Cetacean surveys show presence of dolphins, whales in NMI

The near-shore cetacean surveys being conducted in the Northern Mariana Islands by the Pacific Islands Fisheries Science Center have led to a great deal of sightings of different species of dolphins and whales that would enable scientists to have a closer look at the behavior of these marine mammals and the oceanic framework in the area.

Dr. Erin Oleson, who leads the center’s Cetacean Research Program, said the repeated sightings of cetaceans such as spinner dolphins and fin whales reveal the kind of species that are available in CNMI waters, allowing them to identify important information such as food and movement patterns.

Headquartered in Honolulu, Hawaii, the center administers scientific research and monitoring programs that support the domestic and international conservation and management of living marine resources.

As part of the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service, the center implements a multidisciplinary research strategy and conducts various activities that support its mission of stewardship of living marine resources through science-based conservation and management as well as protection of healthy ecosystems.

Oleson, along with four other core members of the Cetacean Research Program, was recently on island to continue their survey work and share some of their findings during a presentation hosted by the Asia-Pacific Academy of Science, Education, and Environmental Management at the American Memorial Park last Wednesday.

In an interview following her presentation, Oleson said the Cetacean Research Program has been conducting near-shore surveys on Saipan, Tinian, and Guam since March 2010. The surveys-the first of its kind-are funded by the National Marine Fisheries Service and the U.S. Navy.

Oleson said the surveys in the CNMI involve the deployment of two long-term acoustic recorders-one on the west of Saipan and another east of Tinian. The first survey collected data from March to August 2010 while the subsequent survey included data from 2011. For this survey, Oleson noted that they “reconfigured” the long-term acoustic recorder in such a way that they will record data from June of 2012 to June 2013.

While they have only looked at a few months’ worth of data from the surveys, Oleson revealed that there were a number of dolphin species and whales detected in the area, including sperm, Bryde’s, humpback, pilot, and three species of beaked whales, one of which has yet to be identified.

Oleson said their apparatus were also able to record low-frequency sonar emitted by Navy ships. “We’re interested to see how common it is, how much sound comes from that versus other noise sources like ships, fishing vessels or even storms,” she explained. “They may not be a very large contributor but maybe it’s increasing as they build up in the area.”

She also said their group collected samples of spinner dolphins that would allow them to study their genetic population structure, stable isotopes, and how they fit into the marine food web, as well as their contaminants.

When asked about comparable and dissimilar findings between the CNMI and Guam, Oleson noted that the group has done more work in the Northern Marianas than its neighboring island. The 2011 Presidential Early Career awardee pointed out that while there will be linkages in both island jurisdictions, they will also differ in several aspects. For example, interaction between cetaceans and humans is less common in the Commonwealth since it does not have the same tourist infrastructure buildup as that in Guam.

“As we learn more about the populations that are in each area, we’ll be able to look at that more closely,” she added.

According to Oleson, the acoustics in their recorders may also provide some insights into the two Cuvier’s beaked whales that beached on Saipan last year. “We haven’t seen Cuvier’s beaked whales alive around Saipan so that’s actually a fairly interesting addition to our species list.”

She is optimistic that their research work will continue in the foreseeable future, especially since the Navy is building up its operations in the region and that the program has become “really important” given its “interesting” parallelism to Hawaii.

“We know quite a lot about Hawaii from all the decades of research from other people and this is a very similar island archipelago in terms of the oceanography and the species. So I think it will continue for some time,” she told Saipan Tribune.

Oleson said they are interested to hear from the public on what they know about cetaceans in the area. “We’d really like to involve the community in the research and we also know that what we’re learning is only a small fraction of what the community probably really knows.”

For more information, email erin.oleson@noaa.gov or visit http://www.pifsc.noaa.gov/.

Jun Dayao Dayao
This post is published under the Contributing Author. He/she does not normally work for Saipan Tribune but contributes for a specific topic or series.

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