Taking a Closer Look at the North Pacific Chlorophyll Front!

(by guest blogger Lucas Moxey, scientist aboard Oscar Elton Sette SE-15-01)

Over the last few days, activity onboard the oceanographic research vessel NOAA Ship Oscar E. Sette has been fast-paced. Round-the-clock CTD sampling operations, acoustics transects, nighttime Cobb midwater trawls, and sorting & classification of micronekton have been just a few of the scientific activities routinely taking place during the SE-15-01 research cruise. In addition, occasional safety drills and even the celebration of a birthday at sea have also added to the list of recent events.

For the last week, our ship has been sailing north of the main Hawaiian Islands along the 159 W longitude line, conducting numerous transects along the way for collecting a variety of physical, chemical and biological data in an effort to identify and characterize the location and characteristics of the subtropical frontal region. This large oceanographic feature migrates north and south throughout the year in concert with the seasons, and is typically demarcated by two well-defined bio-physical indicators: a sea-surface temperature front (18 degrees Celsius) and an adjacent sea-surface bio-productive chlorophyll front (0.2 mg Chl /m^3). The data collected during this cruise will contribute valuable information to the historical time-series that NOAA ships have been collecting throughout the North Pacific over the last several decades.

During this research cruise, an additional tool is being used for getting a closer “in-situ” look at the unique and complex dynamics that are taking place at the chlorophyll front. Lucas Moxey, a scientist onboard the SE-15-01 cruise, designed and built a customized electronics package for an ocean drifter buoy as part of his graduate research at the University of Hawaii at Manoa – Electrical Engineering Department. Known as SVPs (“Surface Velocity Program”) buoys, these are comprised of a surface float, a tether line and a drogue. In the ocean, the drogue remains submerged at a depth of approximately 15 meters, and the drag that it generates ensures that the surface float remains coupled with the subsurface currents.

The electronics package included in this particular drifter was designed with the objective of collecting different types of information, including sea-surface temperature, salinity, geolocation (latitude & longitude), speed and direction of ocean currents, among other. In addition, the buoy was specifically configured to transmit data back to the scientists via satellite once an hour, in support of the subtropical frontal region research objectives of the SE-15-01 cruise.

During the chilly morning of April 9, upon reaching the chlorophyll front located at 30.5N 159W, the drifter was deployed from the Sette, therefore marking the start of its long journey throughout the Pacific Ocean. Within one hour of its deployment, the buoy was already transmitting real-time oceanographic data directly from within the transition zone chlorophyll front. The drifter is already providing valuable high-resolution information of the oceanic currents that exist in this region, which can be used for complementing and refining the synoptic perspectives provided by the available satellite observations.

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Photo Caption: Lucas Moxey, one of the scientists onboard the NOAA Ship Oscar Elton Sette, preparing the drifter buoy for its ocean deployment at 30.5N 159W (photo by Laura Lilly).

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Photo Caption: A view of the drifter buoy after deployment, showing the float (left) and the drogue (right). The drogue quickly sank to a depth of 15 meters as the paper-soluble tape disintegrated (photo by Laura Lilly).

 

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Photo Caption: Map from April 11 showing the latest geolocation information of the drifter since its release on April 9, 2015. Each data point represents hourly geolocation data.

Posted in Ecosystems and Oceanography Division (EOD), Scientific Operations

Four Million Nine Hundred Ninety-Nine Thousand Nine Hundred and Ninety-Nine

By Kevin Lino

Five million… that number has a pleasant vastness to it. Five million of anything seems overwhelming. Try to picture five million fish. Start small and keep expanding. How would that look? Would they be one compact bait ball of iridescent shapes or a colorful patch work of reef fish schooling together? Well, it would take years to count that high and yet here we stand (or swim) just a few thousand fish away from reaching this landmark.

Image 1: A school of Big Eye Jack (Caranx sexfasciatus) trail behind a towed diver during a survey. Photo by Kevin Lino

Image 1: A school of Big Eye Jack (Caranx sexfasciatus) trail behind a towed diver during a survey. Photo by Kevin Lino

Image 2: Map of Study Region for Jarvis Island, Palmyra Atoll, and Kingman Reef.

Image 2: Map of Study Region for Jarvis Island, Palmyra Atoll, and Kingman Reef.

