Predation of Juvenile Pacific Salmon by the Common Merganser (Mergus merganser) on Eastern Vancouver Island. II: Predation of Stream-Resident Juvenile Salmon by Merganser Broods

1987 ◽  
Vol 44 (5) ◽  
pp. 950-959 ◽  
Author(s):  
C. C. Wood
Keyword(s):  
Body Weight ◽  
Census Data ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Vancouver Island ◽  
Juvenile Salmonids ◽  
Mergus Merganser ◽  
The Common ◽  
Tidal Waters ◽  
Common Merganser

Predation of stream-resident juvenile salmonids by broods of the common merganser (Mergus merganser) was investigated in three streams on eastern Vancouver Island from 1980 to 1982. Daily fish consumption by merganser ducklings was estimated to range from 80% of body weight for ducklings at 10 d of age to 40% of body weight for those at 40 d of age. Merganser ducklings were never observed to eat juvenile salmonids on tidal waters, but did eat them on the freshwater reaches of streams studied. Typically, broods inhabited only the freshwater reaches of their natal stream while young, but spent progressively more time foraging on tidal waters as they grew older. The biomass of broods (and hence potential consumption) on fresh water was estimated by reconstructing the history of individual broods from census data. These results suggest that merganser broods consumed on the order of 82 000–131 000 coho salmon (Oncorhynchus kisutch) fry in the Big Qualicum River between June 10 and August 25. This is equivalent to 24–65% of the observed wild smolt production from this system, assuming that these fry would otherwise have survived as well as uneaten fry.

Predation of Juvenile Pacific Salmon by the Common Merganser (Mergus merganser) on Eastern Vancouver Island. I: Predation during the Seaward Migration

1987 ◽  
Vol 44 (5) ◽  
pp. 941-949 ◽  
Author(s):  
C. C. Wood
Keyword(s):  
Mortality Rate ◽  
Prey Size ◽  
Pacific Salmon ◽  
Size Selection ◽  
Juvenile Salmonids ◽  
Seaward Migration ◽  
Mergus Merganser ◽  
The Common ◽  
Tidal Waters ◽  
Common Merganser

Predation of juvenile salmonids by the common merganser (Mergus merganser) was investigated during the period of seaward migration in two streams where fish populations are enhanced by spawning channels and hatcheries. Observation of foraging behaviour and crop-gullet contents indicated that, during this period, mergansers foraging on freshwater reaches of the streams ate juvenile salmonids almost exclusively whereas those foraging on tidal waters rarely ate salmonids. Maximum rates of salmonid mortality were estimated by assessing merganser abundance and the pattern of foraging activity on fresh versus tidal waters. Maximum mortality rate declined as fish abundance increased (i.e. mortality was depensatory) in all cases where the effects of prey size-selection could be ignored owing to an overwhelming abundance of one prey species. Bounds on maximum mortality rate by species for the entire migration period were computed under different hypotheses about the prey size-selection habits of mergansers; maximum mortality rate did not exceed 10% for any salmonid species over the entire seaward migration.

Dispersion of common merganser (Mergus merganser) breeding pairs in relation to the availability of juvenile Pacific salmon in Vancouver Island streams

1986 ◽  
Vol 64 (3) ◽  
pp. 756-765 ◽  
Author(s):  
C. C. Wood
Keyword(s):  
Pacific Salmon ◽  
Prey Availability ◽  
Vancouver Island ◽  
Egg Laying ◽  
Breeding Pair ◽  
Juvenile Salmon ◽  
Mergus Merganser ◽  
Juvenile Pacific Salmon ◽  
Stream Size ◽  
Common Merganser

Common merganser (Mergus merganser) breeding pairs and broods were censused on eight coastal streams on Vancouver Island to evaluate the relative importance of the number of potential breeding pairs, stream size, and the availability of juvenile Pacific salmon in limiting merganser breeding density. The number of potential breeding pairs did not limit nesting density on at least one stream where juvenile salmon populations were enhanced by a hatchery and spawning channel. At distances > 1 km above tidal influence, breeding pairs were evenly dispersed along the streams during the peak egg-laying and incubation period at maximum densities of 0.4–1.4 pairs/km. Maximum breeding pair counts were higher and more variable among streams on the lower kilometer of freshwater (1–9 pairs) and on tidal waters near the stream outlets (4–9 pairs). Stream size accounted for only a part of the variation in breeding pair counts. The estimated number of broods produced on each stream was highly correlated (r = 0.95) with both drainage area and juvenile salmon production, including production from hatcheries. Possible mechanisms relating the dispersion of breeding pairs to the availability of juvenile salmon are discussed. A "food assessment" hypothesis, whereby breeding pairs choose a nesting stream on the basis of prey availability during the nesting season, could not be rejected on the basis of predictions about hatching dates and duckling survival. This hypothesis has serious implications for mortality of wild salmonids in hatchery-enhanced streams.

