Sevengill sharks, Notarynchus cepedianus

Our Methodology: Introduction



Whale Shark Patterns Credit:




Although this is an all-volunteer, citizen science project, we want to keep the methodology as scientifically current and accurate as possible, while still keeping within the scope and means of a citizen science project. So, here is a summary of the databases and methods used in this long-term (5-10 year) populations dynamics study of the Sevengill Shark (Notorynchus cepedianus).


1. We are not set up for shark tagging, which is both expensive as well as labor intensive and usually requires boats, crew and an affiliation with a marine research institution and grant money to operate.

2. Database #1: The Shark Observation Network. Whether divers enter their data from here on this website, or go directly to, their ‘hard’ data, such as date/time/water temperature, taken from their dive computers, as well as photographs, go into the public database in SON, which is run by Jeffrey J. Gallant, Director, Shark Observation Network,  a partnership of the Greenland Shark and Elasmobranch Education and Research Group (GEERG) and  a marine bio application called BioApp [see here for more info:]

3. Database #2: Photographic Database: we have over 100 photographs, of varying quality, from poor to outstanding, taken over the past 4 years by local divers of Sevengills in the San Diego area. It is the best of these  photographs we plan to run through the pattern recognition algorithm to identify individual Sevengill sharks through the freckling pattern commonly seen on their front and dorsal sides, much as biologist Brad Norman did a few years ago to identify individual Whale sharks via the star-like patterns on their dorsal sides. 

4. Database #3: Video Database: the video database of over 50, mostly high definition, high quality videos, also taken be local divers, will be used also, to aid in determining gender and behavioral patterns observed, as well as bite marks and scratches, etc. They also will be subjected to the pattern recognition algorithm. 

5. Pattern Recognition Algorithm: we will soon be adopting  the Wildbook pattern recognition algorithms, IS3 and SPOT  [see here for more info:[], similar to the one used by Brad Norman to identify the star patterns on Whale Sharks [see here:] and here: [], to identify individual Sevengill sharks via the unique freckling pattern that can be seen on their front and dorsal sides. In this way, we will hope to, over time, identify through these patterns and gender as well, which sharks are returning from year to year and which ones are leaving and not returning.



This is a long-term (5-10 year) long population dynamics study which will endeavor to establish a baseline study of Sevengill sharks in the San Diego area, using the methodology described above.