Sharks and Rays


Sharks, rays, skates, and sawfish (Elasmobranchs), are an extremely diverse group fish. Therefore, it is impossible to make blanket statements about their value. However, studies have shown that sharks keep other populations in check, remove weak or sick individuals, shift prey habitat, and balance ecosystems. 

Sharks are also important for humans for food, tourism, and intrinsic value.

eOceans' research has engaged professional researchers and citizen scientists to document shark and ray populations – describing contemporary and historic baselines, identifying population risks, and understanding conservation needs.

Findings have included:

Note: The paper investigating inverted biomass pyramids, above, is often mis-cited. This is about scientific divers, and the fact that they count fish that enter their transect AFTER the survey starts, therefore inflating the density of mobile fish compared to that of stationary fish. Faster fish are more likely to enter the transect than stationary or slow fish, and therefore more bias of faster fish (top of the ecosystem). 

We also contributed a chapter on the role of citizen science when conducting shark diving expeditions:

Our works has resulted in significant policy outcomes, including: