Rowley Shoals Australian TravellerSharks as Apex predators play an important role in the health of our oceans. A recent study conducted by the University of Western Australia, highlights yet another important impact sharks have on their ecosystems.

So, we are all aware of the role sharks play in protecting seagrass beds, corals and shellfish populations by controlling or influencing the behaviour of turtles, parrotfish and stingrays. And how their diet controls the populations of second tier predators such as seals, thereby protecting populations of prey species. But is it possible that the presence (or absence) of sharks, impacts on the physical characteristics of prey species?

Researchers conducted field work on two Australian coral reefs: Rowley Shoals and Scott Reefs. Rowley Shoals is fairly untouched, but sadly, commercial shark fishing has been allowed on Scott Reefs for over 100 years. Shark populations have obviously taken a major hit, especially in the last couple of years as the demand for shark products have risen exponentially.

From examining 611 fish from 7 different species, researchers discovered that the fish at Scott Reefs, who live without the fear of sharks, have adapted their bodies accordingly. The eyes and tails of the fish examined at Scott Reefs have decreased in size. The eyes are 46% smaller and the tails are 40% smaller than those found on their cousins on healthy Rowley Shoal.

According to researchers Neil Hammerschlag and Shanta Barley; the decrease in eye and tail size is due to the absence of sharks – the fish don’t need to keep such a beady eye out for those hungry sharks, nor beat a hasty retreat if they’ve been spotted. Larger eyes will assist a fish to detect sharks, especially in low-light conditions. Similarly, a bigger tail will help it swim away faster.

Now this may not seem like an awful big deal to most of you reading this, but, it sure does prove that sharks are pivotal role players in our oceans, and on numerous levels. This important discovery now strengthens the fact that sharks need more protection and that without them in our oceans, we can expect apocalyptic conditions.