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Endangering the Endangered: The Effects of Perceived Rarity on Species Exploitation

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Classifying species by threat status can result in conservation benefits such as increased protection, but can also be an incentive to hunters responding to increased consumer demand for goods perceived to be rare, and therefore valuable. Bioeconomic theory provides a framework for examining the population consequences of differing responses of consumers (demand) and hunters (supply) to perceived rarity. We present a series of illustrative case studies of how perceived rarity affects consumer behavior and hunting pressure, and use a model to explore the scenario of most conservation concern (where rarity itself fuels increased exploitation). Rarity-fuelled demand can have two undesirable outcomes: the species may become trapped at a low population size, or escalating hunting effort may drive the species to extinction. Understanding the response of consumers and hunters to perceived rarity is vital for predicting the impact of intervention strategies that seek to minimize extinction risk.
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LETTER
Endangering the endangered: The effects of perceived
rarity on species exploitation
Richard J. Hall1, E. J. Milner-Gulland2, & F. Courchamp1
1Laboratoire d’Ecologie, Syst ´
ematique et Evolution, UMR CNRS 8079, Universit ´
e Paris-Sud, 91405 Orsay Cedex, France
2Division of Biology, Imperial College London, Silwood Park Campus, Manor House, Silwood Park, Buckhurst Road, Ascot, Berks SL5 7PY,
United Kingdom
Keywords
Open access hunting; poaching; supply;
demand; extinction; bioeconomic model.
Correspondence
Richard J. Hall, Laboratoire d’Ecologie,
Syst ´
ematique et Evolution, UMR CNRS 8079,
Universit ´
e Paris-Sud, 91405 Orsay Cedex,
France. Tel: +33 1 69 15 5693; fax: +3316915
5696. E-mail: dr.richard.hall@gmail.com
Received 30 March 2008; accepted 1 April 2008
doi: 10.1111/j.1755-263X.2008.00013.x
Abstract
Classifying species by threat status can result in conservation benefits such
as increased protection, but can also be an incentive to hunters responding
to increased consumer demand for goods perceived to be rare, and therefore
valuable. Bioeconomic theory provides a framework for examining the popu-
lation consequences of differing responses of consumers (demand) and hunters
(supply) to perceived rarity. We present a series of illustrative case studies of
how perceived rarity affects consumer behavior and hunting pressure, and use
a model to explore the scenario of most conservation concern (where rarity
itself fuels increased exploitation). Rarity-fuelled demand can have two unde-
sirable outcomes: the species may become trapped at a low population size, or
escalating hunting effort may drive the species to extinction. Understanding
the response of consumers and hunters to perceived rarity is vital for pre-
dicting the impact of intervention strategies that seek to minimize extinction
risk.
Introduction
The world is facing an extinction crisis (Ceballos &
Ehrlich 2002; Thomas et al. 2004). Organizations such
as IUCN produce lists of species ranked by threat sta-
tus, which are used to prioritize conservation interven-
tions such as regulation of human activities which impact
on these species’ survival. In spite of local enforcement
and international trade restrictions, hunting (here refer-
ring broadly to killing or the collection of live specimens
from wild populations) continues to threaten many en-
dangered animal and plant species (Bulte & Van Kooten
1999; Seidensticker et al. 1999; Davenport & Ndangalasi
2003; Gonzalez 2003; Haitao et al. 2007). To design ef-
fective strategies to deter hunting of threatened species,
there is a pressing need to identify the social and eco-
nomic forces that maintain its profitability, and the con-
sequences for the exploited population.
It is a well-established economic principle that peo-
ple value objects for their rarity—the rarer an item is,
the more desirable it becomes (Ekelund & Herbert 1997).
Owning rare goods increases a consumer’s social status,
since their acquisition may require such perceived at-
tributes such as money, power, skill, and endurance. This
value in rarity extends to products derived from species
perceived to be rare, and there are thriving markets—
legal and illegal—in exotic pets (Slone et al. 1997), hunt-
ing trophies (Baldus & Cauldwell 2004), and luxury
goods such as caviar (Raymakers 2002) to name but a
few. Worryingly, there is increasing evidence that traders
use the threat status of certain species, as indicated by
their listing in appendices of the Convention on Interna-
tional Trade in Endangered Species of Wild Fauna and
Flora (CITES; Rivalan et al. 2007), or the description of
species new to science (Stuart et al. 2006) to capitalize
on increased consumer interest in rare items. Courchamp
et al. (2006) hypothesized that if consumers place dispro-
portionate value on rare species, this could result in a cy-
cle in which increased exploitation further reduces the
population size, which in turn increases its value and ul-
timately leads to its extinction in the wild—a process they
termed the “anthropogenic Allee effect.”
Conservation Letters 1(2008) 75–81 c
2008 Blackwell Publishing, Inc. 75
Effects of rarity on exploitation R.J. Hall et al.
Supply and demand curves provide a means of formal-
izing consumer and hunter behavior within an economic
context, by representing the quantity hunters are pre-
pared to provide to the market at a given price (supply)
and the quantity consumers are willing to buy at a given
price (demand). Here we investigate how these curves
may shift in relation to changes in a species’ perceived
rarity, and outline a number of illustrative case studies.
We then focus on the case of highest conservation con-
cern, that is, where rarity-fuelled demand sustains hunt-
ing targeted at a single, vulnerable species. We investigate
possible consequences for a population subject to open-
access exploitation, when the price per unit catch and the
cost per unit hunting effort depend on the species’ per-
ceived rarity. If increased demand for rare species causes
a jump in their market price, increased hunting pressure
may trap the species at a dangerously low population size.
If demand continues to climb as the species declines, an
ever-increasing market price can offset rising hunter costs
and result in species extinction through an anthropogenic
Allee effect. We conclude with a discussion of the rela-
tive merits of possible intervention strategies designed to
avoid such outcomes, and highlight some “warning sig-
nals” to enable conservationists to detect rarity-fuelled
exploitation.
Perceived rarity, supply, and demand
While a species’ “true” rarity suggests a low popula-
tion size, human perception of rarity is skewed and
scale-dependent: a species may be considered to be rare
if it is widespread but at low densities throughout its
range (e.g., large carnivores), found only in few locations
(e.g., island endemics), locally scarce but more numer-
ous elsewhere (e.g., brown bear in western Europe versus
Alaska), or rarely encountered due to secretive behav-
ior or inaccessible habitat. Additional cues for a species’
rarity arise indirectly through threat listing by a conser-
vation organization, and the associated publicity (wildlife
documentaries, fundraising campaigns) and management
actions (trade restrictions, antipoaching patrols). Here we
discuss how different aspects of perceived rarity affect the
supply of wild specimens to the market by hunters and
consumer demand.
