and easier to identify than the exposed silver 

 grains in the autoradiographs of most otoliths. 

 OTC is less hazardous to handle in the laboratory 

 and can be detected in the otolith for much longer 

 periods than calcium-45. The OTC was still visi- 

 ble in the otolith at least 3 years following injec- 

 tion and has in fact been used in studies for mass- 

 marking offish for identification purposes, where 

 time at liberty may be even longer (Tsukamoto 

 1985). The activity of calcium-45 was evident in 

 autoradiographs of a few otoliths which were de- 

 veloped 2 years following injection; amount of ac- 

 tivity depends upon the effective half-life of the 

 isotope (164 days for calcium-45) and the initial 

 amount of activity in the tissue. An autoradio- 

 graph of a transverse section through the otolith 

 of one of the fish injected and held for 1 year 

 revealed a discontinuous band of very faint, ex- 

 posed silver grains, dispersed primarily over the 

 internal and dorsal areas of the otolith. Associa- 

 tion of the isotope with an annular band was not 

 observed. Autoradiographs are difficult to pro- 

 duce, expensive, and time consuming. On the 

 other hand, OTC is simply observed in the otolith 

 section under ultraviolet light. Our recommenda- 

 tions for validating the daily formation of growth 

 increments in juvenile rockfishes are 1) the use of 

 OTC, if growth increments can be routinely iden- 

 tified following injection, or 2) stress marks, 

 which are induced either when transferring fish 

 from the field to laboratory or by subjecting fish to 

 abrupt environmental changes. Where this type 

 of induced stress is not appropriate, as in environ- 

 mentally controlled laboratory studies, and OTC 

 marking is unsuccessful, marks could reliably be 

 produced with the calcium-45 technique de- 

 scribed in this paper. 



Acknowledgments 



We thank S. L. Boehlert for generously offering 

 her expertise in preparation of the autoradio- 

 graphs. We also appreciate the helpful comments 

 of S. E. Campana, S. Ralston, and an anonymous 

 reviewer on earlier drafts of this manuscript. This 

 research was supported by NOAA, National 

 Marine Fisheries Service, Northwest and Alaska 

 Fisheries Center, Seattle, WA, through contract 

 81-ABC-00192-PR6. 



Literature Cited 



Barkman, R C 



1978. The use of otolith growth rings to age young At- 



lantic silversides, Menidia menidia. Trans. Am. Fish. 

 Soc. 107:790-793. 

 Boehlert, G W. 



1981 . The effects of photoperiod and temperature on labo- 

 ratory growth of juvenile Sebastes diploproa and a com- 

 parison with growth in the field. Fish. Bull., U.S. 

 79:789-794. 



Boehlert, G. W., and M. M. Yoklavich. 



1985. Larval and juvenile growth of sablefish, 

 Anoplopoma fimbria, as determined from otolith incre- 

 ments. Fish. Bull., U.S. 83:475-481. 



Brothers, E B , D. McB Williams, and P. F. Sale 



1983. Length of larval life in twelve families of fishes at 

 "One Tree Lagoon", Great Barrier Reef, Aus- 

 tralia. Mar. Biol. 76:319-324. 



Campana, S. E. 



1983a. Feeding periodicity and the production of daily 

 growth increments in otoliths of steelhead trout (Salmo 

 gairdneri) and starry flounder (Platichthys stella- 

 tus). Can. J. Zool. 61:1591-1597. 

 1983b. Calcium deposition and otolith check formation 

 during periods of stress in coho salmon, Oncorhynchus 

 kisutch. Comp. Biochem. Physiol. 75A:215-220. 

 Campana, S. E., and J D Neilson 



1982. Daily growth increments in otoliths of starry floun- 

 der (Platichthys stellatus ) and the influence of some envi- 

 ronmental variables in their production. Can. J. Fish. 

 Aquat. Sci. 39:937-942. 



1985. Microstructure of fish otoliths. Can. J. Fish. 

 Aquat. Sci. 42:1014-1032. 



DaBROWSKI, K , AND K. TSUKAMOTO. 



1986. Tetracycline tagging in coregonid embryos and lar- 

 vae. J. Fish Biol. 29:691-698. 



Geffen, A J 



1982. Otolith ring deposition in relation to growth rate in 

 herring (Clupea harengus) and turbot (Scophthalmus 

 maximus) larvae. Mar. Biol. 71:317-326. 



Hettler, W F 



1984. Marking otoliths by immersion of marine fish lar- 

 vae in tetracycline. Trans. Am. Fish. Soc. 113:370-373. 



Hurley, G V , P. H. Odense, R K O'dor, and E G Da we. 



1985. Strontium labelling for verifying daily growth in- 

 crements in the statolith of the short-finned squid (Illex 

 illecebrosus). Can. J. Fish. Aquat. Sci. 42:380-383. 



ICHII, T , AND Y. MUGIYA 



1983. Comparative aspects of calcium dynamics in calci- 

 fied tissues in the goldfish Carassius auratus. Bull. 

 Jpn. Soc. Sci. Fish. 49:1039-1044. 



IRIE, T 



1960. The growth of the fish otolith. J. Fac. Fish. Anim. 

 Hush. Hiroshima Univ. 3:203-229. 

 Miller. S J , and T. Storck. 



1982. Daily growth rings in otoliths of young-of-the-year 

 largemouth bass. Trans. Am. Fish. Soc. 111:527-530. 

 MOSER, H G , AND E. H AHLSTROM. 



1978. Larvae and pelagic juveniles of blackgill rockfish, 

 Sebastes melanostomus , taken in midwater trawls off 

 southern California and Baja California. J. Fish. Res. 

 Board Can. 35:981-996. 

 MUGIYA, Y 



1974. Calcium-45 behavior at the level of the otolithic 

 organs of rainbow trout. Bull. Jpn. Soc. Sci. Fish. 

 40:457-463. 



MUGIYA. Y , AND J MURAMATSU 



1982. Time-marking methods for scanning electron mi- 

 croscopy in goldfish otoliths. Bull. Jpn. Soc. Sci. Fish. 



831 



