1 DTU Aqua, Technical University of Denmark
Stress-resilience differences related to emergence time in farmed rainbow trout
Manuel Gesto, Alfred Jokumsen
Section for Aquaculture, DTU Aqua
Technical University of Denmark
2 DTU Aqua, Technical University of Denmark
Swim-up behavior and Emergence time
Individual variation in time from emergence in salmonid fishes.
Has emergence time any effect on fish robustness?? Any effect on stress resilience?
By E. Peter Steenstra By E. Peter Steenstra
3 DTU Aqua, Technical University of Denmark
Previous data
Wild fish with different emergence time seem to have different SCS and competitive ability. Fish emerging early have been shown to be more aggressive, prone to be dominant, proactive.
Farmed fish??
4 DTU Aqua, Technical University of Denmark
Does farmed fish sorted by emergence time differ in how they respond and resist against punctual and repeated stressors?
Hypothesis
5 DTU Aqua, Technical University of Denmark
Three swim-up fractions:
Stress resilience
Vaz-Serrano et al., 2011
Early 20%
Medium 20%
Late 20%
Selecting fish by emergence time: Sorting device
6 DTU Aqua, Technical University of Denmark
Mortality after sorting
0
2
4
6
8
10
12
day1
day2
day3
day4
day5
day6
day7
day8
day9
day10
day11
day12
day13
day14
day15
day16
day17
day18
day19
day20
day21
day22
day23
day24
day25
day26
day27
day28
day29
day30
day31
day32
day33
day34
day35
day36
day37
day38
day39
day40
Cumulative mortality (%)
early
medium
late
7 DTU Aqua, Technical University of Denmark
A
B
C
0
5
10
15
20
25
30
35
40
early medium late
dead
fis
h
Cumulative mortality (/tank) at day 20
Mortality after sorting
8 DTU Aqua, Technical University of Denmark
300 300 300 300 300 3003 x 3 x 3 x
EARLY MEDIUM LATE
Daily stress (air exposure)Acute stress
14 days
stressed
control
Sampling points: 0, 1, 2, 4, 8 h.
Brains and blood
5 g fish
StressControl
Stress resilience test – Exp. Design
StressControl StressControl
9 DTU Aqua, Technical University of Denmark
Stress markers analyzed:
• Fish length/weight – condition factor
• Plasma cortisol
• Plasma glucose and lactate
• Brain serotonergic activity
Data provided information about:
- Normal acute stress response in each fraction
- Effects of repeated stress on the normal acute
stress response - Resilience
Stress resilience test – samples
10 DTU Aqua, Technical University of Denmark
Data – Fish size
Fish size and condition factor – Among Fractions n= 150
11 DTU Aqua, Technical University of Denmark
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
0 60 120 240 480
Time after exposure (min)
Early
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
0 60 120 240 480
Time after exposure (min)
medium
Stress resilience data - Cortisol
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
0 60 120 240 480
Time after exposure (min)
Late
Response to acute stress in control fish
12 DTU Aqua, Technical University of Denmark
Stress resilience data - Cortisol
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
0 60 120 240 480pla
sm
a c
orti
sol
(n
g/
mL)
Time after exposure (min)
early control
early stress rep
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
0 60 120 240 480
pla
sm
a c
orti
sol
(n
g/
mL)
Time after exposure (min)
medium control
medium stress rep
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
0 60 120 240 480
Time after exposure (min)
late control
late stress rep
Response to acute stress in repeatedly stressed fish
Early Medium
Late
13 DTU Aqua, Technical University of Denmark
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
0 60 120 240 480
Sero
ton
erg
ic a
cti
vit
y (
%
5H
IA
A/
5H
T)
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
0 60 120 240 480
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
0 60 120 240 480
Time after exposure (min)
Early Medium Late
control repeated stress
Stress resilience data – Brain serotonergic activity
14 DTU Aqua, Technical University of Denmark
Restrictive feeding – competition tests
Fish (~60 g) from the three different fractions were PIT-tagged and held together in the same tanks.
3 tanks containing 15 fish of every fraction (45 fish /tank) each.
Growth of the fish was then evaluated under different feeding regimes.
Has emergence time any effect on juvenile growth or on juvenile competitive ability for food?
15 DTU Aqua, Technical University of Denmark
Restrictive feeding – competition exp.Competition and growth
After 15 days under normal feeding (~2% body mass/day):
After 10 days of fasting:
16 DTU Aqua, Technical University of Denmark
Restrictive feeding – competition exp.Competition and growth
After 7 days at low density with restrictive feeding (0.5% body mass/day):
Next step:
Stocking density reduced: 15 fish per tank (5 fish of each fraction, size-paired)
17 DTU Aqua, Technical University of Denmark
Conclusions
Acute stress response and stress resilience are different in fish from different emerging fractions.
Early fraction apparently has a higher capacity to habituate to mild stressors, i.e. more resilient.
No relationship has been found between emergence time and fish growth or fish competitive ability.
Performance of farmed trout related to emergence time seem to be highly influenced by fish origin/genetic background
18 DTU Aqua, Technical University of Denmark
Acknowledgements
RobustFish is part of the Organic RDD 2 programme, which is coordinated by International Centre for Research in Organic Food Systems (ICROFS).
It has received grants from the Green Growth and Development programme (GUDP) under the Danish Ministry of Food, Agriculture and Fisheries.
Jonas Müller – Christian Albrechts Universität zu Kiel
Present and former members of RobustFish project: Peter V Skov, Ivar Lund, Lars-Flemming Pedersen, Erik Höglund.
Our technicians: Ole Madvig Larsen, Rasmus Frydenlund Jensen
19 DTU Aqua, Technical University of Denmark
Stress resilience data - Glucose
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
0 60 120 240 480
Pla
sm
a g
luco
se (
mM
)
0,00
0,50
1,00
1,50
2,00
2,50
3,00
0 60 120 240 480
0,00
0,50
1,00
1,50
2,00
2,50
3,00
0 60 120 240 480
Early Medium Late
Time after exposure (min)
control repeated stresscontrol repeated stress
20 DTU Aqua, Technical University of Denmark
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
0 60 120 240 480
Pla
sm
a l
acta
te (
mM
)
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
0 60 120 240 480
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
0 60 120 240 480
Early Medium Late
control repeated stress
Stress resilience data - Lactate
Time after exposure (min)
21 DTU Aqua, Technical University of Denmark
Data – Fish size
Fish size and condition factor – Control vs Repeated stress n=225
*P=0.006
*P=0.005
22 DTU Aqua, Technical University of Denmark
Restrictive feeding – competition exp.Competition and growth
At low density and with restrictive feeding, fish truly compete for food.
Any relationship between dominance and emergence fraction?
Apparently not