The supply curve describes the relationship between
the quantity of a good provided to the market and its
price. For an exploited population, this curve is typically
backward bending (Figure 1), reflecting the fact that in-
creasing hunting effort increases the quantity provided
to the market, up to a point (the maximum sustainable
yield), after which further increases in effort actually re-
duce the quantity provided in the long term (overex-
Figure 1 Supply (bold) and demand (dashed) curves for an exploited
population. The shaded sections of the curves are those that are most
affected by perceived rarity, when the quantity provided to the market is
necessarily limited. The arrows represent the direction of a shift and/or
change in elasticity for each curve, and the adjacent numbers refer to
the analogous economic processes described in Tables 1 and 2. Further
details on the theory underlying the backward-bending supply curve for
a population subject to open access exploitation can be found on pages
131–132 of Clark (1990).
ploitation). The upper branch of the supply curve ac-
counts for the effect of “real” rarity (i.e., a small popu-
lation size) on exploitation: rising hunter costs per unit
catch through increased search times result in higher
prices and lower offtake (Clark 1990). In general, the
slope (elasticity) of this part of the curve will be steep
because most species become harder to find at low pop-
ulation sizes; however, animal behavioral responses can
result in local increases in catchability with rarity (see ex-
amples in Table 1), resulting in a shallower slope and an
increased risk of extinction via exploitation.
A species’ perceived rarity will also affect supply, if con-
servation measures are implemented to increase hunter
costs directly through antipoaching patrols and the threat
of fines/jail sentences, or indirectly by increasing the op-
portunity costs of hunting (i.e., through the provision
of more profitable alternative livelihoods; Table 1). In-
creasing hunter costs following a declaration of rarity
should shift the supply curve upwards and increase its
steepness, thus reducing extinction risk (Figure 1). How-
ever, theoretical studies have suggested that conserva-
tion efforts such as increasing supply from sustainable
sources or increasing the opportunity cost of hunting can
have ambiguous effects on hunting pressure. Damania
et al. (2005) suggest that while increased profitability of
agriculture may shift the allocation of labor from hunt-
ing to farming, increased income enables the purchase
of more efficient hunting equipment, in which selective
hunting worsens the conservation status of some species.
Equally, wildlife farming may prevent or stimulate illegal
76 Conservation Letters 1(2008) 75–81 c
2008 Blackwell Publishing, Inc.
R.J. Hall et al. Effects of rarity on exploitation
Table 1 Summary of the effects of perceived rarity on hunting pressure. Hunting offtake is affected both directly by the scarcity of the hunted species
and indirectly via changes to hunting costs and efficiency induced by conservation interventions. The expectation is that increasing costs per unit catch
(via reduced catch per unit effort and/or increased cost per unit hunting effort) will tend to decrease hunting effort, while price rises lead to increased
effort.
Effect of rarity Consequences for hunting Example
1.1. Reduced stock leads to reduced
offtake
Hunter costs per animal caught are rising (normal
bioeconomic process)
Fisheries, e.g., herring (Bjorndal Conrad 1987)
1.2. Rarity prompts conservation efforts to
directly reduce hunting effort
Hunter costs rise more than proportionally to
changes in stock size
Anti-poaching patrols and penalties, e.g., black
rhinos (Leader-Williams et al. 1990)
1.3. Rarity prompts conservation efforts to
reduce hunting effort by promoting
alternative livelihoods for hunters
Opportunity cost of hunting increases (but
increased income could increase hunter
efficiency, so effects on offtake not obvious)
Profits from managed trophy hunting passed to
local community, e.g., project CAMPFIRE,
Zimbabwe (Bond 2001); COMACO project,
Zambia (www.itswild.org)
1.4. Rarity prompts trade restrictions in
goods derived from the exploited
species
Limited sales opportunities may reduce long-term
incentive to hunt, but pre-enforcement hunting
effort may increase
Spike in trade in animals in the year prior to CITES
uplisting (Rivalan et al. 2007)
1.5. Aggregation or avoidance behavior of
species changes at lower population
sizes
Local changes in Catch Per Unit Effort (CPUE), may
also be associated with a change in hunter
costs per unit effort, so effects on offtake not
obvious
Avoidance behavior reduces CPUE, e.g., tuna
(Walters 2003); animals aggregate in protected
areas which may increase CPUE, e.g., northern
cod (Rose & Kulka 1999)
hunting, depending on market conditions (Bulte & Da-
mania 2005). Nonetheless, empirical support for the neg-
ative effects of these conservation interventions remains
scarce, and farming has had some notable successes in
controlling the exploitation of wild populations, such as
the Nile crocodile (Thorbjarnarson 1999).
The demand curve describes the relationship between
the quantity on the market and the price consumers are
willing to pay; in general, the price increases with market
scarcity (Figure 1) and the steepness (elasticity) of this
relationship depends on the availability of acceptable al-
ternatives. A species’ perceived rarity can affect consumer
decisions in various ways (Table 2). Demand for prod-
Table 2 Summary of the possible effects of perceived rarity on consumer behavior, as represented by the changes in the quantity purchased at given
price (demand). In standard economic theory, the expectation is that price rises lead to reductions in the quantity demanded.
Effect of rarity Consequences for demand Examples
2.1. No obvious effect/minor effect of
rarity; substitutes are available
Standard demand curve, consumers buy less at
increased prices
Bushmeat hunting in West Africa (East et al. 2005;
Wilkie & Godoy 2001)
2.2. No close substitutes for the good;
demand remains high when species
is rare
Highly inelastic demand curve; price rises do not
deter buyers
Specialist collections, e.g., butterflies (Slone et al.
1997); ingredients for traditional medicine, e.g.,
bahaba (Sadovy & Cheung 2003)
2.3. Rarity itself makes the species more
desirable
Demand curve shifts upwards and/or becomes
less elastic as population declines
Trophy hunting, e.g., Caprinae (Courchamp et al.
