INTRUDUCTION OF EXOTIC SPECIES
IN INDIAN AQUACULTURE
Presented by:
Name: Krishna
M.F.Sc. 2nd Sem.
Dept. of Aquaculture
College of fisheries,
(JAU), Veraval - 362265

INTRODUCTION
 Exotic fish is alien species which is not naive and belonging by nature or origin to
another part of the world or brought in from abroad or foreign or strange.
 The use of exotic species for fisheries and aquaculture diversification has been
practiced since the middle of the 19th century.
 Several exotic species have been introduced in the Indian waters and some are now
well established too with varying experiences.
 Examples: Salmo gairdnerii, Pangasius sutchi,
Cyprinus carpio, O. niloticus, H. molitrix,
G. affinis, L. vannamei etc.

Cont…
 The recent illegal introduction of South American catfish (Pterygoplichthys
anisitsi) and Pacu (Piaractus brachypomus) was recorded by NBFGR from river
Ganga and river Periyar.
 Accidental escapes and even purposeful releases of aquaculture species that are
not native to a country create “biological pollution” with irreversible and
unpredictable ecological impacts.

S. No. Common name Species Year of
introduction
Source
1. Common carp C. carpio 1980 Srilanka
2. Bighead carp A. nobilis 1959 Bangladesh
3. Golden carp C. carassius 1968, 1970 England
4. Doctor fish T. Tinca 1974 England
5. tilapia O. mossambica 1972 Bangkok
6. Nile Tilapia O. niloticus 1952 Thailand, Isreal
7. African Catfish C. gariepinus 1978 Thailand
8. Brook trout S. fontinalis 1959 Canada
9. Pangasius sutchi P.
hypophthalamus
1997 Vietnam
10. White leg shrimp L. vennamei 2010 USA
EXOTIC SPICIES IN INDIAN
AQUACULTURE

Source: Raman R.P. et. al, 2013

TRAITS OF EXOTIC SPICIES
 Many features have been attributed to invasive species and invaded ecosystem.
 The common invasive species traits include:
 Fast growth
 Rapid reproduction
 Phenotypic plasticity
 Tolerance of a wide range environmental condition
 Ability to live of a wide range of food type

INTRODUCTION OF NEW SPECIES
Artificial
introduction
Occasional
introduction
Conditions that
lead to
establishment of
exotic species
Species-based
mechanism
Superior
Competition

ARTIFICIAL INTRODUCTION
 The introduction of new species to specific habitats,
or reintroduction of species to the place where it was
once common, in order to restore natural balance to
gain commercial profit.

OCCASIONAL INTRODUCTION
 Many times species are introduced unconsciously or by accident.
 This occasional introduction has severe impact on local community structure
and balance of ecosystem.

CONDITIONS THAT LEAD TO ESTABLISHMENT
OF EXOTIC SPECIES
 There are many mechanisms which help in the establishment of exotics in a
new environment.
 These mechanism generally fall into two different categories:
 One for mechanism which focus on the exotic species, and the other which
focus on the invaded ecosystem.
 In fact, it is a combination of several mechanism that cause an invasive
situation to happen.

SPECIES-BASED MECHANISM
 Species based characteristics focus on competition among different fish
species.
 While all fishes are able to compete in some manner in order to survive
and persist, invasive species have specific trait or combinations of specific
traits that make them especially good competitors.
 In some cases it can be as simple as having the ability to grow and
reproduce more rapidly than native species or in other case it can be better
adaptability in the local environmental conditions; or their feeding habits
like that of carnivorous C. gariepinus eating away the competitor and
wining the competition

SUPERIOR COMPETITION
 A common trait of invasive species is great competitive ability, which can
be stronger against fishes in a new habitat than fishes in their native habitat.
 There can be huge differences between how an invasive species interacts
with its native ecosystem, and with the ecosystem it is invading.
 Often, the invading species has a better chance at acquiring resources,
which can be water quality, space, food or nutrients etc.
 Invasive species can coexist with native species for an extended time, and
only gradually does the superior competitive ability of an invasive species
become apparent, as its population grow larger and denser, and slowly
increases the risk of extinction to other species.

