Dynamics of an Atlantic salmon stock (Salmo salar) in a small Newfoundland river

• Main Author: Chadwick, E. M. P.(Edward Michael Pakenham)
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1982
• Subjects: Indian; Western Arm; Western Arm Brook; Atlantic salmon; Newfoundland; Salmo salar
• Online Access: https://research.library.mun.ca/4150/; https://research.library.mun.ca/4150/1/Chadwick_EMichaelP.pdf; https://research.library.mun.ca/4150/3/Chadwick_EMichaelP.pdf

Dynamics of an Atlantic salmon stock (Salmo salar L.) were studied in a small Newfoundland river, Western Arm Brook. The study examined dynamics of smolts, parr and adults. Smolt production was influenced by annual variation in year-class strength, smolt age, sex ratio and size. Year-class strength was significantly correlated with egg deposition. This was the first stock-recruitment relationship to be developed for Atlantic salmon. Supportive evidence was found on two other Newfoundland rivers, Indian and Little Codroy. On Little Codroy River, year-class strength of smolts was correlated (P < 0.01) with potential egg deposition of adults counted as kelts. On Indian River, egg to fry survival was correlated (P < 0.01) with winter temperature and discharge. On Western Arm Brook, smolt age was significantly correlated (P < 0.01) with annual mean monthly air temperature. Evidence was presented for density-dependent influence on both smolt age and sex ratio. Size of smolts had the lowest annual variation of all biological characteristics. Fork length, weight, ovarian weight and especially annual instantaneous growth rates of smolt were significantly (P < 0.01) different between smolt ages. Ovarian weight of smolts was inversely correlated (P = 0.01) to sea age of adult salmon in 34 Newfoundland rivers. -- Biological characteristics of parr were significantly different between the four habit types: steadies, riffles, outflows and lakes. Parr from riffles were smaller and younger. Parr in outflows grew most during the summer season. However, parr did not remain within habitats and there was a net downstream movement. Downstream movement of parr was significantly correlated with the size of the smolt run in the same year. Mean production in lake and steady habitats was 0.07 g m⁻² y⁻¹, and it was 2.23 g m⁻¹ y⁻¹ in riffles and outflows. Maximum production was estimated to be 5.47 g m⁻² y⁻¹. Only 33% of smolts were produced in riffles and outflows; the remainder were produced in lakes and steadies which ...