2006); Luxury goods, e.g., caviar (Raymakers
2002)
2.4. Conservation measures target
consumers to reduce demand for
wild stock
Demand decreases or remains elastic when the
species is rare
Consumer awareness campaigns and legal trade
bans, e.g., ivory (Bulte & van Kooten 1999)
2.5. Rarity prompts conservation
measures to supply sustainable
alternatives
Saturation of market with an ethical alternative
reduces demand for wild-derived product
Captive breeding, e.g., bulbs of Galanthus spp.
(Entwistle et al. 2002)
ucts derived from a locally scarce population of a hunted
species will be low if it is more abundant elsewhere (re-
sulting in a flat, or elastic demand curve, Figure 1). How-
ever, prices may increase sharply with declining mar-
ket availability for globally endangered species, especially
for consumer groups for which no acceptable alternative
products are available (e.g., collectors of specimens and
exotic pets, luxury products such as caviar). A species’
perceived rarity may stimulate conservation efforts tar-
geted at reducing consumer demand, including owner-
ship restrictions, awareness campaigns appealing to con-
sumer ethics, or the provision of sustainable alternatives
through captive breeding (note, however, that the latter
Conservation Letters 1(2008) 75–81 c
2008 Blackwell Publishing, Inc. 77
Effects of rarity on exploitation R.J. Hall et al.
can stimulate illegal hunting; Clayton et al. 2000; Bulte &
Damania 2005).
Population consequences
of rarity-fuelled demand
Here we focus on the case of most conservation concern,
that is, where a species’ perceived rarity fuels increased
consumer demand. Proxies for a species’ rarity such as
threat listing by a conservation organization can be per-
ceived as official verification that it is a “limited edition”
(Rivalan et al. 2007). This can increase consumer demand
if ownership of scarce goods conveys social status, or if
consumers believe that this is their last chance to obtain
specimens before the species goes extinct. If rare species
attract sufficiently high market prices, this may stimulate
hunting in spite of rising hunter costs.
We investigated the population consequences of rarity-
fuelled hunting using the classic Gordon–Schaefer model
for open-access exploitation (Gordon 1954; see also leg-
end of Figure 2). Open-access exploitation assumes that
hunters are subject to no restrictions, and has there-
fore been widely applied to species that are weakly pro-
tected by law, where hunting restrictions are weakly
enforced and to poaching (Milner-Gulland & Leader-
Williams 1992; Bulte 2003; Ling & Milner-Gulland 2006).
Figure 2 The price (bold line) and cost (dashed line) as functions of popu-
lation size for a species subject to open-access exploitation; the population
is in equilibrium at the intersections of the price and cost curves, and the
stability of this equilibrium is denoted by S (stable) or U (unstable). Changes
in the exploited population size (x) and hunter effort (E) are described by
the Gordon–Schaefer model: dx/dt=rx(1 – x/K)–qEx;dE/dt=α(pqEx cE).
In the absence of exploitation, the population grows according to the lo-
gistic equation with rate rand carrying capacity K. The hunting offtake
is qEx, where the constant q describes the species’ catchability. Hunting
effort is proportional (with rate α) to the difference between the total price
for the quantity caught and the total cost of the associated hunting effort.
The price per unit catch is pand the cost per unit hunting effort is c;both
are assumed constant when the species is abundant, leading to a stable
population equilibrium. When the population declines below the critical
density x=xR, the cost jumps to a new (constant) value. In (a) the price
also jumps to a new fixed level below the rarity threshold, resulting in
the creation of a second stable equilibrium (a “poaching pit”). In (b), the
price increases continuously as the population declines, creating an un-
stable equilibrium below which (to the left of U) the species is hunted to
extinction (an anthropogenic Allee effect).
This model assumes that hunting effort increases when
the price for the amount caught outweighs the hunt-
ing costs, and decreases otherwise (responding to the
marginal change in profit). We also assume that the price
hunters receive is proportional to the market price; any
intermediate agents between the hunters and the market
keep a fixed percentage of the sale price and the rest is
passed on to hunters. Finally, we restrict our attention to
single-species hunts fuelled by the collections, exotic pets,
or luxury markets, while acknowledging that opportunis-
tic “bycatch” of rare species in multi-species hunts may
also pose a serious threat.
In the standard Gordon–Schaefer model, the price and
the cost per unit hunting effort are assumed to be inde-
pendent of the hunted population’s size. Here we relax
this assumption when the population size declines below
a “rarity threshold” (x=xR). Hunter costs per unit catch in-
crease as the population declines, but additionally we as-
sume that the costs per unit effort experience a jump at the
rarity threshold, reflecting increased risks of the hunter
being caught and penalized if antipoaching enforcement
is implemented.
We assume two different responses of price to per-
ceived rarity. First, increased consumer interest in the
species after a declaration of rarity can cause the market
price to jump to a higher fixed value; further price rises
78 Conservation Letters 1(2008) 75–81 c
2008 Blackwell Publishing, Inc.
R.J. Hall et al. Effects of rarity on exploitation
are prevented because alternatives from other wild or
captive-bred populations are available. Plotting the price
and cost per unit catch as functions of population size
enables the equilibrium population size under exploita-
tion to be determined (Figure 2a). When perceived rar-
ity results in a price jump, a stable equilibrium exists be-
low the rarity threshold; elevated levels of hunting trap
the species at a low population size (a “poaching pit”
sensu Bulte 2003), at which it is vulnerable to extinction
through stochasticity or natural Allee effects. Whether
the population can escape this “poaching pit” depends on
the reversibility of perceived rarity among consumers: a
species that has been declared rare may forever be asso-
ciated with rarity (and hence value), in which case the
“rare” population equilibrium becomes globally stable.
A second possible consumer response to a species’ per-
ceived rarity is demand inelasticity, where the price contin-
ues to increase as wild stocks and their market availability
decline (Figure 2b). If demand is sufficiently high that the
price increase outstrips the hunting costs at low popula-
tion sizes, an unstable equilibrium exists, below which
ever-increasing hunting effort leads to the species’ even-
tual extinction (an anthropogenic Allee effect sensu Cour-
champ et al. 2006). We have tacitly assumed a “best-case”
scenario for the species in the absence of hunting, that is,
the per capita population growth rate is positive at low
population sizes. This enables us to disentangle the direct
effects of rarity-fuelled hunting and to show when hunt-
ing pressure alone is sufficient to threaten species with
extinction. In reality, extrinsic factors such as habitat loss
may slow or prevent the species’ recovery from low pop-
ulation sizes so that the additional effect of hunting is se-
vere.
