QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Acevedo-Gutiérrez, A. Articles by Tershy, B. R. Search for Related Content PubMed PubMed Citation Articles by Acevedo-Gutiérrez, A. Articles by Tershy, B. R.

High feeding costs limit dive time in the largest whales

A. Acevedo-Gutiérrez^*, D. A. Croll and B. R. Tershy

Institute of Marine Sciences, Center for Ocean Health, 100 Shaffer Road, University of California, Santa Cruz, CA 95060, USA
^* Present address: Division of Education, California Academy of Sciences, Golden Gate Park, San Francisco, CA 94118, USA

View larger version (31K): [in a new window]   Fig. 1. Lunge-feeding in blue whales and fin whales. (A) A series of three foraging dives. Each spike at the bottom represents a lunge. (B) Representation of one vertical lunge at depth. During a vertical lunge, whales move significantly faster during the ascent than during the descent (Croll et al., 2001), and underwater video recordings indicate that whales lunge upside-down (J. Calambokidis, personal communication, Cascadia Research Collective, 218 West Fourth Avenue, Olympia, WA 98501, USA). Thus, the whale is depicted upside-down and lunging upwards, with the dashed line indicating the invagination of the tongue. Modified from Berta and Sumich (1999).

View larger version (21K): [in a new window]   Fig. 2. Time spent at the surface relative to dive duration. (A) Blue whales; (B) fin whales. For clarity, we depict only non-foraging dives and three-lunge foraging dives. The different slopes between non-foraging and foraging dives indicate that lunge-feeding incurred a cost. Dashed lines, open circles, non-foraging dives; bold solid lines, filled circles, three-lunge foraging dives. The thin solid lines indicate the predicted surface time according to different values of the cost of foraging relative to the cost of traveling to and from the prey patch. Note that for three-lunge foraging dives the relative cost of foraging appears to be 3 for both species.

View larger version (18K): [in a new window]   Fig. 3. The relative rate of increase of the time spent recovering at the surface after a dive significantly increased with the number of lunges per dive. That is, whales spent more time recovering at the surface as the number of lunges per dive increased. By definition, zero-lunge dives are non-foraging dives. *P<0.05, **P<0.01.

View larger version (19K): [in a new window]   Fig. 4. Foraging time relative to dive depth. Open circles indicate observed foraging times for dives with two or more lunges. The solid lines indicate the predicted foraging time ±95 % CI according to the lunging-costly model. The broken line indicates the predicted foraging time according to the no-cost model. Values of r2 are for the lunging-costly models. (A) Blue whales. On the basis of the lunging-costly model, the cost of foraging relative to the cost of travel to and from the prey patch was 3.15 (95 % CI 2.58-3.72). (B) Fin whales. On the basis of the lunging-costly model, the cost of foraging relative to the cost of travel to and from the prey patch was 3.60 (95 % CI 2.35-4.85).

View larger version (13K): [in a new window]   Fig. 5. The lunging-costly model predicted dive duration better than the no-cost model for dives with two or more lunges. Thus, we combined those dives in the graph for clarity. Error bars indicate S.D. (N=7 for blue whales, N=8 for fin whales).