West Coast Groundfish Observer Program Manual, Part2 - NOAA

CHAPTER 6
Figure 6- 4: Location of Gonads
Sexing Roundfish
Roundfish gonads are in the visceral cavity, ahead of the
anus (See Figure 6-5). Insert a knife or scalpel blade in or
near the anus and cut forward toward the head. There are
only two organs attached directly to the anus, the intestine
and the gonads. Carefully move the other organs aside to
get a clear view of the tubes attached to the anus, then pull
on the tubes to discern which is the intestine (coiled and
ending at the stomach) and which is the gonad (ending in
paired structures near the backbone).
The ovaries are paired sacs that are typically pink or orange
(or clear when immature). When the ovaries are mature,
you should be able to see eggs inside (the sacs will look
granular). Pacific cod ovaries often have a black covering
on each sac.
The testes of Gadids (cod family) look very different from
ovaries. When mature, the testes are convoluted, opaque
and smooth in texture. In a mature male, the testes are best
described as “greasy-looking, white, twisted Ramen
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