An Ocean of Life

By Rebecca Ingram

Living on an island, it is easy to see how intertwined our lives are with the ocean. We benefit daily from the ocean’s many resources, whether it be going fishing, diving, or simply walking along the shoreline. But if you live far away from the ocean, you may not realize that the ocean also influences your life in significant ways. The ocean affects weather patterns, the atmosphere, and contributes to global food supplies. Simply put, no matter how near or far, the ocean contributes to all life on Earth.

Scientists boarded the NOAA ship Oscar Elton Sette on April 17th to continue researching biological and oceanographic aspects of the West Hawai‘i marine environment. This research is fueled by the need to develop a better understanding of why this particular island region is so ecologically dynamic and productive. Specifically, we are researching fish larval habitats, species distribution in the water column, and productivity hot spots. (You can read more about our expedition here.) However, this important ship-based research does not tell the whole story.

Off the ship, scientists are investigating another important aspect of this ecosystem. There is a need to understand more about the connections between these biophysical ecosystems and the humans who live near them. People do not simply live in or near an ecosystem, but are an integral participant and rely on resources produced. So the question remains, in what ways does the West Hawai‘i community impact and rely on the marine ecosystem?

Answering this question leads to the primary strategy of Ecosystem Based Management (EBM), a holistic resource management approach that West Hawai‘i has been shifting towards in recent years. EBM recognizes that an ecosystem cannot be teased apart into neatly manageable pieces, but must be viewed through a unifying lens. EBM also specifically integrates humans, both our impacts and our reliance on resources, into management plans. (Read more about the shift toward EBM on the Big Island in a previous blog post.)

The West Hawai‘i Integrated Ecosystem Assessment helps pull both sides of the social-ecological story together and facilitate this fairly new style of resource management. It is a NOAA program focused on merging biophysical and ecological data with human dimensions. Essentially, this is a program that wants to provide managers with the means not only to conserve a species or place, but also conserve the resources valuable to the community. This includes activities like the opportunity to fish, dive, or appreciate the inherent value of being at a place. It also includes resources that stretch far beyond the island, since the health and productivity of West Hawai‘i coral reefs can be traced worldwide.

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Kealakekua Bay: Looking down at popular tourist location, Kealakekua Bay, Hawai‘i, with surface slicks visible offshore. Photo credit: Rebecca Ingram, NOAA.

 

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Kona Coast Sunrise: Looking at the Big Island from the ocean. Photo credit: Jamison Gove, NOAA.

 

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NOAA Scientist: Jon Whitney (PIFSC/UH), aboard a small boat operation launched from the Sette. Photo credit: Don Kobayashi, NOAA.

Lancetfish on the (Long) Line

You’ve probably heard of fish such as bigeye tuna and mahi mahi, but what about lancetfish?  Hawaii’s longline fishery catches lancetfish at about the same rate at tuna, but lancetfish aren’t very tasty so they don’t make it back to shore and on to your plate.  They’re pretty interesting fish, though.  Scientists at PIFSC are working with colleagues form the University of Hawaii at Manoa (UH Manoa), the Monterey Bay Aquarium Research Institute (MBARI), and Stanford University to answer several questions about lancetfish.

How many species of lancetfish are there in the North Pacific?

Until recently, we thought the only lancetfish in the North Pacific was the long-nose lancetfish (Alepisaurus ferox).  However, recent work has shown that lancetfish seem to come in two distinct sizes (shown below), which has us thinking there might be a second species present, too.  We’ll be examining 100 lancetfish collected for us by the PIRO Observer Program to see whether this is the case.  To determine the actual species of each fish, we look at a number of characteristics.  For example, we note the shape and size of their fins and measure where on the body the dorsal fin starts.  We also look at the pattern of spots, or melanophores, on the fishes’ skin and take tissue samples for DNA analysis.

What can lancetfish teach us about the ecosystem?

