First Evidence of Validity of the Fin-Ray Method of Age Determination for Marine Fishes

In 1978, tagged lingcod (Ophiodon elongatus) were injected with oxytetracycline to produce a time mark in the fin rays. Four fish were recovered after being at liberty for approximately 2 or .3 years and all had an oxytetracycline mark. Three of the four fish had formed a number of annual growth zones equivalent to the number of years at liberty, confirming that the mark thought to be an annulus did form once a year. One fish probably formed the appropriate number of annual growth zones but, because growth was reduced, the annuli were difficult to identify. There was no indication that the age of lingcod would be overestimated by the fin-ray method.