Sighting the rare Guitarfish

by Marie Ferguson

A Shovelnose Guitarfish (photograph courtesy of www.Elasmodiver.com)

A few days ago, while conducting a fish REA (Rapid Ecological Assessment) survey my dive buddy, Rusty Brainard, and I enjoyed a rare sighting of a Rhynchobatus djiddensis, Whitespotted Guitarfish, along the northwest side of Tutuila. The guitarfish was spotted while conducting a deep SPC (Stationary Point Count) survey, at approximately 70 feet. We had just completed our final SPC and were on our way to the surface for our safety stop when the 4 foot long guitarfish swam by us with a remora (‘shark sucker’) attached to its underside. Up until this point, a Whitespotted Guitarfish has never been observed or recorded by our research team in American Samoa or other locations during the many thousands of surveys we have conducted across the Pacific Islands over the past decade.

Rhynchobatus djiddensis belongs to the Rhinobatidae or Guitarfish family. It is unique in that it resembles a cross between a shark and a ray with the anterior or front half of its body looking like a ray while the posterior or rear half looking like a shark. Like other rays, guitarfish have small mouths with teeth that are flat and pavement-like and generally prey on crabs, cephalopods and small fishes. Most guitarfish species have been known to occur on continental shelves or insular shelves of large islands in roughly 2 to 50 meters of water depth. Due to the variation over its range, this type of guitarfish has been divided into approximately 5 to 6 species. Little is known about the biology of this species, however data collected has suggested that it does have a low fecundity and very slow growth rate.

According to the ICUN Red List of Threatened Species, the large size and nearshore areas that this species inhabits make it highly susceptible to gillnet and shallow-water trawl fishing. In several parts of the world, such as Tanzania, Rhynchobatus djiddensis is being exploited mainly for its fins and is being commercially fished in bottom-set gillnets. Data recorded has also shown that this species is caught as bycatch in prawn trawls. Other documented areas where this species of guitarfish is either fished intentionally or as bycatch include shores off of Kenya, Mozambique, East Africa and the Middle East in the Western Indian Ocean, many areas in which policing and regulatory enforcement is often limited. The ICUN Red List of Threatened Species has evaluated this species as ‘vulnerable’ due to the “commercially high value and growing demand for its fins, restricted nearshore habitat as well as its limiting life history characteristics”.

If you are out diving or snorkeling and see this elegant and fascinating creature, then make sure to grab a photo and relish in the moment of a rare sighting!

For more pictures of Guitarfish, check out Elasmodiver.com who kindly granted us use of the above photograph.