Hypoxia tolerance is unrelated to swimming metabolism of wild, juvenile striped bass (Morone saxatilis)

Juvenile striped bass reside in the Chesapeake Bay where they are likely to encounter hypoxia that could affect their metabolism and performance. The ecological success of this economically valuable species may depend on their ability to tolerate hypoxia and perform fitness-dependent activities in hypoxic waters. We tested whether there is a link between hypoxia tolerance (HT) and oxygen consumption rate (MO2) of juvenile striped bass measured while swimming in normoxic and hypoxic water, and to identify the interindividual variation and repeatability of these measurements. Fish (N = 18) had their HT (loss of equilibrium) measured twice collectively, 11 weeks apart, between which each fish had their MO2 measured individually while swimming in low flow (10.2 cm s-1) and high flow (~ 67% Ucrit) under normoxia and hypoxia. Both HT and MO2 varied substantially among individuals. HT increased across 11 weeks while the rank order of individual HT was significantly repeatable. Similarly, MO2 i...