Conservation on the Line: Exploring the Eastern Tropical Pacific

Latest update March 18, 2019 Started on January 1, 2019
sea

We're investigating the ecology, movement patterns, and diversity of the Eastern Tropical Pacific's most charismatic game fishes. Join us as we tag, video, and uncover the lives of Panama's legendary billfish, sharks, and other game fish.

January 1, 2019
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Preparation

...and here's the final product! The mold worked like a charm and with a little Vaseline the package popped right out! With a little sanding and Dremel work it will be ready for some instrumentation and deployment!

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Accelerometer update!


Ryan has made a mold of the accelerometer package from our earlier post, and he poured the resin for the first new package today! The body of the package has three main parts: two equal parts of liquid resins that will interact and harden when mixed, and buoyant micro-beads. The beads are the white powder shown in the photos below, and they allow the hardened package to float. A bright orange dye is added so that the package is visible in the waves once it detaches from the fish. The resin takes several hours to fully set in the mold, but the outer shell hardens within a few minutes. The mold pink and can be seen un-filled in the photos below. We’ll keep you updated on the final product when we check later today! Check out the photos below to see the full process!

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Gear Update!
Ryan and I are hard at work building some prototypes of our different research instruments for our next trip to Panama.

Ryan is working on an acceleration data logger (ADL) package that will be anchored onto the side of the marlin and sailfish. The package includes a 9-axis accelerometer with a speed sensor, a miniaturized video camera and a GPS transmitter. You can think of the accelerometer as a ‘fitbit’ or smartwatch for fish, because just like those products do for humans, it will track the activity levels of the fish, in addition to their fine scale swimming and diving behavior which will give us a more complete understanding of their daily activity patterns.

The video camera will give us a fish’s-eye view of the marlin’s swimming and feeding behavior, and even how they interact with other marlin and/or other species like sharks. Because of the large amounts of data and video being generated, we must get the tag back to download it all. Therefore, the tags are designed to detach from the fish after a few days (using special corrodible links that disintegrate after a pre-determined amount of time), and the whole thing comes off and floats to the surface where we can find it. Once the transmitter is above the water line, it transmits the location to the satellites, which then allows us to pinpoint the location and go recover the package.

Every piece of tech has a testing phase, and fish ecology is no different! Ryan built his design using a mix of resins, buoyant micro-beads, and clay, and shaped it down to how he wants it with a Dremel and sandpaper (lots of sandpaper). He designed the shape so that the package would float upright, with the transmitter antennae completely out of the water. From the photo below, I’d say it works like a charm! This prototype will serve as the basis for a new rubber mold so we can create several of these packages very quickly.

I’m currently working on our underwater video station prototypes, and there’s quite a bit of trial and error. The challenge with our BRUVS (Baited Remote Underwater Video Stations) is creating a frame that is sturdy enough to withstand waves and the occasional shark encounter, but light enough to travel with and deploy by hand. Our deck space on the boat is limited, so I’m also trying to make them collapsible.

Right now, we’re testing aluminum pipes to create a solid, but lightweight frame that won’t rust. Our camera will be a GoPro Hero 5, due to its video quality and price-point. The bait canister will be perforated PVC pipe that will stick out of the bait arm in front of the camera. The baitarm will also have a counter balance for the bait canister, and the bottom of the frame will be weighted for stability. We’re also hoping to deploy some of our BRUVS at night! Deepwater animals are known to make nightly migrations to the surface, and we’re hoping to be the first to capture this with BRUVS. To do this, we’re attaching a dive light with a red filter below the camera. It’s believed fish have trouble seeing red light, so we hope the filter will allow us to view them without altering their behavior.

Stay tuned and follow us for more updates on the project, and sneak peaks at our underwater video!

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Alright, time to talk about some of our study species! For this study we’re interested in learning more about the ecology of sharks and billfish – blue and black marlin and sailfish in particular. Today we’ll look at blue marlin and give you an idea of the biology of this fish, the questions we’re asking, and why this fish is important.


