This debate has shown that many conch-l subscribers are passionate about the
subject, but has also frayed tempers. To avoid more fraying, I'm not going
to try to respond to particular arguments. And since I don't have time to
write something new, I'll recycle what I said in the panel discussion on
"Conservation and the future of shell collecting, at the 1995 COA convention
in San Diego, as reported in American Conchologist 23(3):20-21 (1995).
"As environmental awareness increases throughout the world, shell collecting
is often viewed as politically incorrect. But is shell collecting
environmentally incorrect? I will argue that is not, for two reasons: 1) the
impact of shell collecting on molluscan species is far less than the impact
of habitat destruction or commercial fisheries. 2) Shell collectors, because
of their collecting activities, are in position to notice and document
declines in molluscan populations.
"The Conservation Biology of Molluscs (1995, Occasional Paper of the IUCN
Species Survival Commission No. 9, edited by E. Alison Kay) lists 29 regions
that by the mid-1980s had some form of legislation controlling collecting of
marine mollusk: Australia, Bahamas, Belize, Cayman Islands, Cuba, Djibouti,
Egypt, Fiji, Guam, Hawaii, India, Israel, Kenya, Madagascar, Mauritius,
Netherlands Antilles, New Caledonia, Oman, Palau, Reunion, Seychelles, South
Africa, St. Lucia, Sudan, Turks & Caicos, United States, Vanuatu, and
Venezuela. Some restricted collecting of all mollusks, some restricted
commercial exploitation of only a single species. Since the mid-1980's,
several additional countries have restricted shell collecting.
"In order to understand the impact of shell-collectors, we need to know how
many shells they collect. I estimate that there are about 10,000 serious
shell collectors worldwide, meaning people who acquire shells by
self-collecting, trade or purchase, learn the scientific names of shells and
maintain locality data with their specimens. (There are almost 200 shell
clubs worldwide, according to Tom Rice's list, and if each has about 50
members, then 10,000 shell collectors is a reasonable estimate.) The largest
private shell collection range from 100,000 to 1,000,000 specimens; typical
collections range from 1000 to 10,000 specimens. If we take the average
collection as 10,000 specimens, times 10,000 collectors, we find that there
are about 100,000,000 specimens in private collections worldwide. This is
about the order of magnitude in US museums. If we assume that the average
collector is active 20 years, then 5,000,000 specimens are acquired per
year, by the 10,000 collectors. Not all of these are live collected, some
are recycled from old collections, and some are by-products of commercial
fisheries (e.g., lobster nets in Japan, Colombian shrimp boats, scallop
boats in the eastern United States), and so would have been killed anyway.
On the other hand, a large number of specimens that are collected for sale
as specimen shells are discarded as unsalable because of flaws, so we'll
stick with the 5,000,000 specimens per year as a rough estimate of the
worldwide demand for specimen shells.
"How does this compare to the harvest of commercial fisheries? The FAO
Yearbook (volume 71, Food and Agriculture Organization of the United
Nations) tallies 7,655,000 metric tons of marine mollusks harvest in 1990.
Less 2,355,000 metric tons of cephalopods, this comes to 5,300,000 metric
tons, or more than 5 billion kilograms (11 billion pounds) of shelled
mollusks. If an average mollusks weighs 0.1 kg, then more than 50 billion
mollusks are harvested by fisheries each year; 10,000 times more than shell
collectors take. In terms of biomass, the ratio is greater still, since
commercially fished shells are larger on average than specimen shells. Even
if these numbers are off by a factor of ten, the fact remains that
commerical fisheries are far greater in impact than specimen shell collecting.
"The worldwide demand for shellcraft items is harder to estimate. Several
shell dealers have told me that bulk shells for shellcraft, jewelry and
decor are much a higher volume, and more lucrative, business for them than
specimen shells. The Conservation Biology of Mollusks notes that the
exports of capiz shell (the windowpane oyster, Placuna placenta) from the
Philippines alone in 1986 reached 4.5 million individuals. The effects of
habitat destruction are even harder to estimate. However, many mollusks live
at population densities of thousands per square meter (e.g. Batillaria
minima). A shopping mall the size of a football field built on a former
estuary can easily kill millions of mollusks. Even natural forces, such as a
single winter storm at the New Jersey shore can cast millions of mollusks on
the beach to die.
"Overall then, the effect of shell collectors is much less than the effect
of commercial fisheries, habitat destruction, natural forces, or shell
craft. The problem with this argument is that there is no such thing as an
average species. Some species are rare, some are common, some are
widespread, others are narrow endemics, some have planktonic larvae and
produce millions of offspring per year (e.g. oysters), others have direct
development, with only a few young hatching per year (e.g. Achatinella).
Even though the overall effect of shell collecting is small, there are
species, particularly of land and freshwater mollusks, that could be
threatened or driven extinct by injudicious collecting, just as others are
abundant enough to support enormous commercial fisheries. Populations of
some species, such as Strombus gigas and Tridacna have been greatly reduced
in some parts of the world by overfishing, but there is no evidence than any
marine mollusk have ever been threatened by shell-collectors alone. Blanket
bans on shell collecting are not needed to protect mollusks. Bans on habitat
destruction and collection of particular species, along with good management
of commercial fisheries are far more important.
"Although we might be reassured that shell collecting is not in itself
environmentally incorrect, it is essential for the future of conchology that
we counter the perception that it is politically incorrect. The problem is
not just misguided bans on shelling, but declining membership in shell clubs
and interest in the hobby in general. Most of the people in this room are
over 40 years old. Where will the next generation of shell collectors come
from? One way to address these problems is to emphasize the potential for
environment contributions by shell collectors.
"Throughout the country, mollusk faunas are poorly known. For example, the
shells of the New Jersey shore, within a few hours drive for tens of
millions of people, has been ignored for years. Museums have few specimens
from New Jersey collected in the last fifty years, because everyone assumes
that the species are common and widespread, yet here has never been a
comprehensive scientific paper on the mollusks of New Jersey. What if
species have gone extinct in New Jersey, or expanded their ranges from
farther south? Changes in the fauna might reflect changes in global climate,
yet nobody seems to be looking. By starting projects to document local
faunas, shell clubs can not only help to safeguard mollusks and their
environment, but also become more visible in their communities and attract
new members."
Gary
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Gary Rosenberg, Ph.D. [log in to unmask]
Malacology & Invertebrate Paleontology gopher://erato.acnatsci.org
Academy of Natural Sciences http://www.acnatsci.org
1900 Benjamin Franklin Parkway Phone 215-299-1033
Philadelphia, PA 19103-1195 USA Fax 215-299-1170
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