Dublin Core
Title
The Effect Of Water Temperature On Spawning Out Of Season In Rainbow Trout, Oncorhynchus Mykiss
Abstract
Salmonid culture is a production sector with widespread throughout the world. Different stocks of rainbow trout spawn in certain months of the year in hatcheries. This seasonality of spawning imposes considerable constraints on trout farming because the consequent restrictions on the supply of eggs and fry make it difficult for on-growing farm to maintain a continuity of production of table-size fish throughout the year. Hatcheries should artificially control the spawning time of their broodfish so that batches of eggs and fry might be produced all year round. The modification of spawning time are possible using manipulation of photoperiod. This series of studies were carried out in order to identify the effects of varying water temperature on the ovulation of rainbow trout be exposed to photoperiodic manipulation. This study was carried out in two different facilities. In the first facility, the photoperiod regime was only consisted of constant short days (LD 6:18). The water temperature had been changed between 7.5 and 15 °C during the the experiment in this facility. In the second facility, it had been changed between 11 – 25.5 °C. The broodstock was seperated into two different group. These photoperioded regims consist of constant short days(LD 6:18) and altered photoperiod (LD 18:6 from February until May, then LD 12:12 from May until June, then LD 6:18 from June until November) which are acted to advanced spawning. In both experiments, photoperiod regimes changed the maturation time regardless of water temperature. However, when the water temperature is high, modulating effects of the temperature on the maturation and ovulation time were observed. When the spawning time modified to June – August, ovary growth and egg survival rate had been reduced by the temperature effect ( >14 °C). It was found that the egg quality decreased when the water temperature was 17 °C although the eggs could been removed from the fish. Based on the these results, the role of water temperature in determining spawning time should take into account, especially in conjunction with photoperiodic manipulation. Keywords: Photoperiod, Rainbow trout, water temperature, ovulation, egg
Keywords
Conference or Workshop Item
PeerReviewed
PeerReviewed
Date
2012-05-31
Extent
1229