Determination
of the gender of an adult Muskellunge can be done by external
examination of the underside of the fish. The vent area of adult male
and female Muskellunge consists of two openings. The most anterior
opening (furthest from the anal fin and closest to the paired pelvic
fins) is the anus, which functions in the passing of solid waste. The
more posterior opening (closest to the anal fin) is the urogenital pore,
which is where liquid waste (urine) and the reproductive gametes (eggs
or sperm/milt) are discharged. The anus for both males and females will
be similarly proportional to the size of the adult fish, regardless of
sex (For example: A 40" male is capable of eating similar size
forage as a 40" female, and will have to digest and pass a similar
size of solid waste. The size of the anal opening will increase
proportional to the growth of the individual fish). The urogenital pore
differs in size between the sexes based on necessity of function.
Discharge of a liquid urine from both males and females would not
require a large urogenital opening for either sex. However, the
difference lies in the size of opening required to release the
reproductive gametes. The release of a liquid sperm in males does not
require any larger of an opening than that required for the release of
urine. The urogenital opening in females is larger to accommodate the
release of an almost "BB" sized egg. Therefore, in female
Muskellunge, the urogenital opening will be as big, or slightly larger
than the anal opening. On the male Muskellunge, the urogenital opening
will be much smaller than the anus. When viewed from the anal fin
looking forward in the direction of the head, the vent area of a male
Muskellunge will have a "key-hole" shaped appearance (the
shape of a skeleton key hole in an older style door lock). When viewed
in the same direction, the vent area of a female Muskellunge will have
more of a "pear" or "figure-8" shaped appearance to
it. It is more difficult to determine gender on smaller muskie.
** Males are pictured on the left, females on the right **
