Disease prevention and control for gametes and embryos of fish and marine shrimp
J.A.
Brock, R. Bullis-2001
Aquaculture, 197 (1-4): 137-159
(Reproductive Biotechnology in Finfish
Aquaculture
Oceanic Institute, Hawaii, USA, 4 - 7 October 1999
Edited by C.-S. Lee, E. Donaldson and N. Bromage)
Abstract:
Disease
prevention is a facet of the total quality management for gametes and
embryos of fish and marine shrimp. Gamete health is strongly influenced by
broodstock health and nutrition, the quality of the techniques used during
gamete production, collection, storage and pre- to post-hatch conditions in
embryo incubation. Poor quality gametes or unhealthy conditions during
collection and incubation can result in embryo mortality and/or lead to the
attack of the eggs by saprophytic bacteria and fungi. Gametes and embryos
may also provide the means for vertical transmission of certain pathogens
from brood animals to their offspring. There are a number of viruses of fish
and shrimp which may transfer from broodstock to the offspring at the time
of spawning. A few bacterial and fungal pathogens are also dispersed in this
way. For the vertically transmitted biotic agents, the principal biological
impact of the disease occurs typically well beyond egg hatching.
Specific
viruses, bacteria and fungi are the major infectious agents of concern for
the gametes and embryos of fish and marine shrimp. Prevention of the
diseases that stem from these agents involves primarily the application of
the best management practices (BMPs) available for broodstock selection and
maturation; gamete production, collection and storage; and pre- to
post-hatch egg incubation. Specific techniques have been developed for the
control of selected pathogens of high economic significance to fish and
penaeid shrimp culture. Incomplete knowledge regarding BMPs that are
unattainable because of system or other constraints and human error are
important factors hindering the prevention of egg transmitted infectious
diseases of the mass cultured fish and shrimp species.
Using
specific pathogens as examples, like a number of the measures applied by
aquaculturists to eliminate or reduce the pathogen/disease risks associated
with gametes and embryos of fish and marine shrimp, are discussed here. The
tactics highlighted are the application of BMPs to maintain gamete and
embryo health; the use of specific pathogen-free (SPF) broodstock; the
testing and elimination of broodstock carriers of specific pathogens;
chemical treatment of the broodstock to control a specific pathogen; the use
of pathogen-free culture water; chemical and/or physical disinfection of the
culture water; chemical treatment of the gametes, the embryos or the early
life stages; and mechanical rinsing with pathogen-free water of the eggs or
the early larval stages.