Egg/larval viability in fish: do hormones play a role?
Lam, T.J. (1995). Egg/larval viability in fish: do hormones play a role?, in: Lavens, P. et al. (Ed.) Larvi '95: Fish & Shellfish Symposium, Gent, Belgium, September 3-7, 1995. EAS Special Publication, 24: pp. 3
In: Lavens, P.; Jaspers, E.; Roelants, I. (Ed.) (1995). Larvi '95: Fish & Shellfish Symposium, Gent, Belgium, September 3-7, 1995. Special Publication European Aquaculture Society, 24. European Aquaculture Society: Gent. ISBN 90-71625-14-1. XXVI, 521 pp., meer
In: Special Publication European Aquaculture Society. European Aquaculture Society: Bredene. ISSN 0774-0689, meer
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| Abstract |
Egg/larval viability (fertilizability. hatchability and/or subsequent larval survival) is adversely affected by two conditions: overripening (ovulated eggs) and loss of buoyancy (fertilized eggs, particularly in marine fish). Evidence suggests that overripening may result in part from a decline in steroid output (particularly progesterone) from postovulatory follicles. Progesterone replacement delayed overripening. In at least two marine species, grouper (Epinephelus sp.) and Asian seabass (Lates calcarifer), non-buoyant eggs have a lower thyroid hormone content than buoyant eggs. Treatment of non-buoyant eggs (less viable than buoyant eggs) with thyroid hormones improved viability significantly, especially when obviously degenerating eggs were removed from the non-buoyant eggs. The role of hormones will be further examined in relation to fertilization, embryogenesis, early larval growth and development (endotrophic, first-feeding, endo-exotrophic, and post-yolk sac/premetamorphic) and metamorphosis. Although the focus will be on progesterone, thyroid hormones and cortisol, other hormones will be mentioned. |
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