Blue marlin are large, highly migratory pelagic fish, meaning that they roam vast stretches of deep, blue water in the tropical and subtropical regions (generally preferring temperatures above 24° C or 75° F), and can be found in the Atlantic, Pacific, and Indian Oceans. Because they can grow to over 2,000 pounds and reach 12 feet in length, they are one of the most, if not the most, sought after sport fish by recreational anglers around the world. Males typically don’t get as big as females, usually only reaching seven to eight feet in length, while females can reach 12 feet and thousands of pounds. In the Pacific, maximum age is estimated to be 27 years for females and 18 years for males. Their growth is fast and variable, reaching up to six feet in as little as two years. Male blue marlin reach maturity (reproductive age) at about two years, with females ready to spawn at three to four years old. They are fast, agile fish that mainly feed on squid, tuna and other tuna-like fishes. In fact, large blue marlin have been found with 100-150 lb yellowfin tuna in their stomach!

Marlin and other large billfish can be difficult to manage as a fishery, as they regularly travel across international boundaries and the high seas. Most of the harvest of blue marlin occurs as bycatch, or accidental catch by fisherman as they target other species. Today’s oceans see unprecedented levels of fishing pressure, and while managers are optimistic about the blue marlin’s population levels, overall population trends still seem to be decreasing. Tracking the movements of these fish over long timescales will be vital to understand how we can better manage them as they traverse international waters, and how often they may be exposed to fishing activity. While research in other areas of the Pacific is shedding light on the migrations and movements of the species, our knowledge of what drives their movements in the Eastern Tropical Pacific is still lacking.

Blue marlin are caught at Tropic Star Lodge all year round, but the captains consider the season to run from June through March. The bite seems to pick up in August and September, with larger marlin being caught at this time as well. The Eastern Tropical Pacific is a unique ecosystem with variable currents and ever-changing physical and chemical water conditions. Tracking the marlin during these shifts will give us an idea of how they respond to a changing ocean, and what drives their distribution and presence in the waters surrounding Tropic Star Lodge.

We’ll continue to tag more blue marlin each year of this study, and hopefully paint an increasingly accurate picture of the journey these animals make in the Eastern Tropical Pacific Seascape.

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Debriefing

Just getting back from my first trip of 2019 to Tropic Star Lodge, Piñas Bay, Panama and it did not disappoint! The goal of this trip was to complete our satellite tagging work of the 2018-2019 billfish season by tagging two more black marlin, and I can happily say it was a success. The black marlin were there in force, with 35 being released by the Tropic Star fishing fleet in 6 days (changes daily, but roughly 10 boats fishing/day). Given those numbers, I was able to deploy the two satellite tags in my first two days there, so we now have a total of 30 billfish (10 blue marlin, 10 black marlin and 10 sailfish) swimming around the Eastern Tropical Pacific carrying a tag on their back. These tags (pictured in previous posts) record depth, temperature and light levels (sunrise, sunset & time of midday so we can reconstruct where the fish went once the tag comes off) for the entire time the tag is on the fish, which will hopefully be a full year from now. With this information, we hope to determine if these fish are year-round residents, performing an annual migration, or if the waters off Panama are just a pit-stop on a much larger trek. In addition, we can learn about their habitat preferences or environmental drivers of movements with the depth and temperature information, as well as how much of their time they spend in areas with high amounts of commercial fishing activity.
In addition to my tagging work, I was also taking muscle biopsy samples and fin clips from as many marlin and sailfish as I could (you can see the muscle biopsy pole in some of the photos). The muscle samples will be used for what is called stable isotope analysis (or SIA), which can give us an idea of where these predators are feeding in the food chain compared to one another, and if they are getting most of their energy from food that lives close to shore or very far offshore. We hope to determine if these three top-level predators are all foraging on the same things, or if they are ‘partitioning’ the food they are going after, which would be predicted to reduce the amount of competition. Fin clips will also be used for SIA, in addition to population-level genetic analysis. If you look closely at the short video clip, you can see a pod of spotted dolphins, or buffeo (boo-fay-oh; as they call them in Panama), jumping in the background while we are fighting the blue marlin, right next to shore! The amount of life in this region is amazing. Cheers, Ryan

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Preparation

Time for some more background on our project! We have a variety of research projects underway as part of the Eastern Tropical Pacific Seascape Program, but this journal will focus mainly on our tagging and underwater video projects.


