Substance and Energy Expenditure

Oxygen uptake is not very useful in studies of energy expenditure, since 30-40% of it is not used for phosphorylated oxidation or ATP resynthesis, but for other varieties of oxidation such as peroxic and enzymatic oxidation which results in the production of heat (Khaskin, 1981). In any case, the efficiency of oxygen uptake as measured from the PIO coefficient varies according to various eco-physiological factors (Verzhbinskaya, 1968 Arsan et al., 1984 Savina, 1992). The heat produced is dissipated into the environment, except in the case of certain very active fish that possess a heat-exchange mechanism (Stevens et al., 1974) permitting the body temperature to rise and thereby increase muscle power (Love, 1980, p.321). 

The levels of metabolism of Black Sea fish in relation to their natural mobility were determined by Belokopytin (1990). First, the relationship between swimming rate and oxygen consumption in a Brett-type tunnel respirometer was determined, using horse-mackerel, pickerel, anchovy and annular bream. The relationship is described by the equation  

The population coefficients of moderately mobile, as distinct from highly mobile, Black Sea fish decrease to 1.4, and low mobile to 1, i.e. to the approximate values known for standard metabolism. These facts lend emphasis to the importance of conducting experiments in order to substantiate the conversion calculations. It is incorrect to extrapolate experimental data to total metabolism in fish without making direct observations on their motor activity in the natural state (Paloheimo and Dickie, 1966 Beamish, 1968 Brett, 1970 Healy, 1972 Elliott, 1976 Tytler, 1978 Kerr, 1982 Diana, 

Lack of telemetry (measurement from a distance) under natural conditions is, as Brett and Groves (1979) believe, the bottleneck in studies of fish bioenergy. The same opinion was expressed by Klyashtorin (1982), who found that the average daily oxygen consumption of fish in nature exceeded their standard metabolism by anything from 20% to 300%, depending on the mobility of the species. 

We have already stated that total metabolism (Q) is the sum of basal (Qb) and active ( )a) metabolism  

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