Food of Pacific Hake (Merluccius productus) on an Offshore Bank Southwest of Vancouver Island, British Columbia

1972 ◽  
Vol 29 (12) ◽  
pp. 1792-1795 ◽  
Author(s):  
Donald N. Outram ◽  
C. Haegele
Keyword(s):  
British Columbia ◽  
Feeding Activity ◽  
Stomach Contents ◽  
Clupea Harengus ◽  
Merluccius Productus ◽  
Ammodytes Hexapterus ◽  
Large Numbers ◽  
Northern Anchovy ◽  
Engraulis Mordax ◽  
Offshore Bank

In 1196 adult Pacific hake (Merluccius productus) stomachs from off the British Columbia coast euphausiids occurred in 94%; Pacific sandlance (Ammodytes hexapterus) in 26%; Pacific herring (Clupea harengus pallasii) and eulachon (Thaleichthys pacificus) each 5%; and lanternfish, young rockfish, northern anchovy (Engraulis mordax), and pandalid shrimp each in 3% or less. Fish, particularly herring, were of greater importance in the diet of larger hake. The extent of stomach fullness and the stage of digestion of stomach contents were similar for all sizes of hake taken in daylight tows. The presence of fresh to near-fresh organisms in only 9% of the stomachs, coupled with large numbers (52%) of empty to near-empty stomachs, indicated low feeding activity during daylight hours.

scholarly journals Diet of the Pacific Sand Lance (Ammodytes hexapterus) in the Salish Sea, British Columbia, in the 1960s

2014 ◽  
Vol 128 (1) ◽  
pp. 57 ◽  
Author(s):  
J. Mark Hipfner ◽  
Moira Galbraith
Keyword(s):  
British Columbia ◽  
Stomach Contents ◽  
Salish Sea ◽  
Sand Lance ◽  
Strait Of Georgia ◽  
Ammodytes Hexapterus ◽  
Saanich Inlet ◽  
The Pacific ◽  
Pacific Sand Lance ◽  
Calanus Marshallae

The diet of the Pacific Sand Lance (Ammodytes hexapterus) was quantified from the stomach contents of 115 Pacific Sand Lance caught in the Strait of Georgia and Saanich Inlet (Vancouver Island) in the Salish Sea, British Columbia, in the spring and summer of 1966, in the Strait of Georgia in the spring and summer of 1967, and in the Strait of Georgia and Saanich Inlet in the spring and summer of 1968. There were 12 major taxa of prey in diets, 8 of which were Crustacea. Based on an index of relative importance, copepods were the dominant prey in 1966 and 1968, but not in 1967, when cladocerans, larvaceans, and teleosts also were common. The copepods Pseudocalanus spp. and Calanus marshallae were the only taxa to appear in diets in all three years. Pseudocalanus dominated the copepod component of diets in 1966, when sampling occurred in July; unspecified copepod nauplii (an early larval stage) were dominant in 1967 and 1968, when sampling occurred earlier (April to June). With the profound changes that have occurred in the Salish Sea over recent decades, these data can serve as a baseline for comparison.

Competition for Food Between Redside Shiners (Richardsonius balteatus) and Rainbow Trout (Salmo gairdneri) in Two British Columbia Lakes

1961 ◽  
Vol 18 (2) ◽  
pp. 203-220 ◽  
Author(s):  
R. E. Johannes ◽  
P. A. Larkin
Keyword(s):  
British Columbia ◽  
Rainbow Trout ◽  
Interspecific Competition ◽  
Stomach Contents ◽  
Salmo Gairdneri ◽  
Interspecific Aggression ◽  
Large Numbers ◽  
Competition For Food ◽  
Biological Environment ◽  
Richardsonius Balteatus

