Tracking the oceanic movements of right whales

Guest post by Amy Kennedy.

If you’ve ever been whale watching, or watched a nature program about whales, you might think it’s easy to find and study whales and dolphins in the wild. In coastal towns around the globe, the eco-tourism industry has made it fairly commonplace to jump on a boat and spend a few pleasant hours bobbing around and watching marine mammals in their natural habitat.  In those same places, researchers can also get on a boat and spend the day photographing, biopsying and/or recording whales’ sounds.  This research is incredibly valuable and has essentially formed the entire base of knowledge we have about large whales worldwide, but there are some major questions that this type of research cannot answer.  For example, how do you know what a whale is doing while it’s underwater?  How do you know what a whale is doing at night?  How do you know what a whale is doing day after day, month after month, or season after season? Well, one way to answer those questions is to tag it.

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Figure 1: A satellite tag on a humpback whale in the Aleutian Islands. Photo taken under NMFS permit #14245 by Amy Kennedy.  All tagging operations are conducted under NMFS regulated permits and International Animal Care and Use Committee (IACUC) vetted and approved protocol.

Satellite tagging data are being used worldwide to create detailed, fine-scale tracks of whale movements, revealing behaviors that were previously unknown.  For example, a humpback whale tagging project I conducted in the Bering Sea (Alaska, USA) revealed remarkable variation in movement between animals that were tagged at the same time of year and at roughly the same location. All of the whales tagged here between 2008 and 2011 stayed in roughly the same area (feeding near Umnak and Unalaska Islands) except one. Whale G (Figure 2 below) astonished us all by travelling from it’s tagging location to another well known feeding area off Chukotka, Russia before circling back down to an offshore canyon. This whale swam approximately 3,000km in 26 days within a feeding season! This type of long-distance, within-season movement had not been previously documented and could have an impact on stock management and population estimates. There’s really no other way to discover and record individual events like these without satellite tagging technology.

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Figure 2. Satellite tracks of two humpback whales tagged in the Aleutian Islands, Alaska, in 2010.
From: Kennedy AS, Zerbini AN, Rone BK, Clapham PJ. (2014)  Individual variation in movements of humpback whales (Megaptera novaeangliae) satellite-tracked in the eastern Aleutian Islands and Bering Sea.  Endangered Species Research 23: 187-195

The North Pacific right whale (Figure 3 below) is the most endangered large whale population in the world, with only around 30 animals left in the Gulf of Alaska and Bering Sea.  Their population was decimated by a long campaign of Yankee whaling, followed by a devastating decade of illegal Soviet whaling.  Attempting to research an animal that numbers in the tens, yet could be found anywhere in the Pacific Ocean between Mexico and the Arctic, redefines the proverbial “needle in a haystack” search.

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Figure 3: One of only 30 remaining North Pacific right whales (Eubalaena japonica). Photo taken under NMFS permit #14245 by Amy Kennedy.

Fortunately, during dedicated research cruises in 2004, 2008, and 2009 we were able to locate and tag a number of these whales.  The fine-scale movement data we were able to collect has been invaluable in describing the habitat use of this critically endangered animal. In fact, the tracks we recorded from these animals led to the designation of a “Critical Habitat” region (Figure 4 below, black outline) by the National Marine Fisheries Service (a division of the National Oceanic and Atmospheric Administration).

Our tracking data also led to the discovery that North Pacific right whales behave differently as ocean temperatures change.  During warm-water years, the whales travel farther distances, presumably in search of food, than in cold-water years where they stay very close to oceanic fronts that concentrate their prey (Figure 4).

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Figure 4: Satellite tracks of NPRW in the Bering Sea (Alaska, USA) showing the Critical Habitat (black outline) and ocean temperatures in 2004, 2008, and 2009.
From: Zerbini AN, Baumgartner MF, Kennedy AS, Rone BK, Wade PR, Clapham PJ.  (2014) Ecological and management implications of endangered North Pacific right whale (Eubalaena japonica) space-use patterns in the Bering Sea.  Marine Ecology Progress Series: Vol. 532: 269-281.

During the WHALE:SWIM project, we hope to apply this same technology to track right whales in the South Georgia ecosystem.  Like the North Pacific right whale, the southern right whales were decimated by decades of whaling, and very little is known about their fine-scale movement and habitat use in this important feeding ground today.  Tagging data, combined with the acoustic, genetic, and oceanographic information we’ll be collecting during the project, will hopefully provide us with previously unknown information about these animals’ feeding behaviors and movement patterns.

Amy Kennedy will be satellite tracking right whales in South Georgia for the Whale:SWIM project. Learn more about her work here.