Predation by Rainbow Trout (Salmo gairdneri): the Influence of Hunger, Prey Density, and Prey Size

1972 ◽  
Vol 29 (8) ◽  
pp. 1193-1201 ◽  
Author(s):  
D. M. Ware
Keyword(s):  
Rainbow Trout ◽  
Feeding Behavior ◽  
Foraging Behavior ◽  
Food Consumption ◽  
Prey Density ◽  
Prey Size ◽  
Salmo Gairdneri ◽  
Critical Rate ◽  
Total Food ◽  
Total Food Consumption

The feeding behavior of rainbow trout (Salmo gairdneri) was investigated by exposing fish to several densities and sizes of prey over a range of four substrates of varying complexity. Within substrate treatments the rate of predation could be stimulated by increasing either prey density, prey size, or predator hunger. Between treatments, however, both the intensity of predation and total food consumption proved to be inversely related to the complexity of the substrate because a number of prey were able to find cover and thus escape detection.The results further indicate that the nature of foraging behavior may be controlled by a critical rate of food capture. If trout did not exceed an average of.058 captures sec,−1 substrate-oriented search proceeded to wane.

Physiological Response of Juvenile Coho Salmon (Oncorhynchus kisutch) and Rainbow Trout (Salmo gairdneri) to Handling and Crowding Stress in Intensive Fish Culture

1976 ◽  
Vol 33 (12) ◽  
pp. 2699-2702 ◽  
Author(s):  
Gary A. Wedemeyer
Keyword(s):  
Rainbow Trout ◽  
Feeding Behavior ◽  
Coho Salmon ◽  
Physiological Stress ◽  
Oncorhynchus Kisutch ◽  
Fish Distribution ◽  
Salmo Gairdneri ◽  
Crowding Stress ◽  
Normal Feeding ◽  
Intensive Fish Culture

Moving 4–5-in. coho salmon (Oncorhynchus kisutch) held in soft (20 ppm CaCO3) water from the relatively light loading density of 0.5 lb/ft3 to 1, 2, or 4 lb/ft3 (density index, DI = 0.1, 0.2, 0.4, 0.8) caused significant stress as indicated by loss of feeding behavior, but only minimal physiological disturbances, as indicated by lack of hyperglycemia or hypochloremia. However, moving them to 6 or 12 lb/ft3 (DI = 1.2, 2.4) caused significant physiological stress which required at least a week for recovery. Smolting coho salmon were physiologically stressed by population densities of 1 lb/ft3 or more and a subclinical corynebacterial kidney infection was activated. Rainbow trout (Salmo gairdneri) (4–5 in.) were physiologically stressed when moved and held at 1 lb/ft3 or more but retained normal feeding behavior. This indicates that handling and crowding stress will be minimized in softwater areas if densities in fish distribution trucks or in ponds or raceways during disease treatments are held to 0.1–0.5 lb/gal.

scholarly journals Trends in Food Preferences and Sustainable Behavior during the COVID-19 Lockdown: Evidence from Spanish Consumers

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1898
Author(s):  
Shanshan Li ◽  
Zein Kallas ◽  
Djamel Rahmani ◽  
José Maria Gil
Keyword(s):  
Food Consumption ◽  
Risk Perceptions ◽  
Food Preferences ◽  
Purchasing Behavior ◽  
Sustainable Food ◽  
Global Food Security ◽  
Total Food ◽  
Food Expenditure ◽  
Sustainable Behavior ◽  
Total Food Consumption

The COVID-19 pandemic poses a threat to global food security, and it changes consumers’ food buying and consumption behavior. This research not only investigates trends in Spanish consumers’ general food shopping and consumption habits during the lockdown, but also investigates these trends from the perspective of sustainable purchasing. Specifically, total food consumption (C), food expenditure (E), and purchase of food with sustainable attributes (S) were measured. Data were collected from a semi-structured questionnaire which was distributed online among 1203 participants. The logit models showed that gender, age, employment status, and consumers’ experiences were associated with total food consumption and expenditure during the lockdown. In addition, consumers’ risk perceptions, shopping places, trust level in information sources, and risk preference were highly essential factors influencing consumers’ preferences and sustainable behavior. Consumers’ objective knowledge regarding COVID-19 was related to expenditure. Furthermore, family structure only affected expenditure, while income and place of residence influenced food consumption. Mood was associated with expenditure and the purchase of sustainable food. Household size affected purchasing behavior towards food with sustainable attributes. This research provides references for stakeholders that help them to adapt to the new COVID-19 situation.

scholarly journals Control of German Cockroaches with a Hydramethylnon Bait

1996 ◽  
Vol 21 (1) ◽  
pp. 415-415
Author(s):  
Mary H. Ross
Keyword(s):  
Food Consumption ◽  
Food Source ◽  
Total Food ◽  
Alternate Food ◽  
Behavioral Resistance ◽  
Total Food Consumption

Abstract The response of German cockroaches to MaxForce, a 0.05% hydramethylnon bait (Clorox Co.), in the presence of an alternate food source, was evaluated. Also, survivors were saved, mated, and progeny tested to investigate the possible development of either physiological or behavioral resistance. Cockroaches were from 5 field-collected strains from different geographic localities. Ten male and 10 female 6th instars were starved overnight, placed in 5 gal aquaria, and given a choice of dog chow or bait. Tests were run for 48 h. Mortality was recorded during and after the test until 2 d passed with no further death. Bait and dog chow consumption was determined (mg). Bait preference/avoidance was evaluated by dividing bait consumption by total food consumption (bait + dog chow). Six to 8 replicates were done on each strain in each generation.