The distribution, movements, behaviour and food of trout and shiners in Paul and Pinantan Lakes were studied to determine the items and mechanisms of interspecific competition between them. Data from recent years were compared with data for years when trout alone inhabited the lakes.No interspecific aggression was observed. The possibility that the two species were competing for space was discounted. Stomach contents of shiners in Pinantan Lake revealed a marked qualitative diurnal food cycle. In Paul Lake, shiners have drastically reduced the Gammarus population relative to its pre-shiner abundance, forcing trout, as well as the shiners themselves, to shift their diets to other foods. This overgrazing was caused by the concentration of large numbers of shiners over the shoals where Gammarus are also present in their highest concentrations, and the ability of shiners to pursue food deeper into the weeds and to graze an area more thoroughly than trout. In Pinantan Lake, shiners have apparently reduced the density of Daphnia to a point where trout are unable to feed on them as rapidly as in pre-shiner years. The ability of both species to utilize many types of food tends to reduce the intensity of competition.The study demonstrates how false implications may arise from an appraisal of competition not initiated until after the effects of competition have been observed. If observations had not been made on Paul Lake until after competition had been observed, the importance of Gammarus as an item of competition would probably have been overlooked and the whole competitive relationship misconstrued.Environmental factors and behaviour were shown to be important influences on the dynamics of competition. The physical and biological environment and the distribution and behaviour of competitors may be in states of continual flux in which case the niches of the competitors cannot be considered constant.

Interaction between Pacific Cod (Gadus macrocephalus) and Herring (Clupea harengus pallasi) in the Hecate Strait, British Columbia

1986 ◽  
Vol 43 (4) ◽  
pp. 830-837 ◽  
Author(s):  
Carl J. Walters ◽  
M. Stocker ◽  
A. V. Tyler ◽  
S. J. Westrheim
Keyword(s):  
British Columbia ◽  
Historical Data ◽  
Stomach Contents ◽  
Clupea Harengus ◽  
Regression Analyses ◽  
Pacific Cod ◽  
Predator Prey ◽  
Pacific Cod Gadus Macrocephalus ◽  
Clupea Harengus Pallasi ◽  
Gadus Macrocephalus

Pacific cod (Gadus macrocephalus) and herring (Clupea harengus pallasi) in the Hecate Strait have shown fluctuations consistent with the hypothesis that herring recruitment rates are strongly influenced by cod predation. Regression analyses of herring juvenile survival, as measured by log recruits per herring spawner, on Pacific cod abundance indicate that the cod may cause a total instantaneous mortality rate averaging around 0.75∙yr−1 with each cod consuming several hundred herring. Somewhat lower estimates of herring consumption per cod were expected on the basis of stomach contents data, but the discrepancy may well be due to systematic underestimates of cod abundance. Cod recruitment rates are positively correlated with herring abundance, but it is impossible to determine from historical data whether this correlation reflects predator–prey interdependence or the impacts of older cod on their own offspring, since cod and herring abundances are inversely correlated. Peak cod abundances in northern British Columbia during the late 1950's may be partly responsible for the collapse of the herring reduction fishery of the 1960's, and management of the two species should be coordinated to reflect the possibility of similar events in the future.

The Interrelation of Biting and Filtering in the Feeding Activity of the Northern Anchovy (Engraulis mordax)

1972 ◽  
Vol 29 (3) ◽  
pp. 285-293 ◽  
Author(s):  
Charles P. O'Connell
Keyword(s):  
Small Schools ◽  
Feeding Activity ◽  
Relative Concentration ◽  
Dry Weight ◽  
Total Activity ◽  
Filter Feeding ◽  
Nutritional Needs ◽  
Northern Anchovy ◽  
Engraulis Mordax ◽  
Total Feeding

A previous study showed that the northern anchovy (Engraulis mordax) captures Artemia adults (3.7 mm long) by biting and Artemia nauplii (0.65 mm long) by filter feeding. This study shows that the ratio of biting to filtering activity in small schools varies with the relative concentration of Artemia adults and nauplii in the water. Activity was half biting and half filter feeding when Artemia adults were 2% by dry weight of the available biomass, but was entirely biting when Artemia adults exceeded about 7% of the biomass.It is estimated that when feeding activity is half biting and half filtering, Artemia adults and nauplii would contribute equal dry weights to ingestion, and that the sum of the two would be the same as that possible if total activity had been filtering. When relative concentration of Artemia adults is high enough to induce total biting activity, the dry weight ingested per unit time would be double that possible by filtering alone on the nauplii present.Ratios of large-to-small crustaceans are relatively high near the surface at night off southern California, which suggests that biting activity could often exceed 50% of total feeding activity. If the plankton does support a high percentage of biting activity, a large part of the area should usually provide the anchovy with its daily nutritional needs.

