The Spawning cycle of the European hake (Merluccius merluccius, (Linnaeus, 1758)) was studied ill two western Mediterranean areas, the Catalan Sea and the northern Tyrrhenian Sea, including observation of the monthly seasonal variation of the gonad maturity and the gonadosomatic index (GSI). The estimation of the maturity stages by GSI gave similar values ill the two Study areas: the Spawning stage (IV) was easily distinguished from the other maturity stages and its range of variation showed a low overlap with stage Ill and no overlap with other stages. Although in both study areas active females were present during all the sampled months, the peak of reproductive activity was concentrated from February to May in the northern Tyrrhenian Sea but from August to December in the Catalan Sea, which was Subjected to winter cascading events. Batch fecundity gave similar values in the Catalan and northern Tyrrhenian Seas: 204 and 202 eggs per gonad-free female gram. respectively. An asynchronous oocyte development is suggested for M. merluccius in the western Mediterranean.
Spawning pattern and batch fecundity of the European hake Merluccius merluccius (Linnaeus, 1758) in the western Mediterranean.
BELCARI, PAOLA
2008-01-01
Abstract
The Spawning cycle of the European hake (Merluccius merluccius, (Linnaeus, 1758)) was studied ill two western Mediterranean areas, the Catalan Sea and the northern Tyrrhenian Sea, including observation of the monthly seasonal variation of the gonad maturity and the gonadosomatic index (GSI). The estimation of the maturity stages by GSI gave similar values ill the two Study areas: the Spawning stage (IV) was easily distinguished from the other maturity stages and its range of variation showed a low overlap with stage Ill and no overlap with other stages. Although in both study areas active females were present during all the sampled months, the peak of reproductive activity was concentrated from February to May in the northern Tyrrhenian Sea but from August to December in the Catalan Sea, which was Subjected to winter cascading events. Batch fecundity gave similar values in the Catalan and northern Tyrrhenian Seas: 204 and 202 eggs per gonad-free female gram. respectively. An asynchronous oocyte development is suggested for M. merluccius in the western Mediterranean.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
