638 
Fishery Bulletin 99(4) 
These findings are new for summer flounder, because 
no previous studies have used opercular bones to age this 
species. We were disappointed at the poor performance of 
opercular bones because they have been reported useful in 
many other species, including perch (LeCren, 1947), carp 
(McConnell, 1952), yellow perch (Bardach, 1955), north- 
ern pike (Frost and Kipling, 1957), tautog (Cooper, 1967; 
Hostetter and Munroe, 1993), and goldeye (Donald et al., 
1992). Many of these studies show photographs of oper- 
cular bones with clear, easily recognized marks that have 
been interpreted as being formed annually. These studies, 
however, generally have not validated age determination 
in opercular bones; therefore it is unclear whether they 
give accurate ages in these other species. 
Formation of early marks on otoliths and scales 
We sometimes observed an early, presumably false, mark 
prior to the first presumed annual mark on both otoliths 
and scales of summer flounder. Although we attempted 
not to count this early mark, it appeared to be the pri- 
mary cause for disagreements between our readers in 
aging both otoliths and scales. This problem has not been 
reported in summer flounder otoliths, although there is 
evidence of this early false mark on scales (Dery, 1988; 
Bolz et al., 2000). Indeed, a primary problem cited by Bolz 
et al. (2000) for differences in interpretation of summer 
flounder scales was the choice of a first annual mark. 
The early, presumably false, mark that sometimes oc- 
curred on summer flounder otoliths and scales appears 
similar to the first mark reported for Atlantic croaker 
otoliths (Barbieri et al., 1994a) and might be explained 
by similarities in certain life history traits of these two 
species. Both species have a protracted spawning season 
and spawn over a similar time frame in the Chesapeake 
Bay region: Atlantic croaker from mid-summer to late fall 
(Wallace, 1940; Haven, 1957; Barbieri et al., 1994b), and 
summer flounder from early fall to early winter (Smith, 
1973; Morse, 1981; Able et al., 1990). Barbieri et al. ( 1994a) 
reported the formation of a first mark on Atlantic croaker 
otoliths in the first spring following hatching, at 5 to 10 
months, with two patterns of early mark formation: 1) the 
first mark close to, but distinct from, the focus in early 
hatched fish, and 2) the first mark nearly continuous with 
the focus in late hatched fish. As with Atlantic croaker, we 
suggest that the first mark on summer flounder otoliths 
and scales, which we have referred to as an “early, presum- 
ably false, mark,” might actually be laid down in the first 
spring following hatching, at 5 to 8 months, with the same 
two patterns of early mark formation. 
Previous summer flounder aging studies interpret the 
first annual mark to be laid down on scales and otoliths in 
the second spring following hatching (Smith et al., 1981; 
Szedlmayer et al., 1992), at 17 to 20 months, one year af- 
ter the first annual mark is laid down on Atlantic croaker 
otoliths. Despite this difference, fish from these two species 
that are hatched at the same time are currently placed in 
the same year class. It thus appears that the current age 
determination methods differ between these two species. 
For example, according to current conventions (Bolz et al.. 
2000), a summer flounder hatched in October 2000 would 
be called age 1 on 1 January 2002, at a biological age of 
15 months. This age is several months before the first pre- 
sumed annual mark is laid down on the structures in the 
second spring following hatching (2002), even though an 
“early” mark might have been laid down in the first spring 
following hatching (2001). Similarly, an Atlantic croaker 
hatched in October 2000 would be called age 1 on 1 Janu- 
ary 2002 (Barbieri et al., 1994a), at a biological age of 15 
months. However, this age is 8 months after the first an- 
nual mark is laid down on the otolith, which occurs in the 
first spring following hatching (2001). Therefore, the two 
species differ in the way the first annual mark is assigned. 
To resolve the issue of early mark formation in summer 
flounder, we suggest that calcified structures of young-of- 
the-year fish be examined to determine when the early 
mark is formed, as Barbieri et al. (1994a) did for Atlantic 
croaker. Barbieri et al.’s (1994a) validated method automat- 
ically assigns an early first mark, formed at 5 to 10 months, 
to all Atlantic croaker otoliths, whether the mark is dis- 
tinct or not. If the “early, presumably false, mark” in sum- 
mer flounder is similar to the first annual mark in Atlantic 
croaker, an early first mark could likewise be assigned to 
summer flounder otoliths. If this were done, disagreements 
on the first mark on summer flounder structures would be 
fewer, and summer flounder and Atlantic croaker would be 
aged in exactly the same way. That is, both fish would al- 
ready have a first annual mark on the structure when ages 
are advanced to 1 on the 1 January arbitrary birthdate. 
Acknowledgments 
We would like to thank Chesapeake Bay commercial fish- 
ermen for their cooperation and James Owens (VIMS) for 
helping us to obtain samples from them. T. Ihde (VIMS) 
helped develop some of the aging methods and was the 
second reader in our study. J. Foster (VIMS) helped develop 
ideas for the early mark portion of the discussion. Finan- 
cial support for this study was provided by a Wallop/ 
Breaux Program Grant for Sport Fish Restoration from 
the U.S. Fish and Wildlife Service through the Virginia 
Marine Resources Commission, Project F-88-R-2. 
Literature cited 
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Almeida, F. P, R. E. Castaneda, R. Jesien, R. E. Greenfield, and 
J. M. Burnett. 
1992. Proceedings of the NEFC/ASMFC summer flounder, 
Paralichthys dentatus, aging workshop, 11-13 June 1990, 
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U.S. Dep. Commer, NOAA Tech. Memo. NMFS-F/NEC-89, 
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Bagenal, T. B., and F. W. Tesch. 
1978. Age and growth. In Methods for assessment of fish 
