Week of 01/21/2007

Dear EarthTalk: Are the animals used in classroom dissection taken from the wild? If so, wouldn’t this be endangering their populations? Are there other environmental issues associated with classroom dissection?

—William Conway, via e-mail

According to the Humane Society of the United States (HSUS), most animals used in dissection—including amphibians, birds, snakes, turtles, fish and invertebrates—are taken from the wild, even though many have been declining in population. Smithsonian Institution researchers who surveyed 14 major dissection supply catalogs found only one that offered "farm-raised" amphibians; none of the others verified their sources.

Researchers from the World Conservation Union reported in 2004 that a third of all amphibian species around the globe, including frogs, were threatened with extinction. Although habitat loss, pollution and climate changes are the primary causes, demand for dissection specimens only makes matters worse. Analysts estimate that as six million wild frogs are destroyed each year in the U.S. alone for dissection.

Taking frogs from the wild also increases insect populations, including those that carry disease. Frogs eat more than their weight in bugs every day. Farmers the world over have long relied on frogs to keep crops pest-free, but a lack of frogs in recent years has led many farmers to switch to pesticides. Concerns about this prompted India to ban frog sales in 1987. India had been earning $10 million yearly on frog exports, but was spending $100 million importing insecticides, according to the group Mercy for Animals.

The use of formaldehyde in preserving animal specimens is also a concern. Classified by the U.S. Environmental Protection Agency as a "hazardous air pollutant, water pollutant and waste constituent," formaldehyde can cause nausea, headaches and breathing difficulties in people, and has been linked to cancer in animal studies. Teachers and students involved in frequent dissections are exposed to it regularly. Further, schools discard millions of formaldehyde-laden classroom specimens each year, raising questions about its effects on the larger ecosystem as well.

Animal advocacy groups and some educators also question dissection on both practical and ethical grounds. While it is intended to interest students in science, they say, it may be having an opposite affect while also encouraging cruelty to animals outside class. According to the Physicians Committee for Responsible Medicine (PCRM), a 1997 study of seventh graders found that fetal pig dissections fostered callousness toward animals and dissuaded students from pursuing science careers. PCRM also cites surveys where as many as 90 percent of students said they should be able to opt out of dissection.

A number of computer-based teaching tools now on the market provide alternatives to live animal dissection. Digital Frog International’s award-winning "Digital Frog 2" allows a student to "dissect" a computer-generated frog with a digital scalpel. The non-profit TeachKind provides a comprehensive online listing of such resources. Nine U.S. states—Florida, California, Pennsylvania, New York, Rhode Island, Illinois, Virginia, Oregon and New Jersey—now have laws that allow students to beg out of cutting animals and to use such alternatives. Other states have implemented policies that serve a similar purpose.


Dear EarthTalk: What are the pros and cons of marine aquaculture, of raising ocean fish instead of catching them in the wild?

—Jeanne L., Norwalk, CT

Marine aquaculture, an age-old practice in parts of Asia, has grown in popularity in western countries in recent years in response to dwindling supplies of wild fish in the world’s oceans. According to the Pew Oceans Commission, a blue-ribbon panel of fisheries and marine biology experts, high-tech fishing practices, such as drift netting, have led to a potentially irreversible decline in populations of key seafood species. Some shark, tuna and cod species have declined as much as 90 percent in the past few decades.

Most marine biologists agree that, as human population continues to grow worldwide, there will not be enough wild-captured fish to meet demands for seafood. Aquaculture, "the propagation and rearing of aquatic organisms in controlled or selected environments," as defined by the U.S. National Oceanic and Atmospheric Administration (NOAA), is seen by many as the best way to fill the gap. Currently aquaculture supplies about 30 percent of the world’s seafood, up from just four percent 30 years ago.

James McVey of NOAA’s Sea Grant program says aquaculture can reduce the need for seafood imports and provide jobs for coastal communities. "The U.S. currently brings in $10 billion in seafood from other countries," he says. "With increased production capacity, our higher yields from aquaculture will bring down this trade deficit, and improve food security—where we’re not as reliant on other nations for food."

But aquaculture’s down sides give many scientists pause. Studies indicate that, despite the promise of reducing pressures on wild fish, aquaculture requires two pounds of wild-caught fish to use as feed to make one pound of farmed fish. Further, says SeaWeb, breeding farms—where thousands of fish, and their waste, are concentrated—breed diseases that can then escape and contaminate wild fish populations.

To control such outbreaks, many fish farmers treat their stocks with antibiotics that can also make their way into the oceans and wreak havoc. The farmed fish themselves also escape from their pens and interbreed with and take over habitat traditionally occupied by wild populations. Another major problem with aquaculture, according to SeaWeb, is its destruction of natural habitats. The group blames shrimp farming, for example, for destroying coastal mangrove forests in the Philippines, Thailand and elsewhere.

But many scientists do feel that aquaculture has the potential for helping the world’s marine ecosystems rebound—if it is done conscientiously. Among other things, SeaWeb recommends that fish farmers avoid using drugs to fight disease and that governments do more to regulate and police aquaculture operations to make sure otherwise pristine waters are not fouled and sensitive coastal ecosystems are not damaged.

According to the Monterey Bay Aquarium’s "Seafood Watch" program, the greatest power to end irresponsible aquaculture rests with consumers. The organization’s website offers tips on which kinds of farmed seafood to buy and which to avoid. While no one person’s choices will improve the environment dramatically, collectively consumers can play a role in how producers treat the ecosystems they utilize.

CONTACTS: NOAA; SeaWeb"s: Marine Aquaculture; Monterey Bay Aquarium’s Seafood Watch Regional Seafood Guides