Retrospective analysis of Atlantic salmon (Salmo salar) marine growth and condition in the northwest Atlantic based on tag‐recovery data

Abstract

The life history of North American Atlantic salmon (Salmo salar) is characterized by extensive round‐trip migrations between freshwater rearing habitats and marine feeding grounds off the coasts of Canada and Greenland. Growth is rapid during the marine migration, and growth rate and condition factor may be indicators of salmon health during this period. Growth data were evaluated from a tag‐recovery program conducted from 1969 to 1991 using hatchery‐reared Atlantic salmon smolts released in the Penobscot River, Maine, U.S.A. Information from recaptures of 3167 salmon that were at large in the marine environment for 1 month to 3 yr was analyzed. Length–weight measurements coupled with time‐at‐large data were used to estimate von Bertalanffy and allometric growth parameters specific to the marine phase. Variations in growth and condition factor in relation to smolt age, release date, and temperature conditions in the northwest Atlantic were also examined. The von Bertalanffy k parameter declined with ordinal release date, indicating faster growth rates during the first year of smolts released earlier in the spring. The 2‐yr‐old smolts had a larger k than 1‐yr‐old smolts, although 1‐yr‐old smolts grew to a larger asymptotic size. Sea surface temperature had variable effects on growth parameters and condition factor, with temperature at the beginning of the migration and in overwintering habitat during the first year at sea having the greatest influence on length–weight relationships. Determining the mechanisms that influence growth of individuals during the marine phase will help elucidate the factors responsible for historic growth trends, establishing a baseline for current research.

Retrospective Analysis of Seasonal Ocean Growth Rates of Two Sea Winter Atlantic Salmon in Eastern Maine Using Historic Scales

“…Our results related to growth also are similar to recent studies that found the combination of smolt traits (such as length, age, and origin) and environmental variables (such as SST and climate indices) ultimately influence survival of Atlantic Salmon from the Penobscot River (Miller et al 2012), the Simojoki River in the Baltic Sea (Kallio-Nyberg et al 2004), and multiple populations from rivers in Ireland (Peyronnet et al 2008). Additionally, Miller et al (2014) found that smolt age, release date, and SST influenced the marine growth of North American Atlantic Salmon when examined in terms of the von Bertalanffy growth and allometric growth parameters. These studies, in combination with the results of this work, highlight the importance of investigating a series of factors in combination when describing the marine migration of Atlantic Salmon.…”

Nature versus nurture? Consequences of short captivity in early stages

“…In our study, we found significant differences between early captive and wild individuals for CF, which is a fish growth indicator (Gjedrem, 2005); it was significantly higher in free individuals than in the others, suggesting that wild individuals return healthier (Miller et al, 2014).…”

“…Also reduced fitness of hatchery individuals have been found after one generation of captive breeding (Jonsson & Jonsson, ). In our study, we found significant differences between early captive and wild individuals for CF, which is a fish growth indicator (Gjedrem, ); it was significantly higher in free individuals than in the others, suggesting that wild individuals return healthier (Miller et al., ). Nitrogen isotopes, a signal of trophic level (Jutila et al., ), did not reveal differences between the two life types here compared; therefore, differences in CF would not be likely due to different feeding behavior but perhaps to some early modifications by captive rearing, as suggested by Christie et al.…”

“…As an indicator of growth, we have chosen CF for all the samples with available length and weight data because it is an indicator of the size and shape of fish and principally of growth rate (Gjedrem, ). It is also considered to indicate salmon health and fitness potential (Miller, Miller, Mills, & Sheehan, ). Its formula is…”

Demographic and genetic description of Greenland's only indigenous Atlantic salmon Salmo salar population

“…The coastal waters off Greenland are an important feeding area for S. salar from across the North Atlantic (MacCrimmon & Gots, ; Miller et al ., ; Redding et al ., ; Rikardsen & Dempson, ). In Greenland, the distribution of this species varies from year to year, with the northernmost boundary in the Disko Bay region on the west coast and Ittoqqortoormiit on the east coast (Jensen & Christensen, ; Figure ).…”