Research and development of stock management strategies to optimise growth potential in on-growing of Atlantic cod, Gadus morhua, and Atlantic halibut, Hippoglossus hippoglossus

• Main Author: Cowan, Mairi E.
• Other Authors: Migaud, Herve, Scottish Aquaculture Research Forum (027), School of Natural Sciences, Aquaculture
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Stirling 2011
• Subjects: Atlantic cod; Gadus morhua; Atlantic halibut; Hippoglossus hippoglossus; artificial light; kisspeptin; maturation; monosex; stress; shading; semen sexing; sex reversal; sex steroids; Aquaculture; atlantic cod; North Atlantic
• Online Access: http://hdl.handle.net/1893/3028; http://dspace.stir.ac.uk/bitstream/1893/3028/1/Mairi%20Cowan_PhD%20Thesis_2011.pdf

Aquaculture is an essential developing sector for world food production, however the attainment of sexual maturity during commercial on-growing is a major bottleneck to industry expansion. Sexual maturation brings a commercial loss due to reduced growth performance as well as reduced immune function. Furthermore, serious concerns exist over potential genetic interaction with native stocks through broadcast spawning or spawning interaction by escapees. In the north Atlantic region, the Atlantic cod (Gadus morhua) and Atlantic halibut (Hippoglossus hippoglossus) are key aquaculture species in which industry expansion is limited by pre-harvest sexual maturation. However, through a species specific combination of modern technologies and refinement in management practices it is possible that this sexual maturation can be controlled and on-growing potential enhanced. Thus the overall aim of this thesis was to conduct novel research that will improve our understanding of the underlying mechanisms that regulate sexual maturation, whilst also advancing the optimisation of technologies for the management of maturation in cod and halibut. In Atlantic cod, owing to the inconsistent inhibition of maturation in commercial conditions, ever increasing intensities of light and in some cases narrow spectrum technologies are being used to try to combat this problem. Firstly, this PhD project investigated the potential welfare impacts of high intensity artificial lighting which have not been studied to date (Chapter 2). The work specifically investigated the effect of traditional metal halide and novel green cathode lighting on the stress response, innate immunity, retina structure, feeding activity and light perception of Atlantic cod. Results indicated that although acute responses to light were observed, there were no clear significant long term effects of any of the lighting treatments on these parameters. Regarding light perception, interestingly even when subjected to high intensity constant lighting (metal halide mean tank ...