For the PIFSC Coral Reef Ecosystem Division (CRED) fish team, it has taken 15 years of dedicated hard work under the ocean’s surface to get to this point. This happens as our team collects visual census data on reef fish populations throughout the US-affiliated Pacific Islands. As part of the Pacific Reef Monitoring and Assessment Program (RAMP) these surveys support the National Coral Reef Monitoring Program (NCRMP). The goal of our research missions is to conduct integrated, consistent, and comparable monitoring of coral reefs across all regions while assessing and detecting change in natural resources. This is true around large inhabited islands like Tutuila in American Samoa, where we recently completed surveys, well as the tiny remote atolls in the Line Islands chain where we are currently working.

Image 3: A Scalloped Hammerhead Shark (Sphyrna lewini) cruises the bottom amongst schools of anthias at Jarvis Island. Photo by Kevin Lino

Image 3: A Scalloped Hammerhead Shark (Sphyrna lewini) cruises the bottom amongst schools of anthias at Jarvis Island. Photo by Kevin Lino

Image 4: Diver Marie Ferguson tows over a school of anthias at Jarvis Island. Photo by Kevin Lino

Image 4: Diver Marie Ferguson tows over a school of anthias at Jarvis Island. Photo by Kevin Lino

To date, the division has counted 4,890,980 fish throughout our survey areas using several methods. While it is hard to know which method will be used to count the five millionth fish, our primary surveys are conducted by stationary point count (SPC) divers who use a transect line along the seafloor counting every species in that area. Another team is towed behind a small boat counting the larger (over 50 cm) more mobile species– circumnavigating the islands and covering up to 15km each day. Odds are in the favor of the SPC diver to get the count with one of the smaller species that school in their many of thousands, quite likely a cute little 3 cm Chromis vanderbilti. Either way, it is a major landmark for our program and we look forward to seeing which lucky diver will count that fish.

Image 5: A small school of Chromis vanderbilti huddle near the seafloor. Photo by Kevin Lino

Image 5: A small school of Chromis vanderbilti huddle near the seafloor. Photo by Kevin Lino

Our first stop, Jarvis Island, is one of the most pristine reef environments I have ever seen. In the waters surrounding the mostly barren sands above, is a flourishing ecosystem partially driven by upwelling of cold and nutrient rich water from deeper in the ocean. In such productive waters, tens or even hundreds of large sharks, jacks, and manta rays are likely to appear alongside our divers the moment they enter the water. Just off the bottom, the real work begins as thousands of anthias, chromis, and other small species abound in the rugose benthos of healthy corals and algae. After six days at Jarvis, we voyage north toward the masses of fish at Palmyra Atoll and Kingman Reef for the last 12 days of surveys. Both of these remote areas are also quite unique, hosting an abundance of biodiversity to keep divers busy, while getting closer to that fortunate five millionth fish.

We are grateful for the nearly 80 scientists who have worked together to get us this far. One of whom has counted nearly 500,000 more fish than her next highest counterpart. In the last decade working with CRED, Paula Ayotte has rarely missed an opportunity to go to sea and spend hours underwater during these missions. If we had a Hall of Fame, she would be inducted unanimously for so many reasons: not only for counting nearly a million fish on her own, but also for making sure all other divers are trained, and mostly for being the most entertaining dive buddy you could hope for. It has been a pleasure working with her for that time and while it would be nice to be the diver to count the 5,000,000 fish… I’m hoping that Paula gets that count with a three meter manta ray at Jarvis.

Image 6: A Giant Manta (Manta birostris) curiously swims over a diver during a survey. Photo by Kevin Lino

Image 6: A Giant Manta (Manta birostris) curiously swims over a diver during a survey. Photo by Kevin Lino

Image 7: Diver Paula Ayotte amongst a healthy school of Whitebar Surgeonfish (Acanthurus leucopareius) and Convict Tang (A. triostegus) while conducting an SPC dive.

Image 7: Diver Paula Ayotte amongst a healthy school of Whitebar Surgeonfish (Acanthurus leucopareius) and Convict Tang (A. triostegus) while conducting an SPC dive.

Posted in Coral Reef Ecosystem Division (CRED) | Tagged , , , , , , , , , , , , , , , , , , , , , , ,

Coral reef monitoring surveys completed around the islands and atolls of American Samoa

By Bernardo Vargas-Ángel
Operating area of the HA-15-01 ASRAMP Legs II and III.

