Turkish Journal of Fisheries and Aquatic Sciences
2016, Vol 16, Num, 3 (Pages: 591-596)
Sex Ratio Response to High Temperature During Early Development of Rainbow Trout (Oncorhynchus mykiss) in Farmed Stocks
Muhammet Altunok 1 ,Zerife Peker 1
1 Izmir Katip Celebi University, Faculty of Fisheries, Department of Aquaculture, Izmir, Turkey
DOI :
10.4194/1303-2712-v16_3_11
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The objective of the study was to investigate the effect of high temperature on sex ratios of early stage rainbow trout
(Onchorhynchus mykiss) in commercially farmed populations from distinct hatcheries. Almost 32500 larvae from five
different farms were used in experiments as thermal groups and their corresponding controls. Temperature treatments were
conducted at 17.5°C for 40 days starting at day 10 after hatching. In only one population, the sex ratio was skewed
significantly in favor of females in thermally treated group (67.5%), when compared to control group (52.1%) and there was
deviation from the expected 1:1 ratio. In the treatment group the females grew 8.3% more than males. However there was no
repeatiblity and any skewness in sex ratio of progenies from photoperiod induced spawning. Survival rates were not affected
by the thermal treatments. The results showed that the increasing of femaleness of farmed stocks is possible by thermal
treatment in rainbow trout and which depends on percentage of thermosensitive individuals rather than genetic background of
population.
Keywords :
Onchorynchus mykiss, temperature, sex ratio, farmed stocks