Relation of Largemouth Bass Reproduction to Crowded Sunfish Populations in Florida Ponds
D. Hugh Barwick
Florida Game and Fresh Water Fish Commission, Eustis, Florida, 32726 USA

Dennis E. Holcomb
Florida Game and Fresh Water Fish Commission, Eustis, Florida, 32726 USA

D. Hugh Barwick
Florida Game and Fresh Water Fish Commission, Eustis, Florida, 32726
Dennis E. Holcomb


Abstract
Largemouth bass (Micropterus salmoides) were studied in an effort to determine if a repressive factor or predation by sunfishes (Lepomis sp.), or both, caused failure of bass reproduction in ponds crowded with sunfishes. In addition, we observed anosmic bass to determine if lack of olfaction would allow bass to spawn, in the event that a repressive factor operating through the sense of smell was the inhibitor. However, neither a repressive factor nor sunfish predation was believed to be responsible for lack of reproduction. Lack of reproduction was apparently associated with a physical factor that in some way interrupted normal bass breeding activity.


Behavioral Suppression of Spawning in Largemouth Bass
by Interspecific Competition for Space
Within Spawning Areas •
STEPHEN LEE SMITH
Florida Game and Fresh Water Fish Commission
Eustis, Florida 32726
ABSTRACT
Florida largemouth bass, f ail to spawn i n association w ith
Dense p opulations o f stunted sunfish. A recent study indicatedt hat a "physicalf actor" rather
than a chemical factor may be responsible.
Three hatcher• pondsc ontainingm arkedb assw ere stockeda t different pointsi n the bass
reproductivec yclew ith concentrationosf sunfishk nownt o suppresss pawning.I t was determined
that reduced or complete inhibition of spawning of largemouth bass is related to interspecific
populationd entities in the spawning area and is behavioral in nature. Suppression is linked to
aggressive interaction with other species,primarily affects the male bass, and is effective in
suppressing the spawning behavior sequence even before nest construction.
Other workers have reported the failure of
largemouth bass to spawn in the presence of
large numbers of sunfish and concluded that
failure was due to either sunfish predation on
the eggs (Swingle and Smith 1943) or to a
repressive factor excreted by sunfishes which

Barwick and Holcomb (1976) were the first
to indicate that some other factor may be
responsible. By segregation of bass and sunfish
while allowing free flow of water between areas
they obtained successful bass reproduction
and concluded that suppression of spawning
was probably not due to a chemical substance
excreted into the water. It was postulated
that "lack of reproduction was apparently
associated with a physical factor that in some
way interrupted normal bass breeding activity."
The study reported here was an attempt
to determine the nature of this "physical
factor" and the point in the reproductive cycle
at which it is effective.