Genetic management of Atlantic cod (Gadus morhua L.) hatchery populations.

• Main Author: Herlin, Marine Claire Ghislaine
• Other Authors: Penman, David J., School of Natural Sciences, Aquaculture
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Stirling 2007
• Subjects: Atlantic cod; parentage analysis; DNA microsatellite; genetic diversity; Fishes Genetics; Fish hatcheries Management; Aquatic genetic resources; Canada; Norway; atlantic cod; Gadus morhua; Iceland; Turbot
• Online Access: http://hdl.handle.net/1893/421; http://dspace.stir.ac.uk/bitstream/1893/421/1/PhDthesis%20final%20August%202008.pdf

Intensive aquaculture of Atlantic cod is fast developing in both Northern Europe and Canada. The last six years have seen major improvements in the larval rearing protocols and husbandry techniques for this species. Although breeding programmes are currently being developed by both governmental and private institutions in the main cod producing countries (i.e. Norway, Iceland and Canada), most hatcheries still rely on the mass spawning of their own broodstock. Mass spawning tanks are complex systems where fish are left to spawn naturally and fertilised eggs are collected with the overflowing water, with little or no control over the matings of the animals. Few published studies in other commercial marine species (i.e. turbot and sole) have attempted to analyse the output from such systems using microsatellite markers and several parentage analysis software programs. A review of these publications exposed a lack of consistency in the methods used to analyse such complex datasets. This problem was addressed by carrying out a detailed comparison of two analytical principals (i.e. assignment by strict exclusion and assignment by probabilities) and four parentage software programmes (i.e. FAP, VITASSIGN, CERVUS and PAPA), using the DNA profiles, at 5 loci, from 300 cod fry issued from the mass spawning of a large hatchery cod broodstock tank (consisting of 99 fish). This study revealed large discrepancies in the allocation outcomes between exclusion-based and probability-based assignments caused by the important rate of typing errors present in the dataset. Out of the four softwares tested, FAP (Taggart, 2007) was the most appropriate to use for handling such a dataset. It combined the most conservative method of assignment with the most informative output for the results displayed. In an attempt to study the breeding dynamics in a cod commercial hatchery, parental contributions to five groups of 300 fry (from five single days of spawning and from two commercial mass spawning cod tanks) were analysed, based on the ...