Diving depths, diet, and underwater foraging of Rhinoceros Auklets in British Columbia

1993 ◽  
Vol 71 (12) ◽  
pp. 2528-2540 ◽  
Author(s):  
Alan E. Burger ◽  
Rory P. Wilson ◽  
Don Garnier ◽  
Marie-Pierre T. Wilson
Keyword(s):  
British Columbia ◽  
Prey Availability ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Ammodytes Hexapterus ◽  
Bite Marks ◽  
Important Prey ◽  
Cerorhinca Monocerata ◽  
Pacific Sand Lance ◽  
The Mean

Rhinoceros Auklets (Cerorhinca monocerata) were studied at Triangle Island, Cleland Island, and Seabird Rocks, British Columbia, in 1986–1989. Epipelagic schooling fish were consistently the most common prey delivered to auklet chicks at all three localities. Pacific sand lance (Ammodytes hexapterus), Pacific herring (Clupea harengus), juvenile salmon (Onchorhyncus spp.), Pacific saury (Cololabis saura), and juvenile rockfish (Sebastes spp.) were important prey. Bite marks on the fish showed that 73% were attacked from below. The mean deepest depth recorded for 16 auklets was 30 m (range 12–60 m). Eleven time-at-depth records showed that the auklets were epipelagic foragers: 90% of the mean underwater time was spent in the upper 10 m, although most birds had a few deeper dives of 20–60 m. Shipboard transects showed that Rhinoceros Auklets usually foraged in water considerably deeper than 15 m. A model of diving efficiency indicated that a relatively large proportion (> 40%) of the average dive cycle was spent foraging rather than travelling or resting, and prolonged dives invoking anaerobic glycolysis were avoided. We discuss the implications of diving limitations on foraging behaviour and the use of Rhinoceros Auklets as indicators of prey availability.

Lampetra macrostoma, a New Species of Freshwater Parasitic Lamprey from the West Coast of Canada

1982 ◽  
Vol 39 (5) ◽  
pp. 736-747 ◽  
Author(s):  
Richard J. Beamish
Keyword(s):  
British Columbia ◽  
New Species ◽  
West Coast ◽  
Related Species ◽  
Salt Water ◽  
Vancouver Island ◽  
The West ◽  
Large Disc ◽  
Large Numbers ◽  
A New Species

Lampetra macrostoma n.sp., a freshwater parasitic lamprey, is distinguished from related species L. tridentata, L. lethophaga, L. folletti, L. minima, and L. similis by its parasitic habit and very large disc. Other characters distinguishing the species from L. tridentata are its longer prebranchial length, large eye, weakly pigmented velar tentacles, and its ability to remain in freshwater. The recently metamorphosed form readily survives in freshwater and probably is non-anadromous even though it can survive in salt water. The new species has been discovered in two lakes on Vancouver Island, British Columbia, Canada, where it attacks large numbers of resident salmonids. Because of its ability to survive and feed in freshwater, it poses a definite threat to freshwater fishes.Key words: lamprey, new species, non-anadromous lamprey, salmonid parasitism

BIOLOGY AND CONTROL OF THE COAST MOLE, SCAPANUS ORARIUS ORARIUS TRUE, IN BRITISH COLUMBIA

1959 ◽  
Vol 39 (1) ◽  
pp. 34-44 ◽  
Author(s):  
R. Glendenning
Keyword(s):  
British Columbia ◽  
Stomach Contents ◽  
Economic Damage ◽  
Average Weight ◽  
Chemical Fertilizers ◽  
Economic Control ◽  
River Flood ◽  
And Control ◽  
Fraser Valley ◽  
Old Females

