NOAA Teacher at Sea Donna Knutson NOAA Ship Oscar Elton Sette September 1 – September 29, 2010
Mission: Hawaiian Islands Cetacean and Ecosystem Assessment Survey Geograpical Area: Hawaii Date: September 27, 2010
The Elusive Pseudorca
Mission and Geographical Area:
The Oscar Elton Sette is on a mission called HICEAS, which stands for Hawaiian Islands Cetacean and Ecosystem Assessment Survey. This cruise will try to locate all marine mammals in the Exclusive Economic Zone called the “EEZ” of Hawaiian waters. The expedition will cover the waters out to 200 nautical miles of the Hawaiian Islands.
Data such as conductivity, temperature, depth, and chlorophyllabundance will be collected and sea bird sightings will also be documented.
Science and Technology:
Latitude: 22○ 09.1’ N
Longitude: 160○ 12.3’ W
Clouds: 1/8 Cu
Visibility: 10 N.M.
Wind: 9 Knots
Wave height: 1-2 ft.
Water Temperature: 26.6○ C
Air Temperature: 25.2○ C
Sea Level Pressure: 1015.9 mb
Compared to its cousin the Killer Whale, little is known about the False Killer Whales. They do not have many similar traits other than their coloring. They both have black upper bodies with patches of white below. On the pseudorca the lighter color is on the chin and tapers along the stomach backward to the tail.
They are a much smaller animal, with a male maximum length of nineteen feet six inches and a weight of around three thousand pounds. The female is smaller with similar coloring. They have an erect dorsal fin that may be up to fifteen inches high.
The false killer whales may not sound so impressive but as cited in the Honolulu , September 2010 magazine, the pseudorca are not the typical marine mammals. They are actually a type of dolphin (as is the “true” killer whales), they swim extremely fast and have a unique community/friendship relationships. Pseudorca may stay with a group for more than twenty years.
To show a sense of community spirit, when a pseudorca catches a fish it may pass it around to all the other members before it comes back to the original thrower, (kind of like “throwing around the horn” in baseball). They are typically found in groups of ten to twenty members but can be found in broad bands several miles wide.
One population of pseudorca in the Main Hawaiian Islands has been dwindling from several hundred in the late 1980s to about one hundred fifty members today. These animals live primarily within seventy miles of the islands.
Fishing is one reason for the decline in numbers. The whales may see a free meal in yellow fin tuna or mahi mahi on a fisher’s line and become hooked and drown. This has caused an average of eight false killer whales to be drowned or seriously injured in each of the last five years.
Pseudorcas have a low reproduction rate. Their calving interval is very long, up to seven years, so not many whales are being born into the pod to replace those lost accidentally by humans. In July a team of scientists, fishermen and conservationalists turned in a plan on how to reduce the number of false killer whales injured on longlines. One of the recommendations is to close off an area abut 50-75 miles from the Hawaiian longline fishery. There is already a non-fishing mandate that protects the National Monument.
The National Marine Fisheries Service will decide if these regulations should be enacted and then determine if the pseudorcas should be protected under the Federal Endangered Species Act.
One of the prime objectives of the HICEAS cruise is to find, tag, take a biopsy samples of, and pictures of pseudorcas. Because of the interest in protecting these animals, it is very important to get as much information on these animals as possible.
So now here we are into day 26 of our 29 day cruise, and guess who shows up! The pseudorcas! And when they come, get ready! The animals seen yesterday were traveling by themselves or in groups up to ten, and they were spread out over twelve miles!
Erin had established a protocol for monitoring all the different subgroups which would allow the scientists to get a count on the number of individuals present. Once a scientist spotted a group, they had to follow that group until it passed the ship. That was very challenging especially for the groups that were a long distance from the ship and took several minutes to pass.
Then you have the group that wants to merge with that group or one leaves this group and wants to go with that other group. It is not like they have brightly colored clothing to tell them apart! It was quite an exercise in patience and determination.
I did not have a group, but I did have white board markers, which I acquired from running down to the exercise room to snatch them from the maker board below deck. Erin had mentioned someone should be a recorder of groups. I definitely know my way around a marker board, so I started writing the names of the observers, their group’s location and assigned them a letter. At one time we had five different groups being monitored. By the end we had groups A through S!
The scientists could not look away from their group for the entire time it was being counted until it left the area. Wow, they did a great job! As soon as their group left they picked up on another. Some scientists where watching two groups at the same time if they were close to each other. It took a lot of concentration.
Erin copied the data from the board to make sure all was accounted for and then the board was erased to start all over again. We did this for over two hours! The animals were spread over twelve miles! Now that may sound like a lot of pseudorcas, but there typically were not that many animals in a subgroup. They just needed to be monitored for a long time until all data was recorded properly.
When the last pseudorca was past the ship, Erin sent out the small boat. Allan was there to shoot the satellite tag into a fin for tracking the whale. Ernesto was in charge of getting biopsy samples and Corey was in the boat to get pictures with the laser camera. Of course the small boat driver, Mills was there along with Ray to help with lines and such.
They looked like they had a fun time! The whales, who are very curious in nature, would pop up beside the small boat and often swim in small groups beside them. I read that these animals have been seen to act like the bottlenose and spinner dolphins and ride the bow wakes. They never did that on our ship, but were never far away.
The small boat was out for about two and a half hours. They did an amazing job of getting three animals tagged with tracking devices, eight biopsy samples and many great pictures. They were a lot of fun to watch! Their community structure in amazing. I can see why they are not “your typical dolphin”!