Some Factors Regulating Piscivory of Brook Trout, Salvelinus fontinalis, in Lakes of the Laurentian Shield

1991 ◽  
Vol 48 (9) ◽  
pp. 1735-1743 ◽  
Author(s):  
Pierre East ◽  
Pierre Magnan
Keyword(s):  
Brook Trout ◽  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
The Other ◽  
Prey Fish ◽  
Significant Preference ◽  
Prey Refuge ◽  
Semotilus Atromaculatus ◽  
Foraging Pattern ◽  
Creek Chub

A survey of 13 lakes containing brook trout, Salvelinus fontinalis, and northern redbelly dace, Phoxinus eos, five lakes containing trout and creek chub, Semotilus atromaculatus, and six lakes containing trout, dace, and chub indicated that prey-fish could represent up to 30% of trout diet by weight. We observed that trout preyed almost exclusively on dace, predation increased with trout size, predation on dace was significantly higher in the Salvelinus-Phoxinus-Semotilus association than in the Salvelinus-Phoxinus association even though trout were significantly smaller in the former than in the latter association, and predation in the Salvelinus-Phoxinus-Semotilus association was higher in two lakes and nearly always absent in the other four. Laboratory experiments indicated that small trout (150–250 mm total length (TL)) preferred small prey-fish (40–60 mm TL), large trout (250–380 mm TL) showed no significant preference with regard to the size of prey-fish (up to 170 mm TL), trout of both size classes preferred dace when dace and chub were present, presence of refuge (Cassandra calyculata) for prey-fish significantly reduced the number of attacks and captures upon dace, and large trout switched from an active to a sit-and-wait foraging pattern when a prey refuge was present.

Mechanisms responsible for the niche shift of brook charr, Salvelinus fontinalis Mitchill, when living sympatrically with creek chub, Semotilus atromaculatus Mitchill

1984 ◽  
Vol 62 (8) ◽  
pp. 1548-1555 ◽  
Author(s):  
Pierre Magnan ◽  
Gérard J. FitzGerald
Keyword(s):  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
Niche Shift ◽  
Intraspecific Aggression ◽  
Brook Charr ◽  
Semotilus Atromaculatus ◽  
High Level ◽  
Gill Raker ◽  
Creek Chub ◽  
Study Laboratory

When brook charr, Salvelinus fontinalis Mitchill, are in allopatry in oligotrophic Québec lakes, they feed largely on macrobenthic invertebrates. However, when brook charr cooccur with creek chub, Semotilus atromaculatus Mitchill, they feed largely on zooplankton. In the present study, laboratory experiments showed that creek chub were more effective than brook charr in searching for hidden, patchily distributed prey. The searching efficiency of an individual chub feeding in a group was improved through social facilitation. In contrast, the high level of intraspecific aggression observed in brook charr prevents the formation of such feeding groups. In the laboratory, brook charr were able to displace creek chub from the food source because of interspecific aggression. Data are presented showing that chub are morphologically better adapted than charr to feed on benthos (subterminal orientation of the mouth and protrusible premaxillae), while the charr are better adapted than chub to feed on zooplankton (gill raker structure). Differences in feeding behaviour, morphology, and relative abundance between these species appear to be important in the observed niche shift of brook charr in nature.

Resource partitioning between brook trout (Salvelinus fontinalis Mitchill) and creek chub (Semotilus atromaculatus Mitchill) in selected oligotrophic lakes of southern Quebec

1982 ◽  
Vol 60 (7) ◽  
pp. 1612-1617 ◽  
Author(s):  
Pierre Magnan ◽  
Gérard J. FitzGerald
Keyword(s):  
Spatial Distribution ◽  
Resource Partitioning ◽  
Brook Trout ◽  
Food Habits ◽  
Salvelinus Fontinalis ◽  
Niche Shift ◽  
Sympatric Populations ◽  
Semotilus Atromaculatus ◽  
Trout Population ◽  
Creek Chub

The spatial distribution, food habits, and growth of an allopatric brook trout (Salvelinus fontinalis) population was compared with a trout population coexisting with creek chub (Semotilus atromaculatus). Sympatric trout differed in spatial distribution and food habits from allopatric trout suggesting a niche shift of the trout when they live with creek chub. Also, although there is a certain overlap in diet and spatial distribution, sympatric populations of the two species differed on these resource axes. However, growth of sympatric trout is not clearly related to the presence or absence of the creek chub, suggesting that factors other than interspecific competiton may affect growth in the seven study lakes.

