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TRIPLOID FISH
welfare and production considerations
Ian Mayer
Norwegian University of Life Sciences
Oslo, NORWAY
Triploid fish
Production of triploid fish
 Triploids are organisms with three sets of homologous chromosomes (3n).
 While triploids can be found spontaneously in the wild and can be easily induced in many commercially relevant species of fish and shellfish.
Triploid fish
Production of triploid Atlantic salmon Pressure shock: 8,500 – 10,000 psi for 5‐6 minutes
Triploid fish
Triploidy
Diploid (¨normal¨ fish): 2 chromosome sets (2n)
Triploid: 3 chromosome sets (3n)
 larger cells
diploid
triploid
Triploid fish
Applications The major consequence of triploidy is sterility
Triploid fish are functionally sterile
Triploid fish
AQUACULTURE
BENEFITS OF TRIPLOIDS
Sterility mitigates the problems associated with:
① Early sexual maturation ② Genetic interactions with wild fish
Triploid fish
① Early sexual maturation
Early sexual maturation is a major production problem for many commercially
important aquaculture species, including salmonids, sea bass, Atlantic cod.
Early sexual maturation results in:
 Reduced growth: energy is diverted from somatic to gonadal growth
 Reduction in flesh quality
 Reduced immunocompetence
Op mal harvest
weight
Growth
(body weight)
Precocious matura on
Age
Spawning season
Production of triploid fish
Triploid fish
② Mitigates the problems associated with escaped fish
 Farmed fish escape at every level of the production cycle
 Impact of farmed fish on wild fish: is a major environmental concern
 Genetic introgression results in reduced fitness of wild fish and potentially
can accelerate extinction of local populations
Triploid fish
Genetic introgression
Levels of genetic introgression in 20 Norwegian salmon rivers (Glover et al. 2013)
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② Mitigates the problems associated with escaped fish
 Farmed fish escape at every level of the production cycle
 Impact of farmed fish on wild fish: is a major environmental concern
 Genetic introgression results in reduced fitness of wild fish and potentially
can accelerate extinction of local populations
 Sterility would not solve all the problems associated with escapees but
would mitigate the more serious environmental concerns (genetic
introgression) Fishery Management (stock enhancement)
Triploid fish
AQUACULTURE
CURRENT LIMITATIONS OF TRIPLOID FISH
Compared to diploids, triploid fish are characterised by:
① Lower body weight at harvest size
Triploid fish
① Lower body weight at harvest size
Fraser et al. 2013
6000
5129
Weight (gm)
5000
4537
4482
4000
3988
3000
2000
Smolt SW transfer
1000
0
Jan 11
Apr 11
Oct 11
May 12
2n Vaccinated
3n Vaccinated
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Possible reasons for reduced triploid growth
① Ploidy differences in gut morphology
 In Atlantic cod, triploids had a shorter intestine and fewer pyloric caeca compared to diploid siblings. ② Ploidy differences in gut microbial community

Triploid Atlantic salmon were found to have significantly higher levels of total gut microbiota
compared to diploids (Cantas et al. 2011)
③ Impaired feeding behaviour

Ploidy differences in brain morphology (triploids have smaller olfactory bulbs) ‐ possibly indicating that triploids have less effective feeding behaviour (Fraser et al. 2012)
Triploid fish
AQUACULTURE
CURRENT LIMITATIONS OF TRIPLOID FISH
Compared to diploids, triploid fish are characterised by:
①
Lower body weight at harvest size
②
Increased incidence of skeletal deformities
Triploid fish
Radiographic examples of vertebral deformities in adult farmed Atlantic salmon. Fjelldal et al. 2012
Triploid fish
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Increased prevalence of skeletal deformities
in triploid cod
Opstad et al. 2013
Triploid fish
AQUACULTURE
CURRENT LIMITATIONS OF TRIPLOID FISH
Compared to diploids, triploid fish are characterised by:
①
Lower body weight at harvest size
②
Increased incidence of skeletal deformities
③
Increased heart deformities (cardiovascular performance)
Triploid fish
Aplasia of the septum transversum
Fraser et al. 2013
Septum
transversum
Liver
Aplasia of septum
transversum (%)
40
30
20
Diploid
Triploid
10
0
6
8
10
Incubation temperature (°C)
Triploids have:
• More cases of aplasia of the Normal
Aplasia
septum transversum
• Aplasia occurs at lower incubation temperatures
Thomas Fraser - PhD
disputas - Dec 2013
Triploid fish
Is triploidy the future for fisheries management and aquaculture?
CONCLUSIONS
① AQUACULTURE
 There is growing interest in the use of triploids in aquaculture
 The use of triploids would mitigate the production problem associated with early sexual maturation, and additionally would minimize environmental concerns of escaped farmed fish (genetic introgression)
 However, there is currently a reluctance to use triploids as compared to diploids they display inferior growth rates and a higher incidence of skeletal and heart deformities (FISH WELFARE).
Thank you