Biology Reference
In-Depth Information
To assess the reproductive capacity of fi shes, the conventional method
is to estimate the gonado-somatic index. The present trend is to estimate
Fecundity (F). Because F is related to the volume of body cavity available
to accommodate the ripe ovary, F is estimated mostly in relation to body
Length (L) and sometimes to body Weight (W). However, these simple
exercises, when designed more meaningfully to cover the entire life span of
the fi sh, may have far-reaching implications to aquaculture and broodstock
management as wells reproductive senescence, which, in turn, reduce or
cease stem cell production. Some of these estimates made for the fi rst time
in this presentation identify the optimum female size for broodstock and
show that smaller fi sh with a short life span, which are likely to be subjected
to high predation, allocate more of its resource for reproduction, whereas
the larger and long living fi shes allocate for somatic growth. Thereby it is
possible to identify the right candidate species for aquaculture of 'bait fi sh'
and food fi sh. More interestingly, these estimates, covering the entire life
span may also provide valuable information on reproductive senescence and
stem cell production. Conventional fi shery biologists may have to estimate
F of commercially important fi shes covering the entire life span.
Many authors have reported the appearance of mutants during the
embryonic and post-hatching stages. The study on
curveback
syndrome
of mutant guppy stands as a unique example of the spinal stability and
deformity. There is an urgent need to subject mutants for an indepth
investigation for a better understanding of genetic sex differentiation in
fi shes, as models for human diseases and genetic therapy.