Food-searching behaviour of the common merganser (Mergus merganser) II: Choice of foraging location

1985 ◽  
Vol 63 (6) ◽  
pp. 1271-1279 ◽  
Author(s):  
C. C. Wood
Keyword(s):  
Coho Salmon ◽  
Search Pattern ◽  
Flock Size ◽  
Searching Behaviour ◽  
Natural Stream ◽  
Mergus Merganser ◽  
Visit Duration ◽  
The Common ◽  
Common Merganser ◽  
Time Required

Factors influencing the choice of foraging location by the common merganser (Mergus merganser) were investigated by baiting three adjacent, enclosed sections of a natural stream with various densities of juvenile coho salmon (Oncorhynchus kisutch). Merganser abundance within 1 km of the enclosure site increased from < 3 to > 10 birds within 1 week of stocking the enclosures with 43-g coho smolt. Although abundance declined gradually thereafter (as expected from seasonal trends on other nearby streams), the frequency of visits to the enclosure site continued to increase for 22 d until the enclosures were stocked predominately with smaller (2-g) coho fry. Visits were more frequent when other mergansers were already present at the site. Also, the proportion of mergansers flying overhead that landed near a decoy "flock" increased with decoy flock size. In general, the duration of visits to the site was not affected by the number of birds present. Visit duration increased exponentially with increasing fish density and decreased with searching time required until first capture. Mergansers spent more time searching in the most profitable enclosure. Allocation of searching time among the enclosures was not consistent with a "giving up time" decision rule; however, mergansers appeared to follow an area-restricted search pattern both within and among the enclosures.

Food-searching behaviour of the common merganser (Mergus merganser) I: Functional responses to prey and predator density

1985 ◽  
Vol 63 (6) ◽  
pp. 1260-1270 ◽  
Author(s):  
C. C. Wood ◽  
C. M. Hand
Keyword(s):  
Coho Salmon ◽  
Flock Size ◽  
Previous Exposure ◽  
Functional Responses ◽  
Experimental Conditions ◽  
Natural Stream ◽  
Daily Food ◽  
Mergus Merganser ◽  
The Common ◽  
Common Merganser

The hunting performance of the common merganser (Mergus merganser) was evaluated in relation to prey density and merganser flock size by stocking three enclosed sections of a natural stream with known densities of juvenile coho salmon (Oncorhynchus kisutch). Two size classes of coho were stocked: smolt averaging 43 g at densities of 0.02–0.65/m2, fry averaging 2 g at 0.08–1.6/m2 and various mixtures of smolt and fry at a combined density of 0.65/m2. The stream enclosures differed in the amount of cover available to fish. Mergansers were less successful at capturing coho smolt or fry in the enclosures wth cover from undercut banks. Smolt exposed to mergansers earlier that day were less vulnerable than smolt with no previous exposure. The feeding success of individual mergansers was not significantly affected by flock size for flocks of 25 birds or less. A smoothly asymptotic functional response (type II) was observed under all experimental conditions. Coho smolt were selected over coho fry. It is concluded that a merganser's average daily food requirement (ca. 400 g) can be satisfied at smolt densities of 0.02–0.30/m2 depending on the availability of cover for smolt and their previous exposure to mergansers.

