Skating by: low energetic costs of swimming in a batoid fish

Abstract

We quantify the oxygen consumption rates and cost of transport (COT) of a benthic batoid fish, the little skate, Leucoraja erinacea, at three swimming speeds. We report that this species has the lowest mass-adjusted swimming metabolic rate measured for any elasmobranch; however, this species incurs much higher COT at approximately 5 times the lowest values recorded for some teleosts. In addition, because skates lack a propulsive caudal fin and could not sustain steady swimming beyond a relatively low optimum speed of 1.25 BL×s−1 (body length, defined as disc length: 5–6.5 cm), we propose that the locomotor efficiency of benthic rajiform fishes is limited to the descending portion of a single COT-speed relationship. This renders these species poorly suited for long-distance translocation and, therefore, especially vulnerable to regional-scale environmental disturbances.