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.J.M. Reichert et al. J. Exp. Mar. Biol. Ecol. 254 2000 169 –188
1. Introduction
There has been considerable discussion of the role of food in determining maximum growth rates and survival of juvenile flatfishes in nursery areas Miller et al., 1991; Van
der Veer and Witte, 1993; Gibson, 1994. It is generally accepted that among the many factors governing growth of fish, the most important are the quality and quantity of food
as the driving force, temperature as a rate controlling factor, and the size of fish as an allometric scaling factor Brett and Groves, 1979. Abundant food, favorable tempera-
tures, and shelter from predation are key factors in allowing juvenile fish to grow quickly to a less vulnerable or adult size in nursery areas e.g., Gibson, 1994. The
majority of the available information on flatfishes is based on studies of relatively longlived, large, temperate species. Information on growth of shortlived, small subtropi-
cal and tropical flatfish species is limited and almost exclusively based on field-collected material e.g., Topp and Hoff, 1972; Reichert and van der Veer, 1991; Van der Veer et al.,
1994; Joyeux et al., 1995. Experimental data on growth under well-defined conditions is lacking.
Many subtropical and tropical flatfish species have an extended spawning period Topp and Hoff, 1972; McEvoy and McEvoy, 1992; Reichert, 1998. When reproduction
is spread out over several months, the increase in mean size of the population over time cannot be used to estimate growth rates. Since the discovery of daily structures in
otoliths, the microstructure of otoliths has provided a tool to study both growth rates and life history characters in fish e.g., Pannella, 1971; Stevenson and Campana, 1992; Secor
et al., 1995. Various studies have shown that resorption of otolith material does not take place, even under periods of low or even negative growth Simkiss, 1974; Campana,
1983; Neilson and Geen, 1985; Jones, 1992, p. 2. The resulting permanent records of daily increments in otoliths allow detailed determinations of the age of individual fish,
permitting estimates of recruitment, mortality rates, and related parameters in fish populations. Despite wide acceptance of the use of increments in age and growth studies
in fish, and the fact that ‘‘the deposition of daily increments appears to be a universal phenomenon under perhaps all but the most severe conditions’’ Jones, 1992, an
appropriate validation is still essential for a correct interpretation of the otolith microstructure Geffen, 1992.
A strong correlation between otolith growth and somatic growth in fish has lead to the use of otoliths for estimating growth rates of fish e.g., Brothers and McFarland, 1981;
Neilson and Geen, 1985; Volk et al., 1984; Bradford and Geen, 1987; Dickey et al., 1997. A linear relationship between otolith growth and somatic growth has been
described for larval plaice Karakiri and von Westenhagen, 1989, juvenile winter flounder Jearld et al., 1992, juvenile greenback flounder Jenkins et al., 1993, and
larval and early juvenile striped bass Dickey et al., 1997, among others. An uncoupling of a tight relationship between otolith growth and somatic growth has been demonstrated
mostly at the lower, and sometimes the extreme upperend of the fish’s growth spectrum in many studies. Such uncoupling results in slower growing fish having relatively larger
heavier otoliths, e.g. Geffen 1982 for Clupea harengus and Scophthalmus maximus, Mosegaard et al. 1988 for arctic charr, Bradford and Geen 1987 for chinook salmon,
Secor et al. 1989 for Morone saxatilis, Pagrus major and Leiostomus xanthurus, and
M .J.M. Reichert et al. J. Exp. Mar. Biol. Ecol. 254 2000 169 –188
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Wright et al. 1990 for Atlantic salmon parr. Others have argued that such uncoupling is not always present, for instance Dickey et al. 1997 found no evidence for uncoupling
in larval striped bass. Regardless of the presence of an uncoupling, and assuming the rate of growth is neither extremely high nor low, increment width can be used to provide
estimates of recent growth of individual field-collected fish once the relationship between otolith growth increment width and somatic growth is established.
This paper will address aspects of growth in the fringed flounder Etropus crossotus Jordan and Gilbert, 1882, a small flatfish with a subtropical and tropical distribution.
Along the Atlantic coasts it has been described from Chesapeake Bay Virginia, USA, to the northern coasts of South America, but it is most abundant in the South Atlantic
Bight and the Gulf of Mexico, and very common in estuaries and shallow waters of South Carolina, USA Topp and Hoff, 1972; Martin and Drewry, 1978; Ogburn et al.,
1988; Reichert and van der Veer, 1991; Allen and Baltz, 1997; Reichert, 1998. The maximum reported total length of the fringed flounder is 16.9 cm, but individual fish are
rarely longer than 15 cm, and their wet weight is seldom more than 40 g Moe and Martin, 1965; Topp and Hoff, 1972; Reichert and van der Veer, 1991; Reichert, 1998.
Reichert 1998 described aspects of the age, growth, and reproduction of the species, showing that its maximum expected life span is about 14.5 months. The fringed flounder
can be found year round on mud and muddy sand in shallow coastal waters and estuaries at temperatures ranging from 11 to 318C and salinities from less than 5 to over 35 ppt
Topp and Hoff, 1972; Martin and Drewry, 1978; Reid, 1954; Ogburn et al., 1988; Reichert and van der Veer, 1991. The relatively small mouth of the fringed flounder
limits the size of their prey, predominantly small benthic and epibenthic crustaceans and polychaetes Reid, 1954; Topp and Hoff, 1972; Stickney et al., 1974; Reichert and van
der Veer, 1991. Spawning in South Carolina takes place from March through October, and the smallest size at which females can potentially reproduce is 7–7.5 cm SL with a
length at 50 maturity between 8.0 and 8.5 cm SL Reichert, 1998. Reichert and van
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der Veer 1991 and Reichert 1998 estimated a growth rate of about 0.5 mm day at
24 to 288C for juveniles, but detailed information for growth under controlled, good quality conditions was not available. Using experimentally derived data, we investigated
1 the relationship between temperature and growth under defined conditions with no food limitation, 2 the validation of daily increment formation in the otoliths, and 3
the relationship between otolith growth and somatic growth. The data can be used to estimate natural rates of growth of individual fish collected in the field, and to model
growth of fringed flounder populations.
2. Materials and methods
