Ž.Comparative Biochemistry and Physiology Part A 129 2001 797809 The diving behavior of blue and fin whales: is dive duration shorter than expected based on oxygen stores?

Many diving seabirds and marine mammals have been found to regularly exceed their theoretical aerobic dive limit Ž.TADL. No animals have been found to dive for durations that are consistently shorter than their TADL. We attached Ž.timedepth recorders to 7 blue whales and 15 fin whales family Balaenopteridae. The diving behavior of both species was similar, and we distinguished between foraging and traveling dives. Foraging dives in both species were deeper, longer in duration and distinguished by a series of vertical excursions where lunge feeding presumably occurred. Ž.Foraging blue whales lunged 2.4 1.13 times per dive, with a maximum of six times and average vertical excursion of Ž. Ž.30.2 10.04 m. Foraging fin whales lunged 1.7 0.88 times per dive, with a maximum of eight times and average Ž.vertical excursion of 21.2 4.35 m. The maximum rate of ascent of lunges was higher than the maximum rate of descent in both species, indicating that feeding lunges occurred on ascent. Foraging dives were deeper and longer than Ž. Ž.non-feeding dives in both species. On average, blue whales dived to 140.0 46.01 m and 7.8 1.89 min when Ž. Ž. Ž.foraging, and 67.6 51.46 m and 4.9 2.53 min when not foraging. Fin whales dived to 97.9 32.59 m and 6.3 Ž. Ž. Ž.1.53 min when foraging and to 59.3 29.67 m and 4.2 1.67 min when not foraging. The longest dives recorded for both species, 14.7 min for blue whales and 16.9 min for fin whales, were considerably shorter than the TADL of 31.2 and 28.6 min, respectively. An allometric comparison of seven families diving to an average depth of 80150 m showed