One pretty amazing thing about lancetfish is their stomach contents.  Unlike what you might find in a human or tuna stomach (unrecognizable mush), the contents of a lancetfish’s stomach is largely undigested.  This means we can open up their stomachs and see exactly what kind of fish and other marine organisms they’ve been eating.  By looking at enough stomachs, we can get an idea of what lancetfish, and other fish like tuna, are eating.  Knowing what fish eat helps scientists understand the ecosystem as a whole and project how it might change in the future.  We’re also studying the tissues in lancetfishes’ digestive tracts to learn more about how they digest their prey (see below).

Why do there only seem to be two sizes of lancetfish?

Most species of fish caught by the longline fishery span a range of sizes.  This is because fish grow larger as they get older.  Oddly, the lancetfish seem to fall into two distinct size groups.  Even if this is because there are two different species of lancetfish, it still leaves us with questions about how quickly they grow, how big they get, and how long they live.  We’ll be looking at their ear bones, or otoliths, to help answer these questions.  Otoliths have rings in them that scientists can use to age fish, similar to how you might count the rings in a tree to see how old it is.  Unlike trees, though, otoliths are tiny.  Lancetfish otoliths are about the size of a grain of sand.

This blog post is brought to you by Team Lancetfish: Phoebe Woodworth-Jefcoats (PIFSC – ESD), Anela Choy (MBARI), Jeff Drazen (UH Manoa), Joe O’Malley (PIFSC – FRMD), Elan Portner (Stanford), and Jenn Wong-Ala (NOAA Hollings Scholar).  Want to know more about lancetfish?  Send your questions to Phoebe.Woodworth-Jefcoats@noaa.gov.  We’ll answer them in future blog posts as our lancetfish work unfolds.

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Lancetfish seem to come in two sizes, bigger fish about 4 feet long (left) and smaller fish about 2 feet long (right).

 

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Clockwise from top left: One characteristic we use to identify specific species is the shape of the dorsal fin.  We also note which dorsal fin ray is the longest and how far back on the body the dorsal fin starts.  The size, coloration, and number of melanophores on the skin are another characteristic we examine.  Muscle tissue is used for DNA analysis.

 

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Jeff Drazen (UH Manoa) and Anela Choy (MBARI) work on removing a lancetfish’s digestive tract for further study.

How Does Energy Reach the Top of the Food Web?

A paper coauthored by PIFSC scientists looks at how energy makes its way to the top of the central North Pacific food web. The scientists used information on what marine organisms across the food web eat to build a food web model, diagrammed below. This model shows how energy produced by phytoplankton moves up through the food web, all the way to apex predators like tuna, billfish, and sharks. Results from this study deepen our understanding of how energy reaches commercially important species such as bigeye tuna and swordfish.

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Schematic model of the central North Pacific food web used in this study (from Choy et al. 2016)

Ecosystem models are one tool scientists use to study the food web. PIFSC scientists used an ecosystem model to improve their understanding of the middle of the food web, which is occupied by small organisms called micronekton. Micronekton are 2 – 10 cm in length, small enough to fit in the palm of your hand. They include marine animals like small fish, squid, crustaceans, and jellyfish. These animals are a critical part of the food web; they link energy produced at the base of the food web to apex predators at the top of the food web. Yet, compared to the top and bottom of the food web, little is known about these mid-trophic micronekton. They’re challenging to study for two main reasons. One, they live throughout the water column at depths ranging from the ocean’s surface to the ocean floor. Two, they’re pretty good at avoiding the nets scientists use to capture them.

This modeling study showed that some types of micronekton play a bigger role in the food web than others. Much of the energy that reaches apex predators flows through micronekton crustaceans and mollusks – organisms like the shrimp and squid shown here. Mid-trophic fish and jellyfish, on the other hand, transfer comparatively little energy to the top of the food web.

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Micronekton crustaceans with a 6-inch ruler for scale

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Micronekton mollusks with a 6-inch ruler for scale

Understanding how energy flows through the food web, and which organisms transfer the most energy, helps both scientists and fishery managers understand how apex predators may be impacted by future ecosystem change. This knowledge also highlights areas for future research. For example, there’s currently little known about how crustaceans and mollusks in the central North Pacific may be impacted by ocean acidification. Learning how important these organisms are in the food web underscores the need for investigating questions like this.

