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Unravelling the effects of water temperature and density dependence on the spatial variation of brown trout (Salmo trutta) body size

“…Incubation temperature could have influenced the date of emergence from the stream bed and may have caused interpopulation differences in emergence time (Elliott and Hurley 1998;Ojanguren and Braña 2003;Nicola et al 2009), which would lead to variations in the length of trout after the first growing period (Ojanguren and Braña 2003;Nicola and Almodóvar 2004). Water temperature may also influence the physiology of fish, causing differences in enzymes related to food conversion efficiency (Rungruangsak-Torrissen et al 1998) as discussed by Jonsson et al (2005) for Atlantic salmon. Thus, this higher thermal effect on growth in the first year, whether it be direct or indirect, together with an expected higher prey productivity in warmer rivers, would establish spatial differences in growth between the rivers from the first year of life.…”

“…Constraints for body size at one stage may have consequences for later growth and associated life history traits. For instance, embryonic incubation temperature affects food conversion efficiency later in life (Rungruangsak-Torrissen et al 1998), growth trajectories are determined by the first growing period (Vincenzi et al 2008, Parra et al 2009, and fecundity and egg size are positively related to female body size (Elliott 1984), with potential effects on survival and fitness of subsequent generations. Therefore, for predicting potential life history strategies and population trajectories, it is essential to understand which stages are affected by density-dependent growth and whether the operation of density dependence is qualified by environmental factors, as well as to estimate the relative importance of each potential contributory factor along ontogeny (Davidson et al 2010).…”

Different expressions of trypsin and chymotrypsin in relation to growth in Atlantic salmon (Salmo salar L.)

“…These works are summarised as an illustration in Figure 1, showing a series of growth mechanisms, primarily affected by trypsin expression and thus influencing protein and amino acid utilisation and finally growth. Trypsin is found in different isoforms in the pyloric caeca and intestine (Torrissen 1984; Torrissen and Torrissen 1985), and different distributions of these isoforms could determine genetic variation in protein and feed utilisation and growth performance of individuals in aquaculture (Torrissen 1991; Torrissen et al 1993; Rungruangsak-Torrissen et al 1998, 1999a). Variations in trypsin phenotype distributions were also observed in natural marine ecosystem in different isothermal areas where temperature preferences of different phenotypes observed in corresponding to those found in aquaculture (Rungruangsak-Torrissen and Stensholt 2001).…”

“…Variations in trypsin phenotype distributions were also observed in natural marine ecosystem in different isothermal areas where temperature preferences of different phenotypes observed in corresponding to those found in aquaculture (Rungruangsak-Torrissen and Stensholt 2001). Different trypsin phenotypes, induced by variations in temperatures at the very early life, have different temperature preferences for feed conversion efficiency and growth (Rungruangsak-Torrissen et al 1998). As seen in the Norwegian Sea when food abundance was limited, the pattern 1 salmon possessing trypsin isozyme effectively functioning at high temperature of >8 °C were mainly distributed at an average ambient temperature of 9.3 °C.…”

“…Pattern 2′ salmon possessing trypsin isozyme effectively functioning at low temperature of ≤ 8 °C were mainly distributed at an average ambient temperature of 7.7 °C, while the heterozygote salmon of pattern 2 were mainly distributed between these two phenotypes at around 8.7 °C (Rungruangsak-Torrissen and Stensholt 2001). The details of different trypsin isozymes were described in Rungruangsak-Torrissen et al (1998) and Rungruangsak Torrissen and Male (2000). Variations in the expression of trypsin (either by phenotype or enzymatic activity) have been related to feed conversion efficiency and/or growth rate (Torrissen and Shearer 1992; Rungruangsak-Torrissen et al 1998; Lemieux et al 1999; Sunde et al 2001, 2004) by affecting rates of protein digestion, and resulting in differences in amino acid absorption (Torrissen et al 1994; Rungruangsak-Torrissen and Sundby 2000; Sunde et al 2001, 2004) and transport (Torrissen et al 1994; Sunde et al 2001, 2004).…”