Swimming velocities, breathing patterns, and estimated costs of locomotion in migrating gray whales, Eschrichtius robustus

Abstract

This study was conducted to determine the swimming velocities and breathing patterns of south-migrating gray whales (Eschrichtius robustus) and to estimate their minimum costs of transport during migration. Swimming velocities and breathing patterns were monitored with theodolite techniques from a coastal vantage point on Point Loma, San Diego County, CA. Estimates of energy expenditures were based on observed breathing rates and on extrapolations of tidal lung volume and oxygen uptake measurements made on unrestrained and on captive gray whales. The results of 74 whales monitored over 354 whale∙km yielded mean velocities of 2.0 m∙s−1 and mean breathing rates of 0.72 breaths∙min−1. The regression of breathing rates on swimming velocities (V) by the method of least squares is best described by the equation, breathing rate = 0.5 + 0.024 V3.0. The calculated minimum cost of transport for a 12-m, 15-t whale was 0.046 W∙s∙N−1∙m−1 at the observed mean swimming velocity of 2 m∙s−1 during the southward migration. The coefficient of total drag was estimated to be 0.06. Rates of lipid depletion approximate 6% of body weight per month if no supplementary food intake occurs for the 4- to 6-month period each year that gray whales are presumed to fast.

The evolution of cost efficient swimming in marine mammals: limits to energetic optimization

“…Bottlenose dolphins show the lowest ratio between measured and predicted values within this range (Williams et al 1993). Larger cetaceans such as the killer whale (Kriete 1995) and grey whale (Sumich 1983) demonstrate COT TOT that are 2.2^2.9 times those predicted for salmonid ¢sh.…”

“…Flume dimensions must take into account the frontal area and propulsive movements of each species. In addition, water £ows must provide a physiological challenge for the swimmer (Williams 1987 bottlenose dolphins follow a moving boat at sea (Williams et al 1993), and calculating metabolic costs from respiratory patterns of free-ranging killer whales (Kriete 1995) and grey whales (Sumich 1983). A critical feature of these methods is the ability to monitor the subjects at preferred steady state velocities as determined from the routine movements of wild animals.…”

Respiratory pattern of captive Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

“…However, this contrasts to the respiratory physiology of cetaceans. As reported by Sumich (1983Sumich ( , 1986Sumich ( , 1994, the efficiency of oxygen uptake of gray whales (Eschrichtius robustus) is lower at very short RIs. Therefore, the relative density of RIs is unlikely to be the highest at the shortest length.…”

“…1), gray whales E. robustus (Lyamin et al 2000, Fig. 5;Sumich 1983, Fig. 2), bowhead whales Balaena mysticetus (Würsig et al 1984, Fig.…”

“…Understanding the respiratory pattern therefore may increase understanding of the "invisible" underwater behavior. Besides, accurate measures of respiratory intervals (RIs) and quantitative analysis on the breathing pattern can provide valuable information for estimating cetacean abundance by visual "cue-counting" techniques (Hiby and Hammond 1989;Stern 1992;Kopelman and Sadove 1995;Beasley and Jefferson 2002) and for understanding the animals' physiological adaptation to the aquatic environment (Sumich 1983;Watson and Gaskin 1983;Chu 1988;Kooyman 1989).…”