The effect of photoperiod on growth and maturation of Atlantic salmon (Salmo salar) in the Bay of Fundy
In 2001, a study on the effect of photoperiod on growth and early maturation was initiated on a commercial salmon farm in southwestern New Brunswick. Three cages (70-m diameter circles) had lights turned on November 21. A second set of three cages had lights turned on February 15, 2002. Lights were left on 24 h per day. All lights were turned off on May 31, 2002. Six unlit cages served as controls.
Fish were measured in the cages with a synchronized dual video camera. These measurements corresponded with the initiation of extended light, one mo following and at the end of the light regime. A preliminary sample of the fish was taken in July 2002 to collect growth and maturity data based on the gonadosomatic index (GSI). Beginning in August 2002 through February 2003, length, weight and maturity data were collected during harvest from two Xactic® tanks per cage. Additional maturation data was collected from a second site that initiated 24-h light in October 2001.
During the first month, specific growth rates decreased in the November lit cages. By the end of May, November lit cages showed significantly higher growth rates from the control cages. On site one, 21.5% of the control cages matured, 11.1% of the February lit cages and only 1.1% of the November lit cages. On the second site, maturation rates were 17.5% of the control cages and 5.0% of the October lit cages.
2001 - 2003
Atlantic: Gulf of Maine, Scotian Shelf
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