Anchovy temperature

Fish from temperate zones have been most studied, and from these we learn that temperature may influence the character of metabolic rhythm both indirectly, through food supply, and directly, through the limited temperature ranges within which one or other vital activity can or cannot occur. It is the response or the preference that fish show to temperature that shapes the rhythmic pattern. This is well shown in two diametrically opposite fish from the Black Sea, the warm-water anchovy and the cold-water sprat (Figure 34). The curves that describe the course of triacyl-glycerol accumulation in these species mirror each other, as the fish oppose one another in their time of spawning. 

While the character of metabolism is greatly influenced by temperature, its rate depends on foraging conditions. In Chapter 2, distinctions were made between the lipid contents of three races of anchovy. Here, the curves in Figure 35 show the rates of lipid accumulation in Engraulis encrasicholus maeoticus, E. e. ponticus and E. e. mediterraneus from the Azov, Black and Mediterranean Seas, respectively. The abundance of zooplankton in the three... 

Temperature affects food supply in another way also. The Mediterranean sprat, which prefers cold waters, exploits a wider feeding area than fish that inhabit only warm waters, because it takes advantage of a greater water depth and can feed all the year round. It possesses a much greater lipid reserve than the warm-water anchovy, and its range of fatness over the annual cycle is wider (Figure 36). The feeding conditions in the warm Mediterranean waters are therefore more favourable to fish that prefer cooler waters rather than warm. 

Figure 40 The lipid content of Black Sea anchovy following the feeding period, in relation to the average temperature of the water in spring. Temperature data from published sources., lipid content , temperature. (After Shulman and Dobrovalov, 1979.)...

Figure 46 The lipid level of Azov anchovy and the temperature at which they migrate.

Temperature is therefore a determining factor influencing the timing and character of both somatic and generative production in Black Sea fish. All the species examined form a series, which is related to their temperature preference anchovy - horse-mackerel - red mullet - pickerel - whiting - sprat. In the first species the somatic and generative productions coincide, while in the last there is a large space of time between them. In horse-mackerel, red mullet and pickerel there is a partial overlap. 

Figure 58 Relationship between the oxygen consumption of different species and the temperature of the habitat in which they were caught 1, anchovy 2, sprat 3, horse-mackerel 4, pickerel 5, red mullet 6, whiting.

The rate of consumption differs among species when their feeding rate reaches its maximum. Anchovy eat most (in summer), with horse-mackerel coming next. Third are sprats, which have a small body and develop high swimming activity to compensate for the low temperature of the water at the depth in which they live. Red mullet come fourth, and lastly come pickerel and whiting the latter two engage in very little motor activity and consume food poor in calories. The relative levels of food consumption between species may be different when expressed in different ways fresh matter, dry matter or calories. 

Luts, G.I. and Rogov, S.F. (1978). Dynamics of fat content and its formation in kilka and anchovy stocks in the Azov Sea depending on winter temperatures (In Russian). Gydrobiologicheskii Zhumal 14,31-35. 

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