You can read more about micronekton and their role in the central North Pacific food web here: http://www.int-res.com/articles/meps_oa/m549p009.pdf

Where are all the Ranina ranina?

Where are all the Ranina ranina?

By guest blogger Lauren Van Heukelem

One main objective of the SE1503 cruise aboard NOAA ship Oscar Elton Sette was to survey the Commonwealth of the Northern Mariana Islands (CNMI) for Ranina ranina (Kona crab or spanner crab) that have been rumored to exist in the archipelago. This species is widely distributed across the Pacific and Indian Oceans in sandy-bottom habitats. It is an edible crab that generally supports sustainable, small-scale fisheries where it is found in abundance. Considering the depth and remoteness of some of the soft-bottom areas in the Marianas Archipelago, there is lack of information on this species yet strong local science partner interest in better understanding the potential distribution and abundance of this species in the area. Such a project was put forth at the “Marianas Trench Marine National Monument and Mariana Archipelago Ecosystem Science Implementation Plan Workshop” that was held in Saipan in May of 2013, and was subsequently chosen by the PIFSC to complete using a research team from the NOAA ship Oscar Elton Sette. The project was originally slated for 2014 but was postponed to 2015 due to scheduling delays. This served as one of the several primary objectives of project SE1503 over 11-27 June 2015.

All SE1503 Kona crab surveying efforts were undertaken by the crew of PIFSC small boat called SteelToe (SE6) and later after mechanical issues the Sette small boat called SE4. Both small boats were deployed off the Oscar Elton Sette nearly every day of the project with the exception of the days that we traveled between islands (Photo 1). Operations onboard SE6 began every morning at 7:30am with a small boat meeting and ended at 16:30 each evening, just in time for dinner. The crew consisted of our SE6 coxswain and SE1503 Small Boat Logistics Lead Jamie Barlow and deck crewmember Tony Flores. The remaining crew rotated between the scientists of SE1503 taking turns being data recorders and deck helpers throughout the cruise. The primary helpers were Lauren Van Heukelem, Erin Kawamoto, and Eric Cruz, but nearly all the SE1503 scientific staff and some Sette staff did a stint on SE6 or SE4 during the mission.

The surveys consisted of throwing eight sardine-baited ring nets attached to a 300ft ground line in sandy areas, considered to be optimal habitat for Ranina ranina, based on maps created for this cruise (Photo 2, 3, and 4). An example map is shown down below for Sarigan, where our spatially-balanced random point trapping survey locations are shown. These stations are located on prospective soft-bottom habitats and represented the starting points for our survey as we worked our way through the archipelago. We came outfitted with a large set of poster-sized charts for the science party to examine and mull over for the following day of operations, and we also shared a copy with the ship’s bridge. Much thanks to the PIFSC Mapping, GIS, and Graphics staff for generating these products for our project. These survey locations were located at a range of depths up to ~125m. The gear was left for a soak time between 30-60 minutes and then retrieved. Species were recorded upon coming up in each of the eight ring nets. Predation by sharks and other species was also recorded based on condition of bait and nets (Photo 5). We were also able to deploy a camera attached to one of our baited ring nets and view predation events occurring during the net soak time. This particular trap had five sharks fighting over the bait (photo 6). We also took some bottom grab samples to help validate the habitat mapping.

Unfortunately we were unable to confirm that Ranina ranina was present in the CNMI. Seven islands were surveyed (Uracus, Maug, Agrihan, Pagan, Alamagan, Guguan, and Sarigan) using a total of 101 ground lines with 808 nets deployed in various depths and no Ranina ranina were recorded. Although we were unable to locate Ranina ranina during our surveys, this does serve as a useful set of data points towards a better delineation of the distribution and abundance of this species across its range. During the course of the survey we were also able to assist in collecting samples for our fellow scientist Allison Miller when invertebrates came up in our ring nets. This allowed her to sample not only the nearshore ecosystems but also in deeper areas for her genetics study.

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Photo 1: SE 6 arriving back at the Oscar Sette after a day of surveying.

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Photo 2: Sardine baited ring nets used for Ranina ranina capture.

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Photo 3: Tony Flores and Lauren Van Heukelem preparing to deploy a set of eight ring nets attached to a 300ft ground line.

