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Gone Fishing
Eileen McLellan
Broiled, with a touch of herb butter. If I thought about salmon before
becoming a Congressional Science Fellow, it was in terms of food. I had
distant memories from my Scottish childhood of fishermen hip-deep in swirling
mountain streams and of salmon leaping waterfalls. Although my personal
and professional journeys had taken me far from these scenes, I will draw
on every experience of my life during my fellowship year working as a scientist
on Capitol Hill. Perhaps subliminal memories drew me to serve my fellowship
in the office of Oregon Sen. Ron Wyden. After all, Oregon and Scotland
are both known for their rainy climates! In fact, I selected Sen. Wyden's
office partly because I knew that the Pacific Northwest in general, and
Oregon in particular, was a stage on which controversies over resource
protection and endangered species were being played out.
A geologist plays an important role in protecting aquatic ecosystems, as I learned on my odyssey into the world of salmon policy.
But what is a geologist doing working on fish? One of the most exciting
and challenging aspects of working as a Congressional Science Fellow is
that a fellow is not just the “office geologist,” but is the “office scientist,”
expected to address any and all scientific issues. A geologist plays an
important role in protecting aquatic ecosystems, as I learned on my odyssey
into the world of salmon policy.
It is impossible to underestimate the historical and cultural significance
of salmon in the Pacific Northwest. Salmon are a food source, a recreational
asset and, perhaps most importantly, a cultural symbol. Yet this cultural
symbol is in deep trouble. During the 1850s, 8 to 10 million salmon returned
to the Columbia River. During the 1990s, fewer then 1 million returned.
More than 100 stocks have gone extinct and some 214 additional stocks are
listed under the Endangered Species Act (a stock is a genetically distinct
population). The National Marine Fisheries Service estimates that several
stocks have a 90 percent probability of going extinct in the next 10 years.
The extent to which human activities have contributed to the “salmon problem,”
what efforts might reverse them and the economic and social costs of such
efforts are important scientific and political questions.
I discovered this issue during a meeting, when a group of lobbyists
requested that the senator support their proposal to remove the four dams
on the Lower Snake River. They presented a graph showing that the steep
decline of salmon populations began with dam construction. Shifting into
scientist mode, I began to question them about correlation vs. causality.
Did the dams cause the decline, or were there other changes in the region
occurring at the same time that could have an impact on the salmon? We
did not resolve anything in that meeting, but the discussion left me wondering
to what extent the “salmon problem” could be attributed to any one human
activity.
“Dam breaching,” the removal of the four Lower Snake River dams, has
been a controversial proposal in the region for several years. It was initially
proposed by environmental groups, but various federal agencies have become
involved in scientific studies about the impacts of dams and possible ways
of mitigating those impacts. As a science fellow, I felt I could give the
senator an overview of the science used in making policy about the dams.
So began my journey into the realm of fish biology, in which I learned
that scientists of all types suffer similar frustrations: the lack of data
to calibrate models, tension over the level of detail to include in the
models and the often nonscientific selection of some research results over
others for justifying political solutions.
As a geologist, I grew concerned that the debates on fish population
models were obscuring some important issues. Geologists are familiar with
the idea that dams store sediment and cause changes in river channels.
But government studies of the dams contained little discussion of what
would happen to the stored sediment or the river channel if the dams were
breached. Nor did they recognize that, ironically, breaching the dams could
initially have an adverse effect on the salmon as the river system adjusted
to a new equilibrium. Thus the issue that would probably be the first to
catch a geologist's attention is nowhere on the radar screen in the policy
debate.
I kept returning to the lobbyists' graph. The decline in salmon populations
correlates in time not only to dam construction, but also to other major
changes in the Pacific Northwest. Human population growth has reshaped
the land through farming, forestry and urban development. I began to wonder
whether at least part of the “salmon problem” could be related to habitat
loss. Now here was an issue where a geologist could make a contribution!
Salmon require not only cool, clear water but also a complex stream channel:
pools in which to hide and rest, riffles to provide oxygen and supply prey,
debris to provide nutrients to support the food chain and a suitable gravel
substrate for breeding. Many of these features relate, directly or indirectly,
to the underlying geology. Indeed, some of the work on salmon habitat focuses
on identifying different lithotopic units. Different rock types erode differently,
resulting in diverse channel morphology and varied rates of sediment input.
From fish biologists, I learned that salmon had evolved in streams
subject to natural disturbances, such as the input and movement of sediment
from natural processes of erosion and mass wasting. The steep slopes and
prevalence of unconsolidated glacial material in the region, coupled with
the high rainfall, are conducive to landslides, which have had a major
role in delivering sediment and shaping stream morphology. However, the
rates and extent of these natural processes have been accelerated by human
activity, especially by land-use practices throughout the region.
Most of the states, seeking to minimize human impact on streams, have
laws governing activities such as road construction, grazing and timber
harvesting. The best of these laws are not “one size fits all,” but
prescribe different solutions for different lithotopic units.
For example, many streams in the region experience high temperatures,
which stress salmon and other fish. These high temperatures usually result
from the loss of riparian (streamside) buffers. The loss removes the cooling
shade of vegetation. A stream without buffers is also vulnerable to outside
sediment, which enters the stream, making the channels wider and shallower
and causing the channels to heat faster. Many states regulate the protection
of riparian buffers, but it is important to note that the width of a buffer
required to protect the stream will vary depending on local slopes, and
in some cases stream channels may be too wide for buffers to provide much
protection.
On the other hand, some important aspects of salmon habitat are not
governed by regulations. Salmon prefer to lay their eggs in areas where
groundwater upwells into the streambed, which probably creates the constant
flows and temperatures the eggs require as they develop. Unlike the detailed
requirements for riparian buffers, regulations on activities that may alter
the groundwater regime are absent.
A key research question is how much human land use contributes to habitat
degradation, and how well existing laws prevent future degradation.
This question is one that geologists, as members of the scientific
community, are uniquely qualified to address because they can identify
watershed processes and evaluate impacts over short and long time scales.
Current stream conditions reflect not just today's management practices
but the legacy of past land use. The scientist's role is to partition out
past impacts from present; the policy-maker's role is to determine whether
and where to assign responsibility for those impacts.
Geologists have a major role to play in understanding how aquatic ecosystems
function. Perhaps no other group of scientists has an equally intuitive
understanding of the watershed concept, the idea that activities on land
directly influence the health of water bodies.
The increasing recognition that managing endangered species means managing
habitats, coupled with a new understanding that a habitat includes physical
components of the landscape, requires that geologists be actively involved
in what we have often considered “biological” issues.
The challenges for the geological community are to provide the scientific
basis for ecosystem management, and to ensure that our voices are heard
in the policy-making process.