Download Fish Introductions

To vannamei or not to
vannamei …
… that is the question
Marine Cage Culture Sites
Movement of shrimps between countries
within a species’ range is okey.
Borders between countries are political …
Shrimps don’t know that.
Marine Cage Culture Sites
Movement of fish outside its
biological barrier is debatable!
AllQuarantine new arrivals … it could
save the others!
A hypothetical “exotic shrimp transfer network”
Motive for species introduction:
• When a native organism is not suitable
for aquaculture
• When culture of the native stock
crashes
Consequences of Movement
• when a species is introduced, it is not just
individuals of that organism that travel …
parasites and diseases that the organisms
suffer from travel as well
• Problems arise when the exotic organisms
escape from culture facilities either in the
form of adults or larvae.
• Native species may be more susceptible to
the exotic disease
• These exotic species can interbreed or out
compete the native species and destroy the
natural stocks.
Disease and diagnosis
When disease
is present,
only a small
part of the
population
usually shows
clinical
disease
Carriers
Clinical
disease
Sub-clinical
disease
Decreased production
Knowing a Pathogen is Costly
• distribution (how contagious it is)
• duration of infection (will it kill the whole stock?)
• survival time outside the host (does it incubate or hide
somewhere?)
• ability to multiply and remain viable in water
• environmental fate
• number of infectious units required to cause infections
and pathogenicity
• host specificity to determine if cross species infections
or disease are likely to occur
• development of immunity
Disease avoidance approaches
•
•
•
•
•
No introduction
Inspection at source
Inspection upon entry
Quarantine
Introduction of stock known to be clean
Biosecurity is a problem!
The tiger is our own!
Why
lose
it?