Competitive spawning success and fertility of triploid male Atlantic cod Gadus morhua

Feindel, Nathaniel J.; Benfey, Tillmann J.; Trippel, Edward A.

doi:10.3354/aei00006

Cited by 32 publications

(28 citation statements)

References 52 publications

(41 reference statements)

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“…It has been reported in masu salmon Oncorhynchus masou that triploid males demonstrate courtship behavior (“quivering” next to females) and are able to induce a nest building by diploid females (Kitamura, Ogata, & Onozato, ). The most significant observation was that triploid Atlantic cod Gadus morhua males successfully spawned with diploid females (Feindel, Benfey, & Trippel, ). Our results further demonstrate that triploid male zebrafish are able to naturally spawn with diploid females.…”

Section: Discussionmentioning

confidence: 99%

Why are triploid zebrafish all male?

Delomas

Dąbrowski

2018

Molecular Reproduction Devel

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Adult triploid zebrafish Danio rerio has previously been reported to be all male. This phenomenon has only been reported in one other gonochoristic fish species, the rosy bitterling Rhodeus ocellatus, despite the fact that triploidy is induced in numerous species. To investigate the mechanism responsible, we first produced triploid zebrafish and observed gonad development. Histological sections of juvenile triploid gonads showed that primary growth oocytes were able to develop in the juvenile ovary, but no cortical alveolus or more advanced oocytes were found. All adult triploids examined were male (n = 160). Male triploids were able to induce oviposition by diploid females during natural spawning trials, but fertilization rates were low (1.0 ± 3.1%) compared with diploid male siblings (67.4 ± 16.6%). The embryos produced by triploid sires were aneuploid with a mean ploidy of 2.4 ± 0.1n, demonstrating that triploid males produce aneuploid spermatozoa. After confirming that adult triploids are all male, we produced an additional batch of triploid zebrafish and exposed them (and a group of diploid siblings) to 100 ng/L estradiol (E2) from 5 to 28 dpf. The E2 treated triploids and nontreated triploids were all male. The nontreated diploids were also all male, but the E2 treated diploids were 89% female. This demonstrates that triploidy acts downstream of estrogen synthesis in the sex differentiation pathway to induce male development. Based on this and the observations of juvenile gonad development in triploids, we suggest that triploidy inhibits development of oocytes past the primary growth stage, and this causes female to male sex reversal.

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Section: Discussionmentioning

confidence: 99%

Why are triploid zebrafish all male?

Delomas

Dąbrowski

2018

Molecular Reproduction Devel

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“…Hybridisation, sterilisation and polyploidy (e.g. Feindel et al 2010) are possible alternate strategies, but higher initial mortality, greater fingerling costs, poorer growth and uncertainty about consumer acceptance mean that these techniques are not preferred by the industry (Triantafyllidis 2007). As no clear solution exists, investigating techniques to stop cod from spawning in seacages remains a research and development priority for Norwegian aquaculture.…”

Section: Atlantic Cod Eggsmentioning

confidence: 99%

Escapes of fishes from Norwegian sea-cage aquaculture: causes, consequences and prevention

Jensen¹,

Dempster²,

Thorstad³

et al. 2010

Aquacult. Environ. Interact.

247

219

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The escape of fish from aquaculture is perceived as a threat to wild fish populations. The escapes problem is largely caused by technical and operational failures of fish farming equipment. In Norway ), despite the total number of salmon held in sea-cages increasing by 44% during this period. No similar decrease in escaped cod has occurred, suggesting that other measures, such as improved netting materials for sea-cages, are required. In addition to escaping as juveniles or adults, cod may reproduce in seacages, and thus fertilised eggs escape to the environment. The ecological effects of 'escape through spawning' are unclear, and methods to inhibit escape by this mechanism are being explored. To prevent escapes of juvenile and adult fish as sea-cage aquaculture industries develop, we recommend that policy-makers implement a 5 component strategy: (1) establish mandatory reporting of all escape incidents; (2) establish a mechanism to analyse and learn from the mandatory reporting; (3) conduct mandatory, rapid, technical assessments to determine the causes of escape incidents involving more than 10 000 fish; (4) introduce a technical standard for sea-cage aquaculture equipment coupled with an independent mechanism to enforce the standard; and (5) conduct mandatory training of fish farm staff in escape-critical operations and techniques.

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“…This is promising as it indicates that triploid females will not mature before harvest, and growth rates will increase through reduced investment in gonad production. However, problems such as initially higher mortality, greater fingerling costs, maturation of triploid males and consumer acceptance need to be solved before production of triploid fish is taken up by industry (Triantafyllidis et al 2007, Feindel et al 2010. Technical solutions aimed at physically preventing spawned eggs entering the sea have also been suggested.…”

Section: Conclusion and Recommendations To Reduce The Escape Of Atlamentioning

confidence: 99%

Extent and ecological importance of escape through spawning in sea-cages for Atlantic cod

Uglem¹,

Knutsen²,

Kjesbu³

et al. 2012

Aquacult. Environ. Interact.

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The culture of certain fish species to sizes at which they can reproduce has led to the escape of fertilised eggs or 'escape through spawning'. To investigate the extent and ecological importance of spawning in sea-cages for Atlantic cod Gadus morhua (L.), we (1) evaluated the extent, frequency and timing of spawning in cod culture; (2) analysed the quality of eggs released from farms in terms of variation in fatty acids; (3) modelled the distribution of eggs and larvae from a commercial cod culture site; and (4) predicted the post-escape survival of eggs through summarizing existing knowledge on survival rates of different life stages. Collectively, our results indicate that cod farming has the potential to produce large amounts of eggs and larvae through spawning in cages, with numbers of eggs spawned being 4 to 5 times higher in the second than in the first year. Our scenarios suggest that a typical sea-cage with 60 000 fish may produce 1.4 to 21 tons of 3 yr old first generation farmed cod through spawning in sea-cages. The quality of escaped eggs and larvae is likely to be sufficient for larvae to survive until the first feeding, while survival until adulthood, though difficult to predict, may be high under favourable conditions. Simulations indicate that eggs and larvae from farms may mix with those of wild fish during the spawning season, and thus experience comparable larval environments. However, several implementable management measures exist that will diminish the extent of egg escape in future cod farming.

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Competitive spawning success and fertility of triploid male Atlantic cod Gadus morhua

Cited by 32 publications

References 52 publications

Why are triploid zebrafish all male?

Why are triploid zebrafish all male?

Escapes of fishes from Norwegian sea-cage aquaculture: causes, consequences and prevention

Extent and ecological importance of escape through spawning in sea-cages for Atlantic cod

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