Fish migration occurs for various reasons such as finding new habitats, feeding, reproduction, and escaping predators. There are several types of fish migration defined by distance, direction, and purpose. Anadromous fish migrate from salt water to fresh water to spawn, like salmon, while catadromous fish do the opposite, migrating from fresh to salt water to spawn. Potamodromous fish migrate within fresh water systems. Oceanodromous fish migrate long distances within salt water environments. Physical, chemical, and biological factors influence fish migration patterns. Migration allows fish to access new food sources and breeding habitats but also carries risks.

1. FISH
MIGRATION
Presented By:
Anwar Ullah
BS-Zoology
7th Semester

2. Introduction
Migration - The directed movement of large number of animals
from one place to another forvarious reasons.
Or
This synchronous, directed movement of part or all of a population
between discrete( Separate) habitats is called “migration”
• 2.5% of All fishes are Migratory in Nature.
• Migration – from hundred meters (e.g coastal & stream dwelling
fishes) to Thousands of Kilometer (e.g Eels)
• Successful Migration: Motivation, Energy Storage , Locomotion
Ability.

3. Why do Fish migrate? (Reasons)
•Several Reasons:
I. For New Suitable Habitat. (To avoid
unfavorable conditions)
II. For Feeding– Food Searching
III. For Reproduction & Spawning. (To enhance
the survival of offspring's)
IV. Some Fishes Migrate in Order to Escape
from Predators.

4. Types of Fish Migration
1. On the basis of Food, Spawning, Climate & Water
Current:
These Include the Following;
I. Feeding Migration:
 Migration of fish in search of food & water is
called Feeding Migration.
◦ This occurs because the supply of food in any
habitat is not constant, fluctuates from time to
time.
◦Grow fast in size & mature & produce more eggs.
◦Better food facilities, better survival &fast growth
Examples: cyprinids, Salmonids, Percids

5. Cyprinids: Puntius titteya
Salmonids
Percidae

6. 2. Spawning Migration
Migration for the purpose of Spawning- Spawning
Migration.( Spawning :Producing eggs in large
numbers)
More Prominent as compared to others because –
aggregation of thousand of fishes to a particular
habitat.
Examples:
Salmonids, Osmeridae , cyprinids, castostomids
Osmeridae (Smelt)
Cyprinids: Puntius titteya
Catostomidae:
Suckers

7. 3. Climate& RefugeSeeking Migration
Migration in response to harsh climate condition.
Arctic (of ice) & subarctic Fishes Migrate.
 Examples: Thymallus arcticus , Salvelinus alpinus
 Anguilla anguilla: Migrate in order to avoid ground
ice , surface ice & cold water.
Arctic grayling: Thymallus
arcticus Arctic char or Arctic
charr (Salvelinus alpinus)

8. European eel: (Anguilla Anguilla)

9. 4. Contranatant Migration
 Movement of Migratory fishes against the water
current. (The movement of water from one location
to another)
5. Detanatant Migration
 Movement of migratory fishes in the direction of
water.

10. Typesof Migration
(2. On the basis of direction)
TypesofMigration
(Onthebasisofdirection)
Diadromous
Migration
Oceanodramous
Migration
Potamodromous
Migration
Anadromous
Catadromous
Amphidromous

11. A. Diadromous Migration:
 Fish Migration Between Sea & Freshwater for
SPAWNING (laying Eggs).
Three Types:
I. Anadromous Migration ( Sea to FW)
II. Catadromous Migration ( FW to Sea)
III. Amphidromous Migration
Dia: across , Dromous : Path , way

13. 1. Anadromous
• Fisheswhich migrate from the seainto fresh water to
spawn
‘OR’
• Oneswhich stay entirely in seawater andmigrate
upstream to spawn
• AnAnadromous fish, born in fresh water, spendsmost of
its life in the seaandreturns to fresh water to spawn.
• Adults usually die afterspawning
• Commonexamples- Salmon,Trout, Hilsa, striped bass, Sea
lamprey andsturgeon
Salmon

14. striped bass
SeaLamprey
sturgeon

15. LifeHistoryofsalmon
•Salmon hatch in small freshwaterstreams.
•From there they migrate to the
seato mature (1 to 5years).
•When mature, the salmon
return to the same streams where they were
hatched to spawn.

