Review article
The measurement of sperm
motility and factors affecting sperm quality in cultured fish
E. Rurangwa, D.E.
Kime, F. Ollevier, J.P. Nash-2004
Aquaculture, 234(1-4): 1-28
Abstract:
The fish farming industry has been more focused on
the quality of eggs or larvae rather than that of sperm, even though the
quality of both gametes may affect fertilisation success and larval
survival. In some species, poor sperm quality can be a limiting factor in
their culture, however, even when fertilisation success is high, differences
in sperm quality between males when mixed sperm from multiple males is used
may severely reduce the apparent population size and may affect the future
genetic integrity of the stock. Sperm quality in farmed fish may be affected
by different components of broodstock husbandry, during collection and
storage of sperm prior to fertilisation or the fertilisation procedure.
Although other approaches for quantification of sperm quality have been
suggested, motility is most commonly used since high motility is a
prerequisite for fertilisation and correlates strongly with fertilisation
success. The assessment of sperm motility has historically relied on
subjective estimates of motility characteristics, the value of which is
questionable in predicting fertility. Computer-assisted sperm analysis
(CASA) systems that were initially developed to examine sperm quality in
mammals and birds have only recently been applied to fish sperm. CASA can
play an important role in aquaculture since it can rapidly and objectively
quantify the effects of husbandry conditions and sperm handling on sperm
motility and hence, fertilising capacity in farmed fish. This paper reviews
existing methods of sperm quality assessment in fish, surveys the factors
affecting quality and shows how the application of computer-calculated
motility analysis may achieve a better understanding and quantification of
the impact of aquaculture practices on sperm quality and fertilisation
success. The review focuses primarily on teleost fish which predominate in
both aquaculture and research, but also includes some of the studies on
sturgeon which are of increasing interest in aquaculture.
(Laboratory of Aquatic Ecology, Katholieke
Universiteit Leuven, Ch. De Beriotstraat 32, B-3000,
Louvain, Belgium, e-mail: eugene.rurangwa@bio.kuleuven.ac.be)