Operating area of the HA-15-01 ASRAMP Legs II and III.

With work complete in the U.S. territory of American Samoa, the NOAA Ship Hi‘ialakai stopped in the port of Pago Pago Harbor for a short pause between Legs III and IV of PIFSC cruise HA-15-01. Led by the PIFSC Coral Reef Ecosystem Division (CRED), this mission marks the seventh monitoring cruise in the American Samoa region by PIFSC staff and partner agencies since 2002.

Activities to monitor the coral reef ecosystems of American Samoa began on February 17 and concluded on March 30, completing Leg I and comprising Legs II and III of this longer Pacific Reef Assessment and Monitoring Program (Pacific RAMP) expedition. Around Tutuila, Aunu‘u, Ofu-Olosega, Swains, and Ta‘u Islands, and Rose Atoll, the CRED scientists conducted ecosystem surveys of fishes, benthic and coral communities, and microbes, along with the deployment of oceanographic instruments and biological installations.

Shallow coral reef communities at Rose Atoll, conspicuously dominated by the pink-colored encrusting coralline algae.

Shallow coral reef communities at Rose Atoll, conspicuously dominated by the pink-colored encrusting coralline algae.

A pair of the reticulated butterflyfish (Chaetodon reticulatus) at Swains Island.

A pair of the reticulated butterflyfish (Chaetodon reticulatus) at Swains Island.

At Rapid Ecological Assessment (REA) sites, surveys for reef fishes and benthic coral communities documented the richness, abundance, density, and sizes of the biota and assemblages as well as the percent composition of bottom-dwelling organisms and the health conditions of coral colonies. Broad-scale towed-diver surveys recorded observational data on large-bodied fishes (>50 cm total length), percent composition of the seafloor, conspicuous macroinvertebrates, and coral stress.

In addition, teams studied microbial communities, diversity of cryptic invertebrates, water temperature, salinity, and carbonate chemistry. They are also working to assess the potential early effects of ocean acidification on cryptobiota (e.g. small, hidden organisms) and the rates of reef carbonate deposition, bioerosion, and coral calcification.

Across the Territory of American Samoa, this mission completed more than 60 towed-diver surveys totaling more than 130 km of coastline, 325 fish surveys, and 180 benthic surveys. The Ocean and Climate Change team deployed four climate monitoring stations around Tutuila, and four around Ofu-Olosega and Ta‘u, containing arrays of subsurface temperature recorders (STRs), calcification accretion units (CAUs), autonomous reef monitoring structures (ARMS), and bioersion monitoring units (BMUs). Critical findings during this mission included observations of coral bleaching, local warm water temperatures, and the number and distribution of corallivore crown-of-thorns sea stars (COTS).

Bleached and partly dead staghorn Acropora outside Fagatele Bay, Tutuila, American Samoa.

Bleached and partly dead staghorn Acropora outside Fagatele Bay, Tutuila, American Samoa.

Bleaching of scleractinian corals, averaging 10% of colonies, was reported in shallow (3-6 m) reef habitats of Tutuila Island—particularly within Fagatele and Fagasa Bays—as well as the southwest coast of the island and primarily affected species of branching and table Acropora, Isopora, Montastrea, Porties, and Pocillopora. Although bleaching conditions did not appear to be widespread, current NOAA Coral Reef Watch forecasts predict persistent warm conditions, which could potentially result in more severe and extensive coral bleaching across the region. CRED scientists recorded only occasional sightings of COTS and their feeding scars on corals, despite the ongoing outbreak conditions reported by staff of the National Park Service and the National Marine Sanctuary of American Samoa. In contrast to other regions where COTS outbreaks have been reported by CRED scientists, including Guam, the Commonwealth of the Northern Mariana Islands, and Kingman Reef, it appears that in American Samoa, the sea stars prefer to feed at night and hide under ledges and overhangs during the day, making them inconspicuous during daylight surveys.

Preliminary results from surveys conducted by CRED fish team divers, during PIFSC cruise HA-15-01, are provided in the fish monitoring brief below.

