| Summary: | Locomotion in any environment requires the use of energy to overcome the physical forces inherent in the environment. Most large marine vertebrates have evolved streamlined fusiform body shapes to minimize the resistive force of drag when in a neutral position, but nearly all behaviors result in some increase in that force. Too much energy devoted to locomotion may reduce the available surplus necessary for population-level factors such as reproduction. The population of North Atlantic right whales has not recovered following legal protection due to decreased fecundity, including an increase in the intercalf interval, an increase in the years to first calf and an increase in the number of nulliparous females in the population. This reproductive impairment appears to be related to deficiencies in storing enough energy to meet the costs of reproduction. The goal of this study was to determine whether increases in moving between prey patches at the cost of decreased foraging opportunities could shift these whales into a situation of negative energy gain. The first step is to understand the locomotor costs for this species for the key behaviors of traveling and foraging. This study investigated the cost of locomotion in right whales by recording the submerged diving behaviors of free-ranging individuals in both their foraging habitat in the Bay of Fundy and their calving grounds in the South Atlantic Bight with a suction-cupped archival tag. The data from the tags were used to quantify the oc- currence of different behaviors and their associated swimming behaviors and explore three behavioral strategies that reduce locomotor costs. First, the influence that changes in blubber thickness has on the buoyancy of these whales was investigated by comparing the descent and ascent glide durations of individual whales with differ- ent blubber thicknesses. Next, the depth of surface dives made by animals of different sizes was related to the depth where additional wave drag is generated. Finally, the use of intermittent ...
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