scholarly journals Field observations of the Tachie Pluton near Fort St. James, central British Columbia

1998 ◽  
Author(s):  
M G Hrudey ◽  
L C Struik
Keyword(s):  
British Columbia ◽  
Field Observations

Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters

1998 ◽  
Vol 76 (8) ◽  
pp. 1456-1471 ◽  
Author(s):  
John KB Ford ◽  
Graeme M Ellis ◽  
Lance G Barrett-Lennard ◽  
Alexandra B Morton ◽  
Rod S Palm ◽  
...  
Keyword(s):  
British Columbia ◽  
Chinook Salmon ◽  
Stomach Contents ◽  
Orcinus Orca ◽  
Foraging Strategies ◽  
Field Observations ◽  
Killer Whales ◽  
Sympatric Populations ◽  
Mammal Species ◽  
Dietary Specialization

Two forms of killer whale (Orcinus orca), resident and transient, occur sympatrically in coastal waters of British Columbia, Washington State, and southeastern Alaska. The two forms do not mix, and differ in seasonal distribution, social structure, and behaviour. These distinctions have been attributed to apparent differences in diet, although no comprehensive comparative analysis of the diets of the two forms had been undertaken. Here we present such an analysis, based on field observations of predation and on the stomach contents of stranded killer whales collected over a 20-year period. In total, 22 species of fish and 1 species of squid were documented in the diet of resident-type killer whales; 12 of these are previously unrecorded as prey of O. orca. Despite the diversity of fish species taken, resident whales have a clear preference for salmon prey. In field observations of feeding, 96% of fish taken were salmonids. Six species of salmonids were identified from prey fragments, with chinook salmon (Oncorhynchus tshawytscha) being the most common. The stomach contents of stranded residents also indicated a preference for chinook salmon. On rare occasions, resident whales were seen to harass marine mammals, but no kills were confirmed and no mammalian remains were found in the stomachs of stranded residents. Transient killer whales were observed to prey only on pinnipeds, cetaceans, and seabirds. Six mammal species were taken, with over half of observed attacks involving harbour seals (Phoca vitulina). Seabirds do not appear to represent a significant prey resource. This study thus reveals the existence of strikingly divergent prey preferences of resident and transient killer whales, which are reflected in distinctive foraging strategies and related sociobiological traits of these sympatric populations.

Size Selective Predation Among Juvenile Salmonid Fishes in a British Columbia Inlet

1971 ◽  
Vol 28 (10) ◽  
pp. 1503-1510 ◽  
Author(s):  
Robert R. Parker
Keyword(s):  
Growth Rate ◽  
British Columbia ◽  
Prey Population ◽  
Oncorhynchus Gorbuscha ◽  
Field Observations ◽  
Salmonid Fishes ◽  
Selective Predation ◽  
Initial Size ◽  
Salmon Fry ◽  
Series Of Experiments

Field observations suggest early sea mortality of pink (Oncorhynchus gorbuscha) and chum (O. keta) salmon fry is largely due to predation by juvenile coho (O. kisutch) salmon. A series of experiments demonstrates a strong bias toward the smaller individuals of the prey population. This results in an apparent growth rate 0.3–0.5% per day due to the biased mortality alone. With a high innate growth rate [Formula: see text], the prey are shown to "outgrow" the predator [Formula: see text], and hence become unavailable. Chums are shown to have an advantage over pinks through slightly earlier entry into the estuary and a larger initial size. The mechanism of selection used by the predator is not known from this study.

Lakeward Migration of Young Rainbow Trout (Salmo gairdneri) in the Upper Lardeau River, British Columbia

1969 ◽  
Vol 26 (1) ◽  
pp. 33-45 ◽  
Author(s):  
T. G. Northcote
Keyword(s):  
British Columbia ◽  
Rainbow Trout ◽  
Water Temperature ◽  
Water Current ◽  
Salmo Gairdneri ◽  
Field Observations ◽  
Predominant Role ◽  
Emergence Period ◽  
Trout Lake ◽  
Kootenay Lake

Lakeward migration of rainbow trout fry was studied in the upper Lardeau River, where the young emerge from a spawning area immediately below the outlet of Trout Lake utilized by large trout from Kootenay Lake, about 56 km downstream. Most fry move downstream towards Kootenay Lake shortly after emergence; however, some, particularly later in the emergence period, move upstream into Trout Lake. Field observations and experiments suggest that water temperature may be important in inducing different responses to water current in these fish, but may not play such a predominant role or operate at the same levels as proposed earlier for control of young trout migration in the Loon Lake system.

