86, kg were harvested in a single year. However since the 's the harvest of Dolly Varden has dropped drastically in order to preserve their population and fuel tourism.
There are no negative economic impacts of Dolly Varden char on humans. According the State of Michigan, Dolly Varden have no special status. On the US Federal list, Dolly Varden are marked as "Proposed Similarity of Appearance Threatened " meaning they are similar in appearance to bull trout Salvelinus confluentus that are threatened.
Over-fishing can cause serious damage to the adult population and will consequently harm the spawn and future generations of Dolly Varden. No serious natural threats are known to harm Dolly Varden. Catch-and-release is a fishing practice that is strongly encouraged by Alaska's government and strict laws have been in place to prevent over-fishing since Alaska is the only state to have explicit conservation about fishing in its constitution. They operate on a strict "sustainable yield" harvest of wildlife including Dolly Varden.
These laws are enforced by the Alaska Department of Fish and Game. The Alaska Department of Fish and Game along with a variety of federal land management entities are responsible for managing and conserving Alaska's Dolly Varden. Dolly Varden are classified as char, although commonly referred to as trout. One distinguishing factor between trout and char is their difference in the spots on their dorsal side. Char have light spots such as white or yellow on a dark body while trout have dark spots brown to black on a light body.
This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.
Synapomorphy of the Bilateria. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals. Iteroparous animals must, by definition, survive over multiple seasons or periodic condition changes. Alaska Department of Fish and Game. Dolly Varden Salvelinus malma. Southcentral Alaska wild Dolly Varden. Division of Sport and Commercial Fisheries.
Southeast Alaska steelhead and Dolly Varden management. The Nature Conservancy. Anchorage, Alaska: The Nature Conservancy. Armstrong, R.
Baxter, J. Taylor, R. Devlin, J. Hagen, D. Evidence for natural hybridization between Dolly Varden Salvelinus malma and bull trout Salvelinus confluentus in a northcentral British Columbia watershed. DeCicco, F. Dolly Varden: Beautiful and misunderstood Dolly Varden's reputation as varmint undeserved. Alaska Fish and Wildlife News , May: 1. Dolloff, A. Effects of stream cleaning on juvenile coho salmon and Dolly Varden in southeast Alaska. Predation by river otters Lutra canadensis on juvenile coho salmon Oncorhynchus kisutch and Dolly Varden Salvelinus malma in southeast Alaska.
Haas, G. The systematics, zoogeography and evolution of Dolly Varden and bull trout in British Columbia. Henderson, M. Visual prey detection and foraging in sympatric cutthroat trout Salmo clarki clarki and Dolly Varden Salvelinus malma. Hoffman, G. Parasites of North American Freshwater Fishes. In spawning season, males are arrayed in brilliant pink, green, and orange and are among the more beautiful trophies of the north.
In the eastern Pacific, the species inhabits waters from Japan north to the Bering Sea. Attempts have been made to introduce Dolly Varden in California, Colorado, New Mexico, and Wyoming, but none of these attempts succeeded in establishing a sustaining population. In , inland forms of the Dolly Varden trout were reclassified as Salvelinus confluentus , retaining the common name bull trout.
The northern form is primarily anadromous, while the southern form can be stream-resident, lake dwelling, or anadromous. Because they are migratory, Dolly Varden can be found in a variety of habitats. In spring, they leave the large lakes where they winter and head for salt water, where they can be found in near-shore waters during summer months. There, they mingle with salmon and then follow the larger fish upstream, where the dollies can feed on salmon eggs.
Like all chars, Dolly Varden spawn in fall, returning to their natal streams as soon as they reach maturity age 5 to 9. Post-spawning mortality is high, with as many as 50 percent dying after their first spawn and very few spawning more than twice.
Young Dolly Varden spend two to four years in streams before migrating to the sea or to large lakes. They spend the rest of their lives migrating back and forth in often complicated patterns. Dollies may live up to 16 years, but specimens older than 10 years old are uncommon.
In a study released in October , scientists from the University of Washington revealed that anadromous Dolly Varden exhibit a behavior never seen before. They migrate to the ocean to feed for the first few years of their lives, but once they reach a certain weight, they return to fresh water for good.
Other small fish such as smelt, capelin, and sandlance, and juveniles of larger fish probably provide a substantial portion of the Dolly Varden's diet while they are at sea. During the salmon runs it is likely that salmon eggs are of great importance to the diet of both juvenile and adult Dolly Varden. Predators of the Dolly Varden are otters, bears, birds, beluga whales, seals, sea lions, other marine mammals, and humans.
In southwest Alaska, Dolly Varden spawn during the fall primarily in flowing water. In preparation for spawning, the male establishes a territory that he defends against other fish. Prior to spawning the female selects a location within the male's territory and begins to dig the redd.
The male courts the female by circling around her. He then moves alongside her and quivers. The mating pair eject eggs and milt into the small depression and the fertilized eggs are deposited into the gravel. Subsequent digging upstream covers the eggs and protects them from being dislodged by the current.
The fertilized eggs can hatch after 4 to 8 months, usually before the spring. Young Dolly Varden begin to feed after emerging from the gravel. They may either spend their first few years exclusively in freshwater or in the estuary.
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