16. Alevin
FrySmolt
Adult
Spawner
Spawningbedsin FW
SPAWN
Adults change
significantly once they
enter freshwater. They
change color, stop
eating, malesdevelopa
kype (hooked jaw), and
theystopdrinking
Enteringfreshwater
After spawningspawnersdie
Death
Average number of eggs
deposited per female is
Egg around 3,000eggs,
2-3 months forhatching
Youngfree-
swimming, 1-2
inches,learn to
feedParr
(Young Salmon before it leaves
FW.2-5 inches,
Parr marks,As salmonmature
into asmolt, the Parr marks
disappear
Whensalmonprepare
to migrate from
freshwater to the
ocean, they become
smolts, spendsome
time in estuaries
beforeheadingto the
ocean
Salmonspend 1-5
yearsin the ocean,
80%of their lifecycle
Entering into Seawater
Remainin the gravel for
another 1-2 months, yolksac

18. 2. CATADROMOUS
• Catadromous fishes are oneswhich
migrate from fresh water into the
seatospawn
‘OR’
•Oneswhich stayentirely in fresh
waterand migrate downstream to
spawn.
•Bestexamples - eelsof the genus
Anguilla, numbering 16 species,the
best-known of which are the North
American eel (A.rostrata) and the
Europeaneel (A.anguilla)

19. Cont’d…
•It travels several thousand km starting fromrivers
reaching spawning grounds in sea.
•After spawningadultsdie.
•Youngonesare born in the ocean, mature in
freshwater or estuarine habitats, and return to
the ocean to spawn.
•Thismakesthem Catadromousfish

20. Eellife cycle

21. 3. Amphidromous Migration:
 Migration of fishes from sea to
rivers & vice versa, but not for
breeding purpose.
 Mainly for food & change of
environment.
Example: Gobies

22.  These are born
in
freshwater/est
uaries, then
drift into the
ocean as larvae
before
migrating back
into freshwater
to grow into
adults and
spawn

23. B. POTAMODROMOUS
• Themovement islimit only to freshwater.
Lake:(Laketrout - Salvelinus namaycush )
Rivers & Streams: ( brook lamprey -Lampetra spp )
Lake & fluvial habitats: ( white suckers , Catostomus
commersoni )
•Travelslong distancesin rivers to locate suitable
spawning grounds (Somemigrates Upstream and
somedownstream)
•After laying eggs,the parents return to the feeding
areaas food isavailable only for the young ones&
cannot support theadults

24. Cont’d…
•Besides spawning needs, this
type of migration may also be
due to competition, Suchas
increase in population.
•Scarcity of food may also force
fishes to migrate other places,
where food isabundant.

25. LAKE TROUT
brook lamprey
white suckers

26. Potamodromous fish
are born in upstream
freshwater habitats,
then migrate
downstream (still in
freshwater) as
juveniles to grow into
adults before
migrating back
upstream to spawn

27. C. OCEANODROMOUS
•Theseare truly migratory marinefishes.
•Travel long distances with in seato spawn & return to
the feedingareas.
•Thereare no barriers within the seaand fisheshave
learned to migrate in order to take advantage of
favourable conditions wherever theyoccur.
•During migration these speciesvisit spawningareas,
nursery areas, feeding areas, winter areaetc.
Examples:Mackerels, Tunas,Cod,Herrings

28. Tunas
Cod Atlantic mackere

29. • fish are born
near
spawning
grounds,
then drift on
ocean
currents as
larvae before
settling as
juveniles to
grow into
adults before
migrating
back to
spawning
grounds.

30. Factorsinfluencing migration
Influenced by several Physical,Chemical,and
Biologicalfactors
Physical
factors
Temperature
Light intensity
Photoperiod
Water current
Turbidity
depth
Temperature is of more
importance, in sea water rise in
temperature provides stimulus to
Salmon for Migration.
In fresh water temperature
rise fishes moves upstream
for spawning.

31. Chemicalfactors
Chemical factors
pH
Salinity
Odour
Tasteof water
Salinityof water restricts the movement of fishes.
Freshwater speciesare stenohaline (intolerant to large salinitychanges).
Hencethey remain confined to fresh water do not undertake migration involving long
distances
But some specieslike Salmon, Hilsa,Anguilla etc., are euryhaline and canadjust to large
salinity variations i.e. Diadromousfishes

32. Biologicalfactors
• Biological factors
Food
Memory
Stageof sexualmaturity
Predators and competitors
Hormones
 Availability of food is the primary factor for the survival of juveniles
 Memory guidessome speciesduring migration e.g. Salmonreturns to the same
area of river for spawning, where its own hatching & development took place

33. Advantages of fish migration
• Fish get more food, better climatic condition
and breeding place
• Fish gets better adapting in new places.
• There will be wide distribution.
• Less competition.

34. Disadvantages of fish migration
 Chances of loss of life due to the shortage of food for
predators of higher forms, earthquake, tsunami,
cyclone etc
 Mant migratory birds are exposed to innumerable
risks during traveling and die in tremendous numbers
 They are killed by sudden changes in temperature in
weather such as heavy rainfall or snowfall or stormy
wind.
 They are killed by hawks & man during migration.

35. JazakALLAH
ANY QUESTION?