Effects of continuous light and triploidy on growth and sexual maturation in Atlantic cod, Gadus morhua

• Main Authors: Trippel, Edward A., Benfey, Tillmann J., Neil, Steven R.E., Cross, Nicola, Blanchard, Mark J., Powell, Frank
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Société Française d'Ichtyologie 2008
• Subjects: Cod, Growth, Maturity, Photoperiod, Sterility, Triploidy; Psi; atlantic cod; Gadus morhua
• Online Access: https://dx.doi.org/10.26028/cybium/2008-322sp-057; http://sfi-cybium.fr/fr/effects-continuous-light-and-triploidy-growth-and-sexual-maturation-atlantic-cod-gadus-morhua

Early maturation is considered one of the greatest problems in mariculture of Atlantic cod. We examined two approaches to impede early puberty: (i) exposure to continuous light and (ii) induction of sterility by triploidy. Use of continuous light initiated in July delayed onset of sexual maturity, in this case by ~2-3 months though cod returned to their normal spawning period when continuous light was administered for a second year. In the first year, 24 h light compared to natural photoperiod resulted in a lower percentage of mature females (73 vs 90%) compared to males (90 vs 100%). In the second year, > 88% of any gender were mature in both treatments. Using hydrostatic pressure, triploid cod were generated with a 100% success rate at a treatment of 5 min at 58,600 kPa (8500 psi) applied beginning at 30 min post-fertilization for eggs held at 6°C. No sexually mature female triploids were observed, yet 12.5% of triploid males were mature. Female triploids grew at a slower rate than diploids, and for males triploids and diploids were not significantly different in growth (body weight at age 26 mos.). A family by ploidy interaction for growth was nearly significant (p = 0.052) which underlines the importance of conducting extensive testing of the effects of triploidy among a large number of families, perhaps coincident with a selective breeding program, if one is to thoroughly evaluate the scope of this technique in assisting the cod aquaculture industry.