Latitudinal variation in growth of young brown trout Salmo trutta

Abstract

1.A new laboratory-based growth model for brown trout (Salmo trutta) was used to explore latitudinal variation in growth among natural populations. The model included the eects of dierences in ambient temperatures and ®sh size among populations. Annual growth rates of anadromous brown trout parr from 22 Norwegian populations at 61±70 N were compared with predictions from the growth model. Published ®eld data from one Spanish, 15 British and four Danish populations at 44±58 N were included in the analysis to increase the latitudinal range. 2. Among the Norwegian populations, the ratio between observed and predicted growth rates was not signi®cantly dierent from 1Á00 in eight rivers, but was signi®cantly higher in eight, and was signi®cantly lower in six. Observed growth was highest, relative to predicted growth, in the coldest rivers. In Spanish, British and Danish rivers, observed growth did not exceed predicted growth. 3. The ratio between observed and predicted annual growth rate decreased signi®cantly with increasing annual mean temperature. Observed annual growth was higher than predicted growth only in rivers with an annual mean temperature lower than 5Á1 C, and this indicates that some kind of thermal adaptation may occur in trout populations in the coldest rivers. 4. Regression analyses showed that besides the direct eects of temperature and body size predicted by the growth model, annual growth rates were signi®cantly related to annual mean temperature, densities of juvenile salmonids, duration of twilight (average for May±August) and latitude. Adding these variables to the original model increased the explanatory power from 73Á9 to 80Á6%.

Predicted Growth of Juvenile Trout and Salmon in Four Rivers in England and Wales Based on Past and Possible Future Temperature Regimes Linked to Climate Change

“…For trout (Dee only), all BC lengths were within 20% of the predicted values and 70% within 10%. This level of agreement was comparable with that found by Elliott and Hurley (1997) when they applied the same model to data from the Eden, and by Jensen et al (2000) who applied the equivalent growth model for brown trout (Elliot et al, 1995) to data from populations around Europe.…”

A Bioenergetic Analysis of Factors Limiting Brown Trout Growth in an Ozark Tailwater River

“…One interpretation might be that models developed (Elliott 1976;Elliott et al 1995) using satiation-fed brown trout in a laboratory setting may generate inflated optimal growth values, as energy costs associated with variable temperature regimes (Hokanson et al 1977) and maintenance and defense of foraging stations (Li and Brocksen 1977;Fausch 1984) are not included. Field studies, however, have often approached (Edwards et al 1979;Preall and Ringler 1989) and even surpassed predicted optimal growth rates (Allen 1985; Lobó n-Cerviá and Rincó n 1998; Jensen et al 2000). This suggests that, at least under certain circumstances, growth models developed in the laboratory may actually underestimate brown trout growth potential in the wild.…”

Latitudinal variation in growth among Arctic charr in eastern North America: evidence for countergradient variation?

“…Analyses of latitudinal variation in life-history traits are common, with studies investigating reproductive characteristics and growth perhaps among the most familiar (e.g., Paulson & Smith, 1977;Leggett & Carscadden, 1978;Fleming & Gross, 1990;Jonsson & L'Abée-Lund, 1993;Jensen et al, 2000;LombardiCarlson et al, 2003;Power et al, 2005a). Growth studies, in particular, are of fundamental importance with implications for population ecology and understanding effects of exploitation (Conover et al, 1997).…”