|Appears in Collections:||Aquaculture Journal Articles|
|Peer Review Status:||Refereed|
|Title:||Effect of broodfish exchange strategy on the spawning performance and sex steroid hormone levels of Oreochromis niloticus broodfish in hapas|
|Author(s):||Little, David C|
Bhujel, Ram C
Pham, Tuan A
Bromage, Niall R
|Citation:||Little DC, Coward K, Bhujel RC, Pham TA & Bromage NR (2000) Effect of broodfish exchange strategy on the spawning performance and sex steroid hormone levels of Oreochromis niloticus broodfish in hapas. Aquaculture, 186 (1-2), pp. 77-88. https://doi.org/10.1016/S0044-8486%2899%2900368-3|
|Abstract:||The productivity of Nile tilapia (Oreochromis niloticus L.) broodfish, spawned in large hapas (120 m2) in ponds under different exchange and management strategies, was monitored over a 70-day period. Female fish were checked for eggs twice weekly and returned to the same spawning hapa throughout the experiment (0 day) or exchanged for females maintained in separate single sex groups at high density for a period of 7 days at each (3.5 days) or alternate (7 days) harvests. Exchanged females were conditioned in separate hapas (20 m2) in the same pond. Production of eggs per unit area were significantly higher (P less than 0.05) in females exchanged weekly (7 days, 64 eggs m−2 day−1) or at each harvest (3.5 days; 55 eggs m−2 day−1) than for fish remaining in the spawning hapas throughout the trial (0 day, 33 eggs m−2 day−1). A greater proportion of conditioned females (3.5 days and 7 days) was spawned than in the control group (18% females compared to 11% per harvest). Conditioning of female broodfish had no effect on the egg clutch size (P greater than 0.05). Female productivity (eggs kg−1 day−1) was significantly lower for fish exchanged after every harvest (3.5 days) than those remaining in spawning hapas for alternate harvest (7 days) or throughout the experiment (0 day). Gonadal steroid (testosterone, T and oestradiol, 17β-E2) and calcium levels sampled at the end of the experiment reflected spawning performance; serum T and E2 were highest in exchanged females. Non-spawned fish had elevated steroid levels compared to females incubating seed at harvest (e.g., 19.5–91.4 and 7.2–21.5 ng ml−1 T for non-spawned and spawned fish, respectively). Stocking of the Indian Major carp Labeo rohita in spawning hapas to control fouling did not improve water quality and led to a significant depression of seed production (P less than 0.05). Regular exchange of female broodfish from spawning hapas with conditioned fish can improve productivity of hapa-in-pond systems|
|Rights:||The publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.|
|littled_broodfishexchange_2000.pdf||Fulltext - Published Version||260.05 kB||Adobe PDF||Under Embargo until 2999-12-02 Request a copy|
Note: If any of the files in this item are currently embargoed, you can request a copy directly from the author by clicking the padlock icon above. However, this facility is dependent on the depositor still being contactable at their original email address.
This item is protected by original copyright
Items in the Repository are protected by copyright, with all rights reserved, unless otherwise indicated.
The metadata of the records in the Repository are available under the CC0 public domain dedication: No Rights Reserved https://creativecommons.org/publicdomain/zero/1.0/
If you believe that any material held in STORRE infringes copyright, please contact email@example.com providing details and we will remove the Work from public display in STORRE and investigate your claim.