Monterey Bay Whale Watch - November 2012 Feature

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Rare Offshore Killer Whales Feed on Exotic Deep-Sea Fish Opah
in Monterey Bay: First Time Documented!

Click on small pictures below to see full-size photos.

On October 31, our captain John Mayer spotted some killer whales just beyond the canyon edge, 8 miles northwest of Pt. Pinos. After watching the whales for a short time, he suspected that they were the offshore type. There are three types of killer whales found in the North Pacific, "transients" or mammal hunters (seen most often in Monterey), "residents" (fish hunters, which often travel through Monterey in winter, and are most often off Washington state), and the "offshores", a type which is least known with a few observations of them feeding on sharks and fish. Males of this type have a more rounded and narrow fin than transients and females, also with a rounded fin. They tend to have many notches and scratches in their dorsal fin, possibly from catching sharks. On a whale watch trip many years ago, we (Nancy Black and Richard Ternullo) observed them catch a blue shark. However, there are very few observations of the food types for offshores. The offshores are one population, in that all the whales (around 350-500 in population) range from Southern California to the Bering Sea. The groups typically range in size from 10 to over 100, with most sightings numbering 20-100 whales. Unlike the transients and residents which exist in distinct groups (such as southern residents, northern residents, Alaskan residents) that range over part of their entire population range, the offshores consist of one population.

On this day, there were around 25 whales, as offshores are often found in large scattered groups. Just after they arrived, Captain John and naturalist Shawn Swing on our whale watch trip observed part of the group catch and feed on an Opah, an unusual fish usually found in warmer waters. Isiah Foulks, our deckhand, was quick enough to photograph the Opah with the whales. The fish was about 4' long and weighed about 100 lbs. Opahs are a laterally flattened, silver fish, with gray spots and crimson (bright orange) fins, a very beautiful fish known to be occasionally caught by fishermen in offshore waters of Monterey with albacore. John first observed a group of about six whales bringing the Opah to the surface, including some bubble bursts by the whales to likely confuse the fish. John saw that one female type whale brought the fish up in its mouth and let it go as 3-4 whales tightly surrounded it on the surface, preventing the fish from escaping. The fish was definitely in the mouth of the whale and looked injured. After a short time, another whale grabbed the fish and pulled it under. Within a few minutes, the whales tore up the fish as several gulls and a few albatross were seen picking pieces and small gut parts out of the water. It looked similar to the way transients feed on their mammal prey, such as harbor seals, which they quickly consume. This is the first time that we know of offshore killer whales feeding on Opah, a very important observation adding to our knowledge of this type of whale.

Alisa Schulman-Janiger and I (Nancy Black) dashed out after the whale watch returned and were able to locate the whales again with the help of boater Eric Mailander. We both had been working on our update to our previously published killer whale identification catalog, and Alisa has been up here for several weeks from Los Angeles. We followed the whales for just over four hours until dark as they slowly traveled south, and we left them a few miles off of Pt. Lobos. They remained in subgroups of 2-5 whales spread just under a mile. Some were curious about the boat and passed us closely, with a few tail slaps and syphops. They were mostly in the travel mode and not obviously feeding. There were about five albatross' following the whales, as these seabirds often seem to follow killer whales in hopes of picking up leftover pieces if they disperse their prey near the surface. We were able to photograph the group and recognized many whales from previous sightings. We are analyzing the photos from this sighting to determine matches to other areas, as we have previously documented matches from Southern California, Monterey and as far as the Bering Sea.

Everyone was very excited about the event, with some passengers amazed at how many killer whales were present and also appreciated seeing them in the wild. We will continue to look for this group again, or possibly more groups could pass through, as many offshores are seen on the outer coast of the Queen Charlotte Islands/Alaska during the summer (also some throughout the year) and are seen off California primarily during late fall to early spring (more in winter). Our last Monterey offshore sighting was March 2011 and the last California sighting was January 2012 off Southern California.


LINKS:

More on the offshore killer whale ecotype:

Eastern temperate North Pacific offshore killer whales (Orcinus orca): Occurrence, movements, and insights into feeding ecology
Paper by Marilyn Dahlheim, Alisa Schulman-Janiger, Nancy Black, Richard Ternullo, Dave Ellifrit, and Kenneth C. Balcomb III, published in Marine Mammal Science in July 2008:

More about Opah:

Opah Images

Opah seen more often off Southern California - San Diego researchers join effort to better understand the species

NOAA FishWatch - Opah

Hawaii Seafood - Moonfish (Opah)


Offshore Orcas and Opah

Offshore Killer Whales and Opah

Offshore orcas and opah

Offshore Killer Whales and Opah

Offshore orcas

Offshore Killer Whales

Albatross follows orca

Albatross and Killer Whale

Bull offshore orca

Bull Offshore Killer Whale

Orca spyhopping

Killer Whale Spyhopping


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Photos © Isaiah Foulks and Eric Mailander

Last updated November 3, 2012