Mechanism of Hilsa (Tenualosa ilisha) Migration and its Impact to Nature Tenualosa ilisha (ilish, hilsa, hilsa herring or hilsa shad) is a species of fish in the herring family (Clupeidae), and a popular food fish in South Asia. Five type of ilish can be found worldwide. Yearly ilish caught are 5,000,000 ton. Among them, 50%-60% are caught by Bangladesh, 15%-20% are caught by India, Pakistan and rest 5%-10% are caught by Malaysia, Thailand, China, Vietnam and Sri Lanka. The fish contributes about 12% of the total fish production and about 1% of GDP in Bangladesh.

2. Mechanism of Hilsa (Tenualosa
ilisha) Migration and its Impact to
Nature

3. A popular food fish in South Asia. Five
types of ilish can be found worldwide.
Yearly ilish caught are 5,000,000 tons.
Among them, 50%-60% are caught by
Bangladesh.
About 450,000 people are directly
involved with the catching for livelihood;
around four to five million people are
indirectly involved with the trade.

4. Tenualosa ilisha
Family: Clupeidae
Estuarine or a Marine Fish
Contributes 1% of GDP in Bangladesh
It is also the national fish of Bangladesh.

5. Common Names
• Hilsha
• Palla Fish
• Ellis, Ilish
• Ilishii
• ইলিশ
• Pallu machhi

6. Description and habitat
The fish is marine, freshwater, brackish, pelagic-
neritic: Anadromous: Depth range-200 m.
Within a tropical range; 34°N - 5°N, 42°E - 97°E
in marine and freshwater.
It can grow up to 60 cm in length with weights of
up to 3 kg.

7. Food value
In Bangladesh and West Bengal during
Pohela Boishakh ,it is customary to have
ilish with panta bhat typically at breakfast.
The meal is the traditional way to celebrate
the Bengali New Year. It is the National Fish
of Bangladesh.

8. Migration And Behavior
Main causes of migration are spawning and search of food.
The mature fish migrate to the upstream and rivers from the sea during
their spawning season for having less salinity in this environment.
Males ascend to the spawning ground earlier than the females after
spawning the hilsa return to the sea.
The newly hatched larvae gradually become juvenile.
And this jatka started to migrate to the sea later on.

9. Migration Circuit
Most fishes have three points in their migratory circuit
A. The Feeding Ground
B. The Spawning Ground
C. The Nursery Ground

10. Diagrammatic Route of Migration Circuit
Adult Stock Feeding Ground
Spawning Ground Juvenile Nursery Ground
Denatant
DenatantDenatant
Contranatant

11. Many factors influence migratory movements.
They may be physical, chemical and biological.
Physical factors: Bottom materials, water depth, current and tide,
turbidity, temperature, and light intensity.
Chemical factors: Salinity, alkalinity, dissolved gases, odor, tastes, and
pollutants.
Biological factors: Sexual development ,blood pressure, social response,
hunger, food, physiological clock, and endocrine state.

12. Migration of Hilsa Fish
Hilsa is an estuarine or a marine fish. It lives in the water not far from
the coast. It is available in the rivers 150 miles up in Bangladesh.
It has several species:
1.Tenualosa ilisha
2.Tenualosa kanagurta
3.Tenualosa motius
4.Tenualosa tole

13. Two runs or two types of Migration
of Hilsa are Recognized.
1. South – West Monsoon
2.Late Winter

14. South – West Monsoon
Hilsa fish mainly lives in the sea and around the monsoon, when
consequent flooding of all the rivers and it is time to spawn.
Swims against the tide and goes back to the river where its
mother had given birth to it.
Earlier, the Hilsa would move from the Bay of Bengal to
Bangladesh rivers, the Padma, and the Meghna, for spawning.

15. Late Winter
Migration of Hilsa shad is not limited to monsoon only,but it also
migrates short period during winter.
It happens during the month of February to March.

16. Migration Patterns of Hilsa

17. HilsaMigrationinBangladeshSource:DoF

18. MigrationRouteofHilsaDuringPre-FarakkaPeriod

19. Trends in hilsa production during 1983-2008

20. Thank You Very Much Everybody