PEST MANAGEMENT: CONTROL OF ARCHIPS ARGYROSPILUS AND ARCHIPS ROSANUS (LEPIDOPTERA: TORTRICIDAE) ON APPLE

1977 ◽  
Vol 109 (2) ◽  
pp. 171-174 ◽  
Author(s):  
Harold F. Madsen ◽  
S. A. Potter ◽  
F. E. Peters
Keyword(s):  
British Columbia ◽  
Bacillus Thuringiensis ◽  
Pest Management ◽  
Management Control ◽  
Field Observations ◽  
Azinphos Methyl ◽  
Larval Emergence ◽  
Archips Argyrospilus

AbstractTwo leafroller spades are major pests of apple in British Columbia, Archips argyrospilus (Walker) and Archips rosanus (Linnaeus). Field observations showed that both species overwinter in the egg stage and that larval emergence times are similar. Experiments demonstrated that both species are susceptible to sprays of azinphos-methyl, diazinon, or trichlorfon applied at either the pink bud or petal fall stages. Dipel (Bacillus thuringiensis) failed to control larvae of either species.

Laboratory and Field Observations on Two Predators of the Pear Psylla in British Columbia

1963 ◽  
Vol 95 (4) ◽  
pp. 435-438 ◽  
Author(s):  
T. K. Watson ◽  
W. H. A. Wilde
Keyword(s):  
British Columbia ◽  
Effective Control ◽  
Field Observations ◽  
Green Lacewing ◽  
Effective Suppression ◽  
Pear Psylla ◽  
Okanagan Valley

AbstractDuring 1961 and 1962 observations were made on the activities of predators of the pear psylla, Psylla pyricola Förster, in the Okanagan Valley of British Columbia. Attacking the psylla together, the anthocorid bug, Anthocoris melanocerus Reuter, and the green lacewing, Chrysopa oculata Say, gave more effective suppression than either predator alone. DDT and Diazinon drastically reduced numbers of these predators b commercial plantings. In non-sprayed, isolated orchards, trace numbers of these predators maintained effective control of pear psylla populations.

Rhizina Root Rot: Severity and Distribution in British Columbia

1974 ◽  
Vol 4 (1) ◽  
pp. 143-146 ◽  
Author(s):  
James H. Ginns
Keyword(s):  
British Columbia ◽  
Root Rot ◽  
First Year ◽  
Field Observations

Rhizinaundulata Fr. occurred on about one-third of the 160 logging sites sampled 1 year after each area was burned. Three years after burning, apothecia were rarely found. The fungus causes mortality of seedlings planted on burned sites. Severity of attack within a seedling plantation was evaluated entirely on field observations which gave a satisfactory estimate of infection. Most rhizina root rot mortality occurred in the first year after planting and after 2 years the mortality on one study area was 24%.

LIFE HISTORY OF CRICOTOPUS MYRIOPHYLLI OLIVER (DIPTERA: CHIRONOMIDAE) IN THE OKANAGAN VALLEY, BRITISH COLUMBIA

1993 ◽  
Vol 125 (6) ◽  
pp. 979-985 ◽  
Author(s):  
Ian V. MacRae ◽  
Richard A. Ring
Keyword(s):  
British Columbia ◽  
Life History ◽  
Sex Ratio ◽  
Larval Instar ◽  
Field Observations ◽  
Laboratory Rearing ◽  
The Third ◽  
First Instar ◽  
History Of ◽  
Rate Of Emergence

AbstractThe life history of Cricotopus myriophylli Oliver is described from both field observations and laboratory rearing of field-collected larvae. The species appears to be univoltine with four larval instars and has a sex ratio of ca. 2:1, males to females. Emergence begins in late May in British Columbia and continues until mid-September, with first-instar larvae present in the field from mid-June to mid-August. Water temperature does not appear to influence the rate of emergence. In the laboratory at 21 °C, larvae complete each of the third and fourth instars in 10–14 days. Cricotopus myriophylli overwinters primarily in the third larval instar, although second and fourth instars were also recovered in field-collected samples. First-instar larvae and eggs were not recovered from winter samples. This species does not appear to undergo a true diapause.

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