Under this scenario, the population size at which the
species is perceived as rare (xR) may itself become the ex-
tinction threshold, if elevated levels of hunting reduce the
species density into the range where other factors drive
it to extinction. Second, the approach to extinction may
be accelerated by the “double whammy” of natural de-
cline and a scramble by hunters to obtain the last few
specimens. This may explain the demise of the great auk
(Pinguinus impennis), where a combination of hunting and
climate change resulted in a declining population, but
it was a rush by museum collectors desperate to obtain
specimens that resulted in the death of the last known
individual (Fuller 1999).
Discussion
Human responses to a species’ perceived rarity can have
wide-ranging impacts on its population dynamics; the
benefits arising from increased protection and habitat
preservation are well documented, but the potential for
rarity itself to stimulate exploitation is just beginning
to be explored. The case studies presented in this arti-
cle have highlighted both the positive and negative ef-
fects of conservation measures designed at preventing
the extinction of rare species, while the modeling frame-
work has highlighted two alarming possible outcomes
for populations of species subject to rarity-fuelled ex-
ploitation, namely, that elevated hunting pressure may
drive the species to extinction, or trap it at a low pop-
ulation size where it is vulnerable to extinction from
other causes. Other bioeconomic models of hunting have
shown that species extinction can arise if the cost of find-
ing the last individuals is relatively low (Clark 1973),
or through bycatch in a multi-species system (Milner-
Gulland & Leader-Williams 1992), but this is the first ex-
plicit exploration of how human responses to perceived
rarity can further endanger species. While this article has
focused on the effects of hunting (removing individu-
als from wild populations) in response to perceived rar-
ity, it is possible that similar problems may arise through
wildlife watching, if some species face disproportionate
anthropogenic disturbance resulting from increased in-
terest in observing threatened species in the wild (Bain
2002).
Standard economic theory suggests that hunting pres-
sure can be reduced by increasing hunter costs (either
through increased risk of being caught and penalized,
or via the provision of alternative livelihoods). Clearly,
if such measures are to overcome rarity-driven price in-
creases, hunter costs need to increase at least as rapidly
as the price. Unfortunately, effective species protection
is often extremely costly (Burton 1999), and sufficient
funds for antipoaching enforcement may not be avail-
able, particularly if rare species attract high sale prices.
Increasing the opportunity cost of hunting by channeling
money gained from poaching fines and ecotourism into
local communities can reduce poaching (Martin 1986;
Lewis & Alpert 1997). However, when hunting is coordi-
nated by organized gangs, as is often the case for species
with a rarity-based cachet, such local methods are un-
likely to be as effective.
Given the high costs of protecting species, conserva-
tion strategies aiming to reduce consumer demand may
be a more effective solution. It is tempting to suggest
that withholding information on species abundance from
the public domain would avoid an increase in demand
triggered by a rarity effect. Aside from the moral and
technical difficulties of achieving this, a valuable op-
portunity for raising conservation funds driven by in-
creased public awareness of a species’ plight could be
lost. Nonetheless, increased regulation of the type of in-
formation available in the public domain is advisable. In
Conservation Letters 1(2008) 75–81 c
2008 Blackwell Publishing, Inc. 79
Effects of rarity on exploitation R.J. Hall et al.
Britain, information posted on the Internet by birdwatch-
ers eager to share unusual bird sightings has been used by
egg-collectors to locate and rob nests of protected species
(Thomas et al. 2001). Awareness campaigns by the Royal
Society for the Protection of Birds and local ornitholog-
ical societies have proved effective at promoting greater
self-regulation in the birding community when sharing
information on sensitive species.
Conservation interventions appealing to consumer
ethics provide another means to combat rarity-fuelled
demand. Changing the perception that it is fashion-
able or prestigious to own products derived from rare
species has met with some success in curbing demand
for products derived from ivory and fur in Europe and
the United States (Bulte & Damania 2005). The provision
of sustainable alternatives such as organized safari hunt-
ing or “green labeling” of sustainably hunted products
(Lindsey et al. 2007) can control demand for products
derived from wild populations. However, restricted le-
gal trade can stimulate an increase in illegal hunting if
hunters believe that a market exists for illegally derived
stocks (Bulte & van Kooten 1999; Clayton et al. 2000),
especially in market situations where a small number of
suppliers mediate purchases from hunters and supply to
consumers (Bulte & Damania 2005).
The exploration of factors affecting consumer de-
mand provides insight into determining those species that
might be most at risk from rarity-fuelled exploitation.
At-risk species include those that are undergoing well-
documented declines that are likely to result in them be-
ing assigned conservation status, especially in taxa that
are already popular in hobby collections, such as am-
phibians. Scarce species that have attributes for which
there may be no acceptable alternatives to consumers,
will also be particularly at risk. These attributes include
extreme size or morphology (e.g., the Goliath frog Con-
raua goliath), attractiveness or bright colors (e.g., the blue
poison frog Dendrobates azureus), a distinctive taste (caviar
from sturgeon species), or those perceived to have par-
ticular cultural significance or medicinal properties (e.g.,
American ginseng Panax quiquefolius). It is also hoped that
the analyses presented in this article will help conserva-
tionists to identify warning signals highlighting when a
species may be experiencing rarity-fuelled exploitation.
Careful monitoring at the time of a change in the species’
threat status is essential; for example, data on international
trade volumes during their uplisting in CITES appendices
has revealed an effect of rarity-fuelled demand (Rivalan
et al. 2007). Other potential warning signals include an
increase in numbers of poachers apprehended per unit of
antipoaching effort, evidence of increased buyer interest
in rare species (e.g., sharp rises in sale prices or hits on
wildlife trading websites), or behavioral changes in the
quarry species consistent with a response to hunting pres-
sure (e.g., increased vigilance or flocking).
Acknowledgments
R.J.H.wouldliketothanktheAgenceNationaledela
Recherche for funding, members of the Courchamp lab
for helpful discussions, and anonymous reviewers for
their useful comments.
References
Bain, D.E. (2002) A model linking energetic effects of whale
watching to killer whale (Orcinus orca) population
dynamics. Friday Harbor (Washington). University of
Washington Press.
Baldus, R., Cauldwell A. (2004) Tourist hunting and its role in
development of wildlife management areas in Tanzania.
Tanzanian-German Development Cooperation, Dar es
Salaam, Tanzania. Available from: http://www.wildlife-
programme.gtz.de/wildlife/download/hunting wma.pdf.
