A 4-year study (1989-1992) of a population of Lipohrys pavo living in
a brackish lagoon (Maugio, France) revealed three types of male during
the spawning season (April to September): (i) nest-breeder males whic
h are territorial, and have well-developed secondary sexual characteri
stics; (ii) non-functional males which were abundant only in 1991 when
population density was very high and (iii) 1-year-old kleptogamic mal
es with small body size which possess neither secondary sexual organs
nor a testicular gland, although their testes are functional and hyper
developed (up to 10.5% of carcass weight). The percentage of kleptogam
ic males was Fairly stable in the population (from 7.9 to 10.0%) and h
ighly variable in their age class (From 8.5 to 51.3%). It is suggested
that kleptogamy is a conditional strategy adopted by smaller males. (
C) 1995 The Fisheries Society of the British Isles