Mangroves, Fishponds, and the Quest for Sustainability

[GLT]

GLOBAL VOICES OF SCIENCE:
Mangroves, Fishponds, and the Quest for Sustainability
Jurgenne H. Primavera*

Figure 1 Jurgenne H. Primavera
Philippines
Jurgenne H. Primavera, senior scientist of the Aquaculture
Department of the Southeast Asian Fisheries Development Center based
in Iloilo, central Philippines, for more than two decades has been a
tireless champion of replacing unsustainable aquaculture practices
with sustainable ones. In her early research career, in the 1970s, her
studies of the early phases of the shrimp life cycle contributed to
aquaculture know-how and practice, enabling this food-producing
strategy to flourish in the world's mangrove areas, including some in
her own country. As she learned first-hand about the environmental and
socioeconomic perils that poorly managed and overextended aquaculture
can bring, she began to investigate and develop mangrove-friendly
aquafarming methods in order to move toward a sustainable industry
that provides food and jobs while also preserving the environment.
Trained in zoology and marine science, Primavera has published and
lectured extensively on aquaculture and mangrove issues. Among her
numerous awards and honors are her induction as a foreign member into
the Swedish Royal Academy of Agriculture and Forestry and an honorary
doctoral degree from Stockholm University. Earlier this year, she was
chosen as a Pew Fellow in that organization's program in marine
conservation.

All essays and interactive features appearing in this series can be
found online at www.sciencemag.org/sciext/globalvoices




As I write on this late June afternoon, my heart grieves amid news
that a young couple, dearly loved former research colleagues living in
the north of Panay Island in the Philippines where I work, had been
shot over a fishpond dispute. The owner, it seems, did not want them
to use a shortcut on his property that led to the pond the couple was
renting from him. Bullets shattered the jaw, collarbone, and colon of
the husband, a marine biologist who miraculously survived, but they
proved fatal to his wife, an aquaculture nutritionist and university
instructor.

The incident takes me back decades to my home island of Mindanao when
rifle bullets strafed our campus cottage during a short-lived
rebellion. My family and a neighbor crouched inside the bathroom,
while the battle between rebels and government soldiers raged for 4
long hours. The growing insurgency forced me to give up my teaching
job at Mindanao State University and flee to the quiet of the Visayas,
in the central Philippines, where I accepted a research position with
the Aquaculture Department of the Southeast Asian Fisheries
Development Center (SEAFDEC/AQD).

Fast forward to the present, to another potential conflict elsewhere
in northern Panay. This one is centered on the small-scale cutting of
trees in and near a magnificent mangrove stand of Avicennia rumphiana
trees, some of them up to 8 m in circumference. This location has been
among our study sites since 1997. But to make an official complaint
would place my colleagues and me in harm's way from those who earn
income by planting the cleared area with Nypa palm or converting it to
ponds.

Troubles like these come with the mission of protecting the world's
mangroves--the lushly forested environmental buffer zones by which the
sea meets land in so many places around the world--even as these areas
become ever more exploited for aquaculture and other uses. It is a
mission that teeters on the always difficult negotiation by which
ecological and environmental goals, on the one hand, and economic,
social, and immediate human needs, on the other, are adjudicated.

I have observed this difficult dynamic firsthand since the mid-1970s
when the field of aquaculture, the farming of aquatic and marine
plants and animals, was getting started. Indeed, my first studies in
this area--on the growth and survival of shrimp in earthen ponds and
production of breeders for hatcheries--contributed to the foundation
on which increasingly efficient shrimp farming developed, so often, as
it has turned out, to the detriment of mangrove habitats.

Mangroves at Risk
Aquaculture ranks as a phenomenal success story in global food
production. In 1975, when I joined the SEAFDEC/AQD, aquaculture
contributed 8% to the overall yield of the world's fish harvest; now
it provides more than one-third of the yield of the world's fisheries.
Total aquaculture production in 2003 was 54.8 million metric tons,
valued at $67.3 billion in U.S. dollars. More than 90% of this output
comes from Asia, where aquaculture has its origins.