Accessed April 29, 2008.
Bjorndal, T., Conrad J. (1987) The dynamics of an
open-access fishery. Can J Econ 20, 74–85.
Bond, I. (2001) CAMPFIRE and the incentives for
institutional change. In D. Hulme, M. Murphree editors.
African wildlife and livelihoods. James Currey, Oxford, UK.
Bulte, E.H. (2003) Open access harvesting of wildlife: the
poaching pit and conservation of endangered species. Agric
Econ 28, 27–37.
Bulte, E.H., Damania R.D. (2005) An economic assessment of
wildlife farming and conservation. Conserv Biol 19,
1222–1233.
Bulte, E.H., van Kooten G.C. (1999) Economic efficiency,
resource conservation and the ivory trade ban. Ecol Econ
28, 171–181.
Burton, M. (1999) An assessment of alternative methods of
estimating the effect of the ivory trade ban on poaching.
Ecol Econ 30, 93–106.
Ceballos, G., Ehrlich P.R. (2002) Mammal population losses
and the extinction crisis. Science 296, 904–907.
Clark, C.W (1973) Profit maximization and the extinction of
animal species. J Polit Econ 81, 950–961.
Clark, C.W. (1990) Mathematical bioeconomics: optimal
management of renewable resources, second edition.
Wiley, Hoboken, USA.
Clayton, L.M., Milner-Gulland E.J., Sinaga D.W., Mustari
A.H. (2000) Effects of a proposed ex situ conservation
program on in situ conservation of the babirusa, an
endangered suid. Conserv Biol 14, 382–385.
Courchamp, F., Angulo E., Rivalan P. et al. (2006) Rarity
value and species extinction: the anthropogenic Allee
effect. PLOS Biol 4, 2405–2410.
Damania, R., Milner-Gulland E.J., Crookes D.J. (2005) A
bioeconomic model of bushmeat hunting. Proc Royal Soc B
272, 259–266.
80 Conservation Letters 1(2008) 75–81 c
2008 Blackwell Publishing, Inc.
R.J. Hall et al. Effects of rarity on exploitation
Davenport, T.R.B., Ndangalasi H.J. (2003) An escalating trade
in orchid tubers across Tanzania’s southern highlands:
assessment, dynamics and conservation implications. Oryx
37, 55–61.
East, T., Kumpel N., Milner-Gulland E.J., Rowcliffe J.M.
(2005) Determinants of urban bushmeat consumption in
Rio Muni, Equatorial Guinea. Biol Conserv 126,
206–215.
Ekelund, R.B.J., Herbert R.F. (1997) A history of economic
theory and method. McGraw-Hill, New York, USA.
Entwistle, A., Atay S., Byfield A., Oldfield S. (2002)
Alternatives for the bulb trade from Turkey: a case study of
indigenous bulb propagation. Oryx 36, 333–341.
Fuller, E. (1999) The Great Auk. Harry N. Abrams, New York,
USA.
Gonzalez, J.A. (2003) Harvesting, local trade and
conservation of parrots in the Northeastern Peruvian
Amazon. Biol Conserv 114, 437–446.
Gordon, H.S. (1954) The economic theory of a common
property resource: the fishery. J Polit Econ 62, 124–142.
Haitao S., Parham J.F., Lau M., Tien-Hsi C. (2007) Farming
endangered turtles to extinction in China. Conserv Biol doi:
10.1111/j.1523-1739.2006.00623.x.
Leader-Williams, N., Albon S.D., Berry P.S.M. (1990) Illegal
exploitation of black rhinoceros and elephant populations:
patterns of decline, law enforcement and patrol effort in
Luangwa Valley, Zambia. J Appl Ecol 27, 1055–1087.
Lewis, D. M., Alpert P. (1997) Trophy hunting and wildlife
conservation in Zambia. Conserv Biol 11, 59–68.
Lindsey, P.A., Frank L.G., Alexander R., Mathieson A.,
Romanach S.S. (2007) Trophy hunting and conservation in
Africa: problems and one potential solution. Conserv Biol
21, 880–883.
Ling, S., Milner-Gulland E.J. (2006) Assessment of the
sustainability of bushmeat hunting based on dynamic
bioeconomic models. Conserv Biol 20, 1294–1299.
Martin, R.B. (1986) Communal Areas Management
Programme for Indigenous Resources (Project CAMPFIRE)
In R.H.V. Bell, E. McShane-Caluzi, editors. Conservation and
wildlife management in Africa. Peace Corps, Washington, D.C.
Milner-Gulland, E.J., Leader-Williams N. (1992) A model of
incentives for the illegal exploitation of black rhinos and
elephants: poaching pays in the Luangwa Valley, Zambia.
J Appl Ecol 29, 388–401.
Raymakers, C. (2002) International trade in sturgeon and
paddlefish species—the effect of CITES listing. Int Rev
Hydrobiol 87, 525–537.
Rivalan, P., Delmas V., Angulo E. et al. (2007) Can bans
stimulate wildlife trade? Nature 447, 529–530.
Rose, G.A., Kulka D.W. (1999) Hyperaggregation of fish and
fisheries: how catch-per-unit-effort increased as the
northern cod (Gadus morhua) decreased. Can J Fish Aquat
Sci 56 (Suppl. 1), 118–127.
Sadovy, Y., Cheung W.L. (2003) Near extinction of a highly
fecund fish: the one that nearly got away. Fish Fisheries 4,
86–99.
Seidensticker J., Christie S., Jackson P. (1999) Riding the
tiger. Cambridge University Press, Cambridge, UK.
Slone, T.H., Orsak L.J., Malver O. (1997) A comparison of
price, rarity and cost of butterfly specimens: implications
for the insect trade and for habitat conservation. Ecol Econ
21, 77–85.
Stuart, B.L., Rhodin A.G.J., Grismer L.L., Hansel T. (2006)
Scientific description can imperil species. Science 312,
1137.
Thomas, M., Elliott G., Gregory R. (2001) The impact of egg
collecting on scarce breeding birds 1982–1999. RSPB
Conserv Rev 13, 39–44.
Thomas, J.A., Telfer M.G., Roy D.B. et al. (2004) Comparative
losses of British butterflies, birds and plants and the global
extinction crisis. Science 303, 1879–1881.
Thorbjarnarson, J. (1999) Crocodile tears and skins:
international trade, economic constraints, and limits to the
sustainable use of crocodilians. Conserv Biol 13,
465–470.
