Fish Energetics Research Articles

Effect of Fluctuation of Intensity and Spectral Structure of Light on the Growth and Energetics of Young Fish

Effect of Fluctuation of Intensity and Spectral Structure of Light on the Growth and Energetics of Young Fish

Retenção de proteína e energia em juvenis de "black bass" Micropterus salmoides

O objetivo deste trabalho foi avaliar alterações nas formas de reserva de energia na carcaça de juvenis de "black bass" (14,46 ± 0,81 g de peso vivo). Peixes condicionados a aceitar alimento artificial foram estocados em 90 gaiolas de volume 60 L alojadas em caixas de 1.000 L em laboratório com condições ambientais controladas, e alimentados por 64 dias com rações extrusadas com níveis de proteína variando entre 34 e 54% (incrementos de 4%) e teores de energia digestível variando de 3.600 a 4.100 kcal kg-1 de alimento (incrementos de 125 kcal kg-1). Foram analisados as variáveis de ganho de peso, consumo alimentar diário, relação hepato-somática, relação víscero-somática, deposição protéica e energética, glicogênio tecidual hepático e lipídio visceral. Não houve interação (P > 0,05) entre níveis de proteína e energia para os parâmetros avaliados. Os níveis de proteína e energia digestível dietética que garantiram melhor desempenho foram 42% e 3.850 kcal kg-1, respectivamente. Dietas com teores médios de 42% de proteína bruta, induziram um alto acúmulo de glicogênio hepático (P < 0,0442), assim como aumento da relação hepato-somática (P < 0,0001), mostrando alta eficiência no acúmulo de energia prontamente utilizável bem como melhor capacidade de retenção dos nutrientes, quando os níveis de carboidratos foram inferiores a 30% na ração. O aumento dos níveis de energia das dietas, através da inclusão de óleo nas rações, induziu aumentos significativos no acúmulo total de lipídios na carcaça quando as médias eram agrupadas por níveis de energia, e induziu acúmulo de lipídios nas vísceras para os agrupamentos de médias tanto por teor de proteína (P < 0,0001) como de energia dietética (P < 0,0021).

Notes: Fish Energetics: Larger Individuals Emerge from Winter in Better Condition

We tested the hypothesis that larger individuals in a temperate fish population emerge from winter in better energetic condition than do smaller individuals. We sampled adult male bluegills Lepomis macrochirus in Lake Opinicon, Ontario, after spring ice break and just before active feeding began. By extracting neutral and membrane-bound polar lipids. we estimated the energetic condition of each individual. We found that both the mass of lipids and the lipids per gram of body weight were significantly and positively correlated with body size. These results are attributed to the allometric relationships between body size and energy reserves and between body size and metabolic rate. Body size, therefore, profoundly affects energetic state, which may explain why individuals of different size vary in their reproductive behavior and survivorship.

Book Reviews

Muir, J.F. & Roberts, R.J. (Eds.) (1985) Recent Advances in Aquaculture Balon, E.K. (1985) Early Life Histories of Fishes: New Developmental, Ecological and Evolutionary Perspectives. Tytler, P. & Calow, P. (Eds.) (1985) Fish Energetics: New Perspectives. Casper, S.J. (Ed.) (1985) Lake Stechlin—a temperate oligotrophic lake. Denny, P. (Ed.) (1985) The Ecology and Management of African Wetland Vegetation. Salanki J. (ed.) (1985) Heavy Metals in Water Organisms.

Fish bioenergetics and growth in aquaculture ponds: II. Effects of interactions among, size, temperature, dissolved oxygen, unionized ammonia and food on growth of individual fish

In a previous paper, predictions of the individual effects of size, temperature, dissolved oxygen, unionized ammonia and food on fish growth from an organismal model of fish bioenergetics and growth agreed well with available data. Model predictions of the combined effects of size and temperature, size and food, temperature and food, and dissolved oxygen and food on growth also agreed well with available data. Model predictions of six undocumented two-factor interactions were consistent with other known interactions and general principles of fish energetics. The model was also used to predict maximum, optimum, and maintenance rations under controlled environments.

X‐ray microtags for identification of individuals in studies of fish energetics

In a study following growth and food intake of individuals within a population it was important to obtain individual rather than group mean measurements. A technique is described which combined the benefits of X‐ray readable microtags with the radiographic method for measuring food intake described by Talbot & Higgins (1983). Its usefulness was established in an eight–month study on hatchery reared juvenile Atlantic salmon, Salmo salar L.

A Bioenergetics-Based Model for Pollutant Accumulation by Fish. Simulation of PCB and Methylmercury Residue Levels in Ottawa River Yellow Perch (Perca flavescens)

A pollutant accumulation model is developed which successfully predicts concentrations of PCBs and methylmercury in tissues of yellow perch (Perca flavescens) from the Ottawa River, Canada. The model is based on pollutant biokinetics coupled to fish energetics. The expression for metabolic rate includes a growth dependent term for estimating the contribution to metabolism of seasonal and annual growth in each age-class. Uptake of pollutant from food is based on caloric requirements for respiration and growth coupled to concentration of pollutant in food and its assimilation efficiency from the diet. Uptake of pollutant from water is based on flow of water past the gills for respiration coupled with concentration of pollutant in water and the efficiency of its assimilation by gills. Pollutant clearance is related to body weight raised to the power of −.58, but is independent of metabolic rate. Under steady state conditions of chronic exposure, the predicted ratio of uptake to clearance is roughly constant at all weights, and the slope of a curve of log pollutant concentration in tissues vs. log body weight can be used to establish the exponent of body weight for clearance.

The Effect of Time of Food Deprivation on the Routine Oxygen Consumption of Largemouth Black Bass (Micropterus Salmoides)

One component of a predatory fish energetics model which is currently being structured and studied in our laboratories is described by the experimental components analysis approach. The purpose of the predictive model is to permit the incorporation of routine metabolic requirements of predatory fish into a much larger mathematical model of the energy needs of largemouth black bass and other predators which behave in similar fashion. The submodel presented here is intended to describe and predict only one of the several components which interact and contribute to the food requirments of largemouth black bass in particular and certain other predators in general.