Effect of hypoxia on rockfish movements: implications for understanding the roles of temperature, toxins and site fidelity

Abstract

We used a high-resolution acoustic telemetry array to study the effect of seasonal hypoxia (defined as dissolved oxygen concentration [DO] < 2 mg l −1) on the movements of quillback rockfish Sebastes maliger and copper rockfish S. caurinus at Cape Perpetua Reef, Oregon, USA. Over 18 weeks in summer 2010, a period with both normoxic and hypoxic conditions at the reef, both species showed high site fidelity. Home range was variable within species, was much larger than previously shown, and was influenced by foray and relocation behavior. Several quillback rockfish forayed well off of the reef into sand and gravel areas. Foray departure time was synchronous among individuals and related to time of day (sunset). Hypoxic conditions reduced home range for copper rockfish by 33%, but home range was variable for quillback rockfish, with no change in foray behavior. We propose that the origin, chemistry, and temperature of the hypoxic water mass and the species' innate behavioral tendencies must be considered, along with DO, in determining the effects of hypoxia on fish.

Oxygen limitations on marine animal distributions and the collapse of epibenthic community structure during shoaling hypoxia

“…From our study, the generally low‐oxygen occurrences among species, the range of oxygen occurrences within species, and the significance of the oxygen predictors support the importance of oxygen variability as an important driver of community structure in some hypoxic systems (e.g., Matabos et al ., ). Thus, the minimal responses to hypoxia and unexpected tolerance to severe hypoxia observed in some species from the northeast Pacific (Rankin et al ., ; Eerkes‐Medrano et al ., ) may be explained by an adaptation to the oxygen dynamics characterizing this region. Over evolutionary time scales, the long‐term oxygen dynamics of a system will determine the response of the community (Levin et al ., ) and predict the lower limits of community persistence.…”

Seasonal changes in abundance and compelling evidence of migration for 2 rockfish species (Sebastes auriculatus and S. caurinus) inhabiting a nearshore, temperate-water artificial reef

“…For some fish species, seasonal changes in abundance may be attributed to an influx of juveniles that leads to higher counts during certain times of the year (Allen and Horn, 1975;Relini et al, 1994, Allen et al, 2002, Barreiros et al, 2004. In our study, although the proportion of juvenile brown rockfish was significantly greater in the summer, juveniles of both species (length <10 cm) accounted for a very small proportion of the overall counts by season.…”

“…Collectively, the studies indicate that most adults of both species maintain high site fidelity, although some exceptions have been observed; that habitat type (e.g., high-relief, low-relief, natural, artificial) may influence site fidelity and movement behavior; and that some level of homing ability from beyond their putative home range is likely. Estimates of home range for brown and copper rockfish vary widely, from <10 m 2 over high relief habitat to 4656 m 2 over low relief habitat (Matthews 1990b;Tolimieri et al, 2009;Rankin et al, 2013). The goal of our study was to determine whether there were patterned seasonal changes in abundance on the reef for either species, and if so, whether the observed patterns differed between species.…”

Toward a decade of ocean science for sustainable development through acoustic animal tracking

“…Itakura et al (2021) described a wide thermal tolerance for the stripped seabass Morone saxatilis , that actively avoided both high temperatures and bottom hypoxic waters during summer. Similarly, hypoxic upwelling events caused a 33% reduction in the home range size of the copper rockfish Sebastes caurinus (Rankin et al, 2013). All these studies provided key baseline information on the optimal environmental conditions of the studied species, which is highly useful to understand and predict their present and future population trends.…”