Perceived food safety risk from wildlife drives expensive and unnecessary habitat destruction around farm fields

Meticulous attention to food safety is a good thing. As consumers,
we like to hear that produce growers and distributers go above and
beyond food safety mandates to ensure that healthy fresh fruits and
vegetables do not carry bacteria or viruses that can make us sick.
But in California's Salinas Valley, some more vigorous
interventions are cutting into the last corners of wildlife habitat and
potentially threatening water quality, without evidence of food safety
benefits. These policies create tensions between wildlife preservation
and food safety where none need exist, say scientists for The Nature
Conservancy, writing in the Ecological Society of America's journal Frontiers in Ecology and the Environment. The study will be published online ahead of print on Monday, May 6th, 2013.
"Farming practices for food safety that target wildlife are
damaging valuable ecological systems despite low risk from these
animals," said lead author Sasha Gennet.
Check the back of your bag of spinach or prepackaged salad
greens, and you'll probably find that they came from the Salinas Valley.
Salad is big business in California.
In the aftermath of a deadly 2006 Escherichia coli serotype
O157:H7 outbreak traced to California spinach, growers and distributers
of leafy greens came together to create the California Leafy Green Handler Marketing Agreement
(LGMA) on best practices for the industry, enforced by third-party
auditors and inspectors. The LGMA established standards for farm work
hygiene, produce processing and transport, and proximity to livestock.
About 99 percent of California leafy greens now come from participating
farms.
But produce farmers in the Salinas Valley report pressure from
some powerful buyers to take additional precautions not mandated by
government or industry standards. These buyers insist that swathes of
bare ground wider than a football field is long separate the leafy
greens from rivers, wetlands and other wildlife habitat.
Other precautions include treating irrigation water with
chemicals toxic to fish and amphibians, and setting poisoned bait for
rodents.
"The California Leafy Green Hander agreement is transparent,
flexible and science based," said Gennet. "Going above and beyond it
just creates costs for farmers and doesn't improve safety."
It also creates costs for wildlife. Although scant evidence
exists of risk of food-borne disease spread by wildlife, the risk of
rejection of produce by major buyers is too much for most growers to
bear, say Gennet and her co-authors. They measured changes in wetlands
and riverside habitat in the Salinas Valley between 2005 and 2009,
finding 13.3 percent converted to bare ground, crops or otherwise
diminished. Widespread introduction of fencing blocked wildlife
corridors. Low barriers even kept out the frogs.
Unlike the LGMA standards, individual corporate requirements for
farm produce are generally not transparent to the public. But in
surveys, farmers report pressure from auditors to implement fences and
bare ground buffers around spinach, lettuce, and other leafy greens.
Such pressures have set back years of collaboration between
growers and environmental advocates to make farm edges slim sanctuaries
for wildlife, as well as buffers between agricultural fields and
waterways. Fallow strips along streams and rivers provide corridors for
migrating animals and birds.
"This is an area that is already 95 percent altered – the habitat
that remains is critical," said Gennet. "Removing 13 percent of what is
already heavily-impacted habitat and cutting off wildlife corridors is a
significant loss."
The Salinas River and its tributaries are an important rest stop
on the Pacific Flyway, a major migration route for neotropical
songbirds, and home to raptors and shorebirds. The waterways are also
corridors for deer and other big animals moving between the high country
of the Diablo Range and coastal Big Sur mountains that flank the
valley.
Wetlands and buffers of trees, grasses, and shrubs help to keep
runoff from fields out of the waterways, slowing erosion of soil and
blooms of algae downstream. An overabundance of fertilizer has created
problems for domestic drinking water as well as the ecosystems of the
Salinas River watershed and its outlet, Monterey Bay.
"California has a big problem with concentrated nutrients in
waterways, and there is a lot of pressure on growers to reduce those
inputs – so to the extent that riverside wildlife habitat could be a
benefit all around, a coordinated approach to agricultural management
and policy makes the most sense," said Gennet.
"The policies that these distributors are forming are very
narrow," said Lisa Schulte Moore, an agricultural ecologist at Iowa
State University who is not affiliated with the Nature Conservancy
study. Nervous distributers are looking at specific risks in isolation,
she said, and not asking "does the food system create a healthy human
environment?"
Schulte Moore works with Iowa farmers to incorporate native
grassland habitat alongside corn and soy fields. Her experiments look
for native grass mixtures that don't tend to invade the crops and are
highly attractive to beneficial native insects, including the natural
enemies of agricultural pests. "If we design the systems right there
could be substantial benefits to the agricultural system as a whole,"
she said.
The key word, Gennet says, is "co-management." As a community, we
need to approach food health, wildlife health, and water health in the
Salinas Valley as parts of an integrated system. She would like to see
California growers, buyers, and consumers rely on standards like the
LGMA. "We think it's been a good process, using the newest science and
trying to take a constructive approach. If everybody stuck to those
standards, that would be a good outcome," said Gennet.
Citation: Farm practices for food safety: an emerging threat to floodplain and riparian ecosystems. (2013) Sasha Gennet, Jeanette Howard, Jeff Langholz, Kathryn Andrews, Mark D Reynolds, and Scott A Morrison. Frontiers in Ecology and the Environment doi:10.1890/1202443
Contact: Liza Lester
llester@esa.org
202-833-8773 x211
Ecological Society of America