Abstract
A bstract Dive habits of four Northeast Pacific blue whales ( Balaenoptera musculus ) were studied using satellite‐monitored radio tags. Tags summarized dive‐duration data into eight 3‐h periods daily. One tag additionally summarized dive depth and time‐at‐depth information for these same periods. Tracking periods ranged from 0.6 to 12.7 d and provided data for 17 three‐hour summary periods, representing 2,007 dives (788 of which provided depth information). Total number of dives during a 3‐h summary period ranged from 83 to 128. Seventy‐two percent of dives were ≤ 1 min long. All whales spent >94% of their time submerged. Average duration of true dives (dives >1 min) ranged from 4.2 to 7.2 min. Seventy‐five percent of depth‐monitored dives were to ≤16 m, accounting for 78% of that animal's time. Average depth of dives to >16 m was 105 ± 13 m.