Walters, C. (2003) Folly and fantasy in the analysis of spatial
catch rate data. Can J Fish Aquat Sci 60, 1433–1436.
Wilkie, D.S., Godoy R.A. (2001) Income and price elasticities
of bushmeat demand in lowland Amerinidian societies.
Conserv Biol 15, 761–769.
Editor: Dr. James Blignaut
Conservation Letters 1(2008) 75–81 c
2008 Blackwell Publishing, Inc. 81
... Plants and animals have been collected in the wild and exchanged for other items or services throughout all of human history (van Uhm, 2016). While wild populations can benefit from commercialization under specific conditions such as wildlife "farming" (Tensen, 2016), most populations suffer negative consequences either directly through over-exploitation (Hall et al., 2008) and the long-term evolutionary and ecological impacts of domestication (Mathews et al., 2005). Escaped domesticated individuals can also cause indirect negative impacts through pathogen transmission and causing shifts in shared habitats (e.g. ...
... facilitating the spread of invasive plants) (Mallinger et al., 2017;Graystock et al., 2015;Meeus et al., 2011). There are many examples of plants and animals that have been driven to the brink of extinction by the collection of specimens from wild populations (Hall et al., 2008), and several examples of species that were "saved" by domestication but now exist only as domesticated relatives to their wild progenitors (Petruzzello, 2020). While some "domesticated" species develop traits that make successful reintroduction into the wild unlikely (Kelley et al., 2006), frameworks are being continually tailored to maximize the potential for success (Seddon et al., 2007). ...
Article
Full-text available
Exploitation of insects and spiders through commercialization represents a serious threat to rare species and to common species that provide valuable ecological services. The speed, scope, and anonymity, of online commerce places full monitoring and managing of exploitation beyond the resources available to regulatory agencies. To assess the level of online commerce of insect and spider species and services and to test the feasibility of focused searches by student-specialists to generate “leads” for regulatory agencies to pursue, a group of entomology students lead by entomologists and wildlife biologists performed a directed search for sales of insect and spider species listed on CITES Appendices, the IUCN Red List, and the U.S. Endangered Species List, and species that provide services Focused searches by student-specialists proved effective, locating sales of 79 listed species across all lists. The proportion of listed species discovered for sale varied from 2% to 55% across protected lists and the sale prices of species varied from 2 to 3,850 USD. The number of listed species for sale also varied across platforms with less than 6 found on either Amazon or Alibaba and more than 30 found on Etsy and Ebay. In contrast to the listed species, numbers of insects and spiders sold to provide services can range in the billions of individuals and total sales can range in the millions USD. While all species for this purpose do provide a service, they each present unique risks to other species in their genera, guild, and to the larger ecological community, in some cases threatening ecological functions. To effectively monitor the impact of invertebrate service species, we propose incorporating these “livestock” into the existing regulatory framework used for vertebrates.
... Modern global trade of bêche-de-mer is driven by a contagious roving bandit syndrome whereby sea cucumbers are fished increasingly further away from their main market in China as nearby stocks are depleted (Anderson et al., 2011; with the most valuable species at the greatest risk of exploitation and extinction (Branch et al., 2013). As species become rarer over time due to high price, they become locally extinct and unable to repopulate (Hall et al., 2008;Purcell et al., 2014). The tropical bêche-de-mer fishery is of great socioeconomic importance as the main source of income for many fishing communities in developing nations because the dried product can be produced without sophisticated infrastructure and stored without refrigeration (Nash and Ramofafia, 2006;Purcell et al., 2013;Muthiga and Conand, 2014). ...
... Shifts away from an exploitative focus should be adopted, most critically for CITES and IUCN-listed species. Further, managers should ensure protection of high-value, at-risk species to avoid supporting pathways of opportunistic exploitation, whereby exploitation of abundant low-value species facilitates continued opportunistic depletion of rare high-value species (Fig. 8) an underappreciated pathway to extinction in global ecology (Hall et al., 2008;Branch et al., 2013). Specifically, for sea cucumbers within the Queensland fishery (with relevance elsewhere), we suggest the following: ...
Article
Tropical sea cucumbers are in peril due to overharvest. Sixteen species are endangered or vulnerable (IUCN) with high-value teatfish recently listed on CITES Appendix II. In light of these listings, we review the Queensland Sea Cucumber Fishery, which harvests CITES-listed black teatfish (Holothuria whitmaei) and white teatfish (H. fuscogilva), and other IUCN-species, from the Great Barrier Reef (GBR), Australia. Teatfish harvest on the GBR has experienced serial catch reductions and fishery closure due to local depletion, a trend observed globally for sea cucumbers and of concern for the at-risk GBR World Heritage Area. We provide the first case study for teatfish while their trade continues, and highlight other species of concern. The major target species of the fishery, Actinopyga spinea (~ 50% of total catch), is not a traditional species in the global trade. With over one million individuals harvested annually, its fishery and its ecological consequences require attention. We synthesise knowledge on teatfish population parameters, identify knowledge gaps and suggest measures to reduce fishery impacts. Continued global exploitation of at-risk marine invertebrate species, coupled with scientific uncertainties, emphasise the urgent need for targeted research and to apply the precautionary principle to avoid detrimental outcomes in their conservation status.
... However, while the most advertised species are allowed for exploitation, species whose exploitation is prohibited fetch higher prices. This higher price of forbidden species is in line with Hall et al. (2008) and Moorhouse et al. (2017), who pointed out that restrictions on trade and the threatened status of certain species can increase their desirability among consumers. This attribution of greater value to rare species by consumers may trigger a process that Courchamp et al. (2006) called the "anthropogenic Allee effect". ...
... This attribution of greater value to rare species by consumers may trigger a process that Courchamp et al. (2006) called the "anthropogenic Allee effect". Such a process is based on a vicious cycle in which the demand for a rare species increases its exploitation and decreases its population, making the species even rarer and, consequently, more desired, which may culminate in its extinction in nature (Hall et al., 2008). ...
