OP/ED written by Bryan Watts as it appeared in Richmond Times Dispatch
Oct,19,2011
(http://www2.timesdispatch.com/news/oped/2011/oct/19/tdopin02-watts-chesapeake-wildlife-in-the-balance-ar-1392188/)
In November, the Atlantic States Marine Fisheries Commission (ASMFC) will
decide on the path forward for managing the Atlantic menhaden fishery. At issue
is whether to increase target population levels, which would effectively reduce
commercial harvests of menhaden. At risk are populations of birds and other
wildlife enjoyed by millions of residents throughout the tidal reach of the
Chesapeake Bay.
Menhaden, often called the "most important fish in the sea," are the energy
changers of bay waters. They filter plankton, converting it into oil-rich
tissues and making this vast energy reserve available to consumers higher up on
the food chain. Demand for this energy-rich oil is at the heart of the conflict
between commercial menhaden fisheries on the Atlantic Coast and many
recreational anglers who claim that menhaden harvest levels have greatly
compromised the health of striped bass and other prized species that depend on
menhaden for food.
But striped bass and commercial harvesters are not the only ones chasing
menhaden. Menhaden are critical prey for many of our bird populations as well,
including bald eagles, osprey, brown pelicans, royal terns, and common loons -
species that provide the sights and sounds of the visible living fabric that we
identify with the Chesapeake Bay experience.
The current ASMFC regulation allows for harvests down to 8 percent of the
projected unfished population (or conversely, catching up to 92 percent of all
menhaden in the bay and ocean). The population is technically classified as
overharvested if it is driven below the 8 percent threshold. Even with this
alarmingly generous threshold, a recent scientific assessment has indicated
that menhaden have been overfished in 32 of the past 54 years. Allowing
menhaden stocks to be harvested to such low levels has implications for other
consumer communities.
In 1971, during the height of the DDT era, Bob Kennedy worked with breeding
osprey in Mobjack Bay as a graduate student at the College of William and Mary
under Mitchell Byrd. Kennedy determined that osprey pairs were producing chicks
at a rate well below that needed to maintain the population, largely because
DDT in their system made their eggshells too thin to be viable. Only one in
four eggs hatched due to DDT contamination, but of the chicks that hatched,
nearly eight of 10 survived to fledge.
During the next few decades, three additional William and Mary graduate
students would work with osprey in Mobjack Bay and provide a portrait of a
changing population. The United States ultimately banned DDT, and by the early
1980s osprey pairs were producing more than twice as many chicks as in the
early 1970s, and their population was growing.
Surprisingly, however, by 2006 osprey productivity in Mobjack Bay had declined
again back to levels not seen since the DDT era. This time the underlying cause
had changed.
More than 35 years after DDT, graduate student Andy Glass found that nine of
every 10 eggs hatched, but only four of every 10 chicks survived to fledge.
Chicks were hatching, but they were starving in the nest.
Why? In the 1970s adult osprey were delivering nearly three times more fish to
nestlings than in 2006. In the 1980s during the period of highest productivity,
more than 70 percent of the fish delivered to nests were menhaden. By 2006
menhaden represented less than 27 percent of the diet. None of the other fish
species in the osprey's diet are equivalent to menhaden in energy content. So
the adults were providing fewer fish to their chicks, and the fish were of
poorer quality.
Significantly, over the same four decades, the menhaden population as measured
by haul seines in Maryland had declined by more than 90 percent.
What is now before the ASMFC are proposals to make no change, as well as one to
increase the population threshold from 8 percent to 15 percent of unfished
levels. Though that would represent a modest change, it would be a welcome
movement toward considering the needs of fish, birds, marine mammals and the
broader bay ecosystem.
The Chesapeake Bay is a tremendous and shared resource. We all have a voice in
how that resource should be used for the highest public good. Let ASMFC hear
your voice.
Bryan D. Watts is Mitchell A. Byrd Professor of Conservation Biology and
director of the Center for Conservation Biology at the College of William and
Mary and Virginia Commonwealth University. Contact him at bdwatt@xxxxxx. Public
comments on proposed changes in harvest limits are being accepted by the
commission through Nov. 2. Express your view by visiting http://www.asmfc.org/.
