Papahānaumokuākea Associated Cetacean Ecology Survey (PACES) Week 4 Field Report

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Overview

by Amanda Bradford, Chief Scientist

The NOAA ship Oscar Elton Sette left the Papahānaumokuākea Marine National Monument (PMNM) on 4 June 2013 and arrived back to Pearl Harbor the following day, representing the end of the Papahānaumokuākea Associated Cetacean Ecology Survey (PACES).  Like Week 1, Week 2, and Week 3, the fourth and final week of PACES was a productive one, with 27 sightings and 29 acoustic detections of cetaceans, despite the weather taking a decided turn for the worse toward the end of the week.  Over the entirety of PACES, 91 cetacean groups were sighted by the visual observers and 120 groups were detected by the passive acoustics team.  These sightings and detections encompass at least 15 species, and a variety of supplemental information (photo-identification images, biopsy samples, satellite-tracked movements, and oceanographic data) was collected for many of the sighted individuals (summarized below).  I want to thank each member of the science party and of the ship’s personnel for their expertise, dedication, and hard work – their commitment to excellence produced excellent results!

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PACES science family, I mean, team (left to right, back then front): Suzanne Yin, Andrea Bendlin, Adam Ü, LTjg Erik Norris, Justin Garver, Patrick Rex, Allan Ligon, Shannon Coates, Amanda Bradford, Dawn Breese, Yvonne Barkley, Jenny Trickey, and Louise Guiseffi. Photo by LCDR Hung “Doc” Tran.

Visual observations

by Suzanne Yin and Dawn Breese in collaboration with Andrea Bendlin, Justin Garver, Allan Ligon, and Adam Ü

The last week of the PACES cruise brought the usual assortment of cetacean species: pilot whales (often associated with rough-toothed or bottlenose dolphins), a trio of Stenella species (spinner, spotted and striped dolphins), and a couple sightings of sperm whales.  A couple sightings of beaked whales and one sighting of our target species, false killer whales, rounded out our week.  However, pilot whales were definitely the flavor of the week, as we saw them almost every day.  Unfortunately, on each occasion they proved to be uninterested in approaching the ship, although we were able to obtain photographs for identification purposes during some sightings.  While circumnavigating French Frigate Shoals by ship and small boat, the ship observers were amazed to find several large, spread out subgroups of pilot whales, which the small boat team was able to approach for directed sampling.  Sighting rates were noticeably lower during our last two tracklines because the end of the week brought the return of the familiar central North Pacific Beaufort sea state 6 conditions.  Thanks to all of the Sette officers and crew whose tireless efforts, good spirits, and whale dances allowed us to complete our mission successfully!

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Ship-based sightings of cetaceans made on completed tracklines (red lines are standard survey effort, purple lines are nonstandard survey effort) during the fourth week of PACES. Map covers the PMNM (yellow boundary) from Gardner Pinnacles in the west to Nihoa Island in the east.

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A group of about 20 rough-toothed dolphins was seen on 28 May almost 85 km SE of Garner Pinnacles, representing a new species for the fourth week of PACES. Photo by Andrea Bendlin, taken under Permit #15240.

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Sightings of cetaceans (91 in total: 88 ship-based and 3 small boat-based) made on completed tracklines (red lines are standard survey effort, purple lines are nonstandard survey effort) during all of PACES. Map covers the PMNM (yellow boundary) from Pearl and Hermes in the west to Nihoa Island in the east.

Acoustic monitoring

by Yvonne Barkley in collaboration with Shannon Coates, Patrick Rex, and Jenny Trickey

The acoustics team wrapped up operations this week after 30 days of effort.  Our star species in Week 4 was the pilot whale with a total of eight detections, the most we’ve had during the entire survey.  Their vocalizations were really fun to listen to, with burst pulses, harmonics, and buzzes.  Two of these pilot whale detections were mixed species groups with rough-toothed dolphins.  It will be interesting to look back at the recordings and attempt to decipher between the different whistles of both species.  The amount of sperm whale detections took a noticeable dive this week (no pun intended).  We only experienced a total of two sperm whale detections compared to previous weeks where we detected anywhere from nine to seventeen.  There were nine acoustic detections of false killer whales during PACES, five of which were visually sighted, over 50 percent!  The overall acoustic detections are displayed in the table below.  The acoustics team would like to thank the ship’s personnel for their fine efforts during PACES, particularly the members of the deck and engineering departments who assisted with array deployment and recovery and Electronics Technician, Charlie Goertzen, who helped troubleshoot various issues along the way.

