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The problem of age-determination in the Indian Mackerel, Rastrelliger kanagurta, by means Of scales and Otoliths

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Relation http://eprints.cmfri.org.in/1586/
 
Title The problem of age-determination in the Indian
Mackerel, Rastrelliger kanagurta, by means
Of scales and Otoliths
 
Creator Seshappa, G
 
Subject Mackerel fishery
 
Description • The study of the scales of Rastrelliger kanagurta (Cuvier) collected from different
centres during the period 1955-67 and 1969-70 showed that at all centres specimens below
21 cm in total length were without scale-rings; a small percentage of specimens in the
• 21-22.9 cm group showed rings, while a large percentage among those above 23 cm total
length showed the rings in all the centres, this percentage being the smallest (63.1 %) at
Calicut and largest (94.3%) at Karwar. Two rings occurred frequently in specimens
above 25 cm and up to four rings occurred in the very large specimens of Vizhinjam and
Mandapam, but in these large specimens reading of the rings was difficult as they frequently
became faint and obscured as a result of the thickening of the scales subsequent
to the ring-formation. The scale-rings seem to be formed as a result of a physiological
strain on the fish during the process of growth and ripening of the gonads and also spawning.
When clear rings were not noticed in mackerel with gonads in advanced stages,
there were thin margins, which indicated the beginning of ring formation. The otoliths
did not show any annuli that could be used for age-determination.
It is suggested that the mackerel reaches a total length of 11-15 cm by the end of
the first year, 21-24 cm by the end of the second year, 25-27 cm by the end of the third
year, and 28-29 cm by the end of the fourth year of life.
 
Publisher CMFRI/ICAR
 
Date 1969
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
Identifier http://eprints.cmfri.org.in/1586/1/Article_04.pdf
Seshappa, G (1969) The problem of age-determination in the Indian Mackerel, Rastrelliger kanagurta, by means Of scales and Otoliths. Indian Journal of Fisheries, 16 (1&2). pp. 14-28.