Downstream migrations and estuarine residence by Atlantic salmon (Salmo salar) parr and smolts were studied in a small river on the northwest coast of Newfoundland in 1983 and in 1987. There were large downstream migrations in the spring and small downstream migrations in the fall. The major differences between the two types of migrant were that parr migrated about 1 wk before smolts and at a younger age compared with smolts and while parr remained in the estuary throughout the summer, smoits did not. Modal age and mean size were less for parr sampled in the estuary compared with those sampled at the counting-fence which suggested that the smallest parr were not captured by the fence. The estuarine population of parr represented a significant proportion of the river's total production of salmon. Parr were found throughout the estuary in salinities up to 24 parts per thousand but were most abundant near the river mouth. There was evidence that larger parr became smolts and eventually migrated to sea, but smaller parr probably returned to the river for overwintering. It is clear that estuaries should be included as habitat used for rearing Atlantic salmon.

Fisheries Resecrrch Branch, E)epsartrnenb of Fisheries and Oceans, P.O.Bsx 5667, St. John's, N ' d . A4C 5x1 CHADWICK, E. M. P. 1982. Stock-recruit~nent relationship for Atlantic salmon (Stzlmo srrlar) in Newfoundland rivers. Can. J. Fish. Aquat. Sci. 39: 1496 -1501 .A stock-recruitment relationship was developed for Atlantic salmon (Salrno s a k r ) in Western Arm Brook, a small Newfoundland river. Supportive evidence was also found on Indian and Little Codroy, two other Newfoundland rivers. On Western Arm Brook, year-class strength of smolts was correlated ( P < 0.01) with egg deposition. On Little Codroy River. smolt year-class strength was conelated ( P < 0.01) with potential egg deposition of adults counted as kelt. On Indian River egg to Gy survival was correlated ( P < 0.01) with winter temperature and discharge. On the basis of these findings, the current recommended egg dewsition of 2.4 eggsam-' of par-rearing habitat was considered inadequate for Newfoundland rivers. Chadwick, E. I%%. P. 1982. Stock-recruitment relationship for Atlantic salmon (Salmo sa/crs) in Newfoundland rivers. Can. J. Fish. Aquat. Sci. 39: 1496 -1501. Nous avons Ctabli une relation stock-recrutement pour le saumon atlantique (Salrno sakar) dans le ruisseau Western Arm, un petit cours d'eau de Terre-Neuve. Cette relation est en outre appuyke par des donnCes recueillies dans les rivibes Indian et Little Codroy, Cgalement A Terre-Neuve. Dans le ruisseau Western Arm, il y a correIation ( P < 0,OL) entre les effectifs de classe d'5ge des smolts et le nornbre d'oeufs dCpos6s. Dans %a rivi&re LittleCodroy, les effectifs de cIasse d'iipe des smolts sont en corklation ( P < 0,01) avec le nombre potentiel d'oeufs d6posCs par des adultes d6nombrCs comme charognxds. Bans la rivi2reIndian, la suwie de l'oeaaf a 19alevin est en corrklation (P < 0,BBI) avec la ternpkrature et le dCbit. D'apres ces rCsultats, on est d'avis que le nombre d'oeufs dCpos6s prksentement recommand6 de 2,4 oeufs* mb2 d'habitat d'Clevage jusqu'au stade tacon est iinadequat pour les rivikres de Ten-e-Neuve.

No abstract

In order to understand the factors which determine sea age of Atlantic salmon (Salmo salar), ovarian development of smolts was examined in 14 groups which varied in parental sea age, smolt age, and size. Parental sea age of smolts explained most of the variation in ovarian development. Smolts from one-sea-winter parents had a higher percentage of the more advanced oocyte stages in their ovaries, while smolts from two-sea-winter parents had a low percentage, and those from three-sea-winter parents had none. Annual within-stock variation and covariance with freshwater age were not significant. Hatchery-reared smolts had similar ovarian development to their wild counterparts. There was also a significant, positive correlation between fork length of smolts and ovarian development within groups.

Factors affecting sexual maturation of Atlantic salmon (Salmo salar L.) juveniles in fresh water were analysed under wild conditions in Little Codroy River (southwest Newfoundland). Large size after the first year of life and short winters favoured maturation of age 1 + male parr. Incidence of maturing I + males was greater where high densities of parr (>0.2 individuals m I; tish >6cm fork length) were recorded in the second season of growth. These results were discussed according to current knowledge on early maturation in Atlantic salmon.