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Photo 4: Jamie Barlow getting us in position while the crew prepares the nets.

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Photo 5: Jamie Barlow bring up a ring net that had had the bait removed by a predator.

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Photo 6: Video screenshot of shark removing bait from a ring net.

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Map 1: Example map of Sarigan and our spatially-balanced random point trapping survey design targeting prospective soft-bottom habitats in the depth range 0-125m.

SE1503 – Sharks on the Ship and Videos from the Deep

By Guest Bloggers Cassie Pardee and Diona Drake

Here we present another update from project SE1503 aboard NOAA ship Oscar Elton Sette performing fisheries oceanographic research in the Mariana Islands (11-27 June 2015).

We have been trapping from the Sette with lobster pots, minnow traps, and a BIG trap around most of the archipelago, to supplement the trapping survey being done by the small boat team. Each morning we are never sure what we are going to pull out of the water. We are targeting relatively deep 50-125m soft-bottom areas using the best available mapping information, ship sounders, as well as a small Ponar bottom grab to assist in placing our gear in those areas with unconsolidated substrate (http://youtu.be/gfJqcSpTOSQ). Surprisingly, we are bringing up a more than a few sharks. We are surprised because the small openings in our traps would have seemed to be an effective deterrent to shark bycatch. The most common species being captured include white tip reef sharks (Triaenodon obesus), gray reef sharks (Carcharhinus amblyrynchos), and nurse sharks (Ginglymostoma cirratum). The gray reef and nurse sharks have all been brought up in the giant fish trap (Figure 1). Some of the sharks are so wide, we can hardly believe that they could fit through the trap opening. The white tip reef sharks really love the little, black lobster pots which have even smaller openings and less space. We have even brought up two sharks in one pot a few times (Figure 2), and once three white tips were jammed into a single lobster pot. All of the sharks are released alive once they have been quickly measured, photographed, and two non-invasive fin clips are taken from their dorsal fins for genetic analysis (Figure 3).

During our daytime BIG trap deployment we have been attaching GoPro and FlyWire cameras to the outside and the inside of the trap to see bottom type and what is really going on after we lose sight of the trap. The video footage has been very revealing. Sometimes we will bring up an empty trap and then watch video footage to see fish swim in and then back out of the trap, or watch as sharks and sting rays try repeatedly to enter the trap but are too big to fit through the opening. We have captured video images of garden eels (http://youtu.be/BuJmBKAVRO4), tiger sharks (https://youtu.be/HnirPxNu-Fk), huge sting rays (https://youtu.be/0Vh-oCiaqlU), giant hermit crabs (http://youtu.be/IxxN3InCGgQ), schools of juvenile fishes (https://youtu.be/3s_zIJvuWh0), and various other fish species (some cunning enough to swim in and out of the trap). The video footage exposes a whole new aspect to how the trapping process works and gives us the opportunity to see other species in the area that were too smart (or too big or too small) to get caught in our traps. We also tried collecting some video during the night (http://youtu.be/YZpHLdxJ2zo). While our trapping work is part of a broader ecosystem survey, the findings will feed into a better understanding of how fishing gear operates. The mechanics of the capture process are often overlooked, yet are a key component of fishing gear efficiency and fishery stock assessments that rely on data from fishing gear.

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Figure 1. Nurse shark and gray reef shark brought up in the BIG trap.

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Figure 2. Two white tip reef sharks being released from a lobster pot.

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Figure 3. A white tip reef shark being released after measurement and fin-clips.

Project SE1503 Aboard NOAA Research Ship Oscar Elton Sette: Midwater Trawling & Soft-Bottom Trapping!

Big traps, Lobster traps, Minnow traps…Oh My!

June 15, 2015

Written by PIFSC guest blogger Cassie Pardee

Photos courtesy of Diona Drake and Don Kobayashi

One of the many projects on SE15-03 is the deployment of different traps to varying deep water depths (~100-300m) to sample species living in the deeper soft-bottom habitats. Each evening we deploy a group of 6 lobster pots (photo 1) and two minnow traps and then deploy the BIG trap (photo 2). I say BIG because I have been inside this trap three times now and I find it to be quite roomy (photo 3). The traps sit on the bottom overnight and in the morning we bring up the haul to see what we caught.

