Sunday, October 02, 2011

Galapagos Sharks - local anthropogenic Extinction!

Saint Paul's Rock - apparently, not remote enough! Pic by Andre Seale

I always wanted to go diving there.
Now, not so much.

Looks like we've wiped out the Sharks at Saint Paul's Rocks.
Situated smack in the middle of the Atlantic, this is as remote as it gets - but apparently, not remote enough for the fishermen to wipe out all requiem Sharks, principally the local Galapagos Sharks that appear completely gone, but also the previously abundant Silkies that however continue to turn up sporadically. Keep in mind that as recently as 1982, the resident Galapagos sharks have been described as "one of the densest shark populations of the Atlantic Ocean"(Edwards, A.J. and Lubbock, H.R. (February 23, 1982). "The Shark Population of Saint Paul's Rocks")!

From the Abstract.
Until the mid-20th century, visitors to St. Paul’s Rocks invariably commented on the remarkable number of sharks around the Archipelago.
These observations contrast with those of expeditions carried out during the last decade, which report no carcharhinid reef sharks while scuba diving in the archipelago, despite many more hours of underwater fieldwork than previous expeditions. All quantitative and qualitative methods conclude that the reef shark Carcharhinus galapagensis is locally extinct at St. Paul’s Rocks after a sharp decrease in abundance that took place following the commencement of fishing.

You can download the whole paper here.
Table 1 with the historical observations is both particularly interesting and particularly depressing. But there's also real interesting stuff about indications for a possible trophic cascade insofar as there are now many free swimming Moray Eels - incidentally very much like in Malpelo where in many weeks spent there, I've only seen very, very few coastal Sharks but zillions of Morays!
Highly recommended reading!


Anonymous said...

This is very sad, but,...

Aren't the Galapagos in the Pacific? How could they have been the densest shark population in the Atlantic?

Just a thought...

Anonymous said...

My mistake. Just re-read it all. Sorry.