Differential Survival among Batches of Atlantic Cod (Gadus morhua L.) from Fertilisation through to Post-Metamorphosis

PLoS One. 2016 Jun 30;11(6):e0158091. doi: 10.1371/journal.pone.0158091. eCollection 2016.

Abstract

Aquaculture production of cod has decreased from over 20,000 tonnes in 2009 to less than 2,000 tonnes in 2014 and the industry faces many challenges, one of which is high and unpredictably variable mortality rates in the early life stages. Hence, full-cycle farming with hatchery produced juveniles is still considered unprofitable compared to fisheries and on-growing of wild cod. In the present study, potential batch differences in progeny survival of wild-caught, hatchery-spawned Faroe Bank cod (Gadus morhua L.) were investigated at two defined periods during early life history; i) the embryo stage (60 day degrees post fertilisation) and ii) the fry stage (110 days post hatch), post metamorphosis. The fry stage experiment was conducted in three replicates (N = 300 per replicate), and a panel of three polymorphic microsatellite markers was used for parental analysis. Mean survival rate at the embryo stage was 69% (± 20% SD). Survival was positively associated with egg diameter (P < 0.01), explaining 90% of the variation in egg survival rates. The data were too scarce to conclude either way concerning a possible correlation between survival rates between the two periods (P < 0.10). Offspring from three batches (from a total of eight) dominated in the fry stage, contributing over 90% of the progeny, and results were consistent over all three replicate tanks. The skewed batch representation observed may be of relevance to the effective management of selective breeding programmes for cod.

MeSH terms

  • Animals
  • Aquaculture
  • Female
  • Fertilization
  • Gadus morhua / physiology*
  • Male
  • Metamorphosis, Biological*

Grants and funding

This work has received financial support from the Faroese Research Council (http://www.gransking.fo/) and Fiskaaling, the Aquaculture Research Station of the Faroes (http://www.fiskaaling.fo/) (GD and PEP). JBT and DJP are partly supported by the MASTS (The Marine Alliance for Science and Technology for Scotland; http://www.masts.ac.uk) pooling initiative which is funded by a Scottish Funding Council grant (HR09001) and contributing institutions. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.