Coast moles were studied and trapped from 1935 to 1945 at Agassiz, British Columbia. They cause economic damage in the lower Fraser Valley by injuring growing crops and by covering up to 15 per cent of the surface of a field with their hills.The moles ate almost any arthropod, annelid, or molluscan that they captured, but earthworms comprised 93 per cent of the stomach contents. Adults ate nearly twice their weight in earthworms daily, or 100–150 grams, representing more than 100 worms. The populations of moles apparently varied in proportion to those of the earthworms.The moles mated from January to early March. The young were born in March or April. Yearling females had two embryos; 2-year-old females had three; and mature females had four. Of 940 trapped during the winters, 45 per cent were over 1, and 6 per cent were over 3 years old. The average weight of mature 74 males was 74.3 ± 5.6 grams; the average weight of 30 mature females was 69.8 ± 4.1 grams.Natural control was ineffective. The disastrous Fraser River flood of 1948 lowered the numbers significantly, but recovery was rapid.Artificial controls tested included: poisons, caustic irritants, explosives, flooding, earthworm poisons, combinations of chemical fertilizers and irrigations, mechanical and chemical barriers, commercial mole destroyers, poison gases, deterrents, and traps. Only the last two were of value; crude flake naphthalene was a deterrent, and the scissors type was the most effective trap. In heavy infestations as many as three moles per man-hour were trapped. Naphthalene was expensive but protected small plots for up to 6 weeks. For economic control by trapping an area of 300 to 500 acres should be trapped in one season. Smaller areas are quickly reinfested, since the moles travel up to 1 mile.

scholarly journals Diel feeding pattern and diet of rough scad Trachurus lathami Nichols, 1920 (Carangidae) from the Southwestern Atlantic

2006 ◽  
Vol 4 (4) ◽  
pp. 419-426 ◽  
Author(s):  
Maria Raquel de Carvalho ◽  
Lucy Satiko Hashimoto Soares
Keyword(s):  
Feeding Activity ◽  
Stomach Contents ◽  
Feeding Time ◽  
Frequency Of Occurrence ◽  
Southwestern Atlantic ◽  
Calanoid Copepods ◽  
Teleostean Fish ◽  
Dark Cycle ◽  
Percent Number ◽  
Decapod Larvae

Diel changes in feeding activity and dietary composition of the rough scad Trachurus lathami were investigated through the analysis of stomach contents of 307 fish sampled over a 24-h period on the continental shelf off Ubatuba (23º 35'S 45ºW). Stomach contents were analyzed by frequency of occurrence (O%), percent number (N%), percent mass (M%), and feeding index (FI% = O% * M%). Rough scad fed on mollusks (Gastropoda, Crepidula sp.), crustacean (Ostracoda, Copepoda, decapod larvae), chaetognat and teleostean fish. The main items were calanoid copepods (Eucalanus sp. and Centropages sp.). According to the analysis of the stomach fullness and prey digestion, T. lathami is both a diurnal and nocturnal feeder, showing some seasonal variation in feeding time. According to the Chronobiology concept, it was raised the hypothesis of circadian rhythm in feeding of this fish, probably synchronized by light/dark cycle.

scholarly journals Variations of Salminus hilarii diet (Ostariophysi, Characidae): seasonal and ontogenetic effects

2015 ◽  
Vol 75 (3) ◽  
pp. 574-580
Author(s):  
GA Villares Junior ◽  
R Goitein
Keyword(s):  
Prey Size ◽  
Pearson Correlation ◽  
Feeding Activity ◽  
Stomach Contents ◽  
Food Composition ◽  
Spearman Correlation ◽  
Statistical Comparison ◽  
Significant Difference ◽  
Ontogenetic Effects ◽  
Size And Morphology

AbstractThis study described the variations seasonal and ontogenetic of Salminus hilarii diet. Samples were collected in the Sorocaba River, São Paulo, Brazil, one of the few rivers where individuals of the species still occur in a higher frequency. The preys consumed were analyzed by Importance Alimentary Index (AIi). To determine similarities between year seasons, the AIi data were analyzed by the Morisita-Horn index and reduced in cluster analysis, along with a statistical comparison made by one-way ANOSIM test (5%). The feeding activity was analyzed according to the stomach repletion index and compared among the year seasons using non parametric variance analysis Kruskal-Wallis test (5%). Comparison of prey consumed between immature and adult individuals was made by Spearman correlation (5%). A Pearson correlation (5%) was applied between the standard length of the fish and prey consumed, as well as between the mouth and prey heights. The analyzes of stomach contents showed that the diet of this species was exclusively piscivorous, with significant difference of prey consumption during the period, the same happening among adult and immature individuals. It was observed that these fishes use to swallow their prey whole and that significant correlations between size of predator and prey size can be observed. There is also correlation between the mouth height and the maximum prey depth. Salminus hilarii feeds on the available prey, and the species food composition and feeding activity depends on prey`s abundance, their size and morphology, as do the water temperatures.

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