Effects of temperature fluctuations and photoperiod on hatching in the parasitic copepod Salmincola edwardsii

1990 ◽  
Vol 68 (6) ◽  
pp. 1330-1332 ◽  
Author(s):  
Robert Poulin ◽  
David C. Conley ◽  
Mark A. Curtis
Keyword(s):  
Brook Trout ◽  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
Temperature Fluctuations ◽  
Parasitic Copepod ◽  
The Other ◽  
Hatching Rate ◽  
Experimental Conditions ◽  
Effects Of Temperature ◽  
Daily Changes

In laboratory experiments, we studied the effects of the day–night cycle (photoperiod and temperature fluctuations) on the initiation of hatching and hatching rate in egg sacs of the copepod Salmincola edwardsii, ectoparasitic on brook trout (Salvelinus fontinalis). Pairs of egg sacs were removed from adult female copepods; for each pair, one sac was placed under experimental conditions and the other one was kept under constant conditions, providing an ideal control. Photoperiod had no significant effect on the initiation of hatching or hatching rate. The observed effects of temperature fluctuations were associated with water temperature itself, and appeared independent of whether it was fluctuating or constant. We conclude that hatching in S. edwardsii is not rhythmical but spontaneous, showing no relationship with daily changes in host vulnerability.

Effects of temperature and photoperiod on the duration of hatching, swimming, and copepodid survival of the parasitic copepod Salmincola edwardsii

1993 ◽  
Vol 71 (5) ◽  
pp. 972-976 ◽  
Author(s):  
David C. Conley ◽  
Mark A. Curtis
Keyword(s):  
Water Temperature ◽  
Brook Trout ◽  
Laboratory Experiments ◽  
Hatching Success ◽  
Salvelinus Fontinalis ◽  
Parasitic Copepod ◽  
Swimming Activity ◽  
The Other ◽  
Egg Hatching ◽  
Effects Of Temperature

We conducted laboratory experiments to test whether various temperature and photoperiod regimes had any effect on the duration of egg hatching, swimming activity, and copepodid survival in the parasitic copepod Salmincola edwardsii, commonly found on brook trout (Salvelinus fontinalis). Pairs of egg sacs were removed from adult female copepods; one of each pair was exposed to a different photoperiod than the other, at the same temperature. Experiments were conducted at 8, 12, 16, and 20 °C. Temperature had a significant effect on the duration of copepodid swimming activity and survival, and the onset of egg sac hatching was directly related to increasing water temperature. However, hatching duration and hatching success were not affected by temperature over the range tested. Photoperiod had no effect on hatching duration, hatching success, swimming activity, or copepodid survival. Our findings indicate that S. edwardsii copepodids can swim and survive for more than 2 weeks; much longer than the 2 days customarily reported in the literature. This must be accounted for in the development of strategies to control transmission.

Larval development of the parasitic copepod Salmincola edwardsii on brook trout (Salvelinus fontinalis)

1994 ◽  
Vol 72 (1) ◽  
pp. 154-159 ◽  
Author(s):  
David C. Conley ◽  
Mark A. Curtis
Keyword(s):  
Larval Development ◽  
Brook Trout ◽  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
Infection Intensity ◽  
Parasitic Copepod ◽  
Developmental Time ◽  
Adult Males ◽  
Pectoral Fins ◽  
Adult Females

We conducted laboratory experiments to determine the developmental time from larva to adult of the parasitic copepod Salmincola edwardsii on brook trout (Salvelinus fontinalis) at 13 °C. Healthy fingerlings were exposed to large doses of recently hatched copepodids for 12 h. Three infected fingerlings were sacrificed at 12-h intervals until day 6 and then at 24-h intervals until day 20 postexposure. The gills, opercula, and pectoral fins were the major sites of attachment. Adult males were detected as early as day 3 and as late as day 8 postexposure, with the greatest number occurring about day 5. Adult males may live for up to 3 days at 13 °C. Adult females were detected as early as day 11 postexposure but not consistently until day 13, indicating that permanent bulla attachment took place between 11 and 16 days postexposure. Infection intensity declined rapidly until day 9 postexposure then less quickly for the rest of the experiment.

Biotic and Abiotic Determinants of the Diet of Brook Trout, Salvelinus fontinalis, in Lakes of the Laurentian Shield

1992 ◽  
Vol 49 (5) ◽  
pp. 1001-1009 ◽  
Author(s):  
Sylvain Lacasse ◽  
Pierre Magnan
Keyword(s):  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Zooplankton Community ◽  
White Sucker ◽  
Linear Regression Models ◽  
Prey Fish ◽  
Rock Outcrops ◽  
Zooplankton Community Structure ◽  
Morphoedaphic Index ◽  
Terrestrial Insects

From a survey of 12 lakes containing brook trout, Salvelinus fontinalis, 12 lakes containing brook trout and creek chub, Semotilus atromaculatus, and 13 lakes containing brook trout and white sucker, Catostomus commersoni, we built seven multiple linear regression models to account for the mean percent weight of different prey categories in the diet of brook trout. Presence of chub and sucker, zooplankton community structure, sampling date, morphoedaphic index, and the importance of rock outcrops accounted for 88% of the variation in weight of zoobenthos eaten by trout, which was the preferred prey in allopatry. Thirty percent of the variation in weight of zooplankton eaten by trout was explained by the importance of macrophytes and other refuges for fish. Models for amphipods, dipteran pupae, swimming insects, terrestrial insects, and prey-fish explained between 36 and 63% of the variation. The presence of white sucker or an index of their impact (mean length or density of Cladocera) and the characteristics of littoral habitats appeared in six of seven models. Littorasl habitats seemed particularly determinant for the inclusion of prey-fish in the diet, more prey-fish being eaten when regufes were abundant. Variables related to lake morphometry and physicochemistry appeared less regularly in the models.