Article
Social media platforms have increasingly played an influential role in boosting the online wildlife trade, by providing an easily accessible way to share information, advertise specimens, and arrange sales. We investigate how the online trade in freshwater and marine fishes for ornamental purposes operates through social media in Brazil, aiming to gain an understanding of the characteristics of that trade, and of the actors operating in it. A six-month monitoring of advertisements posted on Facebook groups was conducted, through which we recorded 1121 posts announcing the sale of ornamental fishes, totaling 5005 specimens belonging to at least 608 species, 66% of which were non-native to Brazil and 25% forbidden to be traded by national legislation. For freshwater fishes, native species were the most advertised and at a lower number of specimens/ad than marine fishes, which, conversely, mostly comprised non-native species. We found that higher prices were associated with non-native, prohibited, and large-sized species. Brazil is both an important commercial market for ornamental fishes, and one of the top countries for the use of social networks. Therefore, it may lend itself as a useful case-study that can help increase our general understanding of the functioning of the online wildlife trade. The high number of ads and species involved recorded, coupled with the potential offered by the online trade to increase unmonitored and unregulated sales are significant issues that need to be addressed by national environmental agencies and social media platforms.
... However, while the most advertised species are allowed for exploitation, species whose exploitation is prohibited fetch higher prices. This higher price of forbidden species is in line with Hall et al. (2008) and Moorhouse et al. (2017), who pointed out that restrictions on trade and the threatened status of certain species can increase their desirability among consumers. This attribution of greater value to rare species by consumers may trigger a process that Courchamp et al. (2006) called the "anthropogenic Allee effect". ...
... This attribution of greater value to rare species by consumers may trigger a process that Courchamp et al. (2006) called the "anthropogenic Allee effect". Such a process is based on a vicious cycle in which the demand for a rare species increases its exploitation and decreases its population, making the species even rarer and, consequently, more desired, which may culminate in its extinction in nature (Hall et al., 2008). ...
Article
Social media platforms have increasingly played an influential role in boosting the online wildlife trade, by providing an easily accessible way to share information, advertise specimens, and arrange sales. We investigate how the online trade in freshwater and marine fishes for ornamental purposes operates through social media in Brazil, aiming to gain an understanding of the characteristics of that trade, and of the actors operating in it. A six-month monitoring of advertisements posted on Facebook groups was conducted, through which we recorded 1121 posts announcing the sale of ornamental fishes, totaling 5005 specimens belonging to at least 608 species, 66% of which were non-native to Brazil and 25% forbidden to be traded by national legislation. For freshwater fishes, native species were the most advertised and at a lower number of specimens/ad than marine fishes, which, conversely, mostly comprised non-native species. We found that higher prices were associated with non-native, prohibited, and large-sized species. Brazil is both an important commercial market for ornamental fishes, and one of the top countries for the use of social networks. Therefore, it may lend itself as a useful case-study that can help increase our general understanding of the functioning of the online wildlife trade. The high number of ads and species involved recorded, coupled with the potential offered by the online trade to increase unmonitored and unregulated sales are significant issues that need to be addressed by national environmental agencies and social media platforms.
... a saviour or a risK factor? Naturally rare species, or morphs of species, may suffer more from exploitation, as consumer demand makes them more attractive than standard varieties (Courchamp et al. 2006;Hall et al. 2008;Dee et al. 2019a). Price premiums also reflect perceived rarity and thus can drive markets for collection in the wild (Rhyne et al. 2012b). ...
... Further, the spatial distribution of rare species also can provide insights into the areas that should be prioritized. Although the SMBC region varies weakly in diversity, PESM-NSV and PECB embrace more taxonomic and phylogenetic diversity, and a larger parcel of rare species that typically can cocorrespond to more exploited species (Hall et al., 2008). On the other hand, if conservation decision-making emphasizes a functional approach, ecological research indicates that areas to be prioritized are those that have high functional diversity (e.g., evenness, divergence, dispersion, and/or redundancy). ...
Article
Conservation decision is a challenging and risky task when it aims at prioritizing species or protected areas (PAs) to prevent extinction while ensuring fair treatment of all stakeholders. Better conservation decisions are those made upon a broader evidence base that includes both ecological and social considerations. However, in some of the most biodiverse ecosystems on Earth — tropical forests, for instance — multicriteria decision-making has been constrained by the following (i) ecological and social datasets available have been obtained in an independent, non-integrated manner, with social data typically more scarce than ecological ones, and (ii) capacity in social and/or interdisciplinary data analysis among decision-maker is limited. We describe a conservation prioritization exercise that combined findings from independent ecological and social research conducted in the Brazilian Atlantic Forest, and propose methods to integrate, analyze and visualize data. We found that the outcomes based on combined ecological and social research findings were, in some cases, different from those based on any of these lines of evidence alone. Indeed, the input from relatively basic social research significantly changed the outcomes of decision-making based on the results of ecological research. Results corroborate the importance and cost-effectiveness of broadening the interdisciplinary evidence base for conservation decision-making, even when social data is scarce and analytical capacity is limited.
... A demand escalating to "dangerous levels" as described by Biggs et al. is taken to mean that the aggregate demand exceeds the legal supply to the extent that poaching to supply the residual demand will increase to a level driving population decline. However, there are a number of factors in addition to legality that may modify demand, including most notably price and rarity of the product (Hall et al., 2008), availability and price of substitute products (Chen and 't Sas-Rolfes, 2021) and consumer preferences about quality and attention to animal welfare (Wyatt et al., 2021;Hanley et al., 2017), as well as consumer income, use and perceived need for rhino horn (Dang and Nielsen, 2018;Hinsley and 't Sas-Rolfes, 2020). Building an economic model of trade in endangered species products, Fischer (2004) argued that two demand externalitiesstigma and outrageimpact the utility of using such products. ...
Article
Full-text available
A legal rhino horn trade is suggested in order to reduce poaching. To examine the implications of this proposition, we conducted a choice experiment with 345 rhino horn consumers in Vietnam, investigating their preferences for legality, source, price and peer experience of medicinal efficacy as attributes in their decision to purchase rhino horn. We calculated consumers' willingness to pay for each attribute level. Consumers preferred and were willing to pay more for wild than semi-wild and farmed rhino horn but showed the strongest preference for legal horn, although higher-income consumers were less concerned about legality. The number of peers having used rhino horn without positive effect reduced preference for wild-sourced horn and increased preference for legality. Our results suggest that a legal trade in rhino horn would likely continue to face competition from a parallel black market. Whether poaching would be reduced depends on the legal supply of wild and semi-wild horns, campaigns ability to change consumer preferences, and regulation efforts.