As the winch and crane bring up the traps from the abyss we wait with baited (!) breath to find out what’s inside. On our first deployment in Uracas the big trap came up with three comet groupers and an amber jack weighing in at 27 pounds (photos 4 and 5), but our lobster traps returned basically empty. However, during our second overnight deployment in Maug the roles were reversed. The big trap came back with nothing and our hopes were dashed, but we retrieved full lobster traps with conger and moray eels (photo 6), some shrimp, a hermit crab, and another crab species. The fun part about the trapping process is we aren’t really sure what we are going to catch each night, so it is always a surprise to see what comes up from the deep.

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Photo 1: Open lobster traps waiting to be baited

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Photo 2: Baited big trap waiting to be deployed into the water

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Photo 3: Cassie in the trap after setting up the video camera

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Photos 4 and 5: Catch from the big trap from the first overnight deployment with Uracas in the background.

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Photo 6: Moray eel from the lobster traps after the second overnight deployment

Midwater Trawling Operations!

June 15, 2015

Written by PIFSC guest blogger Allison Miller

After a slightly delayed start, we are up and running here on the Oscar Elton Sette for research project SE1503. Two days ago we visited the island called Uracas (or Farallon de Pajaros) where we deployed the SteelToe (also called SE6, a small boat which sets our the “ring-net” traps), our “BIG” trap, and our crab “pots” during the day. We call our trap “BIG” because it is very BIG (Figure 1). So big, that scientists and volunteers can sit in it (Figure 2), but don’t worry we didn’t throw it overboard until they got out.

We deployed our first midwater Cobb trawl the night we were at Uracas. At approximately 9:00pm we deployed the net. The net mouth spans 50 feet in diameter and tapers down in size to about two feet in diameter (Figure 3) where it meets our trawl “cod-end” bag. This bag is what collects most of the organisms. Before we deployed the net, we zipped the bag to the small (two foot) end of the net (Figure 4) and tied three TDRs (temperature-depth recorders) to two different points on the net (the headrope and the footrope). Then our amazing deck crew team deployed it off the stern of the ship.

This trawl followed a four-step trawl plan; the net was deployed at its deepest depth for approximately 20 min then it was moved up to a second depth for 20 min, then to a third for 20 min, and finally to a fourth depth for 20 min. At each depth it was given 15 minutes to equilibrate (called “EQ” on the radio) before the 20 minute time period began. We will follow this four-step Cobb trawl plan for the duration of the cruise, with some minor tweaks to the depths depending on patterns in the scattering layers and our desire to capture both deep-water species as well as the larval forms of insular species which are generally shallower.

At 1:00am, a few of us sleepy scientist and volunteers accumulated on the back deck of the ship and we waited as the trawl line was dragged in. At approximately 1:30am our sleepiness had been replaced with excitement as the main net came aboard the stern deck. As it came in, we carefully checked and picked organisms off the net and placed them in a small tub. By the time our trawl bag (or “goodie bag” as some called it) came aboard, our small tub was already a quarter of the way filled with pelagic fish, cnidarians, crustaceans, and a cookie-cutter shark (Figure 5)! We unzipped the trawl bag from the net and then weighed everything we collected (called the “wet weight”). After that, we began processing our catch. By 5:00am we had successfully counted, weighed, and measured everything we collected in our trawl bag (Figure 6). We were all pretty tired, but we felt proud and pleased with our first midwater Cobb trawl.

-Allison

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Figure 1: Our “BIG” trap.

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Figure 2: The “BIG” trap is so big that four small scientists and volunteers can sit in it.

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Figure 3: The trawl “cod-end” bag attached (zippered) to the rear part of the main net, which is essentially a coarse mesh plankton ring net.

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Figure 4: The main net tapers down to the trawl “cod-end” bag.

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Figure 5: Pelagic fish, cnidarians, crustaceans, and a cookie-cutter sharks collected by the midwater Cobb trawl.

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Figure 6: Example of our post-processed midwater Cobb Trawl specimens.