scholarly journals The analysis of contemporary markets with selected organic products in the Czech Republic and in selected foreign countries

2012 ◽  
Vol 50 (No. 9) ◽  
pp. 417-422
Author(s):  
I. Živělová ◽  
J. Jánský ◽  
T. Koudelková
Keyword(s):  
Czech Republic ◽  
Great Britain ◽  
The Netherlands ◽  
Food Consumption ◽  
The Czech Republic ◽  
Total Food ◽  
Foreign Countries ◽  
Organic Products ◽  
Contemporary Situation ◽  
Total Food Consumption

The paper aims to analyse the contemporary situation on markets with selected organic products in the Czech Republic as well as in selected European countries. The attention is paid especially to the share of organic products´ consumption (cereals, potatoes, fruits, vegetables, milk, pork, poultry and eggs) in the total food consumption in the Czech Republic, in Spain, in Sweden, in the Netherlands and in Great Britain.

Feeding Response of Atlantic Salmon (Salmo salar) Alevins in Flowing and Still Water

1978 ◽  
Vol 35 (3) ◽  
pp. 329-332 ◽  
Author(s):  
D. M. Rimmer ◽  
G. Power
Keyword(s):  
Atlantic Salmon ◽  
Food Consumption ◽  
Salmo Salar ◽  
Water Current ◽  
Feeding Response ◽  
Atlantic Salmon Salmo Salar ◽  
Total Food ◽  
Prey Items ◽  
Total Food Consumption

Atlantic salmon (Salmo salar) alevins presented with lake zooplankton in still water readily consumed prey items, but only if the prey were nearby and moving. Feeding was initiated from the bottom or from midwater, but no search or pursuit behavior was noted. Stomach analyses of alevins exposed to lake zooplankton assemblages for 3 h in still and flowing (7.2 cm∙s−1) water revealed that the two groups consumed similar diets, but that the still-water group had a greater total food consumption. We conclude that for alevins to feed successfully, food need not be carried in a water current, but that motion of the prey is necessary. This motion can be provided by water current or by the prey. The role of prey motility in the feeding of young salmonids is briefly discussed. Key words: Atlantic salmon, alevins, feeding, water current

scholarly journals The Impact of Water-Related Pollution on Food Systems in Transition: The Case of Northern Vietnam

2021 ◽  
Vol 13 (4) ◽  
pp. 1945
Author(s):  
Vincent Linderhof ◽  
Marieke Meeske ◽  
Vasco Diogo ◽  
Anne Sonneveld
Keyword(s):  
Surface Water ◽  
Food Consumption ◽  
Fish Consumption ◽  
Urban Areas ◽  
Food Systems ◽  
Environmental Pressures ◽  
Northern Vietnam ◽  
Landscape Characteristics ◽  
Total Food ◽  
Total Food Consumption

In Vietnam, agricultural practices such as fertilizer and pesticide use affect the landscape as well as the availability and safety of food. For instance, pesticides and fertilizer end up in surface water used for drinking water, crop irrigation, and in fish tanks. However, the link to actual food consumption and health is complex and information is lacking. This study considers potential water-related exposure to toxic hazards in northern Vietnam food systems, through the consumption of food commodities and of water. Water pollution is operationalized by considering the following two channels: (i) pesticide and nutrient leaching to surface water (share of surface water) and (ii) industrial runoff from facilities located in urban areas (share of urban areas). We explore how potential exposure to toxic hazard is related to food consumption choices. Using a sample of the Vietnam Household Living Standard Survey (VHLSS) for 2014, we estimate how shares of food consumption categories in total food consumption are affected by household and landscape characteristics, the latter also reflecting potential environmental pressures. In districts with higher shares of surface water, the share of fish consumption is higher and the share of meat consumption is lower. From an environmental and health perspective, households in water-rich areas thus may have a higher probability of being exposed to toxic chemicals due to higher fish consumption. In districts with higher shares of urban areas, the shares of meat and cereals in total food consumption value were lower, and the shares of fish and fruit and vegetables were higher. The results indicate that food consumption is affected by landscape characteristics that may also influence the level of exposure to water-related environmental pressures, and that this combined effect may potentially exacerbate food safety and health risks. The actual impact is more complex and should be analyzed with more sophisticated data and methods.

Risk of Epibenthic Prey to Predation by Rainbow Trout (Salmo gairdneri)

1973 ◽  
Vol 30 (6) ◽  
pp. 787-797 ◽  
Author(s):  
D. M. Ware
Keyword(s):  
Rainbow Trout ◽  
Prey Size ◽  
Food Resource ◽  
Independent Set ◽  
Equation System ◽  
Benthic Invertebrate ◽  
Salmo Gairdneri ◽  
Food Chains ◽  
Prey System ◽  
Benthic Food

A model is developed to describe the risk of aquatic prey to visual predators in general, and is evaluated with particular reference to rainbow trout (Salmo gairdneri). The equation system uses several principles of visual mechanics to determine predation rates and therefore requires statistics on the physical properties of the food resource, besides the visual acuity and other searching constraints of the predator.Application of the model to an independent set of field data accounted for 47% of the seasonal variation in the occurrence of four benthic invertebrate prey in the diet of trout from Marion Lake, B.C. Considerably better agreement — 70% of the variation — was obtained using a three prey system. Sequential comparisons between the predicted and observed pattern of predation suggest that prey activity, prey exposure, prey density, and prey size are four of the major determinants of prey risk in benthic food chains.

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