As with land-based agriculture, all of this aquatic food production
and economic activity has come with environmental problems and social
conflicts. Foremost among these is the loss or modification of habitat
in places where aquafarmers clear mangroves for ponds and where they
install cages or pens above seagrass beds and coral reefs. Other
environmental effects include the loss of bycatch (unwanted fish and
invertebrate species) during the collection of wild "seed" used for
stocking in ponds and of adult brood-stock for hatcheries,
introduction of exotic species, spread of parasites and diseases,
interactions of escapees from ponds or pens with wild populations,
misuse of chemicals and antibiotics, salinization of soil and water,
and coastal pollution. Many of these ecological impacts of shrimp
aquaculture have brought along social problems, among them
privatization of public lands and waterways, the decline of open-sea
fisheries, rural unemployment, and social disruption.

Even the seemingly reasonable assumption that aquaculture is an
efficient way to produce new protein is undermined by the dependence
of shrimp, salmon, and other cultured aquatic carnivores on raw fish
and on fish meal and oil in pelleted feeds. Careful calculations
indicate that some cultured species actually are net consumers of
fish.

In the 1980s, I began to ring warning bells about the perils of
runaway shrimp farming. At the time, aquaculture was perceived as the
coming Blue Revolution that would help solve world hunger, provide
jobs, and fight poverty. Because of my cautionary views, I became
marginalized in aquaculture circles. At some meetings I was ostracized
and my research papers sometimes seemed harder to get through
editorial decision-makers than the reviewers' comments would have
suggested. Even so, other researchers would subsequently confirm my
conclusions on, for example, the boom-and-bust nature of unplanned and
poorly managed shrimp culture. And in recent years, momentum to
develop sustainable aquaculture practices has been building.

Figure 2 Vanishing mangroves. The expanse of fish and shrimp pens
in the foreground of this aerial view of Dagupan in the Philippine
province of Pangasinan used to be filled with mangroves.

CREDITS: GIL S. JACINTO

For my part, I have received invitations from foreign groups,
including the Global Wetlands Economics Network and the International
Foundation for Science, to expose the plight of mangroves and share my
ideas about aquaculture sustainability. At times, I have done so in
high-profile media outlets, such as a BBC documentary in 2002.
Although I had always been confident that even my early alarmist
attitude was justified, I received my final peer vindication last year
when Stockholm University presented me with a Ph.D. in science honoris
causa for showing "… that mangroves are key areas for recruitment of
fish and shrimp and that development of conventional shrimp farming
may have far-reaching negative economic and social implications… ."

For greater sustainability, the aquaculture industry must acknowledge
its interdependence with fisheries and other stakeholders.
Ecologically damaging practices need to be replaced with ecologically
sound ones, such as locating culture ponds outside mangroves where
possible, using native species whose inevitable escapes into nearby
waters would be relatively innocuous, and stocking hatchery fry rather
than wild seed whose collection entails the loss of bycatch.

Because surrounding waterways can be the source as well as recipient
of contaminants and pathogens, systems of low water exchange between
ponds and the surrounding environment can minimize such risks. Levels
of suspended solids or sediment are reduced if pipes that provide
aeration are set on the pond bottom, rather than on the surface, and
also by means of settling ponds. Water quality can be maintained with
natural biofilters such as clams and other bivalves. Probiotics are
commercial suspensions of appropriate types of bacteria added to the
pond that operate on the principle of competitive exclusion (of
harmful bacteria). The so-called greenwater technique enhances shrimp
growth and survival by means of a combination of phytoplankton and the
presence of herbivorous fish in the pond. Finally, lower stocking
densities of shrimp and their polyculture with suitable fish species
can minimize waste levels and produce synergistic benefits.

Already, the culture of seaweeds and fish in cages in subtidal bays
and rivers is compatible with adjoining mangroves and suitable for
family-level operations.

But there remains a need for mangrove-friendly aquaculture technology
in intertidal forests, in which mangrove trees spend high tides with
their roots submerged and low tides with their roots exposed. That's
why one of my current projects, funded by the European Commission, is
to develop sustainable so-called aquasilviculture. An approach I have
developed, which combines the rearing of mud crabs inside intertidal
pen enclosures, has been replicated by local people's organizations in
the Philippines. Meanwhile, several studies have shown that mangrove
estuaries can process nutrients, such as those from fertilizers, in
aquaculture pond effluents at least over short spatial and temporal
scales. That opens up the possibilities of integrating intensive
aquaculture with natural or constructed mangrove wetlands in a way
that could be sustainable through careful management and planning.