Pacific Reef Assessment and Monitoring Program
Fish monitoring brief: American Samoa 2015

By Adel Heenan

About this summary brief
The purpose of this summary brief is to outline the most recent survey efforts conducted by the Coral Reef Ecosystem Division (CRED) of the NOAA Pacific Islands Fisheries Science Center as part of the long-term Pacific Reef Assessment and Monitoring Program (Pacific RAMP). More detailed survey results will be available in a forthcoming status report.

Sampling effort

  • Ecological monitoring took place in American Samoa from February 15 2015 to March 30 2015.
  • Data were collected at 338 sites. Surveys were conducted at Ofu and Olosega (n=52), Rose (n=47), Swains (n=32), Tau (n=46) and Tutuila (n=162).
  • At each site, the fish assemblage was surveyed by underwater visual census and the benthic community was assessed.

Overview of data collected
Primary consumers include herbivores (which eat plants) and detritivores (which bottom feed on detritus), and secondary consumers are largely omnivores (which mostly eat a variety of fishes and invertebrates) and invertivores (which eat invertebrates).

Figure 1. Mean total fish biomass at sites surveyed.

Figure 1. Mean total fish biomass at sites surveyed.

Figure 2. Mean hard coral cover at sites surveyed.

Figure 2. Mean hard coral cover at sites surveyed.

Spatial sample design
Survey site locations are randomly selected using a depth-stratified design. During cruise planning and the cruise itself, logistic and weather conditions factor into the allocation of monitoring effort around sectors of each island or atoll. The geographic coordinates of sample sites are then randomly drawn from a map of the area of target habitat per study area. The target habitat is hard-bottom reef, the study area is typically an island or atoll, or in the case of larger islands, sectors per island, and the depth strata are shallow (0-6 m), mid (6-18 m), and deep (18-30 m).

Sampling methods
A pair of divers surveys the fish assemblage at each site using a stationary-point-count method. Each diver identifies, enumerates, and estimates the total length of fishes within a visually estimated 15-m-diameter cylinder with the diver stationed in the center. These data are used to calculate fish biomass per unit area (g m-2) for each species. Mean biomass estimates per island are calculated by weighting averages by the area per strata. Island-scale estimates presented here represent only the areas surveyed during this cruise. For gaps or areas not surveyed during this cruise, data from this and other survey efforts will generally be pooled to improve island-scale estimates.

Figure 3. Mean consumer group fish biomass (± standard error). Primary consumers are herbivores and detritivores, and secondary consumers are omnivores and invertivores.

Figure 3. Mean consumer group fish biomass (± standard error). Primary consumers are herbivores and detritivores, and secondary consumers are omnivores and invertivores.

Figure 4. Mean fish biomass per size class (± standard error). Fish measured by total length (TL) in centimeters (cm).

Figure 4. Mean fish biomass per size class (± standard error). Fish measured by total length (TL) in centimeters (cm).

Each diver also conducts a rapid visual assessment of reef composition, by estimating the percentage cover of major benthic functional groups (encrusting algae, macroalgae, hard corals, turf algae and soft corals) in each cylinder. Divers also estimate the complexity of the surface of the reef structure, and they take photos along a transect at each site that are archived to allow for future analysis.

About the monitoring program
Pacific RAMP forms a key part of the National Coral Reef Monitoring Plan of NOAA’s Coral Reef Conservation Program (CRCP), providing integrated, consistent, and comparable data across U.S. Pacific islands and atolls. CRCP monitoring efforts have these aims:

  • Document the status of reef species of ecological and economic importance
  • Track and assess changes in reef communities in response to environmental stressors or human activities
  • Evaluate the effectiveness of specific management strategies and identify actions for future and adaptive responses

In addition to the fish community surveys outlined here, Pacific RAMP efforts include interdisciplinary monitoring of oceanographic conditions, coral reef habitat assessments and mapping. Most data are available upon request.

For more information
Coral Reef Conservation Program
Pacific Islands Fisheries Science Center
CRED publications
CRED monitoring reports
CRED fish team
Fish team lead and fish survey data requests: ivor.williams@noaa.gov, adel.heenan@noaa.gov

Posted in Coral Reef Ecosystem Division (CRED) | Tagged , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

Three Days North into the Blue aboard SE1501!

By PIFSC EOD guest blogger Laura Lilly, guest scientist acoustician aboard SE1501, under Chief Scientist Phoebe Woodworth-Jefcoats.

