Winner et ai.: Age and growth of Archosargus probatocephalus in Tampa Bay, Florida 
165 
genetic break at the site of the subspecies boundary at 
Apalachee Bay, Florida (Seyoum et ah, in press). These 
recent genetics results, coupled with the known mor¬ 
phological differences between A. p. probatocaphalus 
and A. p. ouiceps, support the validity of the 2 sub¬ 
species of sheepshead within its U.S. range (Caldwell, 
1965), but further study is necessary to better un¬ 
derstand processes that contribute to the genetic and 
morphological differences between these subspecies. A 
comparison of similarly collected age and growth data 
is necessary to determine the existence and extent of 
any subspecific differences in growth. 
A fishery can modify the population size and age 
characteristics of a species by selectively removing 
younger, faster-growing fish (Ricker, 1975), possibly 
accounting for the larger fish collected in northwest 
Florida. Dutka-Gianelli and Murie (2001) suggested 
that because of the lower density of the human pop¬ 
ulation of northwest Florida, sheepshead there may 
have experienced less long-term fishing mortality than 
those in Tampa Bay. Sheepshead enter the fishery in 
Florida waters at -280 mm FL (-305 mm TL), at ap¬ 
proximately the size predicted for age-3 sheepshead in 
Tampa Bay (Table 4). Predicted sizes at age are similar 
between sheepshead in Tampa Bay and those in north¬ 
west Florida through age 3 (mean difference of 13.2 
mm FL), but after that age, sheepshead from northwest 
Florida consistently are predicted to attain larger sizes 
at age (mean difference of 52.4 mm FL). 
Regional differences in sheepshead growth param¬ 
eters are apparent, but within Florida waters it is un¬ 
necessary to manage sheepshead regionally. Several 
fishery management actions, including the ban on en¬ 
tangling gear, a minimum size limit, and recreational- 
bag (15 fish) and commercial-possession (50 fish) limits 
were enacted for sheepshead in Florida waters during 
the 1990s. These actions have brought about a decrease 
in combined landings of sheepshead and an increase 
in the size of sheepshead landed; transitional spawn¬ 
ing potential ratios of sheepshead in Florida have in¬ 
creased since 1996 and, in 2009, were 37% and 29% 
for the Atlantic and gulf coasts of Florida, respectively 
(Munyandorero et al.^). Further studies, to better de¬ 
fine the stock structure and to describe estuary- or 
stock-specific differences in growth, would be benefi¬ 
cial and help refine the management of sheepshead in 
Florida waters. 
Acknowledgments 
We thank staff of the Florida Fish and Wildlife Con¬ 
servation Commission’s Fisheries-Independent Moni¬ 
toring program and its Age and Growth Lab for aiding 
with sample collection and processing and the prepa¬ 
ration and reading of otoliths, D. Harshany for mea¬ 
suring marginal increments, and R. Crabtree and M. 
Murphy for scientific expertise. We also are grateful 
to D. Leffler, T. Tsou, A. Acosta, R. Taylor, M. Murphy, 
R. McMichael, J. Quinn, J. Leiby, and B. Crowder for 
their critical reviews that greatly improved this man¬ 
uscript. This work was supported in part by funding 
from the U.S. Fish and Wildlife Service under Federal 
Aid for Sportfish Restoration Project Number F-43 as 
well as from Florida’s saltwater fishing licenses. The 
statements, findings, views, conclusions, and recom¬ 
mendations contained in this document are those of 
the authors and do not necessarily reflect the views of 
the U.S. Department of the Interior and should not be 
interpreted as representing the opinions or policies of 
the U.S. government. 
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