Rough waters for
native Chinese fish
IN THE POLICY FORUM “China’s aqua-
culture and the world’s wild fisheries” (9
January, p. 133), L. Cao et al. identify the
increasing growth of aquaculture in China
as potentially placing considerable pressure on global marine stocks. The impact of
aquaculture on wild fisheries will also be felt
much closer to home, particularly in China’s
Aquaculture in Asia is increasingly reliant
on the farming of alien species, whether
stocked from other countries or intentionally translocated from remote water basins
within the same nation (1). Recent estimates
suggest that more than 100 alien species
of freshwater finfish are farmed in China
(2). Many of these species have become
widely established in the wild either as a
result of escape from aquaculture ponds or
through deliberate introductions into lakes
and freshwaters to enrich wild fisheries.
Unfortunately, the consequences have usually been disastrous. Several alien finfish
threaten native species through predation
(3), competition (4), the spread of pathogens
(5), and hybridization (6). The end result is
often the decline in native finfish and associated wild fisheries. For example, following
the introduction of bighead and silver
carp in Lake Xingyun for aquaculture, the
proportion of the endemic barbless carp in
the total fish yield declined from 50% to less
than 1% within a few decades (7).
China is recognized as a major center
for global freshwater fish diversity with a
high level of endemism, attributable to its
major river systems that have been isolated
for millennia (8). Thus, while the economic
value of alien aquaculture species provides
a strong incentive to their introduction,
the loss of wild fisheries and the extinction
of endemic species as well as the reduced
resilience of freshwater ecosystems should
be taken into account in regulations regard-
ing stocking practices (9). In the absence of
effective regulation of species introductions
and translocations to support aquaculture
development in China, progressive reduc-
tions in the size and sustainability of wild
freshwater fisheries are to be expected.
Philip E. Hulme
The Bio-Protection Research Centre, Lincoln
University, Canterbury, 7647, New Zealand.
1. S. S. De Silva, T. T. T. Nguyen, N. W. Abery, U. S. Amarasinghe,
Aquac. Res. 37, 1 (2006).
2. P.Jia,W.Zhang, Q.Liu, Fish.Res.140,66(2013).
3. M. Luo etal.,Acta Hydrobiol.Sin.36, 932 (2012).
4. J. Qin, J. Xu, P. Xie, J. Fresh w. Ecol. 22, 365 (2007).
5. K. V. Radhakrishnan, Z. J. Lan, J. Zhao, N. Qing, X. L. Huang,
Biol. Invasions 13, 1723 (2011).
6. W. Tang, Y.Chen, Zool.Sci. 29,311(2012).
7. P.Xie, Y.Y.Chen,Science 294,999(2001).
8. B. Kang,etal.,Fish Fish. 15, 209 (2014).
9. P. E. Hulme, P. Pysek, W. Nent wig, M. Vila,Science 324, 1015
The value of
FOR CENTURIES, HUMANS have collected
specimens and deposited them in scientific
collections housed in zoological or natural
history museums. Such documentation is
essential for the recognition and classification of our extinct and extant biodiversity.
As technology improved, we created DNA
databases that have helped us to understand
the evolutionary relationships between
organisms. Both genetic archives and
museum specimens are well recognized as
important biodiversity repositories, and
scientific literature routinely refers to them.
Equally important, but often overlooked,
are audiovisual archives, which allow us
to record complementary information that
could not be recovered from dead specimens or DNA sequences. Sound archives
are particularly interesting, as they capture
behavior with great accuracy and are often
involved in conspecific recognition. These
digital archives are relatively inexpensive to
store and curate, and are usually obtained
with no harm to the focal species and no
need for collection.
Unfortunately, audiovisual archives are
being neglected; voucher numbers, which
provide access to the files and the possibility
of replication, are often not available in arti-
cles. Furthermore, the files are not always
georeferenced, despite the importance
of verifying the presence of certain taxa
in a specific space and time. To raise the
standards of documentation, we call for
all scientific journals to require authors to
deposit their audiovisual recordings in sci-
entific collections or online repositories, just
as they do for specimens, DNA sequences,
and even raw data.
Luís Felipe Toledo,1* Cheryl Tipp,2
1Fonoteca Neotropical Jacques Vielliard, Unicamp,
Campinas, 13083-970, Brazil. 2British Library, London,
NW1 2DB, UK. 3Fonozoo, Museo Nacional de Ciencias
Naturales-CSIC, Madrid, 28006, Spain.
*Corresponding author. E-mail: email@example.com
Tyranny of trees in
TREE PLANTING, FIRE suppression, and
exclusion of megafaunal herbivores (native
or domestic) are ecologically reasonable
restoration strategies in deforested landscapes, but similar interventions can be
catastrophic when applied to grassy biomes
such as grasslands, savannas, and open-canopy woodlands (1). As hopes grow that
carbon payment schemes will finance forest
restoration (2), we must clearly distinguish
between “reforestation”—planting trees
on deforested land—and “afforestation”—
converting historically nonforest lands to
forests or tree plantations (3). Afforestation
of grassy biomes can severely compromise
ecosystem services, including hydrology (4)
and soil nutrient cycles (5), and markedly
reduce biodiversity (6).
Despite these high environmental costs,
grassy biomes, particularly those with
seasonally dry tropical climates, are prime
targets for carbon sequestration programs
that emphasize tree planting (1, 7). Threats
of afforestation and agricultural conversion
are exacerbated because the grassy biomes
are not formally recognized by the United
Edited by Jennifer Sills
Bighead carp threaten native species in China.