| Autor: |
Uzars, D., Baranova, T., Yula, E. |
| Rok vydání: |
2023 |
| Předmět: |
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| DOI: |
10.17895/ices.pub.21960227 |
| Popis: |
Analysis of the long-term biological data sets (1967-1990) on diet, liver weight and maturation of cod revealed the general trends in accumulation of energy in the liver and gonadal maturation dynamics. The study confirms relationship between energetic condition of cod and food supply. The liver condition index of cod and abundance of clupeids in cod food during the autumn/winter and spring was positively correlated. The sex- and maturation-specific differences in cod diet, liver weight, and utilization of energy for gonadal growth and spawning were defined. The ripening females on the spawning grounds were hardly feeding on clupeids. Liver condition index of females continued to increased and reached the maximum at the final maturation stage. The feeding intensity and liver condition index of maturing males decreased earlier than of females at the final gonad ripening stage. Cod of both sexes at spawning condition nearly ceased feeding. The liver condition index declined. In 1967-1977, at favourable oxygen/temperature conditions on the spawning grounds, the gonad development trends prior to the spawning in January determined the gonad growth during the main spawning season in March-April. During the 1980s the spawning population of cod was influenced by poor hydrographic conditions - low oxygen saturation and temperature. The changes in distribution and age composition of the spawning population of cod caused a decline in proportion of males on the spawning grounds. The diverging courses of proportion of maturing cod in prespawning and spawning seasons indicated that hydrographic conditions likely were the cause of the gonad development delay and spawning disturbance during the stagnation period of 1980s. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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