June 2009

Aloha! Thank you all for your support helping House Bill 366, protection for Hawaiian manta rays, in it's recent journey through the legislative process. It is now in it's final stage on Governor Lingle's desk, and we are cautiously confident that she will sign it and the Bill will become law. You can be sure we will let you know when this happens, but today we would like to update you on some of our other activities and programs that keep us busy at Manta Pacific Research Foundation.

The mission of Manta Pacific Research Foundation has always been based on the 3 pillars of Research, Education, and Conservation of manta rays. We are a 501(c)(3) organization that operates completely on our Board members' and volunteers' efforts and we continue to strive to grow and expand our reach. Please consider making a donation to further our efforts.

Pelagic Manta Rays tagged of off Baja
And they're big!

Tim Clark, Science Advisor for Manta Pacific Research Foundation (MPRF) just returned from tagging manta rays in the Revillagigedos Islands as part of a long-term tracking project.

The islands, which lay approximately 600 kilometers South West of Baja, are known for their abundance of manta rays, sharks, and wintering humpback whales. However, fishing efforts have heavily impacted the manta rays. Fishing vessels have been observed catching manta rays near the island in nets and by harpoon, but it is not known if they are also caught in mid-pacific purse seines. The goal of the project is to determine if manta rays in the Revillagigedos are resident to particular islands, or if they have more extensive migration patterns. Understanding the movement patterns and habitat use of the manta rays in the area will help managers determine what fisheries are impacting the local population and how to best protect the mantas.

Tim, together with collaborators Dr. Bob Rubin, Karey Kumli, Guy Stevens, and Mauricio Hoyos, spent ten days at sea deploying an array of underwater receivers, tagging animals with acoustic tags, and taking photographs to identify individual manta rays. Twenty-five manta rays were identified during the trip, a combination of both pelagic "chevron" and "black" mantas. The manta rays off Baja are thought to be a different species than the coastal mantas commonly seen off of Hawaii, and little is known about their movement patterns. Tim and colleagues also placed acoustic transmitters on nine animals, and deployed underwater monitors on three of the islands. Anytime a tagged manta ray passes by one of the receivers, it will record the tags unique ID code and the time it was present. This will give us an idea of how frequently the manta rays use the islands, and the degree of movement between islands.
This research will provide unique insight into how the Revillagigedos manta rays spend their life, and will let us know if they are local residents or pelagic wanderers. While Mexican law can protect local residents, pelagic wanderers would have to be protected by international treaties. This information will be vital in our efforts to save these very unique manta rays.

How big are our flapping friends?
Laser measuring mantas

Visitors to the Big Island who enjoy the wonder of our manta rays often ask how big they are? That's a good question. Until now manta ray size estimates on the Big Island have been rather subjective. Since 2007, Manta Pacific Research Foundation has been using a camera mounted laser measurement system to accurately measure the sizes of manta rays in the Kona population. The image above shows MPRF Board member Eli Michael taking a measurement on one of the local mantas. In a survey of Kona dive professionals, Big Bertha (one of the most commonly seen rays), was thought to be anywhere from 14 to 18 feet wide. That is BIG! Unfortunately, like most fish stories, it was a bit of an exaggeration. Bertha measures in at approximately 11 feet from wing-tip to wing-tip according to our laser measurements. Still, that is Big! The manta rays we commonly see along the coast tend to be smaller than their open ocean cousins. These pelagic rays, which are now considered to be a distinct species, can reach sizes over 20 feet!

To accurately measure free-swimmmg manta rays, we are using a system of video and still cameras mounted to a set of parallel laser beams. When calibrated, the laser dots seen on images of manta rays can be used to accurately measure their size. Most females are in the 10-12 foot range, while male mantas are generally smaller, from 8-10 feet. One of the youngest measured is Blain, an immature male first sighted on Dec.1 2007 with an estimated size of 5-6 feet. Now, three years later, he is still immature but measures up at about 8 feet! We plan to continue our study to investigate individual growth rates and age of sexual maturity. With many new manta sightings yearly it will be interesting to see who are the smallest manta rays and how small are newborn mantas. Over time we can watch individuals grow, which will allow us to infer the age structure of our local population. Besides fulfilling our innate curiosity about the manta rays, this information will help us in our efforts to conserve our flapping friends.

You can help support this effort with your donations! Please support MPRF.

At 159 rays and counting
New individuals continue to be identified

As of May 21 2009, our ID database has 159 individual mantas listed. The last 2 recently added are Denny Ray and Victory. Denny is a new male manta first seen at Garden Eel Cove, but he appears to be a fully grown male, with an approximate 9' wing span. He is named for House Representative Denny Coffman from District 6, West Hawaii, who was one of the chief sponsors of House Bill 366, the manta ray protection act that makes it illegal to kill or capture manta rays in Hawaii. Victory is another "pelagic" ray seen by divers in South Kona. The pelagic rays are now known to be a different species of ray and are thought to have very different life history's from the smaller coastal mantas we see feeding close to shore at night. Where do they go? What are they doing?

MPRF continues to maintain the identification database of Kona rays on the website, but it is the contributions of all the dive professionals in Kona that make it possible. Without their "eyes" on the mantas, we would have far fewer individuals and far more "duplicates" than we do. Thanks go to everyone involved.

Kona ray seen at Molokini
Tek Ray returns? Or leaves again?

Recently divers in Maui were able to capture a photo of Tek Ray. Pauline Feine of Mike Severns Diving was in the water at Molokini and was able to get a shot of this manta as it swam overhead. It turns out this is Tek Ray, who was first sighted offshore from South Kona in June 2006.

This is the first confirmed sighting of a ray moving between the islands. It is generally accepted that the pelagic ray's are more migratory than the smaller coastal manta species, however we now have proof. The bigger picture though is still elusive. We sure would like to know where he's been and what he's been doing for the past 3 years. Perhaps he's on his way back to Kona? Perhaps he was just there and is leaving again? Only an expensive GPS satellite tag and another willing pelagic manta will let us know for sure!

At Manta Pacific Research Foundation, our mission is to study manta rays in their natural habitat, conduct scientific research, provide education programs for the public about manta rays and the marine environment, and to establish and promote worldwide manta ray conservation.
Sincerely,

Eli, Glennon, Jan, Keller, Tim, Vicky, Wendy
Manta Pacific Research Foundation