#FieldWorkWin: Signing off from Saipan

By Marie Hill, Amanda Bradford, Allan Ligon, and Adam Ü

We recently concluded a series of small-boat surveys for whales and dolphins (aka cetaceans) off Saipan in the Mariana Archipelago. Our primary target species was the endangered western North Pacific humpback whale.  Between February 11-22, we were able to survey on 6 days.  We were not able to survey as much as we would have liked due to rough sea conditions and stormy weather.  Despite this challenge, we had 13 encounters with a total of 25 individual humpback whales (including 2 calves), more than twice the number of individuals we photo-identified in each of our two previous field seasons (2015 and 2016).

Survey tracks (gray lines) and cetacean encounter locations during our small-boat surveys off Saipan (February 11-22, 2017)

We collected biopsy samples from 11 whales (that we will use for genetic analyses) and fluke images from 19 whales (that we will use for comparing to other North Pacific humpback whale photo-identification catalogs).  Most of the whales that we encountered this year are new to us. However, three individuals were seen in previous years and are in our photo-identification catalog.  One is a male that we photographed and biopsy sampled in 2015. Another is a female that we photographed and biopsy sampled last year.  She was with a calf in 2016 but not this year. The third was an individual of unknown sex that was first seen in 2007 during a shipboard survey in the Marianas conducted by the U.S. Navy. We collected a biopsy sample of this whale and will now be able to determine its sex.  This is the second humpback that we have matched to the 2007 survey.

A male humpback whale photographed off the west side of Saipan in 2015 and 2017. Photos: NOAA Fisheries/Marie Hill

One of our humpback whale encounters was particularly interesting because it was with a very active competitive group of five whales.  Breeding humpback whales are known to form competitive groups where males compete with each other for access to females.  One of the whales repeatedly lunged out of the water with his mouth full of water and slapped his “chin” on the surface creating a big splash. He was letting the other males know that he meant business!

A male member of a competitive group of breeding humpback whales displays to other males in the group. Photos: NOAA Fisheries/Amanda Bradford

During our short-finned pilot whale encounter on our first day of surveys, we deployed a satellite tag on an individual that we last reported off the east side of the island of Pagan.  We thought that the tag had come off the animal because we had not received any transmission for a 4 day period. On February 27, we started receiving signals again! The whale was 120 nautical miles southeast of its previous location and appeared to be following the Marianas Trench south.  Over the following week the tagged whale continued to move south going back and forth across the Mariana Trench until the tag stopped transmitting on March 10th.  Preliminary matching to our photo-identification catalog revealed that this group of short-finned pilot whales is new to us.  We have seen some groups of individuals multiple times over the years that regularly use the waters around the southernmost islands of the Mariana Archipelago (Guam, Rota, Saipan, Tinian, and Aguijan), but other groups may only be occasional visitors to these islands.

Track from a satellite tag deployed on a short-finned pilot whale at Marpi Reef (about 10 nautical miles north of Saipan) on February 11, 2017.

All photos taken with research permits (NMFS and CNMI DFW).  Funding was provided by U.S. Navy Commander, U.S. Pacific Fleet and PIFSC.  We would like to thank those individuals and organizations that provided logistical support, including Mike Trianni (PIFSC CNMI); Steve McKagan (PIRO CNMI); the CNMI DFW; Sam Markos, Benigno Sablan, Benigno Sablan Jr., Ymanuel Sablan, Aisha Sablan, and Claire Sablan (owner, captains, and crew of the Sea Hunter); and the Hyatt Regency.

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Listening Along Longlines for False Killer Whales

By Ali Bayless

 A scientific paper was recently published by Fisheries Research that describes an investigation of the sounds made by false killer whales near longline fishing gear and how these sounds relate to fishing activity and depredation. Depredation is the act of a marine mammal removing fish, either bait or target catch, from fishing gear. PIFSC scientist and lead author of the paper Ali Bayless describes the issue of depredation and how her team’s research is helping us to better understand how to reduce it.

