Figure 6. a) Structural equation model showing the relationship
between predictor variables affecting length increment (combined from
age 1 year to age 4 year olds) and the effect of increasing length
increment on age at maturation in the perch populations in Lake Vaggatem
and Lake Skrukkebukta. Arrows represent causal pathways, highlighted
black lines represent significant relationships and grey lines represent
non-significant relationship within the model. Numbers in boxes denote
the effect size of standardized coefficients and R2 is
shown for each endogenous variable. b) Relationship between somatic
growth and maturation in perch in the Pasvik watercourse illustrated by
the maturation reaction norm, length at age for perch in the Pasvik
watercourse (grey dots) with blue dotted line representing a slow growth
rate, i.e. “cold and high density situation” (10th percentile) and
orange dotted line representing a fast growth rate, i.e. “warm and low
density situation” (90th percentile). The population estimated
probabilistic maturation reaction norm (PMRN) midpoint (solid line), the
25th and 75th percentile (dashed
lines).