As with all meticulously-arranged science plans, the original schedule for our April cruise aboard the NOAA Ship Oscar Elton Sette from Honolulu to the North Pacific subtropical frontal zone (STF) went out the window before we even set sail. After remaining in port several extra days to sort out gear issues and chase down a rat that had stowed away onboard, we finally steamed out of Pearl Harbor on the night of Friday, April 3.

The goal of our cruise is to examine and document the physical oceanography and biology of the North Pacific subtropical frontal zone, an area of high biological productivity marked by both a chlorophyll and a temperature front. The chlorophyll front is an important foraging ground and thoroughfare for sea turtles, elephant seals, tuna, swordfish, and seabirds. Additionally, there is evidence that the STF is experiencing long-term shifts in its position and intensity, with the chlorophyll front shifting farther north and decreasing in concentration. Sampling the STF during the present El Niño conditions and positive phase of the Pacific Decadal Oscillation will contribute to our understanding of these long-term variations.

Due to our pre-cruise delays, we had to remove the northbound sampling leg of our cruise, which meant that we have spent the past three days steaming straight from 22oN latitude (Oahu) to 32.5oN, just north of the frontal zone and roughly at the same latitude as Los Angeles, CA. Now that we’ve arrived at our northernmost station, we will turn around and begin seven days of southbound sampling, ending up back in Honolulu.

But in the meantime, our three-day transit has not been wasted! What does one do to pass the long, tedious hours floating through monochrome blue and grey? As it turns out, plenty! Below is a sampling of ways in which we’ve occupied ourselves while we wait for science operations to begin.

  • Sea legs – The first, and arguably most important, step of any sea voyage is to re-settle one’s balance and stomach after the seasickness that comes from being on a constantly rocking platform. Thanks to plenty of sleep, Dramamine, Saltines and a calmer swell, we’ve all finally found our sea legs.
  • Nighttime shifts – Our cruise involves round-the-clock science operations, so half the scientists have to change their internal clocks from a normal daytime routine to a nocturnal, middle-of-the-night “dead-watch” setting. As the days progress, more and more people are sleeping (and waking up) at odd hours. Breakfast is now nearly empty, while dinner finds many dead-watchers stumbling out for their first cup of morning coffee. Thanks to our extra transit time, everyone seems to have successfully made the transition, and is ready for nighttime collecting!
  • Exercise – In the interest of keeping up (physical) appearances, some high-energy members have ventured into the ship’s small gym, rotating between the elliptical, rowing machine and free weights in attempts to keep workouts from getting too monotonous. The more intrepid and strong-legged have even attempted the treadmill, which, in choppy seas with large swells, can feel like running inconsistent rolling-hill intervals. Needless to say, we’re staying sharp on our toes!
  • Bird-watching – As one of several (or perhaps the only) enthused birders on board, I have been vigilantly scanning the horizon non-stop with my binoculars, and informing everyone in sight every time I spot an albatross flying behind the ship…even if it’s the same albatross that has been following us for three days. In the absence of actual data collection during our northward transit, the frequency of birds can be a useful proxy for our impending arrival into the highly productive region of the chlorophyll front. Yesterday, a flock of red-footed boobies accompanied the ship for several hours (and left their mark on the bow, much to the Commanding Officer’s chagrin). Sadly, our troll-lines have not had corresponding luck in catching fish for dinner.
  • Easter Sunday – It’s easy to forget what day it is when you’re at sea, but we had an amazing Easter dinner, thanks to our galley whizzes Clem, Lenette and Doc.
  • The ship’s crew! – Over the past three days, we’ve gotten to know our wonderful, industrious, humorous and accommodating ship’s crew, who have navigated us through rough seas and squalls (aka a minor drizzle yesterday afternoon) to arrive safely at our first sampling station. Let the science begin!

Our science collection will fall into a familiar round-the-clock routine. During the day, we will conduct CTD casts and water sample collections, which give us information about the temperature, salinity, oxygen, nutrients and chlorophyll levels in the water column. At night, we will conduct trawls of the upward migration of the deep scattering layer (DSL), a huge subsurface layer of mesopelagic fishes, squids and crustaceans, part of which moves up toward the ocean surface at night to feed. Sampling this layer helps us understand the composition of species that larger predators forage on. In between CTDs and trawls, we will conduct transects focused solely on acoustic backscattering of the DSL, to give us even more information about the location and concentration of mesopelagic organisms.