Fishermen in Hawai‘i use a fishing technique known as “longline” that uses baited hooks targeting bigeye tuna attached at regular intervals along a main line that stretches for miles behind the boat. False killer whales are known to take tuna as well as bait from longlines at high rates in certain areas of the Pacific Ocean, a behavior known as depredation. This behavior can cause a whale to become hooked or entangled in fishing gear, which can lead to injury and even death of the animal. This type of unintentional injury and death (called bycatch) exceeded sustainable levels for the population of false killer whales in pelagic (offshore) waters of Hawai`i. The aim of our research is to better understand and ultimately reduce false killer whale depredation and bycatch.


False killer whale hooked in the mouth on longline gear after attempting to take bait or catch from the line. Photo: NOAA Fisheries/Pacific Islands Region Observer Program

Observations of false killer whales interacting with longline gear are limited since this activity mostly occurs underwater at depths between 40 and 100 meters.  However, false killer whales make specific sounds that are easily detected and identified, which makes acoustics (that is, the science of sound) a great way of determining whether these animals are present around longline fishing gear.  By monitoring these sounds, we can learn more about when and where whales interact with the gear in relation to specific fishing activities.

In order to monitor longline fishing sets for false killer whale sounds, a sturdy, light-weight acoustic recorder was needed that could be easily used by fishermen with minimal disruption to the fishing process.  We partnered with engineers at Scripps Institution of Oceanography in California to develop such a system, and the longline High-frequency Acoustic Recording Package (HARP) was born.  The HARP is made up of a hydrophone (underwater microphone) and a pressure case that houses a small computer set up to save all recorded sounds. The HARP can be easily attached directly to the main fishing line among branchlines with baited hooks as shown in the diagram below.


Diagram of longline fishing set with HARP attached.

The fishing vessel Katy Mary was hired to complete a total of 6 fishing trips for this study and multiple HARPs were attached on each fishing set, spread across the length of the main fishing line.  With multiple HARPs, we were able to record sounds across an entire set and capture any false killer whale sounds within range of the recorders.


HARPs onboard the fishing vessel Katy Mary getting prepared for deployment on longlines. Photo: NOAA Fisheries/Josh Tucker

A total of 90 fishing sets on the Katy Mary were monitored for false killer whale sounds in 2013 and 2014. We listened for two different types of sounds made by false killer whales: echolocation clicks and whistles.  We heard false killer whales 26 different times on 19 different fishing sets. The timing of false killer whale sounds was related to the timing of fishing activities, and 57% of detections were found to occur when fishermen were hauling the gear back on board the vessel.  This suggests that there may be some sound related to the hauling of fishing gear that these animals are cueing in on, much like a dinner bell would alert us to the presence of food nearby.


The number of false killer whale sound detections was highest during the hauling phase of fishing operations. Detections were either clicks, whistles, or a combination of both.

Movements of false killer whales along fishing lines were also investigated by looking at sound detections across multiple HARPs on a given set. We found that detections got sequentially farther away from the vessel during the haul, suggesting that the animals are aware of the vessel’s location and movement and have some motivation to stay ahead of the vessel.  This also supports the idea that there may be a sound cue related to the hauling of the gear that animals are reacting to.

False killer whale presence near fishing lines was also compared with depredation records for each set.  Only 3 of the 19 sets with false killer whale sound detections also showed signs of depredation, meaning there were visible signs of damage to hooked target fish. However, only catch depredation can be reliably determined by visual inspection of retrieved lines. It is possible that undetected bait depredation was also occurring and may be more prevalent than previously thought.

This novel approach to understanding how false killer whales interact with longline gear has provided an efficient and easy-to-use system for acoustic monitoring of the Hawai‘i longline fishery. This work is ongoing with deployments of HARPs on vessels across the fleet on a volunteer basis to further understand how and when these interactions are occurring.


