Kootenay Trout Hatchery Alevin Cleanup Method
Doug Crawley
Kootenay Trout Hatchery
Aelvin Clean-up Method
Kootenay Trout Hatchery Location
• S.E Corner of B.C.
• One of 5 Trout
Hatcheries within
FFSBC
• Produce trout/char
and KO for B.C.
recreational fishery
• Also a conservation
hatchery for WSG
Egg Production
• In 2008
• RBT = 2.5 million
• EBT = 1.5 million
• WCT = 100,000
• KO = 6.0 million
Total =10.1 million
Challenges of Egg Husbandry
• Water supply
Critical Qualities
– Low in silt, iron,
manganese
– Temp 8C-13C
– Upwelling flow
– O2 rich
• Bacteria
Can Be Present
– Egg surface and
internal
– Waterborne
• Saprolegnia
Saprolegnia = bad news
•
•
•
•
Biggest challenge
Can be devastating
Major labor draw
Unhealthy egg
environment
• Chemicals may be
required
This is what we don’t want !
We strive for a healthy fungus free environment for our alevins
Incubation System at KTH
Upwellers
Health Trays (FAL)
Upwellers
• GE are incubated in 5
gallon upweller buckets
with capacity ~100K eggs
• The water flow keeps
eggs in motion reducing
fungus spores from taking
hold.
• Eggs receive a constant
clean flush
• Material in suspension is
passed over the overflow
and eliminated.
• Simple system.
Eggs in Upwellers
• GE’s incubated in
Bucket upwellers
As long as
possible.
• Usually until 240
ATU’s = 6 days
after they reach
the EE STAGE
• Then transferred
to Heath Stacks.
Heath Trays
• After picking at the
EE Stage eggs
are transferred to
heath trays and
picked over once
more.
100% Hatch
• Dead eggs,
unhatched alevins
and egg shells
remain inside the
tray.
• Huge potential for
fungus to flourish.
• Very unhealthy
environment.
• Big challenge to
clean up
Post Hatch Cleanup
Manual Cleanup at
this stage requires
many manhours
and is difficult.
It is critical that a
thorough cleanup
takes place.
Critical that alevins
develop in a heathy
environment.
Handling Alevins
So how tough is
An Alevin after hatch?
If handled gently they
are surprisingly tough.
Need to handle them
only in water.
KTH Alevin Cleanup Method
Alevins Brought Out From the Heath Stacks just after 100% hatch
Tray contents are then dumped into tub of water
Tray is then sprayed clean or a new one is used
Contents of Tub are rinsed and purged 3 or 4 times to remove waste
Rinse with fresh clean water each time to rid shells
Alevins will stay in a ball in the bottom of the tub
2nd Tub is Prepared with water and Grader
The contents from 1st tub are gently poured over the submerged
grader in Tub #2 never breaking contact with water.
Alevins will find
their way through
the grader without
any need for
shaking.
Slowly raising and lowering the grader
sometimes helps.
Use different sized graders for different sized eggs
for best results in removing dead eggs/alevins
If done gently there is no issue with damaging the yolk sac
The alevins seem to take this handling with no problems.
When the alevins have all passed through then the dead
material can be put into a 3rd tub for inventory
Alevins will be sitting on the bottom of Tub 2 ready for
Relocating to clean Heath Tray.
Final rinse before going back into the heath tray
Alevins gently poured back into the heath tray
Always in contact with water.
Benefits of Cleanup Method
• Takes 10 minutes per tray as opposed to up to
60 minutes picking individual heath trays.
• After cleaning is finished no more cleaning effort
is needed until troughing.
• Labour savings over year = 200 manhours
• Healthy fish after troughing. Significantly
reduced incidents of flavobacterium outbreaks in
our trough room since using this method.
• Low tech. Equipment costs are very minimal.
HAPPY JOE !!!