Dvina Gulf, there was an increased catch in 1950 but not in 1951. The smaller catch in 1951 is 

 explained by the premature catching of the 1948 year class when two summers (1+ years) and when 

 two years old. 



The introduction of the prohibition of spring catching of the small Kandalaksha herring had 

 a double aim: the restoring to strength of the spawning population and the use in fishery of the 

 1948 year class at a more mature age and greater weight. As a result of the prohibition, the 1948 

 year class was almost entirely protected from being caught in spring 1950 and became the object 

 of a fishery only when three years old. In the spring of 1951, on the spawning grounds there were 

 caught, by means of a controlled catch, 2, 000 centners of herring. In the summer and autumn of 

 1951, the catch amounted to about 11, 500 centners. In the spring of 1952, there were caught 800 

 centners of sf)awning and 4200 centners of fat herring. In the spring of 1953, there were caught 

 about 800 centners of herring. In the summer and autumn of the same year, as many as 2, 000 

 centners and finally in 1954 about 500 centners were caught. 



Thus the catch of the 1948 year class was spread over several years. 



Two thousand two hundred centners were caught at the age of three full years; 3+ year-olds 

 and 4-year -olds amounted to 12, 500 centners; 4+ year- and 5-year-olds --about 5, 000 centners, 

 5-1- and 6 around 2,000 centners. The exploitation of the 1948 year class provided the fishing indus- 

 try with around 20, 000 centners of herring. In addition, thanks to the abovementioned interdiction, 

 the 1948 year class was caught at a maturer age, when the herring had reached a greater weight. 

 The increase in weight of the 1948 year class according to A. P. Vilson's data, can be seen from 

 the following figures: 



Years Age groups of herring Weight in grammes 



1950 Two -year -olds 15 



1951 Three-year-olds 27.5 



1952 Four " " 37.5 



1953 Five " " 55 



1954 Six " " 70 



The annual increases in the weight of the herring constituted: for the third year 12.5 

 grammes, for the fourth year 10 gm. , for the fifth year 17.5 gm. , for the sixth 15 gm. 



If we allow for an annual natural mortality of not more than 25-30%, the biomass 5-30%, the 

 biomass of the year class is bound to increase from year to year. 



If the 1948 year class had been used at the age of 2-3 years, then the catch would have been 

 less by half. It follows that the restriction on the fishery on the spavraing grounds has increased the 

 catches of fat herring and in the final total has shown a greater productivity of fishery than there 

 could have been if there had been an intensive catch of the generations when young. As a result of 

 the interdiction, the spawning jxjpulation of the herring was increased, and the fecundity of the in- 

 dividual herring and of the species grew (Table 3). 



Marking showed the great intensity of the herring fishery in Kandalaksha Gulf. In the region 

 of marking, there were along a stretch of 4-4.5 km. in the spring of 1953 five control sets of fish- 

 ing gear in aU, In the course of five days, 99 out of 1070 herring marked werecau^t for a second 

 time. In 1954, the number of fish caugjit for the second time constituted 20% /Vilson (7)7- Earlier 

 in the region of Valas-Ruchey Inlet in the spring there had been from 25 to 35 fish-traps, I.e., the 

 intensity of the fishery had been several times greater. Therefore, we are entitled to assume that 



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