Right now, Ryan Logan, the PhD student on the tagging project, is on his way to Tropic Star Lodge to finish tagging some marlin for this year’s field season. We use miniPATs, or Mini Pop Off Archival Tags, to study how large, highly migratory game fish like marlin and sharks move across the open ocean. Created by Wildlife Computers, Inc., the tags can calculate an animal’s position on Earth using the angle and level of sunlight, and an internal clock. The information is then stored and transmitted to satellites once the tag pops off and reaches the surface. We can use this information to reconstruct the large-scale movements of the animal across the ocean. The tags can be set to pop off or transmit after a certain time period, and they can also record temperature and depth, which can tell us what temperatures the animal prefers, and how often and deep it dives. I’ve attached a few photos of our tag prep below, so you can see what they look like and their relative size. We also apply an anti-biofouling agent to each tag, otherwise small animals and plants may grow on it while it’s attached to the animal, increasing drag. You can see the tags drying in the photo below. Once we’re in the field, we’ll post some photos of how we apply the tags to the animal, so watch this space! Also, check out this site to see how we’re tracking animals all around the world: http://www.ghritracking.org/

For our video project, we’ll be using some pretty basic tech: GoPro cameras. Known as Baited Remote Underwater Video Stations, or BRUVS, they can be used to study animals without capturing them, and they’re a unique way to study animal behavior. They’re design is pretty simple; we attach a GoPro camera to a metal frame suspended under a buoy. The frame has a bait arm attached, and attracts wildlife into the camera’s field of view as it floats in the waves. By deploying these BRUVS at different depths and over different types of habitat (rocks, reefs, deep water, etc.) we can start to understand how fish communities change from the coast to the open ocean. For our game fish this means understanding what prey fish are available, and how the different sport fish species are feeding on them. We’re interested in discovering how these species overlap, by both the habitat they use and the fish they eat. As we deploy and recover more BRUVS, we’ll post our interesting finds, deployment issues, and design changes as they happen in the field!

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Expedition Background

We're a group of marine scientists and graduate students from the the Guy Harvey Research Institute at Nova Southeastern University. Together with Tropic Star Lodge and the Guy Harvey Ocean Foundation, we'll tag, video, and study some of the most charismatic fish on the Pacific coast of Panama. Join us as we work to understand the lives of the open ocean's top predators. Find out more here: (http://etps.ghriresearch.org/)


Known the world over for its bountiful fishing and spectacular ecosystems, the Eastern Tropical Pacific Seascape includes the waters and islands stretching from Costa Rica to Ecuador, including the Galapagos Islands. Containing four UNESCO World Heritage Sites, the Galapagos and Cocos Islands, and Malpelo and Coiba Islands, the seascape is an ecologically unique and economically important region for the countries that border it. Consisting of waters managed by four different nations, the region suffers from a lack of sustainable management, rampant illegal, unregulated and unreported (IUU) fishing, a lack of scientific information, and the unknown consequences of climate change.

It's also a world-class sport fishing destination. Nestled between the foot of the untouched Darien jungle and the deep blue sea is Tropic Star Lodge. For decades, Tropic Star Lodge has been a giant in the recreational marlin fishing industry, and more IGFA World Records have been set there than anywhere else in the world. As one of the first fishing lodges to move to a circle-hook only and strict catch and release policies, the lodge is quickly becoming a leader in sport fish conservation. Recently, with the help of the Panamanian government, the lodge established a 20-mile marine protected area around itself in order to protect the fertile fishing grounds from commercial, industrialized fishing. Now, they're partnering with us to better understand the fish they catch and the ecosystem that supports them.

With this journal, we hope to bring you behind the scenes of cutting edge marine research, both in the field and in the lab. Following along you'll see the glamorous side of research (tagging massive fish on the open ocean) and the not so glamorous side (typing, so much typing). From tag preparation to crunching data to incredible fish caught at the foot of a mountain jungle, we hope to bring awareness to this amazing ecosystem.

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