Figure 3 Water world. Boys swim in this creek by a healthy
intertidal mangrove during high tide.

CREDITS: J. H. PRIMAVERA

A Menagerie of Mangroves
My earliest training was in zoology, and when I began studying the
taxonomy of mangroves, I found the diversity of these habitats
challenging. On a trip to the Mai Po, Hong Kong, mangroves in 1993,
experts from Thailand and Vietnam effortlessly called off the
scientific names of mangrove species--Avicennia marina, Kandelia
candel, Aegiceras corniculatum, etc. Feeling ignorant, I vowed to
master the Indo-Pacific species of mangroves. Indeed it took me 10
years to write and publish, with UNESCO support, the Handbook of
Mangroves in the Philippines--Panay, which came out last year. The
diversity of mangroves and their wide distribution in the archipelago
in the past are reflected in the names of many coastal towns and
villages. The name of the country's premier city, Manila, derives from
Maynilad, meaning there is nilad, referring to the mangrove
Scyphiphora hydrophyllacea, which grew profusely along Manila Bay in
pre-Hispanic times.

Mangroves, seagrass beds, and coral reefs bordering the 7150
Philippine islands have contributed appreciably to the livelihood and
well-being of coastal communities over the centuries through their
provision of various goods and services. Foremost among mangrove
products are fish, shellfish, and other invertebrates that provide the
most available and inexpensive protein in the Filipino diet. Other
natural benefits afforded by mangroves include coastal protection,
erosion control, sediment trapping, and recycling of nutrients from
terrestrial run-off and river discharges.

Latest estimates, as of 2000, have placed the global coverage of
mangroves at 15 million hectares (ha), a drastic decline from 18
million ha in the 1990s. The losses have been particularly heavy in
Southeast Asia, which hosts a third of total mangrove area. The
anthropogenic causes of such losses include overexploitation of
mangroves and conversion of mangroves to settlements, rice fields,
salt beds, tourist resorts, and industrial facilities. But
brackishwater pond culture, which dates back to 1400 in Java, has also
taken its toll. Many thousands of hectares of culture ponds in the
Philippines and Indonesia were carved out of mangrove swamps because
these habitats were considered ideal for growing milkfish (Chanos
chanos), a food fish favored by local people. Around half of the
279,000 ha of Philippine mangroves that disappeared between 1951 and
1988 were converted into ponds mainly for milkfish, but also for
shrimp.

Aggressive mangrove and wetlands development became national policy in
the Philippines in the 1950s. Some of these policies supported
aquaculture development by enforcing a form of rent control on the
mangroves. The original fee for leasing a pond was PhP50, or about $2/
ha per year. This fee was way out of line with the estimated values of
$538/ha per year and $42 to $156/ha per year, respectively, for fish
and wood harvests from Philippine mangroves. By underpricing the
rights to harvest public forests and by not penalizing low pond
productivity, these policies and practices encouraged rampant
conversion of mangroves to aquaculture ponds.

Both a 1991 decree and one in 1992 mandated an increase in the rental
to PhP1000, or about $20/ha per year, but its implementation was
delayed indefinitely on both occasions by a strong fishpond industry
lobby. In the past 2 years, the government presented a series of
expert witnesses, including myself, who cited published valuations
from the mangrove literature and aquaculture studies of mangroves and
fishponds to justify the pond rental increase. The court is expected
to rule within the year.

Actually, numerous laws, decrees, and ordiances aim to protect
remaining mangrove areas. These include guidelines for mangrove-pond
conversion and reversion of abandoned ponds to forest. Ownership
policies, such as the Mangrove Stewardship Agreement that legitimizes
de facto claims of local communities over coastal resources, improve
the success rate of replanting programs. Even so, coordination is
lacking between the national forestry and fisheries agencies tasked to
administer mangroves and ponds. Legislation to conserve, protect, and
rehabilitate Philippine mangroves has not been wanting--it is their
implementation that is generally weak, hampered by inadequate manpower
and resources, and overall lack of political will to enforce the laws.

