McFarlane and King: The validity of the fin-ray method of age determination for Ophiodon elongcitus 
461 
11111 
Figure 2 
Annuli are indicated by dots, OTC ( oxytetracycline ) mark indicated by arrow. A, C, E were photo- 
graphed by using white light and B, D, F were photographed by using ultraviolet light. (A and B) Fish 
numbered B8223905 at liberty for 2 years, with OTC mark evident after fourth annulus. Total age was 
6+. (C and D) Fish numbered B8227766 at liberty for 3 years, with OTC mark evident after twelfth 
annulus. Total age was 15+. (E and F) Enlargements of sections C and D after the fifth annulus. 
Between 1983 and 1986, 1002 tagged lingcod were recov- 
ered. From these, 460 lingcod fin rays were obtained for 
age determination validation: 348 recovered in 1983, 65 
recovered in 1984, 43 recovered in 1985, and 4 recovered 
in 1986. The number of observed annuli after the OTC 
marks corresponded well to the number of expected annuli 
based on the number of years at liberty (Table 1). Lingcod 
recovered in 1983 were expected to have one annulus af- 
ter the OTC mark and approximately 94% of the samples 
were estimated to have one annulus. Lingcod recovered in 
1984, 1985, and 1986 had estimated annuli after the OTC 
mark that corresponded to the expected number of annuli 
in 92%, 91%, and 75% of the samples, respectively. 
In most cases, the presence of the OTC mark was eas- 
ily discernible and appeared as a crisp distinct line. Annu- 
li following the mark were also clearly visible. Fish num- 
bered B8223905 was recovered in July 1984 and aged at 6 
years. The OTC mark formed just beyond the fourth annu- 
lus (Fig. 2A) and was obvious under ultraviolet light (Fig. 
2B). After the OTC mark, two complete annual growth 
zones were present corresponding to the two years at lib- 
erty. Each annual growth zone consisted of an opaque 
(summer) and a translucent (winter) zone. The OTC mark 
at the beginning of the summer opaque zone (Fig. 2A) in- 
dicated that growth had just begun prior to tagging and 
injection in July. 
Fish numbered B8227766 was recovered in July 1985 
and aged at 15 years. As with fish B8223905, the OTC 
mark was also formed at the beginning of an opaque zone 
but was a broad band covering the whole summer zone 
