Osmoregulatory Ability of Wild Coho Salmon (Oncorhynchus kisutch) and Dolly Varden Char (Salvelinus malma) Smolts

1988 ◽  
Vol 45 (8) ◽  
pp. 1487-1490 ◽  
Author(s):  
Scott W. Johnson ◽  
Jonathan Heifetz
Keyword(s):  
Water Temperature ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Small Stream ◽  
Fish Size ◽  
Dolly Varden Char ◽  
Seawater Challenge ◽  
Osmoregulatory Ability

Osmoregulatory ability of wild coho salmon (Oncorhynchus kisutch) and Dolly Varden char (Salvelinus malma) smolts migrating from a small stream in southeastern Alaska was assessed by plasma Na+ levels after a 24-h seawater challenge. Osmoregulatory ability of coho salmon was unaffected by time of out-migration, water temperature, and fish size. Osmoregulatory ability of Dolly Varden char was apparently affected by time of out-migration or water temperature but not by fish size. Char migrating in the first half of the migration period, when water temperature was usually < 8.0 °C, had lower plasma Na+ levels than did char migrating in the second half when temperatures were [Formula: see text]. A plasma Na+ threshold of 170 mmol∙L−1, used by others to separate smolts from silvery parr, indicated that 70% of the coho salmon and 80% of the Dolly Varden char we sampled were physiologically prepared to enter seawater. The remaining fish may have suffered some level of osmoregulatory stress.

Microhabitat Partitioning among Stream-Dwelling juvenile Coho Salmon, Oncorhynchus kisutch, and Dolly Varden, Salvelinus malma

1990 ◽  
Vol 47 (12) ◽  
pp. 2297-2306 ◽  
Author(s):  
C. Andrew Dolloff ◽  
Cordon H. Reeves
Keyword(s):  
Habitat Use ◽  
Coho Salmon ◽  
Focal Point ◽  
Oncorhynchus Kisutch ◽  
The Other ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Fish Size ◽  
Dolly Varden Salvelinus Malma ◽  
Natural Streams

Microhabitat use and partitioning among age 0+ and 1+ coho salmon, Oncorhynchus kisutch, and age 0+, 1+ and 2+ Dolly Varden, Salvelinus malma, was studied in small (<2 m wide), natural streams on Prince of Wales Island, Alaska, and in laboratory stream channels. Coho salmon occupied midwater positions that they defended from other fish. Dolly Varden were more closely associated with the stream bottom and were seldom territorial. For each species, the depth of water, depth of focal point, and distance to nearest fish increased with fish size, whereas the distance to nearest cover decreased as fish size increased. Most fish selected focal point velocities between 0.0–9.0 cm∙s−1.Woody debris was the most frequently used cover type and most fish occurred over gravel substrates ranging from 2–100 mm particle diameter. Habitat use by each species in the laboratory was similar to the pattern observed in the field. Each species occupied similar habitats both when alone and when the other species was present. Although habitat use by juveniles of coho salmon and Dolly Varden overlapped among several key parameters, each species primarily exploited resources not readily available to or selected by the other in the natural streams we studied.

Predation by River Otters (Lutra canadensis) on Juvenile Coho Salmon (Oncorhynchus kisutch) and Dolly Varden (Salvelinus malma) in Southeast Alaska

1993 ◽  
Vol 50 (2) ◽  
pp. 312-315 ◽  
Author(s):  
C. Andrew Dolloff
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
River System ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Southeast Alaska ◽  
River Otters ◽  
Juvenile Salmonids ◽  
Dolly Varden Salvelinus Malma ◽  
Lutra Canadensis

The effect of predation by river otters (Lutra canadensis) on juvenile coho salmon (Oncorhynchus kisutch) and Dolly Varden (Salvelinus malma) in a Southeast Alaska watershed was inferred by examining the number and size distribution of sagittal otoliths that were found in otter scats. Individual scats contained up to 408 otoliths, indicating that at least 200 fish had been eaten between defecations. Otoliths from juvenile salmonids outnumbered those from coastrange sculpins (Cottus aleuticus) by about six to one. Based on examination of over 8000 otoliths found in otter scats, at least 3300 juvenile salmonids were eaten by two river otters and their two young in the Kadashan River system during a 6-wk period in late spring 1985.