Figure 4 Postharvest portrait. Milkfish, and perhaps some shrimp
and crabs, have just been harvested from this drained milkfish pond in
Iloilo Province, central Philippines. With mangrove stumps now
visible, it will be dried, filled, and restocked with "seed" organisms
for the next crop.

CREDIT: J. H. PRIMAVERA

Consider the requirement by a number of "greenbelt" promulgations that
a mangrove strip of 20 to 50 m along riverbanks and one of 50 to 100 m
facing the open seas be maintained regardless of the economic activity
in the area. Today, an aerial view of the Philippine coastline will
show a monotonous succession of ponds with hardly any green signs of
such mangroves.

As the December 2004 tsunami has shown, this is not merely a matter of
aesthetics. Man-made structures such as shrimp/fish farms and tourist
resorts along the coastline are no match for rampaging waters. It is
time to enforce these greenbelt and other mangrove-preserving laws,
because only a solid wall of trees can slow down a moving wall of
water. More than ever, there is a need to preserve or rehabilitate
mangrove-beach forests and coral reefs to serve as natural barriers
that diminish the tremendous wave energy generated by tsunamis, as
well as by typhoons. Tsunamis appear every 20 to 50 years in the
Philippines, but in a single year 20 typhoons may devastate the
country by inflicting massive losses of life and property.

Mangrove Sense
Only a fifth of the 500,000 ha of Philippine mangroves at the turn of
the 20th century remain, whereas brackishwater ponds have increased
almost fourfold, from 61,000 ha in 1940 to 230,000 ha at present. Many
of these ponds have no associated legal papers--either the lease has
expired or the application is pending. Often single families own up to
hundreds of hectares of pond area. Twenty hectares is the most that a
Filipino pond operator can realistically manage by himself, so many
ponds are underutilized or abandoned, and productivity is low compared
to that of Thai shrimp farms, which average 2 ha or less. By reducing
farm sizes, Filipino aquaculturists can increase pond yields and
afford to pay the still modest lease fee of PhP1000/ha per year. The
remaining areas, especially those facing waterways, could be reverted
to greenbelts, finally coming into compliance with Philippine laws.
Also, by redressing the present imbalance between the respective areas
of mangroves and ponds, aquaculturists can embrace the more holistic
approach, known as Integrated Coastal Zone Management, which
incorporates an understanding of the complementary rather than
competing roles of aquaculture and more traditional open-sea
fisheries.

My environmental bias goes back to a childhood imprinted with mangoes,
avocados, and a dozen other tropical species of backyard fruit trees,
as well as yearly floods due to rampant logging that had denuded the
forests in my home province. The floods were particularly bad and had
downed many bridges in 1961 when, as a high school student, I took the
government science examinations. To travel to the testing center in
the next province, my father and I had to cross rivers on coconut
trunks or bamboo poles. A decade later, my passion to work for a
sustainable environment was greatly reinforced by my participation in
the historic 1972 U.N. Conference on the Human Environment in
Stockholm.

I am determined to continue mentoring younger researchers in
sustainable aquaculture and mangroves. Sadly, most Filipino students
of marine biology prefer the "glamorous" coral reefs and seagrass beds
to muddy, mosquito-infested mangroves. This is unfortunate because,
given a chance, mangroves can be thoroughly enchanting, the mud and
insects notwithstanding. Imagine numerous white filaments of
Sonneratia alba flowers gently falling from the canopy in the early
morning breeze, or the unspeakable beauty of thousands of fireflies
lighting up Sonneratia caseolaris trees on a moonless night.

We scientists in developing countries need to come down from the Ivory
Tower and disseminate results not only in peer-reviewed journals but
also through advocacy and the popular media. We must not forget our
hearts even as we apply our minds. We do science not in a vacuum but
against the grinding poverty and environment-unfriendly character of
modern times, and we can use our scientific knowledge to reduce
suffering and make life more full for fellow humans and creatures.
With a Pew Fellows grant in marine conservation, I will pursue
initiatives in mangrove management and rehabilitation through
education and local governance. Success will be had on the day my
grandchildren walk with me through these habitats, understanding their
importance, appreciating their diversity, and captivated by their
magic.

10.1126/science.1115179
The author is with the Aquaculture Department, Southeast Asian
Fisheries Development Center, Tigbauan, Iloilo 5021, Philippines. E-
mail: jhp...@aqd.saefdec.org.ph