A preliminary study of insulin participation in the growth regulation of coho salmon (Oncorhynchus kisutch)

1977 ◽  
Vol 55 (10) ◽  
pp. 1756-1758 ◽  
Author(s):  
Bryan Ludwig ◽  
David A. Higgs ◽  
Ulf H. M. Fagerlund ◽  
Jack R. McBride
Keyword(s):  
Body Weight ◽  
Growth Regulation ◽  
Specific Growth ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Kisutch ◽  
Growth Promoter ◽  
Pancreatic B Cells ◽  
Preliminary Study ◽  
Specific Growth Rates

As part of an ongoing survey to identify hormones capable of stimulating growth in Pacific salmon, groups of underyearling coho salmon were injected with bovine (Ultralente) insulin (0.32, 1.0, 3.2, or 10 IU/kg body weight) into the peritoneal cavity either once or twice weekly for 70 days.All doses of insulin, when injected twice weekly, increased the values for specific growth rates and decreased those for food–gain ratios relative to solvent-injected controls, but the differences were not statistically significant. All doses of insulin caused a marked increase in the granulation of the pancreatic B cells. Plasma glucose concentrations in starved coho injected with 10 IU insulin/kg body weight were significantly lower than in solvent-injected controls 4 h after injection.It is concluded that proper evaluation of the effectiveness of insulin as a growth promoter for salmon requires further studies preferably using insulin preparations specific to teleosts.

Notes on the Feeding Behavior of the Common Merganser (Mergus merganser)

The Condor ◽  
1974 ◽  
Vol 76 (4) ◽  
pp. 472
Author(s):  
Bertin W. Anderson ◽  
Michael G. Reeder ◽  
Richard L. Timken
Keyword(s):  
Feeding Behavior ◽  
Mergus Merganser ◽  
The Common ◽  
Common Merganser

Healthy PNPLA3 Risk Allele Carriers Present with Unexpected Body Fat Composition. A Study of One ousand Subjects

2014 ◽  
Vol 23 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Agnieszka Kempinska-Podhorodecka ◽  
Marcin Krawczyk ◽  
Marta Klak ◽  
Malgorzata Blatkiewicz ◽  
Frank Lammert ◽  
...  
Keyword(s):  
Body Weight ◽  
Liver Disease ◽  
Fatty Liver ◽  
Fatty Liver Disease ◽  
Alcoholic Fatty Liver ◽  
The Metabolic Syndrome ◽  
Anthropometric Characteristics ◽  
The Common ◽  
Total Fat ◽  
Alcoholic Fatty Liver Disease

Introduction: The common PNPLA3 (adiponutrin) variant p.I148M represents a major genetic driver of progression in non-alcoholic fatty liver disease (NAFLD). NAFLD is commonly associated with traits of the metabolic syndrome, therefore it is mostly suspected in obese individuals. Here, we investigate the association between the PNPLA3 variant and anthropometric traits in a cohort of healthy individuals.Patients and methods: We recruited 1,000 (500 females; age 18 - 66 years) healthy blood donors. The PNPLA3 variant was genotyped using TaqMan assays. All individuals were phenotyped with respect to anthropometric characteristics. We also determined the percentage of total fat (F%) and active tissue (TA%) of body weight.Results: Healthy carriers of the PNPLA3 [IM] and [MM] genotypes, although not differing in height from individuals with the genotype [II], displayed significantly lower body weight and lower BMI (both P = 0.005), higher TA% (P = 0.03) but lower F% (P = 0.03) and smaller waist, chest and shin circumferences (all P < 0.05). Separate analysis for males and females demonstrated an association between the [IM] and [MM] genotypes and higher TA% but lower F% (P = 0.04) in females. In males, BMI and total weight were significantly (P = 0.04) lower among carriers of the [M] allele.Discussion: Healthy individuals carrying the prosteatotic PNPLA3 allele p.I48M may be leaner as compared to the carriers of the common allele. Hence in clinical practice they might be overlooked since they do not necessarily present with the anthropometric characteristics commonly associated with severe hepatic steatosis.Abbreviations: ATX - autotaxin; BMI - body mass index; F% - total fat of body weight in %; Fkg - total fat of body weight in kilograms; GWAS - genome-wide association study; LPA - lysophosphatidic acid; NAFLD, non-alcoholic fatty liver disease; NASH - non-alcoholic steatohepatitis; PA - phosphatidic acid; PNPLA3-patatin-like phospholipase domain containing 3 (adiponutrin); TA% - active tissue of body weight in %; TAkg - active tissue of body weight in kilograms; WHR - waist-to-hip ratio.

Field Observations on the Common Striped Possum (Dactylopsila Trivirgata) in North Queensland.

