October 20, 2009
In Development: New Photographic Database of Seven Gill Sharks in San Diego Area
Active REEF and Reef Check diver Mike Bear, along with a group of other interested divers, have initiated a photo database showing the unique "freckles" of the bluntnose sevengill shark in order to provide data to any researcher wishing to monitor the activities of the animal. Sevengills have recently been seen by divers in increasing numbers in the San Diego area of the California coast. I encourage all divers, both recreational and scientific, to contribute. Watch this site in the next few days for more information on the sevengills.
Scientific monitoring of them is a grad school project waiting to happen! -Dida Kutz
contributed by Mike Bear, email
Given the fact that divers in the San Diego area are having increasing numbers of encounters with the Bluntnose Sevengill Shark, Notorynchus cepedianus, also known as the Broadnose Sevengill shark, some of us have decided to begin assembling an informal, photographic database of Sevengill sightings.
There are several reasons for this:
1. We are seeing repeated sightings of this species in the same areas, but without a system to identify individual animals, we have no way of knowing if the same shark is being seen over and over........or, there are multiple sharks in the area. This can best be resolved by comparing photographs which show the unique pattern of dark "freckles" on the backs of each shark, similar to the patterns seen on whale sharks.
2. To our knowledge [please correct us if we are wrong], the marine science community does not appear to be tracking what appears to be a resurgence in the population of this species. While we have done no scientific population studies, because we are not scientists, it would appear that this species is being sighted dramatically more often within the last 2 years than 5-10 years ago. We don't know if it's due to the cessation of the use of gill nets, migration of prey, or just randomness.
3. Some on this list have already generously contributed their photographs to this informal database and we would like to "grow" it, because the more evidence you collect in aggregate form, generally, the higher the accuracy of the data.
Already, by comparing the dark freckling patterns in the photos we already have, side by side, it is quite obvious, even to the non-scientists, that at least two different individual sharks are inhabiting or roaming the area known to San Diego divers as 'Broomtail Reef.' Now, we just need to confirm their sex. We think they are female, as claspers are not visible.
We think that the dark freckling pattern may be as unique as fingerprints on each animal and therefore invaluable in identfiying them.
4. Our purpose here as lay-divers is not to supplant whatever work scientists may [or may not] be doing in the field of Notorynchus cepedianus study. What we can do, however, is assist them by assembling an informal photographic database of local sightings, along with pertinent data, such as time of day, date, conditions, GPS location where possible, etc. and then make this data available to researchers.
IF YOU WOULD LIKE TO CONTRIBUTE PHOTOS TO THIS INFORMAL DATABASE, HERE IS WHAT YOU WILL GET:
1. A guaranteed watermark inside the body of the photo, in bold letters, identifying you as the photographer and a "All Rights Reserved 2009 /Do Not Copy'" copyright notice, to protect your work. The database is proprietary and not open to the general public.
2. An opportunity to contribute to a database, which, once it expands over the next couple of years, might greatly contribute to the general scientific knowledge of the migration, feeding and mating habits of this species.
Again, the reason for this is, the recent dramatic increase of sightings and encounters being reported by divers, just in the last 24 months. We can't prove it, but we think a resurgence of the numbers of this species is taking place and we'd like to document it.
Requirements for the Photos:
--that they were taken within the last 2 years in the Southern California area; Channel Islands or Catalina are fine.
--they can be either B&W or color, as long as they are good enough quality to show some identifying markings, either the black freckles on the back, or some other distinguishing feature. A photograph of a tail disappearing in the distance doesn't do us much good.
--basic data showing: Date/Time of Day/Location: ideally, with a GPS number, but that's not mandatory and any other data you feel is pertinent, such as what you were doing when the encounter occurred, ie; hunting, taking photographs, etc.
We hope that down the road, the photographic data collected will help marine science professionals, where possible, track individual animals in given areas.
We also hope that those with access to sophisticated pattern recognition software might be able to use it to analyze the 'freckle data' to identify individuals.
Thanks so much in advance!
Cheers,
Mike Bear and some local interested divers in San Diego
'Rapture of the Deep'
Posted by Dida at October 20, 2009 1:34 PM
