Genetic and environmental factors affecting growth, physiology and reproductive patterns in two forms of Atlantic salmon Salmo salar (Linnaeus) 1758, in Newfoundland

MacLean, Donald A. (1984) Genetic and environmental factors affecting growth, physiology and reproductive patterns in two forms of Atlantic salmon Salmo salar (Linnaeus) 1758, in Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

Newfoundland has numerous populations of landlocked Atlantic salmon (Salmo salar). Several of these populations are stunted, exhibiting a marked reduction in size at any age compared with other anadromous and landlocked populations. A population of stunted landlocked salmon from 5 Mile Pond East on the Avalon Peninsula was investigated. Data collected on ecology and life history reveal the population to be an extremely slow-growing, short lived form of Atlantic salmon. -- Anadromous and landlocked Atlantic salmon examined at the smolt stage revealed a difference in the degree of smoltification and salinity tolerance exhibited by the two forms. Anadromous fish had a decrease in lipid, increase in water content and the increased salinity tolerance characteristic of true smolts. While wild landlocked 5 Mile Pond East fish experienced a similar reduction in lipid and increase in water, neither they, nor cultured landlocked salmon survived a challenge to sea water. -- The two pure lines and the reciprocal hybrids between the early maturing stunted 5 Mile Pond East fish and a later maturing anadromous form were reared in the laboratory for a period of 2.5 years. Ninety percent of female parr of the dwarf landlocked strain matured at age 2+ while no females of the anadromous form matured at this time. Ovary weight differed in the two pure forms at age 0+ and the numbers, size and stages of previtellogenic oocytes also differed at age 1+. Ovarian patterns of development and the time of onset of sexual maturation in the two hybrid forms appeared intermediate to that of the parental forms.

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