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, andchanges 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.

CONTROL AND 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.