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Desventuradas Expedition: Fish Bigger Than We Are

National Geographic Explorer-in-Residence Enric Sala is setting off on his first big expedition of the year: to explore the remote islands of Desventuradas, hundreds of miles off the coast of Chile. Jen Casselle is a veteran member of Enric’s Pristine Seas project, and is a Research Biologist at the Marine Science Institute, University of California Santa Barbara focuses on conservation and ecology.

By Jenn Caselle

Today the science team did a survey dive at the farthest western tip of Isla San Ambrosio. We had been waiting for days for the weather to clear and the large ocean swell to die down enough for us to access this exposed and rugged rock sitting just removed from the main island.

Despite enduring rough conditions, we decided it wasn’t going to get much better any time soon so we prepared our equipment and our science gear with a mixture of excitement and trepidation.

Exposed points on oceanic islands like this are known for the abundance of large animals.  Water currents move strongly past these areas, bringing planktonic food for the small fishes that in turn become the food for the larger fishes.  We expected this to be the case here at San Ambrosio but as we entered the water and fought the currents ripping over to the reef, alternately being pulled down to the depths and then shot back up, we wondered whether this was a good idea after all!

Very large Juan Fernandez Jacks (known to our Chilean colleagues as Jurel) darted through the clouds of smaller brightly colored fish, hoping for a meal in the confusion while also hoping not to become the meal for the even bigger amberjacks cruising nearby.  At one point, fifteen yellowtail jacks swam past me. Even the smallest of the group dwarfed me in size and weight.

 

How the Ocean Could Be

Our science team has worked in a lot of places, in many oceans and between us we have observed untold numbers of reefs with myriad sea life.  Yet it’s only when we come to pristine places, like the Islas Desventuradas, that we are reminded of how it used to be before humans.  It’s only when I see fish bigger than me that I realize this is how it could be again.

Fishing pressure around the world has not only removed massive numbers of fish, but has had the effect of “shrinking” those that are left.  As the largest individuals are fished out, the ones left behind tend to grow faster, mature younger and die earlier.  Over long time periods, this means that these fishes will adapt to the missing giants among them and tend to stay smaller in size. For most of us, these little, young fish are who we see on our local reefs and this, unfortunately, has become the new normal. Our team has been lucky enough, by diving in places with no or very little fishing, to see just how large some of these fishes can get, when allowed to feed and grow naturally.

As I continued my survey in what we later affectionately labeled the “washing machine” of the western point of Isla San Ambrosia, I felt a resurgence of hope that once again our reefs and oceans will be filled with “fish bigger than me.”

 
This expedition is supported by Blancpain and Davidoff Cool Water.

Learn More

Follow All Desventuradas 2013 Blog Posts

Enric Sala’s Pristine Seas Expeditions

Desventuradas Blogs en Español

Comments

  1. michael hack
    United States
    February 21, 2013, 8:12 am

    Interesting blog, Jennifer. But I don’t understand how and why the fish “adapt to the missing giants and stay smaller”.