Arctic spring-streams experience extreme seasonal fluctuations in light but maintain relatively constant water temperatures. As ecosystem productivity and metabolism are closely linked to light availability and temperature, the decoupling of these two drivers in arctic spring-streams provides an opportunity to assess their individual effects on the energetics of consumers. We measured respiration rates of Dolly Varden char (Salvelinus malma) from five spring-streams in arctic Alaska, USA, that lie along a temperature gradient from ~1 to 13°C. Char were sampled five times (n = 4 per stream per date) during August and November 2023, and February, June, and August 2024. Respiration rates were measured sequentially at five temperatures along our study site gradient (3.0, 5.5, 8.0, 10.5, 13.0°C). Specimens were then sacrificed and frozen for subsequent estimates of body mass, lipid content, energy density, and tissue δ13C and δ15N. Preliminary data show that mass-corrected respiration rates of cold-adapted S. malma were higher (0.6 – 2.3 mg O2/h) than those of warm-adapted individuals (0.2 – 1.6 mg O2/h) when measured at 3 and 5.5°C during all seasons. When measured at their native temperatures, however, respiration rates of S. malma from all streams were lower during winter (November and February) than during summer. Ongoing work includes body tissue analyses to assess potential physiological responses (i.e., starvation) to differences in temperature and light regimes across seasons.