... Non-native populations of threatened species have the potential to be exploited and therefore the subject of legal protection, and may be targeted for trophies, meat, or as part of the pet or timber trade [2][3][4]. In Australia, a number of ungulate species were introduced by Acclimatisation Societies in the nineteenth century are now threatened with extinction in their native range; rusa deer (Rusa timorensis) and sambar deer (Rusa unicolor) are listed as vulnerable by the IUCN, while banteng (Bos javanicus) and hog deer (Axis porcinus) are listed as endangered. ...
Article
Full-text available
Background: The establishment of non-native populations of threatened and legally protected species can have many implications for the areas where these species have been introduced. Non-native populations of threatened species have the potential to be exploited and therefore the subject of legal protection, while conversely, if they have become invasive in their introduced range, there is the likelihood that population control will be carried out to reduce abundance and negative impacts associated with introduced species. From both a legal and invasive species monitoring standpoint, it is important to know how many individuals are present. Methods and results: Short tandem repeats (STRs) were developed for the hog deer, an endangered species that was introduced following European settlement to Victoria, Australia using Illumina MiSeq sequencing technology. These markers were combined with previous STRs characterised for hog deer to create a 29-plex identification system. A total of 224 samples were genotyped across the population in Victoria, and further analyses of null allele frequencies, deviation from Hardy-Weinberg equilibrium, and the removal of monomorphic or low amplifying markers resulted in a final marker panel of 15 loci. Despite low values for number of alleles at each locus (2-4), probability of identity showed sufficient discrimination power, with an average probability of identity at 2.94 × 10-6, and a probability of sibling identity of 8.9 × 10-4 across all sites. Conclusions: It is feasible to create an informative DNA profiling system that can distinguish between individuals for applications in both wildlife forensic and population control research.
Technical Report
Full-text available
The purpose of this brief is to summarize the findings of an investigation into the effectiveness of policy interventions aimed at addressing the illegal and unsustainable trade in wildlife and wildlife products. Such interventions include (but are not limited to): legislative and enforcement measures; measures to influence consumer behaviour; trade policy responses; and engagement of local communities. The scope of analysis includes both domestic and international wildlife trading activities but is limited to those that are officially designated as illegal in one or more jurisdictions.
Article
Full-text available
Misinterpretations of elevated catch-per-unit-effort (CPUE) in the northern cod (Gadus morhua) fishery contributed to overestimations of stock size, inflated quotas, and unsustainable fishing mortality in the 1980s and early 1990s. We hypothesize that concentration of the fish and fishery led to extreme hyperstability in the CPUE–abundance relationship. In the late 1980s, migrant cod began to concentrate within the Bonavista corridor, their most southerly cross-shelf migration route. By the spring of 1990, approximately 450 000 t was concentrated within 7000 km2at densities quadruple those of the 1980s. Densities remained high through 1992, while abundance declined fivefold. During this period, cod hyperaggregated (local densities increased with decreasing biomass) in the Bonavista corridor and CPUE increased. To the north, no hyperaggregation occurred, and densities and CPUE declined with biomass. In the Bonavista corridor from 1990 to 1993, CPUE was hyperstable with local cod density. Areas of high cod densities (>0.1 fish·m–2) shrunk as regional estimates of cod biomass declined. The spatial extent of the fishery contracted proportional to the shrinkage in area occupied by the fish. Hence, CPUE was related to abundance at the local scales of a fishing set (local acoustic density) but not to abundance at regional or stock scales.
Book
Comprehensive survey of the development of economic analysis from earliest times to the present.
Article
We extend the traditional G-S model of open access by defining a non-concave harvesting function. We demonstrate the possible existence of multiple equilibria and perverse comparative statics and show that small changes in the underlying economic parameters may trigger large jumps in species' abundance. Finally, we briefly discuss implications for management.
Article
This study models the relationships between financial gains, detection and penalties for poaching rhinos and elephants in Luangwa Valley, Zambia during 1979-85. It explores how sentencing strategies affect the decisions of poachers in relation to changes in detection rate, penalty and economic variables. A penalty which varies with the output of a poacher is, in theory, a more effective tool against poaching than a fixed penalty. However, the probability of capture is a highly significant factor in the poacher's decision to hunt. Organized and local gangs have very different reactions to law enforcement. Local poachers will respond to local investment schemes, but the deterrence of organized gangs can only be achieved with improved law enforcement operations. -from Authors
Article
Since 1 April 1998, the international trade in Acipenseriformes (25 species of sturgeon and 2 paddlefish) is monitored and controlled under CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). CITES trade data for 1998 suggest that the international trade in caviar is substantial, totalling 275 tonnes, and dominated by a few nations: 95% of the caviar is exported and imported by less than 20 countries. The 1998 world exports, as reported by CITES Parties, also included 44.6 tonnes of sturgeon meat and 0.5 million live specimens (juveniles and fertilised eggs) of sturgeon and paddlefish. Data analysis and consultation with relevant authorities and traders indicate that CITES listing of all Acipenseriformes has resulted in better monitoring and control of the international trade of these species. Range states were recommended to establish annual export quotas for specimens and products of Acipenseriformes, but the scientific bases for setting these quotas are often unclear and would benefit from verification by independent experts. This mechanism was initiated following the decision adopted in April 2000 of incorporating Acipenseriformes in the Significant Trade Review of CITES. Primary results concluded that for six species (Acipenser gueldenstaedti, A. nudiventris, A. schrencki, A. stellatus, Huso huso and H. dauricus) the provisions of CITES were not implemented properly by range States and international trade may therefore be detrimental to the survival of wild populations. Under the Significant Trade Review CITES has the capacity to influence the conservation strategy implemented by exporting countries that are Parties to the Convention. It is an on-going process that will continue as long as the CITES forum considers that ranges States do not comply with CITES provisions.
Article
Abstract It is widely assumed that commercial fisheries of highly fecund species are particularly resilient to exploitation, and that, should populations become seriously diminished, economic constraints will force fishing to cease before biological extinction can occur. Indeed, among commercially exploited marine fishes there is not one confirmed global extinction. Here we document, using nonconventional means, a story that not only questions such assumptions but that should also alert us to how little we know about significant fisheries in some parts of the world. Our case study is that of the highly threatened Chinese bahaba, Bahaba taipingensis, a member of the Sciaenidae (the drums or croakers), and an example of a fecund and commercially important group of fishes that appears to be especially vulnerable to fishing. We also demonstrate that the careful use of informal, or traditional, information can provide a powerful, sometimes unique, means of identifying and assessing the status and history of species that might be quietly slipping away before we learn anything about them.
Article
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