Mercury bioaccumulation in elasmobranchs? Study

Conservation sources have been waging a war on shark products for the past five years saying that shark fins and meat for human consumption are loaded with mercury. Here's another first rate study that backs those assertions up.

 

 Nicholas Kutil and David L. Taylor.

ABSTRACT:

Mercury (Hg) is a toxic environmental contaminant that bioaccumulates in fish tissues,
including numerous marine species. Cartilaginous fish of the subclass Elasmobranchii are important ecological constituents of marine ecosystems, yet the fate of Hg contaminants in their body tissues is largely unknown.

In this study, four species of elasmobranchs: little skate (Raja erinacea), winter skate (R. ocellata), smooth dogfish (Mustelus canis), and spiny dogfish (Squalus acanthias), were collected from the Rhode Island/Block Island Sound, and the Hg content (ppm wet wt) of white muscle tissue was analyzed using automated combustion atomic absorption spectrometry. Diet and feeding habits for each species were also assessed by stomach content and stable nitrogen (δ15N) and carbon (δ13C)
isotope analyses. Mean Hg concentrations differed significantly among species, with highest
levels measured in smooth dogfish (mean Hg = 0.680 ± 0.107 ppm, n = 15), followed by
spiny dogfish (mean Hg = 0.312 ± 0.034 ppm, n = 44) and skates (mean Hg = 0.110 ± 0.008
ppm, n = 78 and 0.069 ± 0.005 ppm, n = 56 for little and winter skate, respectively). The Hg
concentration of skate muscle tissue did not vary by body weight, suggesting that Hg does
not bioaccumulate in these species.

Conversely, smooth and spiny dogfish bothbioaccumulate Hg with respect to body size, although smooth dogfish have a higher Hgcontent relative to spiny dogfish. The elevated Hg concentration of smooth dogfish may beexplained by their higher trophic level status, as determined from δ15N signatures (meanδ15N = 13.29 ± 0.88, 11.82 ± 0.60, 12.33 ± 0.65, and 12.12 ± 1.06 for smooth dogfish, spiny dogfish, little skate, and winter skate, respectively). The enriched δ13C values of skates and smooth dogfish indicated benthic foraging (range of mean δ13C = -16.39 ± 0.32 to -17.42 ±0.46), which was further confirmed by the dominance of decapods and crustaceans in the
stomach contents. Conversely, squid and butterfish were the principal prey of spiny
dogfish, and the contribution of these pelagic prey was reflected in the depleted δ13C
signature (mean δ13C = -21.97 ± 0.83). Future work includes researching the effect habitat
use and prey Hg to better understand bioaccumulation patterns in these species.


Presentation at the 2012 Winter Meeting of the Southern New England Chapter (SNEC).

January 26, 2012

University of Rhode Island
SOURCE and PDF-DOWNLOAD

Sharksafe.org Adds Multilingual Support

Certification Program Uses Chinese and French Versions
to Raise Awareness of Shark Conservation.


Oakland, Califonia - November 2009 -- The Center for
Oceanic Awareness, Research, and Education, known more
commonly by its acronym "COARE", announced today the
availability of multilingual resources for its Shark
Safe certification program.

The website, www.sharksafe.org, which allows both
consumers and businesses to learn more about the Shark
Safe certification program, is now available in several
languages, including Chinese and French.

Using an easily recognizable logo to distinguish
participating establishments, the Shark Safe program
offers certification to qualifying restaurants and
select businesses that demonstrate a measured commitment
to shark conservation. Now available in several
languages, the website is expected to reach and
influence an even greater audience.

"The need for shark conservation is a global issue, so
our efforts need to transcend international borders,
cultural differences, and language barriers," said
Christopher Chin, COARE's Executive Director.

"We're particularly proud of and excited about the
Chinese version of our website," said Chin. "The vast
majority of sharks that are killed are taken for their
fins, which end up in shark fin soup - a delicacy
entrenched in Chinese culture and tradition."

"With an estimated 1.3 billion native speakers, Chinese
is, by far, the most widely spoken language on the
planet, and we are thrilled to be able to extend our
message to such a key audience," said Pete Wang, one of
COARE's volunteer translators.

"We have observed that a number of well-intentioned
shark conservation efforts have failed to persuade their
intended audience, and sometimes even alienated those
they meant to engage, because they failed to account for
language and cultural differences," said Richard Nelson,
one of COARE's directors. "Our program takes both
language and culture into consideration, and works with
communities to decrease the demand for products that are
harmful to sharks and the ocean."


The mission of the Shark Safe certification program is
to protect oceanic ecosystems by encouraging practices
that do not negatively impact shark populations.
"Sharks are one of our oceans’ top predators, keeping
the entire ecosystem in check, but shark populations
have declined dramatically over the last few decades as
a result of human greed and lack of understanding,"
said Chin. "If people knew more about these animals,
they would want to protect them."

As a conservation based website, www.sharksafe.org also
offers information about the plight of sharks and about
the need for their conservation. As further development
of the website continues, it will serve as a portal for
consumers to locate certified Shark Safe establishments
quickly and easily.

COARE began development of its Shark Safe program in
early-2007, seeking to protect sharks by raising
awareness of threats to shark populations and by
reducing the demand for shark products. In July of
2007, Jim Toomey, the artist behind the popular
syndicated cartoon Sherman's Lagoon, joined the effort
and helped form the Shark Safe logo in use today.
"Sharks have resided in a dark corner of our mythology
for thousands of years, which is partly the reason why
saving this vital animal from extinction will require a
special effort," said Toomey.

About COARE

The Center for Oceanic Awareness, Research, and
Education, Inc. (COARE) is a tax-exempt nonprofit
organization based in the San Francisco Bay Area. Its
purpose is to study our oceans and increase public
awareness of the earth's marine environment through
educational programs and outreach. COARE seeks to
enlighten people, young and old, to the plight of the
oceans, to change the way they think and act, and to
encourage them to create positive and lasting change.
For more information about COARE, visit
http://www.coare.org.

COARE, Shark Safe, and the Shark Safe logo are
trademarks of The Center for Oceanic Awareness,
Research, and Education, Inc. All other company names
or marks mentioned herein are those of their respective
owners.

Media Contact
Jennifer Bowyer, media@coare.org, +1-510-495-7875

The Front Lines of Stupidity?