CRITERIA TO BE CONSIDERD IN
INTRODUCING NEW SPECIES
Fill a needs
Not compete with valuable native species
Not cross with native species and produce
undesirable hybrids
Not be accompanied by pests, parasites or
diseases and;
Live and reproduce in equilibrium with its new
environment.

BENEFITS OF EXOTIC SPECIES
INTRODUCTION
 Improve production and economic benefits from fisheries and aquaculture.
 Use of exotic species for fisheries and aquaculture diversification deal with
rising demand for food and nutritional security.
 The development of aquaculture worldwide.
 Approximately 17% of the world’s finfish production is due to exotic species.
 Approximately 20 percent of the world’s farmed salmon and
directly employs more than 30,000 people.

IMPACTS
OF
EXOTIC
SPECIES
Ecological
impacts
Impacts on
Biodiversity
Transmission
of diseases
Genetic
dilution
Economic
impacts

ECOLOGICAL IMPACTS
Competition of exotic fishes with the native species for living space with
same niche preference, for food with fishes of similar types of feeding habits,
or of omnivorous feeding habits ,or predation on native fishes by these,
spreading parasites and pathogens, thereby are some common ecological
concerns.

IMPACTS ON BIODIVERSITY
 Habitat destruction
 Invasive species cause loss of biodiversity including species extinction, and
changes in hydrology and ecosystem function.
 The impact on global biodiversity of human introduction of non-
native species that have subsequently become invasive is subjective.

TRANSMISSION OF DISEASES
 Of particular concern to exotic species is that the level of uncertainty will be
higher with new introductions on what pathogens may be present and may cause
problems in the new environment.
 The diseases which comes from other country to India is:
 Epizootic ulcerative syndrome
 Epizootic haemorrhagic necrosis
 Taura syndrome and
 Yellow head disease.

GENETIC DILUTION
 The genetic impact of introduction of exotic fishes on native fishes can be
classified into 2 categories:
 Reduction of effective population size by the ecological, biological
& genetic effect of introduction and,
 Alteration/extinction of gene pools of the species/stocks by
crossbreeding or hybridization & backcrossing.

ECNOMICAL IMPACT
 The economic impacts can be seen at two levels –
1. Capture Fisheries and
2. Aquaculture
 Economic costs due to invasive species can be separated into direct costs due
to production loss and management costs of invasive species.
 Since the exotic fishes never fetch higher price than the native varieties and
also the decline of native fish production is observed in the presence of
exotic species in natural waters, the total economic returns declined for the
stakeholders of the capture fisheries.
 In aquaculture however it provided immediate gain, in most cases without
consideration of the long term ecological consequences.

CONTROLAND MANAGEMENT
OF INTRODUCTION
 For effective management of exotic species, knowledge about their ecology,
morphology, reproductive biology and physiology is essential.
 The management of introduction has to be multi-pronged involving all the stake
holders.
 It has to be implemented at several scales, from a homeowner working in his or
her own backyard to large government agencies like directorate of fisheries of
state Govt., ICAR, NBFGR, NFDB etc. taking a state wise and nation-wide
approach respectively.
 To finally involving major intergovernmental agencies like FAO, NACA, World
fish center, ICES, EIFEC etc. to coordinate, monitor and manage the transfers and
introduction of species on international level.

The American Fisheries Society protocol consist of the following
steps:
Rationale
Search
Preliminary
assessment of
the impacts
Publicity
and
reviews
Experimental
research
Evaluation and
recommendation
Introduction

CONCLUSION
 India is one of the mega biodiversity country having more than 2700 species of
fishes.
 There are plenty of cultivable species in the country.
 Any further introduction of exotic fish species would be a threat to the existing
species diversity.
 The introduction of Tilapia, Common carp, Pangasius and white leg shrimp
have greater adverse impact on aquatic ecosystem and also on culture practices.
 The introduction of exotic species result in competition for limited food, space,
ecological niche and may results in genetic erosion, predation and pathogen
entry.
 In the other hand, introduction of the exotic species can be used for broadening
species diversity in aquaculture systems of a particular country and also for
economic benefits,
 The recent action by the Govt. of India to introduce only SPF L. vennamei and
controlled culture of P. hypophthalamus are the new steps in this direction.