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EarthFix Conversations: Catching Up With Orcas

April 5, 2012 | KUOW
CONTRIBUTED BY:
Ashley Ahearn


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  • Orca foraging behavior has been shown to change depending on how close they are to vessels. credit: NOAA NMFS Northwest Fisheries Science Center, taken under permit
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Orca foraging behavior has been shown to change depending on how close they are to vessels. | credit: NOAA NMFS Northwest Fisheries Science Center, taken under permit | rollover image for more

So, if you were an orca where would you hang out? Most of the time, in the summer anyway, scientists have a pretty good handle on where to find the resident orcas of Puget Sound. But, for most of the year those orcas aren’t home — and scientists want to know where their winter vacation getaways are.

Dawn Noren Collecting Data on Hand Held Device 2006

(Dawn Noren)

Dawn Noren is one of those scientists. She’s a research fishery biologist with the National Oceanic and Atmospheric Administration’s Marine Mammal Program at the Northwest Fisheries Science Center and has spent a lot of time observing orcas in the San Juan Islands and beyond. EarthFix’s Ashley Ahearn asked Dawn Noren about her work.

EarthFix Conversation with Dawn Noren by EarthFix

Dawn Noren: The research that I primarily was focusing on was looking at vessel interactions –- how they change their behavior related to vessel approaches and number of vessels there, and during that time, I also conducted group-behavior data to look at how the behavior of the whales might vary across the San Juan Island region to see if there’s hot spots for foraging or resting or other behaviors.

EarthFix: And what did you find?

Dawn Noren: We did see that there is a propensity for whales to be traveling throughout the region and also a hot spot for foraging tends to be on the Southwest side of San Juan Island although foraging can occur throughout the range, we just saw a lot of foraging behavior on the southwest side as well.

dominant_behaviorCOLOR copy

(Orca forage hotspot? Southwestern San Juan Island (shown in green))

EarthFix: Any idea why they hang out there?

Dawn Noren: Well, I think there’s a place called Salmon Bank there, and we also see fishermen near there so I think it probably is a good spot for fishing and the killer whales tend to be foraging there. Why the salmon are drawn to that area? I’m not sure, except they are funneling up to return to spawn. The Fraser River is a huge area where the chinook from the Fraser River are going, so they’re probably catching those fish at that location.

EarthFix: And these are southern resident killer whales?

Dawn Noren: That’s correct. This is an endangered group of whales, and one of the risk factors is prey availability and prey quantity and quality, so it’s really important to potentially protect these foraging areas for them if they’re prey-limited.

EarthFix: How do you feel your research could be used in protecting these animals and helping these animals going forward?

Dawn Noren: Well, I think my research, as well as others that have been published previously, suggests that there are certain areas in the San Juans where these whales could be relying on an area to really focus on foraging. And so I think that, by knowing where those areas are, if you’re going to potentially close areas to vessels, maybe we should focus on areas that might be important to the foraging behavior of these whales, since other studies have shown that vessels might actually cause these whales to switch from foraging to traveling.

EarthFix: And why is that a problem if they switch from foraging to traveling?

Dawn Noren: Well, these guys are already potentially prey-limited and so if they’re already prey-limited and, then, they’re reducing their time spent foraging, it’s probably an additional burden that they’re going to have to deal with.

EarthFix: Now, Dawn, you were out on a boat not too long ago for quite some time.

Dawn Noren: Yes, 21 days aboard the Bell M. Shimada trying to figure out where the southern resident killer whales are in the wintertime.

EarthFix: So, you were following one of the whales from K pod?

Dawn Noren: Our goal was to search for any resident killer whale we could find, and then we actually found J pod in the Strait of Juan de Fuca, and, so then, the goal, then, was to try to tag one of the whales in J pod so we can then do more directed studies of these animals in the coastal waters when they’re not in the San Juan area. And our goal is not just to find out where they’re going, but what they’re eating, and so often during our research cruises, we’ll find them, maybe, the last day or the second to last day or not at all, and then you only have maybe one day with them if you can keep up with them. At night we often lose them.

Tagged SRKW map The J pod orca’s tag fell off soon after it was attached but here’s where he went.

The beauty of the tag is the animal’s tag is leading you to the animals and then you go out to where the animals location are to do more directed studies to figure out what they’re eating by collecting prey remains, take behavioral data etc.

EarthFix: Right, so it’s one thing to study the southwestern side of San Juan Island and talk about that as an important area, but really we’ve got this vacuum of information as you get out into the open ocean.

Dawn Noren: Vacuum of information is absolutely right. Eight months of the year, we still don’t have a good handle on what they’re doing, and so, that’s the majority of the time, and obviously we need to figure out what they’re doing and where they’re going at that time of year.

© 2012 KUOW
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