Burbot hatchery design, development and renovations at the Univ. of Idaho

Presenter: Nathan R. Jensen

Objectives:

1. Introduce you to burbot and where they’re located

2. Present the status of Kootenai(y) River burbot

3. Inform about the systems and practices at the U of I

Burbot morphology

Can grow to 8 kg

Burbot are distributed circumpolar

1. North American Lota lota maculosa

2. Eurasian Lota lota lota

Two subspecies: VanHoudt 2003

Paragamian et al. 2000KVRI 2000

1. Burbot populations collapsed in the Kootenai(y) River

~50 remain in Idaho

2. Petition to classify endangered denied ca. 2000

Not enough information to classify as a distinct population segmentConservation aquaculture development needed

Kootenai River Burbot Status:

BC Ministry of Environment 2004

Kootenai(y) River and recovery area

Captive spawning behavior:

1. Spawning occurs February – April

2. Volitional spawning is common

3. Spawn with or with out hormone

Burbot eggs:

1. ~1 mm diameter

2. Pelagic

3. Semi-buoyant

1 mm

Burbot larvae:

1. 3-4 mm at hatch

2. No mouth for >10 days post hatch

3. Require live feeds

1 mm

1 mm

Burbot larvae continued…

5. Feeding begins 4-5mm

6. Must provide live prey ≥ 30 days

50-75 days better 1 mm

Burbot juveniles:

1. Labor intensive to keep tanks clean while weaning to commercial diets

2. Optimum temperature for growth unknown

Water temperature ranges:

1. Adults 0 - 24 ˚CSpawn 0 - 4 ˚C

2. Eggs 3 - 5 ˚C

3. Larvae 4 - 10 ˚C

4. Fingerlings 10 - 24 ˚C KVRI 2000

1. Spawning, grow-out systems

2. Egg incubation, larval first feeding system

3. Live feed production systems

4. “Pond” culture systems

Systems needed at U of I:

KVRI 2000

1. Tap water is usedDegassed, Carbon filtered, Sodium Thiosulfate treated14 - 18˚ C< 2 L per minute inflowRecycling water system with chiller to maintain 4˚ C

2. Rearing tanks:Three - 1800 LSix - 1100 LScreened to keep eggs in

Adult rearing/spawning system:

1. Tap water is usedRecycled to chill to 3˚C Water leaves head box and flows through tanksIncubators set over top of insulated tanks

2. 36 incubator / 10 million egg capacity

3. Hatch collects in tanks with 500 micron mesh screening

Incubation/larval rearing system:

Egg incubation:

X1. Imhoff cone and pelagic egg

jar’s are better than McDonald type jar’s

2. Incubation period typically lasts 30-40 d

3. Fungus must be controlled

Artemia

Commercial weaning diets

Algae , Rotifer

Generalized larvae feeding strategy

Day 10 post hatch Day 25 post hatch Day 50 post hatch

1. Rotifers: Brackish rotifers are used10-15 ppt NaCl

2. Artemia:Cysts decapsulatedHatched in 19 L water containers5 ppt NaCl

Live feed production systems:

0

50

100

Mill

ions

of o

rgan

ism

s / d

ay

Live feeds production 2008

Rotifers Artemia

Live feeds production 2008

Larvae / juvenile weaning systems:

1. Raceway style troughs and circular tanks are used

2. Inflow typically 1L / minute

3. Intensive cleaning required daily; lasts 100 d

Larvae / juvenile weaning continued…4. Foremost bottle neck to

production of burbot

5. Waste causes fungus and subsequent gill disease

Bottom dwelling

6. Salt (5 ppt) and Formalin (170 ppm) used to control fungus

7. Cannibalism is common

1 mm

Hatchery design/technique renovations: 1. Spawning:

Develop an automated egg collection system

2. Incubation:Use H2O2 rather than FormaldehydePhase out pelagic egg hatching jars

3. Live feeds:Increase rotifer production by maintaining two systems and increasing salinity

4. Larval feeding:Test different larval weaning dietsH2O2 will be used to control fungus…

Hatchery design/technique renovations… 5. Incorporate semi-intensive outdoor tanks and stock earthen ponds

Cow creek pond and Fredrick’s pond Photos J M Barron 2008

Semi-intensive outdoor tanks at UI

Production summary of feed transitioned juveniles since 2004

3 0 73

850

2000

0

1000

2000

2004 2005 2006 2007 2008

Juveniles

Thank you!Nathan R. Jensen

njensen@uidaho.edu

Funding :Kootenai Tribe of Idaho andThe Bonneville Power Administration Project:198806400; Contracts:20490, 25349