False killer whales are highly social and form stable, long-term bonds. They even share food with each other. We hope our work leads to less of this food coming from longlines. Photo: NOAA Fisheries/Adam Ü

Many thanks to Jerry Ray (captain of the Katy Mary) and his crew, Josh Tucker and the PIRO Observer Program, and our collaborators at Scripps Institution of Oceanography. Funding for this research was provided by PIFSC, PIRO, the NMFS Take-Reduction and Bycatch Reduction Engineering Programs, the Marine Mammal Commission, and the National Fish and Wildlife Foundation.

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Hawaii Bottomfish Heritage Project Underway

Bottomfishing has a unique tradition in Hawai‘i that dates back to ancient times. Ancient Hawaiians targeted bottomfish such as ‘ōpakapaka (Hawaiian pink snapper, Pristipomoides filamentosus) using fishing canoes launched from shore. They located fishing spots by triangulating landmarks and used customary knowledge to read winds, waves, and currents. Line was made using woven plant fibers or hair. Stones were used to drop baited shell or bone hooks to depths of 350 meters to catch fish.

Some things never go out of style. The popular “make dog” rig for bottomfishing closely mirrors traditional fishing methods. Photo courtesy of Sureto Matsumura

Today, fishers use advanced technology to target bottomfish, such as custom fiberglass boats outfitted with gas efficient 4-stroke engines and sophisticated location and sonar equipment such as GPS, depth, and fish finders. Although technology has made locating fish and fishing spots easier, bottomfishing still requires a tremendous amount of knowledge and skill. Bottomfishers must be able to read ocean currents, skillfully maneuver their boat, and have a sophisticated understanding of ocean bathymetry. It may take a decade or more of sustained effort – maybe a lifetime – to become a good bottomfisher.

Onaga catch off to market, Maalaea Harbor, Maui. September 1980.Photo courtesy of Salvador Santos

The Hawai‘i bottomfishing community, the Western Pacific Regional Fisheries Management Council, and stock assessment scientists at the Pacific Islands Fisheries Science Center (PIFSC) are interested in documenting the culture, traditions, and fishing techniques unique to Hawai‘i bottomfishing community in order to ensure sustainable management for future generations. Thus, the Socioeconomics Program at PIFSC are partnering with the Pacific Islands Fisheries Group (PIFG) to conduct an oral history of bottomfishing in Hawai‘i.

Oral history differs from other types of social research by placing the focus on collecting personal experiences and reflections of past events through stories. Interviewees or ‘narrators’ are encouraged to tell stories in their own way. PIFG is interviewing bottomfishermen on the islands of Maui, Hawai‘i, Kaua‘i, O‘ahu, Moloka‘i, and Lāna‘i in order to:

  • develop a bottomfishing “family tree” to visualize knowledge transfer over time;
  • document traditional knowledge and changes in fishing techniques, including rotation of fishing spots and introduction of new technologies;
  • understand adaptations to weather, climate and regulatory regimes;
  • detail individual-level gear innovation; and
  • record culture, practices, and traditions specific to bottomfishing, including social and cultural sharing of catch and preferred meal preparation for various bottomfish species.

Stay tuned for updates from the field throughout 2017.

Sampan arriving at Maalaea Harbor, Maui. 1980. Photo courtesy of Salvador Santos

This project is supported by NOAA Preserve America Initiative and a National Marine Fisheries Service Pacific Islands Region Cooperative Research grant.

For more information about this research feel free to contact us:


For more information about other research from the PIFSC Socioeconomics Program visit our website or browse recent blog posts.

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Finding mobile needles in a moving haystack: counting whales and dolphins in Hawaiian waters

By Amanda Bradford

A scientific paper was recently published in NOAA’s Fishery Bulletin that provides abundance estimates of whales and dolphins in Hawaiian waters using data from a ship-based survey that took place in 2010. PIFSC scientist and lead author of the paper Amanda Bradford describes how these estimates were made and how they help us maintain healthy populations of whales and dolphins.