1996 ◽  
Vol 23 (6) ◽  
pp. 755 ◽  
Author(s):  
KA Handasyde ◽  
RW Martin
Keyword(s):  
Body Weight ◽  
Home Range ◽  
Foraging Behaviour ◽  
Male Body ◽  
Radio Tracking ◽  
Minimum Convex Polygon ◽  
Far North ◽  
Large Trees ◽  
The Common ◽  
Primary Habitat

Habitat utilisation and foraging behaviour by the common striped possum (Dactylopsila trivirgata) was investigated by means of spotlighting and radio-tracking at Shiptons Flat, far north Queensland. Vine forest was the primary habitat of D. trivirgata; however, animals were also observed in open eucalypt (Eucalyptus tereticornis) woodland. Information collected on foraging behaviour suggests that D. trivirgata are generalist insectivores consuming some fruit and other foodstuffs, such as honey. Radio-tracking data were used to calculate the home-range areas of two subadult males. The home range of the smaller male (body weight 290 g) was 5.2 ha (by the 95% harmonic mean (HM) method) or 6.5 ha (by the minimum convex polygon (MCP) method), and that of the larger male (body weight 415 g) was 21.2 ha (95% HM) or 21.3 ha (MCP). Large trees with hollows, which are utilized for denning, appear to be an important feature of the habitat for this species. D. trivirgata exhibits a pronounced degree of sociality and may breed seasonally. Observations suggest that amethystine pythons (Morelia amethistina) may be major predators of D. trivirgata at Shiptons Flat.

MUSCLE PROTEINS OF PACIFIC SALMON (ONCORHYNCHUS): II. AN INVESTIGATION OF MUSCLE PROTEIN AND OTHER SUBSTANCES SOLUBLE IN SALT SOLUTIONS OF LOW IONIC STRENGTH BY COLUMN CHROMATOGRAPHY

1962 ◽  
Vol 40 (7) ◽  
pp. 919-927 ◽  
Author(s):  
H. Tsuyuki ◽  
E. Roberts ◽  
R. E. A. Gadd
Keyword(s):  
Sockeye Salmon ◽  
Moving Boundary ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Muscle Protein ◽  
Deae Cellulose ◽  
Ophiodon Elongatus ◽  
The Pacific ◽  
Other Substances ◽  
Low Ionic Strength

The muscle myogens and other components of the spring salmon (O. tshawytscha), chum salmon (O. keta), coho salmon (O. kisutch), and sockeye salmon (O. nerka), as well as the lingcod (Ophiodon elongatus), were separated by the use of diethylaminoethyl (DEAE) cellulose columns. Significant amounts of slowly dialyzable inosine and inosinic acid which may lead to spurious peaks in moving-boundary electrophoretic separations have been shown to be present in the muscle myogen preparations. The basic differences in the muscle myogen components of the Pacific salmon and the lingcod are compared.

scholarly journals Evidence for Freshwater Residualism in Coho Salmon, Oncorhynchus kisutch, From a Watershed on the North Coast of British Columbia

2017 ◽  
Vol 130 (4) ◽  
pp. 336 ◽  
Author(s):  
Eric A Parkinson ◽  
Chris J Perrin ◽  
Daniel Ramos-Espinoza ◽  
Eric B Taylor
Keyword(s):  
British Columbia ◽  
Fresh Water ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Kisutch ◽  
Water Levels ◽  
North Coast ◽  
The North ◽  
Seaward Migration ◽  
Mature Fish

The Coho Salmon, Oncorhynchus kisutch, is one of seven species of Pacific salmon and trout native to northeastern Pacific Ocean watersheds. The species is typically anadromous; adults reproduce in fresh water where juveniles reside for 1–2 years before seaward migration after which the majority of growth occurs in the ocean before maturation at 2–4 years old when adults return to fresh water to spawn. Here, we report maturation of Coho Salmon in two freshwater lakes on the north coast of British Columbia apparently without their being to sea. A total of 15 mature fish (11 males and four females) were collected in two lakes across two years. The mature fish were all at least 29 cm in total length and ranged in age from three to five years old. The occurrence of Coho Salmon that have matured in fresh water without first going to sea is exceedingly rare in their natural range, especially for females. Such mature Coho Salmon may represent residual and distinct breeding populations from those in adjacent streams. Alternatively, they may result from the ephemeral restriction in the opportunity to migrate seaward owing to low water levels in the spring when Coho Salmon typically migrate to sea after 1–2 years in fresh water. Regardless of their origin, the ability to mature in fresh water without seaward migration may represent important adaptive life history plasticity in response to variable environments.

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