dc.contributor.author | Liu, Qi | |
dc.date.accessioned | 2019-11-20T13:44:52Z | |
dc.date.available | 2019-11-20T13:44:52Z | |
dc.date.issued | 2019-11-20T13:44:52Z | |
dc.identifier.uri | http://hdl.handle.net/10222/76636 | |
dc.description.abstract | Farming diploid Arctic charr (Salvelinus alpinus; Labrador strain) in Atlantic Canada is greatly impeded by unwanted sexual maturation and associated loss of growth and meat quality. Up to 70% of fish in both sexes mature at age 2, due to accelerated growth from both a high energy diet and rearing in ‘warm’ 10°C well water. The goal to reduce maturity to <20% was achieved by manipulating photoperiod, rearing temperature and feeding in a series of five lab-based trials each lasting 12-18 months ending age 2. To explore the relationship between somatic growth and the physiological decision to mature, all fish were identified with a PIT-tag and measured monthly. Continuous light (LL) overwinter effectively reduced maturation. Histological analysis of germ cells revealed the change between natural daylength (LDN) and LL induced a dichotomous response, stimulating some fish and inhibiting others, dependent on the direction and timing of photoperiod change. Food deprivation and/or 5°C overwinter alone were less effective than LL at reducing maturation, but combining all three factors reduced maturity to <5%. Paradoxically, body weight, condition factor and lipid content were poor indicators of whether an individual would mature or not. Plasma melatonin monitoring indicated 50 lux at night was a sufficient intensity for effective LL treatment. Charr failed to exhibit a circannual rhythm of sexual maturation under LL and LD 8:16 suggesting the conventional thinking on the mechanism by which photoperiod controls sexual maturation among salmonids requires further investigation. | en_US |
dc.language.iso | en | en_US |
dc.subject | Age at Maturity | en_US |
dc.subject | Salmonid | en_US |
dc.title | Photoperiod and Growth Manipulation Reduces the Problem of Unwanted Sexual Maturation in Arctic Charr, Salvelinus alpinus | en_US |
dc.date.defence | 2019-10-07 | |
dc.contributor.department | Department of Biology | en_US |
dc.contributor.degree | Doctor of Philosophy | en_US |
dc.contributor.external-examiner | Dr. Tillmann Benfey | en_US |
dc.contributor.graduate-coordinator | Dr. Sophia Stone | en_US |
dc.contributor.thesis-reader | Dr. Tony Manning | en_US |
dc.contributor.thesis-reader | Dr. Christophe Herbinger | en_US |
dc.contributor.thesis-reader | Dr. Leslie MacLaren | en_US |
dc.contributor.thesis-supervisor | Dr. James Duston | en_US |
dc.contributor.ethics-approval | Received | en_US |
dc.contributor.manuscripts | Yes | en_US |
dc.contributor.copyright-release | No | en_US |