Responses of the fish ectoparasite Salmincola edwardsii (Copepoda) to stimulation, and their implication for host-finding

Parasitology ◽  
1990 ◽  
Vol 100 (3) ◽  
pp. 417-421 ◽  
Author(s):  
R. Poulin ◽  
M. A. Curtis ◽  
M. E. Rau
Keyword(s):  
Shock Waves ◽  
Mechanical Stimulation ◽  
Strong Evidence ◽  
Brook Trout ◽  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
Selective Pressure ◽  
Host Finding ◽  
And Shock Waves ◽  
Energy Stores

SUMMARYThe short-lived infective copepodid stages of the copepod Salmincola edwardsii, ectoparasitic on brook trout, Salvelinus fontinalis, are under strong selective pressure to evolve efficient host-finding mechanisms. In laboratory experiments, we quantified the effects of visual and mechanical stimulation on the activity of the copepodids. We found that shadows passing above the copepodids and shock waves passing through the water generated marked increases in the rate and length of upward swimming bursts, which resulted in more time spent suspended in the water column and greater distances travelled. However, we found no strong evidence for a relationship between the magnitude of the copepodids' response and the intensity of stimulation. Although these responses are not host-specific, they allow the parasites to conserve their limited energy stores by increasing their host-finding activity only when potential hosts are nearby.

scholarly journals The Effects of Kefir Usage for Probiotic Purpose on Growth Performance of Brook Trout (Salvelinus fontinalis)

2018 ◽  
Vol 10 (11) ◽  
pp. 101
Author(s):  
Huriye Ariman Karabulut ◽  
Ilker Zeki Kurtoglu ◽  
Ozay Kose
Keyword(s):  
Survival Rate ◽  
Growth Performance ◽  
Brook Trout ◽  
Statistical Difference ◽  
Salvelinus Fontinalis ◽  
The Body ◽  
The Other ◽  
Control Group ◽  
Fish Diet ◽  
Commercial Fish

The effects of probiotically used kefir on growth, survival rate and meat yield characteristics of brook trout (Salvelinus fontinalis) were investigated in this study. For this purpose, kefir was added to trial diets at different rates 20 ml/kg feed (G2), 40 ml/kg feed (G3) while commercial fish feed was used as a control 0 ml/kg feed (G1). Total 270 fish with mean weight 24.38±0.37 g were used during the experiment. Each group had three replicate, and 30 fish were placed in each tank. Experiment was carried on for 90 days. At the end of the experiment, some growth parameters, survival rate and meat yields of the groups were determined. The best weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR) and survival rate (SR) values were obtained in G2 (20 ml/kg) group (104.31±0.11, 1.30±0.08, 1.40±0.18, 98.88±0.51 respectively). At the end of the study, the differences between the control group and the other groups were not statistically significant in terms of FCR, Condition factor (CF) and survival rate (P < 0.05). However, the differences between the control group and the other groups were statistically significant in terms of WG, WGR and Wf (P < 0.05). The statistical difference between the G2 group and the G1 group was not significant at the SGR, whereas the statistical difference between the G2 group and the G3 group was significant (P < 0.05). The body composition of the fish, hepatosomatic index (HSI), viscerosomatic index (VSI) values, fish meat crude protein and crude fat content were not affected by the addition of kefir to fish diet at different ratios. As a result, it was observed that the addition of kefir at 20% of the diet positively affected the growth performance and survival rate of the brook trout.

Selection by Brook Trout (Salvelinus fontinalis) and Juvenile Atlantic Salmon (Salmo salar) of Shade Related to Water Depth

1975 ◽  
Vol 32 (9) ◽  
pp. 1652-1656 ◽  
Author(s):  
R. John Gibson ◽  
G. Power
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Water Depth ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
The Other ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Selection For ◽  
Salmon Parr

Salmon parr and small brook trout were observed in two stream tanks providing choices of cover. One tank was shallow (24–29 cm) and the other deep (43–50 cm). In the shallow tank brook trout occurred most frequently in shade. When salmon were the sole species, they were most frequently in shade, but were mostly away from shade in the presence of trout. This selection for shade was not evident by either species in the deep tank.

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