At least 25 species of cetaceans (whales and dolphins) can be found in the waters around the Hawaiian Islands.  All marine mammals in the United States are protected by the Marine Mammal Protection Act (MMPA), which was passed in 1972. The MMPA covers a suite of conservation and management measures designed at making sure activities like military sonar, oil and gas development, commercial fisheries operations, and even scientific research do not cause marine mammal populations to fall below sustainable levels–in other words, to become too small to recover from losses of individual animals.


From baleen whales to sperm whales to beaked whales to dolphins, a high diversity of cetaceans (at least 25 species) can be found around the Hawaiian Islands.

As part of these measures, the MMPA specifies that stock (or population) assessment reports be prepared for all known marine mammal populations in U.S. waters.  For my colleagues and I in the PIFSC Protected Species Division, that means all known marine mammal populations across the vast U.S. Pacific Islands region–from the main to the Northwestern Hawaiian Islands, from American Samoa to the Mariana Islands.  A stock assessment report synthesizes relevant information, like where the population is distributed and how much it is affected by humans, so that we can determine how the population is doing–its status, in other words.  An important part of determining the status of a population is estimating its size, or how many individuals are in the population.  If we do not know how many whales or dolphins there are, we will not know how to help keep their populations healthy and sustainable.

Since we are not able to go out and count all individuals one by one, we rely on sampling methods that allow us to use sighting rates of some animals in the population to help us estimate the total number of animals in the population.  One of these methods, called line-transect sampling, involves surveying an area from some platform, in our case a ship, on established tracklines (or transects) and then using detection rates of cetacean sightings off those lines to estimate the density of cetaceans in the entire area that was surveyed.  We can then multiply that density by the size of our whole study area to get an estimate of population size.  This method is particularly well-suited for surveying large areas like the U.S. Hawaiian Islands Exclusive Economic Zone (EEZ), which is about 2.5 million square kilometers (that is, larger than the combined areas of the two largest U.S. states, Alaska and Texas).


A schematic of line-transect sampling showing a ship on a transect (black line) in part of a study area. When a cetacean sighting is made, we get a measure of its perpendicular distance from the trackline, labeled as x. These values of x from multiple sightings within a strip (yellow lines) show us that our ability to detect sightings generally decreases the farther they are from the trackline. However, we can quantify this detectability, which allows us to estimate the density of animals within the strip and ultimately the abundance of animals in the entire study area.

When we conduct a line-transect survey for cetaceans, we use a 225-ft NOAA research vessel that is staffed with a dozen or more scientists—including a team of visual observers.  This team consists of six observers who rotate through three positions searching for cetaceans 180° forward of the vessel from the ship’s flying bridge, which is about 15 meters above the sea surface.  The three positions are a right- and left-side observer who search for cetaceans through 25-powered binoculars that we call “big eyes” and a center observer who collects data on a computer, while also searching with naked eye.  When cetaceans are sighted within three nautical miles of the trackline, we stop our search effort so that various data can be collected, including the information that allows us to calculate the perpendicular distance to the sighting.


Visual observers search for cetaceans from the flying bridge of a NOAA research vessel. Photo: NOAA Fisheries/Ernesto Vázquez

The formal survey we carry out for the purpose of estimating cetacean abundance around the Hawaiian Islands is called the Hawaiian Islands Cetacean and Ecosystem Assessment Survey, or HICEAS.  HICEAS is a line-transect survey of the entire Hawaiian Islands EEZ that takes place over four months during the summer and fall using two NOAA research vessels.  The survey design of HICEAS is a series of parallel transects that form a grid that provides comprehensive coverage of the study area.  The first HICEAS took place in 2002.  During that survey, 23 species were encountered and abundance was estimated for 19 of them.  Those estimates represented the first abundance estimates for most Hawaiian cetacean stocks.  To make sure we are not missing important changes in population size, we consider abundance estimates to be expired after 8 years.  Therefore, a second HICEAS was carried out in 2010.


