A researcher’s perspective by Christine Ward-Paige
As a scuba diver and marine biologist, my research uses scuba divers observations from around the world as a non-destructive way of gathering information on shark and ray populations (www.eShark.org). Recently, we assessed the value of such observations for analyzing trends in shark abundance and distribution.
Using a computer simulation and field survey, we found that methods used by recreational divers are not inferior to scientific methods and that all divers, regardless of skill, can help detect and count sharks. We also interviewed dive instructors throughout Thailand to quantify their recollections. The 49 dive instructors conducted approximately 83,000 dives in total at 29 sites and reported 10 different shark species on 83 percent of the sites.
All of these species have vulnerable or near threatened status by the International Union for the Conservation of Nature (IUCN). The dive instructors reported little change in species distribution and maximum school size between the 1990’s and 2000’s. However, historical reports of higher abundance and diversity combined with current rarity and small school size of sharks suggest that recent changes may be negligible compared to longer-term declines.
Our study shows that properly designed surveys can use the observations of recreational divers as a cost-effective, effort-intensive and non-lethal source of data for monitoring trends in abundance, distribution and diversity of sharks, rays and other marine organisms worldwide. These data can provide essential information to prioritize conservation areas and evaluate the success of management measures, such as shark sanctuaries.
You can help this work by reporting your every dive to eShark.org, even if you didn’t see a shark or ray, which is equally important information. Take pictures and consult books and local experts to identify correctly the species you see. The better your information, the more helpful it can be in conserving sharks.
Thank you to Project AWARE, Kon-Tiki Krabi, Scuba-Fish (Koh Lanta), Koh Tao Easy Divers and all the divers that have so far participated in this initiative. For details see Ward-Paige CA & Lotze HK (2011) Assessing the value of recreational divers for censusing elasmobranchs.