We are all excited to begin sampling, and to discover the current composition of the STF and surrounding areas this spring. Stay tuned for more!

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Photo caption: A partial lunar eclipse on our first night underway – a nice reward for those trying to transition over to the night watch (photo by Jessica Chen).

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Photo caption: Blog post author Laura Lilly scans for birds while riding a stationary bike on deck (photo by Adrienne Copeland).

Posted in Ecosystems and Oceanography Division (EOD), Scientific Operations | Tagged

Explore Honolulu retail seafood pricing trends

By Justin Hospital

A new PIFSC report provides a summary of retail (consumer-level) fish price data collected from Honolulu seafood markets during 2007–2011. This represents one of the first efforts to explore consumer price trends in the State of Hawaii. A small sample of local seafood retailers were selected for participation in the monitoring program. These included owners, operators or representatives of local seafood outlets and both local and remotely-owned grocery stores and supermarkets. Retailers were visited on a weekly basis and posted price data were collected for fish species and product forms common in the marketplace. Observations regarding country of origin labeling practices were documented in conjunction with pricing.

The goal of this study was to advance a preliminary understanding of:

  • the prevalence of local species and product forms in Honolulu retail fish markets;
  • price differentials and value-added benefits across the seafood value chain;
  • consumer demand for various fish species;
  • the role of imports in the Hawaii seafood market

Data summaries in the report include:

  • retail market presence/absence estimates;
  • weekly retail price averages by species, product form and origin;
  • monthly time series for retail prices;
  • annual retail price spreads (difference between prices consumers pay and the price fishers receive)

These summaries are available for many species, families and product forms common in Hawaii markets including tuna, bottomfish, reef fish, and pelagic species (non-tuna).

An understanding of market composition, consumer demand for species and product forms, and the cultural importance of different species can be inferred from market presence-absence findings

Price differentials across the value chain shed light on consumer demand and value-added benefits attributed to consumer-level seafood products

 

The findings of this research have important implications for considering consumer-level effects of fisheries management as well as seafood security for Hawaii communities.

Retail price comparisons across species provide insights into the dynamics of market demand and consumer preferences

Aggregate price data at the retail and ex-vessel level can mask species-specific pricing dynamics which are important for monitoring considerations

Results from this project are available in a variety of formats:

  • Explore the data collected and summarized in the report through an online interactive visualization tool
  • Click to download a fact sheet
  • The full report is available for download here

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

Posted in Socioeconomics and Planning Group | Tagged , , , , , , , , , , , , , , , , , , , , , , , ,

Humpback Whales in the Marianas

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

The Pacific Islands Fisheries Science Center’s Cetacean Research Program returned to Saipan in the Marianas during February-March 2015 to look for humpback whales (Megaptera novaeangliae).  We have known that they occur there during winter/spring months (December-April) from accounts by local fisherman and dive operators, from a sighting at Marpi Reef during a 2007 shipboard survey of the Guam/CNMI EEZ, and from recordings from our passive acoustic devices on the seafloor off Saipan and Tinian.  We surveyed in the waters off Saipan, Tinian, and Guam in February 2010 and again in April 2014, but didn’t find any humpbacks.

We didn’t know exactly what to expect this time except for the rough sea conditions that typically occur during winter months in the Marianas.  We started out by looking for humpback whale blows from an elevated shore station on the west side of Saipan (Figure 1).

Figure 1_shore station

Figure 1: Looking for humpback whale blows from our shore station on the west side of Saipan. (Photo credit: Allan Ligon)

We had heard previous accounts of humpbacks swimming relatively close to shore outside of the lagoon and outer reef off the west side of the island.  While we were initially setting up our shore station, we spotted a breaching whale several miles offshore.  We knew then that we were in luck, and our timing was right!  We found humpbacks every day we went out on the water for a small-boat survey (Figure 2).

Figure 2_photographing humpbacks

Figure 2: On the water, we initially spotted each humpback whale in the distance by their blows. We then approached them to collect photographs and biopsy samples when possible. (Photo credit: Adam Ü)

It quickly became clear to us that the place to be was on Chalan Kanoa (CK) Reef (a.k.a. Double Reef or 6-Mile Reef) due to its relatively easy access from the harbor and regular whale presence.  All but two of our humpback whale sightings were over CK Reef (Figure 3).  Unfortunately, we were unable to effectively survey other areas around Saipan/Tinian due to the poor sea conditions.