A false killer whale sighted by the NOAA ship Oscar Elton Sette during HICEAS 2010. Photo: NOAA Fisheries/Corey Sheredy

Over 16,000 kilometers of line-transect effort was conducted during HICEAS 2010, which led to 198 cetacean sightings.  Abundance was estimated for the 19 species seen while on line-transect effort, although 23 species were encountered overall during the survey.  The resulting abundance estimates range from 133 to 72,528 individuals and are lowest for killer and baleen whales and highest for the smaller-sized dolphin species.  Note that the recently-published paper presents all the HICEAS 2010 abundance estimates except those for false killer whales, which were reported in an earlier paper.  Overall, cetacean density in the Hawaiian EEZ is low compared to other regions, reflecting the relatively low amounts of nutrients in our offshore waters.  As a point of comparison, cetacean density has been estimated to be at least 3.5 times higher in the eastern tropical Pacific and 4.5 times higher in the California Current, both areas with relatively high nutrient production.


Locations of the 198 cetacean sightings (black dots) made during HICEAS 2010. The gray lines represent completed transects and the outer black line shows the extent of the Hawaiian Islands EEZ.


Abundance estimates for 19 cetacean species in the Hawaiian Islands EEZ resulting from HICEAS 2010. The coefficient of variation (CV) is a measure of the precision of each estimate. Precise line-transect estimates will have CVs less than 0.3, but ours tend to be greater than 0.3 because sighting rates are low in our study area. We take the precision of an abundance estimate into account when we determine the status of a population.

These abundance estimates are set to expire in 2018, so we are gearing up for another HICEAS, which will take place in the summer and fall of this year.  HICEAS 2017 will be similar in design to the previous two surveys.  We will be rolling out a HICEAS 2017 website in the near future that will allow viewers to follow our progress, so stay tuned for more information!

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Rough-toothed dolphins were the most abundant species encountered in the Hawaiian Islands EEZ during HICEAS 2010. What species will be the most abundant during HICEAS 2017? Photo: NOAA Fisheries/Adam Ü

Thanks to the large number of hard-working scientists who contributed to HICEAS 2010, as well as to the officers and crew of the NOAA ships McArthur II and Oscar Elton Sette.  HICEAS 2010 was a collaborative effort between the Southwest and Pacific Islands Fisheries Science Center.  All work was carried out under research permit.

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Update from the Field: Have You Seen These Whales?

By Marie Hill and Amanda Bradford

When we last checked in, our team of scientists was waiting for the weather in Saipan to clear up so we could get back on the water to look for more endangered western North Pacific humpback whales. Well, we are still waiting! While the wind and swell conditions have kept us landlocked, the team has been cataloging and identifying the humpback whale photos we took during our first two days on the water. We collected full fluke images from 10 of the 11 humpbacks we encountered and their fluke markings allow us to identify different individuals—like a whale’s fingerprint. Most of the whales have primarily dark flukes with some white markings. We compared the fluke images to our existing catalog of identified individuals and found no matches.  However, we are interested to know if these whales have been seen in any other parts of the western North Pacific—for example, off Japan, Philippines, or Russia. If you have humpback whale fluke photos from these or other areas, please let us know if you have also seen these whales!

All photos taken with research permit (NMFS and CNMI DFW).  Funding was provided by U.S. Navy Commander, U.S. Pacific Fleet and PIFSC.

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A Whale of a Week in Saipan: Dispatches from the Field

By Marie Hill and Amanda Bradford

It’s #WhaleWeek and a team of PIFSC scientists is on a mission to find endangered western North Pacific humpback whales off the coast of Saipan in the Commonwealth of the Northern Mariana Islands. Marie Hill, Amanda Bradford, Allan Ligon, and Adam Ü are using the vessel Sea Hunter captained by Benigno “Uncle Ben” Sablan for two weeks of humpback whale surveys. Here are their dispatches from the field so far…stay tuned for more!