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Summary of ship-based acoustic and visual cetacean detections made during PACES; sightings with a * were made on 8-9 May before acoustic monitoring began.

Photo-identification, biopsy sampling, satellite tagging, & small boat surveys

by Erik Norris in collaboration with Shannon Coates, Andrea Bendlin, Justin Garver, Allan Ligon, Patrick Rex, Adam Ü, and Suzanne Yin

Almost 800 photos were taken in Week 4 during 14 ship-based sightings of five cetacean species, bringing the PACES total to over 2,800 photos taken of 12 species during 36 sightings.  The small boat worked with three of the Week 4 sightings, each of pilot whales, although one sighting was of a mixed pilot whale/rough-toothed dolphin group.  The first two pilot whale groups approached by the small boat were part of our dedicated French Frigate Shoals survey.  On 29 May, the small boat was launched for a nearshore circumnavigation of French Frigate Shoals, while the ship surveyed more offshore waters.  We had not gone very far (see below) when the ship called us over to try to approach first one and then another group of pilot whales for directed sampling.  While we were not able to satellite tag any of the individuals, we did collect two biopsy samples and over 100 photo-identification images between the two groups.

The small boat was launched again on 1 June in association with a mixed pilot whale/rough-toothed dolphin group over 100 km SSE of French Frigate Shoals.  Although few photos were taken of the rough-toothed dolphins, over 120 images were collected for pilot whale photo-identification.  Small boat operations during the fourth week of PACES spanned just over 9 hours and 100 km of effort.  We were hoping to conduct a nearshore small boat circumnavigation of Nihoa Island on either 3 or 4 June, but the weather did not cooperate.  In total, the small boat was launched 10 times during PACES and carried out over 34 hours and 330 km of effort.  We would like to thank the Sette’s officers and deck crew for ensuring that the small boat launches and recoveries were conducted safely and carefully.

In addition to the two pilot whale biopsy samples, three bottlenose dolphin biopsy samples were collected from the ship, one on 28 May (90 km SE of Gardner Pinnacles) and the other two on 30 May (50 km ENE of French Frigate Shoals).  Between the ship and small boat, a total of 23 biopsy samples were obtained from six species during PACES: six spinner dolphins, seven bottlenose dolphins, five false killer whales, two pilot whales, two sperm whales, and one humpback whale (actually a sloughed skin sample).  Finally, the satellite tags previously applied to two false killer whales are still transmitting.  A preliminary look at their movements through the end of PACES is shown below.

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Movements through 8 June of two false killer whales satellite tagged during PACES. The first individual (turquoise track) was tagged off Laysan Island on 15 May. The second individual (orange track) was tagged 75 km SE of Maro Reef on 26 May. These movement tracks are based on raw data, such that some positions may change or be eliminated following appropriate quality checking and data processing.

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Upper left inset shows ship (purple line) and small boat (white line) survey effort around French Frigate Shoals on 29 May. The small boat approached the ship-based pilot whale sightings, resulting in the collection of two biopsy samples and numerous photo-identification images.

 

Oceanography

by Louise Giuseffi in collaboration with Robert Spina, Erik Norris, and Amanda Bradford

The Oceanography team had a successful fourth and final week of sampling.  CTDs were performed 1-2 times per day before sunrise and just after sunset, with daily water samples collected from 12 consecutive depths ranging from the surface to 1,000 m.  XBTs and Surface samples have been collected 3-4 times daily, sometimes overlapping with cetaceans sightings.  The sightings for which we have accompanying oceanography data for this week include: #65 of Mesoplodon beaked whales; #68 and #83 of bottlenose dolphins; #70 and #73 of pilot whales; #71 of sperm whales; #75 of an unidentified beaked whale, #76 of unidentified dolphins, #84 of pilot whales and rough-toothed dolphins; and #86 of spotted dolphins.  Survey Tech Robert Spina kept the oceanography operations running smoothly throughout PACES – we are extremely grateful for his enthusiasm, hard work, and vast skill set.  We would also like to thank the ship’s command for adeptly handling the ship and the deck department for operating the winch during the CTD operations.

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Summary of oceanography stations during PACES.

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