Figure 3_Marianas 2015 winter sightings

Figure 3: Cetacean and whale shark sightings. Black line represents 100-m depth contour around the islands and CK Reef.

During the eight days that we were on the water, we saw four mom/calf pairs (Figure 4).  We saw two of the four pairs over multiple days and collected biopsy samples from three of the moms.

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Figure 4: Humpback whale mom/calf pair no. 3 photographed on 6 March 2015. We collected a biopsy sample from the mom. (Photo credit: Amanda Bradford)

The presence of moms with small calves suggests that the waters off western Saipan and likely adjacent areas may be a breeding area for humpback whales.  Research on humpbacks in the North Pacific has demonstrated that these whales feed during the summer off the coasts of California, Oregon, Washington, Alaska, Canada, and Russia.  During the fall and winter, they travel as far as 3,000 miles south to mate and calve in warmer waters.  The known North Pacific breeding grounds are off Mexico, the Hawaiian Islands, the southern islands of Japan, and the northern islands of the Philippines.  Exactly where our humpbacks came from is a mystery.  We hope that genetic analyses from the biopsy samples we collected will help to inform us.

In addition to the mom/calf pairs, we confirmed with photographs that there were four other non-calf individuals on the reef, bringing the total number of documented whales to 12.  There may have been more than 12 whales using the area, but because of difficult whale behavior (e.g., long dive times, fast travel) and rough sea conditions, we weren’t able to get close enough to take photos of every whale sighted.  Only two individuals showed their flukes (Figure 5), which are used as primary identifiers for individual humpback whales.  These individuals could possibly be matched to humpbacks within existing photo-identification catalogs from other parts of the Pacific.

CNMI-000102

Figure 5: The “tail-end” of the flukes of a humpback whale photographed over CK Reef (Saipan) on 7 March 2015. (Photo credit: Amanda Bradford)

Although humpbacks were our primary focus, we were also hoping to see other cetacean species.  Because the sea conditions were so poor (mostly Beaufort sea states 5-6 and 6-8 ft swells), we had little chance of seeing anything except large whales unless other species came to us.  We got lucky and had a single bottlenose dolphin (Tursiops truncatus) approach our boat to bow ride for a few minutes while we were following a humpback mom/calf pair.  Several days later, we saw a group of six pygmy killer whales (Feresa attenuata) that were swimming around and along with two adult humpback whales that appeared to be socializing.  Unfortunately, we were unable to collect any individual catalog-ID photos or biopsy samples from either the bottlenose dolphin or pygmy killer whales because of the conditions and our focus on the humpbacks. However, we did collect a fourth biopsy sample from one of the humpbacks with the pygmy killer whales.

As if finding humpback whales wasn’t good enough, we were incredibly lucky to see two different juvenile whale sharks (Rhincodon typus) a couple days apart (Figure 6).  This was a lifetime first for most of us!  The whale shark is the largest living fish and can grow to 40 ft. in length.  We found that whale sharks are easier to work with than whales.  They were very interested in our vessel and swam closely around it, providing us with the opportunity to record some close-up footage from our pole-mounted video camera.  We could have spent hours with them, but remembering that we are whale biologists we had to break away.

Figure 6_Whale shark 2

Figure 6: Open mouth of a juvenile whale shark off Saipan/Tinian. (Photo credit: Adam Ü)

This research was conducted under NMFS permit 15240 and CNMI DFW license no. 03086-2015 issued to PIFSC CRP. Funding was provided by PIFSC and U.S. Pacific Fleet.  We would like to thank those individuals and organizations that provided us logistical support, including Mike Trianni (PIFSC CNMI), Eric Cruz (PIFSC Guam), Steve McKagan (PIRO CNMI), Erik Norris (PIFSC JIMAR), the CNMI DFW, Sam Markos, Ben Sablan, Fred Guzman, and Aesha Sablan (owner, captains, and crew of the Sea Hunter), and the Hyatt Regency.

Posted in Protected Species Division (PSD) | Tagged , , , , , , ,