Validation of Daily Growth Increments in Statoliths of Japanese Common Squid Todarodes pacificus.

Abstract

In order to validate daily growth increments in statoliths of Japanese common squid Todarodes pacificus, squid were reared for 67 days and fed twice with saury fillets which were immersed in tetracycline HCl (TC) solution. The interval between the first and second oral administrations of TC was 35 days. Two fluorescent marks with TC were observed in the ground and polished statoliths under UV light. The mean number of growth increments between two marks with TC was 34.9(n=17, SD=1.2). This number corresponded with the number of days elapsed (35 days) between two TC administrations. It was concluded from this result that growth increments in the statoliths of T. pacificus were formed daily.