Relationships between body size and secondary sexual characters, and sperm characters in male Dolly Varden char (Salvelinus malma )

2016 ◽  
Vol 26 (3) ◽  
pp. 397-402 ◽  
Author(s):  
Toshiaki Yamamoto ◽  
Noritaka Hirohashi ◽  
Eiji Fujiwara ◽  
Tatsuya Suzuki ◽  
Hatsuna Maruta ◽  
...  
Keyword(s):  
Body Size ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Dolly Varden Char ◽  
Secondary Sexual Characters ◽  
Sperm Characters ◽  
Secondary Sexual

Aggressive interactions affect foraging and use of space in a drift foraging salmonid, Salvelinus malma (Salmoniformes: Salmonidae)

2019 ◽  
Vol 187 (3) ◽  
pp. 774-781 ◽  
Author(s):  
Jeffrey L Cullen ◽  
Gary D Grossman
Keyword(s):  
Foraging Behaviour ◽  
Field Studies ◽  
Habitat Choice ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Intraspecific Interactions ◽  
Use Of Space ◽  
Aggressive Interactions ◽  
Dolly Varden Char ◽  
Alaskan Stream

Abstract Although intraspecific interactions likely affect habitat choice and foraging behaviour in animals, our knowledge regarding how these factors interact is frequently limited to either lab or field studies, but not both. We observed pairs of dominant and subordinate drift-foraging Dolly Varden char (Salvelinus malma) in an Alaskan stream, and quantified intraspecific interactions and foraging behaviour. Dominant individuals had higher foraging rates, occupied slower holding velocities and were displaced shorter distances during bouts compared to subordinate individuals. Individuals initiated bouts more frequently from the downstream position, than from lateral or upstream positions. Dominant individuals were more likely to occupy the upstream position after a bout than subordinates, which ensures that dominants have the first opportunity to capture drifting prey.

Combined phylogenetic analysis of ribosomal ITS1 sequences and new chromosome data supports three subgroups of Dolly Varden char (Salvelinus malma)

1999 ◽  
Vol 56 (8) ◽  
pp. 1504-1511 ◽  
Author(s):  
Ruth B Phillips ◽  
Linda I Gudex ◽  
Kathleen M Westrich ◽  
Alfred DeCicco
Keyword(s):  
Phylogenetic Analysis ◽  
Dna Sequences ◽  
Lake Trout ◽  
Salvelinus Alpinus ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Dolly Varden Char ◽  
The North ◽  
Rdna Sequences ◽  
Kamchatka River

A phylogenetic analysis of the subspecies of Salvelinus malma (Dolly Varden char) was done using DNA sequences from the first internal transcribed spacer (ITS1) of the ribosomal DNA (rDNA). Sequences were obtained from the northern S. malma malma from the Noatak River, Alaska, and the Kamchatka River, Russia; from the southern North American form S. malma lordi from the Fox River, Kenai peninsula, and Auke Bay near Juneau, Alaska; and from the southern Asian form S. malma krascheninnikovi from Belaya River in Sakhalin Island, Russia. These sequences were combined with others from Salvelinus alpinus (Arctic char) from several locations in the North Pacific and Europe and analyzed using maximum parsimony and neighbor joining algorithms with Salvelinus namaycush (lake trout) as an outgroup. The resulting trees had two well-supported groups: S. m. malma and S. m. krascheninnikovi in one group and S. m. lordi and various populations of S. alpinus in the other. Salvelinus m. malma and S. m. krascheninnikovi were sister taxa, and S. m. lordi was most closely related to S. alpinus from Northwest Territories (S. a. erythrinus). New chromosome data from S. m. malma from northwestern Alaska supported the three named subspecies because S. m. malma from both Alaska and Russia have 2n = 78 compared with 2n = 82 for the two southern forms and the location of the nuclear organizer regions (NORs) was different in each of the three subspecies.

Resource partitioning as a factor limiting gene flow in hybridizing populations of Dolly Varden char (Salvelinus malma) and bull trout (Salvelinus confluentus)

2001 ◽  
Vol 58 (10) ◽  
pp. 2037-2047 ◽  
Author(s):  
John Hagen ◽  
Eric B Taylor
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Secondary Contact ◽  
Life History Stage ◽  
Bull Trout ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Salvelinus Confluentus ◽  
Dolly Varden Char ◽  
Northwestern North America

Dolly Varden char (Salvelinus malma) and bull trout (Salvelinus confluentus) hybridize in areas of secondary contact in northwestern North America but maintain their genetic integrity in spite of gene flow. We examined juvenile stream ecology and adult reproductive ecology of these species in sympatry to test for specializations to alternative niches that may act as a basis for natural selection against hybrids. Juvenile Dolly Varden occupied deeper, faster water and foraged more during daytime in the drift, whereas bull trout used shallower, slower water and made more nighttime foraging attempts towards the substrate. The species showed extensive diet overlap (Schoener's index = 0.7–0.9), and we found evidence for density compensation between species among sites. Our results suggest no obvious basis for selection against hybrids at the juvenile stream-rearing life-history stage. Bull trout, however, are adfluvial, whereas Dolly Varden are permanent stream residents. Bull trout are also much larger at maturity (50–80 cm vs. 12–15 cm) and build redds in faster, deeper water using larger substrate sizes. Consequently, hybrid genotypes may be selected against in these alternative life-history niches or during reproduction owing to their intermediate size at maturity and size-dependent spawning habitat use and mate choice.

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