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Wednesday, August 04, 2010

Random Shark Panel

In a study published in March 2007, focused on the mid-Atlantic section of the United States, 11 species of sharks saw dramatic declines in their numbers (from 1972 to 2005). Those species and their noted declines are as follows:

"Declines in seven species range from 87% for sandbar sharks (Carcharhinus plumbeus); 93% for blacktip sharks (C. limbatus); up to 97% for tiger sharks (Galeocerdo cuvier); 98% for scalloped hammerheads (Sphyrna lewini); and 99% or more for bull (C. leucas), dusky (C. obscurus), and smooth hammerhead.

The remaining four
elasmobranch-consuming great sharks were caught too rarely to detect trends from this survey. Two of those, great white (Carcharodon carcharias) and sand tiger (Carcharias taurus) sharks, were each caught only once and early in the UNC survey (in 1974 and 1978, respectively). The only survey that has caught enough sand tigers to note a trend targets sharks in Chesapeake Bay and suggests a decline of over 99% between 1974 and 2004."

The study goes on to note that the prey of the sharks studied, specifically 14 different species of ray, skates and smaller sharks experienced a population boom and in turn heartily attacked their prey - sea scallops. The cownose ray in particular is attributed with causing a depletion of scallops by fall of 1996. The scallop industry plummeted, and the scallops, with their quantities depleted were unable to perform their role in the circle of life. Scallops filter ocean water.

While people may fear sharks or not like sharks for the alleged damage sharks cause other species, it is worth noting that the sharks fill a very necessary role in the ecosystem. Take one piece out and it all begins to fall apart.

The stunning thing to me is that it was just one species of shark with a marked decline, it was eleven different species. The least significant decline over the course of the thirty year study was 87%. Think about that. Imagine 87% of your neighborhood being wiped out, or 87% of your food source, employer, or income. Devastating when it's put in those terms, isn't it? Sharks serve a purpose and mankind needs to realize that before it's too late and we're all snacking on cownose rays because that's all there is.

--Ransom A. Myers, Julia K. Baum, Travis D. Shepherd, Sean P. Powers, Charles H. Peterson;
Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal Ocean; Science, March 2007

(Shark Facts courtesy F.O.A.M.er Doug Zawisza and Science magazine.
Panel: Aquaman (Vol.7) #2 by Rick Veitch and Yvel Guichet)

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