Fig 1.
(A) Graphic representation of experimental design illustrating different environments (incubation and experimental tanks) to which eyed embryos and groups of fish were exposed. (B) Experimental timeline, milestones, and treatment (photoperiod) cycles (early = black dots, middle = grey shaded, late = grey line). Grey triangle indicates the date (20 March 2007) fish were transferred ("ponded") from completely dark egg incubation trays into respective experimental photoperiod treatments (early, middle, late). Black triangle indicates the date (19 November 2007) when fish were first sampled for physiological measures.
Fig 2.
Mean (± SE) length (A, B), weight (C, D), condition factor (E, F) and percent lipid (G, H) aligned by calendar date (A, C, E, G) and by photoperiod date (B, D, F, H) of Yakima spring Chinook salmon reared under three different photoperiod regimes, early emerge (circles), middle emerge (squares), and late emerge (triangles). Best fit polynomial regression curves (condition factor: y = 0.1386 + 0.0076x + 0.000017x2 + 1E-08x3, p = 0.00039, r2 = 0.798; % lipid: y = -3.483 + 0.05869x + -0.00006778x2, p = 0.00258, r2 = 0.630) are added to photoperiod date graphs to show seasonal trends in condition factor and lipid profiles.
Table 1.
Results of ANOVA analysis of tank means of length, weight, K and percent lipid through time for juvenile spring Chinook salmon reared.
Fig 3.
Graphic representation of polynomials for K (gray solid line) and percent lipid (gray dotted line) plotted with hours of daylight (black dotted line) and feed rate (black solid line).
Fig 4.
Linear regression of K vs. percent lipid for individual Yakima spring Chinook salmon.
Table 2.
Correlations among length, weight, K and percent body lipid.
Fig 5.
Comparison of seasonal changes in whole body lipid for juvenile Yakima River spring Chinook salmon either rearing naturally in the Yakima River (Beckman et al. 2000, squares), rearing in the Cle Elum hatchery under standard Ks, with seasonally changing temperature and feeding rates (Larsen et al. 2006, triangles) or this study (circles).
There is a common increase in lipid from the summer solstice through the fall, however the magnitude of change in lipid levels vary according to feeding rates and metabolic demand characteristics of the different environments.