Horse-mackerel annual

Figure 32 Accumulation of lipids and proteins with age in the large form of horse-mackerel showing overall trends (smooth curves) and annual cycles. (After Shulman, 1972a.) Solid lines proteins, broken lines lipids. Note the greater annual fluctuations of lipids.

It is not difficult to assess the average biomass of a fish stock over many years, using data on the numbers and biomass of samples. In Black Sea anchovy, it is 284 kt in May. By November the figure doubles as a result of replenishment and of somatic increase. The average annual biomass (B) amounts to 426 kt for anchovy, 280 kt for sprat, about 36 kt for horse-mackerel, 6 kt for red mullet and 9 kt for whiting (no data are available for pickerel). Results of the studies on annual specific and absolute production in populations of the fish examined here and Px/B coefficients are given in Table 11. 

Having tested this method, many workers will still want to asses annual production from positive values only. If such is the case, Table 12 can be used to determine coefficients of conversion for annual production estimates for all components or for positive values only. Estimates are highest for anchovy, somewhat less in red mullet, horse-mackerel, pickerel and sprat, while there is no difference in whiting. This is the ranking of the species studied for differences between somatic and generative production. It has... 

Ivanov (1983) reported that the natural mortality of horse-mackerel in the Black Sea was 45% and the removal by commercial fishery 13%, making 58% elimination (losses from predators being disregarded) or 21 kt. However, our calculations showed that the total annual production of this fish was 26 kt, a difference of 20%. This value may be reduced if the losses from predators are taken into account. Assuming such losses to be 10%, as in the case of sprat, the total elimination of horse-mackerel would be 68% or about 25 kt. The difference between production and elimination is then only 4%. 

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