February 11, 2017

After our late arrival on the 9th and a day of setting up on the 10th, we were excited for our first survey. Today turned out to be an amazing day!  Definitely a record breaker for a winter survey and ranked among good summer days. First, the conditions were excellent. We had a little bit of swell, but nothing that hampered our operations or visibility. We started out the morning with three humpback whales about ten minutes after leaving the boat channel. They were very close to the fringing reef.


First humpback whales encountered during two weeks of surveys off Saipan. Photo: NOAA Fisheries/Marie Hill

We made it up to Marpi Reef (about 10 nautical miles offshore) and spent the rest of the day there because that was the place to be! First, we were greeted by a group of spinner dolphins. Shortly after leaving the spinners, we saw blows from multiple humpbacks and headed over to work with them, but on the way we got distracted by short-finned pilot whales.


Spyhopping short-finned pilot whale encountered over Marpi Reef. Photo: NOAA Fisheries/Marie Hill

There were multiple subgroups, and we worked with a couple of them.  We deployed a satellite tag and collected a biopsy sample from the tagged individual.

During the pilot whale encounter, bottlenose dolphins showed up and then made occasional appearances throughout the rest of the day.

While on Marpi Reef, we encountered eight humpbacks (all adults), from which we collected four biopsy samples.




Bottlenose dolphins checked in with us regularly out at Marpi Reef. Photo: NOAA Fisheries/Marie Hill


One of eight humpback whales seen out at Marpi Reef off the coast of Saipan.                          Photo: NOAA Fisheries/Marie Hill

We actually had to force ourselves to leave Marpi Reef so that we could make it back before dark. On our way back, we encountered another group of bottlenose dolphins and another group of spinners off the west side of Saipan. What a full and great day!

February 12, 2017

This morning started out nicely. The swell came up early (we were not expecting it until tonight or Monday), but the wind was really light. We encountered two humpbacks close to our first sighting yesterday. However, they were two (of the eight) individuals that we had seen yesterday at Marpi Reef; one of which we had biopsy sampled. We were able to collect more photos, but we didn’t get close enough to biopsy sample the other individual. The conditions came up much sooner than we expected, and we decided not to return to Marpi. A trifecta of swell, wind, and rain encouraged us to head in.

February 13-14, 2017

A small craft advisory, resulting from combined seas of 10-12 feet and 15-25 kt winds, has kept us off the water for the past couple of days.  Low visibility, resulting from rain, has prevented us from conducting shore surveys. We are spending our time working up the photos that we took during our first two days on the water.

We are also keeping up with the movements of the short-finned pilot whale tagged out at Marpi Reef. During our 2010-2016 surveys in the Marianas, we had only one other sighting of short-finned pilot whales off Saipan. Our previous satellite tag data from short-finned pilot whales tagged off Guam and Rota showed that some individuals travel up here, but we have never tagged a short-finned pilot whale this far north. It will be interesting to see where our tagged whale goes. After being tagged, the whale moved east and then north of Marpi Reef. During this #WhaleWeek, the tagged whale traveled to the northwest and was 32 km west of Farallón de Medinilla before changing direction to the southwest. We are hoping that they will come back down to Saipan so that we can collect more photos and biopsy samples.


Satellite tag track of a short-finned pilot whale tagged at Marpi Reef. The location where the whale was tagged is marked by a red dot.



The short-finned pilot whale tagged at at Marpi Reef before it began traveling north.     Photo: NOAA Fisheries/Amanda Bradford

All work was conducted under NMFS permit 15240 and CNMI DFW license no. 03564-17 issued to PIFSC. Funding was provided by U.S. Navy Commander, U.S. Pacific Fleet and PIFSC.


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