Differences in growth rates, longevity, fecundity, and time of spawning between two populations of landlocked Atlantic salmon (Salmo salar) in Newfoundland were attributed to food quality and quantity. Salmon in Flatwater Pond, an oligotrophic lake with a poor invertebrate population and no forage fish, grew slowly (145 mm at age 2+, 245 mm at age 5+), suffered high mortality (approximately 60% in males after age 2+ and in females after age 3+), had very low fecundity (an average of 153 eggs per female), and were sexually mature by late August. Salmon in Gambo Pond, an oligotrophic lake with a good invertebrate population and an ample forage fish population in the form of Gasterosteus aculeatus, grew more rapidly reaching 157 mm at age 2+, 367 mm by age 5+, and 437 mm by age 8+. Longevity of the Gambo Pond stock was greater than that of Flatwater Pond (39.6% of the Gambo sample were older than 4+ years compared with 3.2% for Flatwater Pond). Gambo Pond salmon are not sexually mature until October.Salmon in both lakes exhibited seasonal movement into deeper water when the surface warmed above 14 C. At Flatwater Pond this movement contributed to an early end to the growing season.Scale reading was found to be an unreliable method for determining past spawning activity. Spawning marks were found on only 1 of 17 females known to have spawned previously.
The effects of ozonation on select waterborne steroid hormones in recirculation aquaculture systems containing sexually mature Atlantic salmon Salmo salar