Migration of fishes and their importance of spawning migration

Kerala university of fisheries
& ocean studies, kochi
Presented by,
Ashish sahu
FRM
Instructor,
Dr. Jayalaxmi

WHAT IS MIGRATION?
Migration is the movement of large
number of animals from one place to
another.
Migratory behaviour of fish is a
regular phenomenon.
Their journey is purposed mainly
for feeding and reproduction.

Climate Migration
Or
seasonal Migration:
Gametic Migration
Or
spwaning Migration
Alimental Migration
Or
Feeding Migration:
Osmoregulatory
Migration
MIGRATION IN FISHES
Types fish migration on the basis of needs:

Diadromous
migration
Potamodromous
migration
Oceanodromous
migration
Patterns of migration
Anadromous
migration
Catadronous
migration
Amphidromous
migration

1. Diadromous migration:
•it is the migration of fish between sea
and freshwater, vice versa.
•This migration is of three types-

1. Anadromous migration:
from sea to fresh water for spawning.
Eg. Salmon, Hilsa, Lamprey etc
Oncorhynchus nerka
Hilsa

Anguilla anguilla
2. Catadronous migration:
from river to sea for spawning.
Eg. Eel (Anguilla spp)

3. Amphidromous
Migrate from freshwater to sea
water vice versa. Not for breeding
purpose.
Eg. Gobies

2. Potamodromous migration:
It is migration of fresh
water from one habitat
to another for feeding or
spawning.
Eg. Carps, Catfish, Trout
Carp
Trout

3. Oceanodromous migration:
•It is the migration of fish within
sea in search of suitable feeding and
spawning ground.
•eg. Cod, Herring, Tuna, Mackerel.

 Tuna are highly migratory fish
which can migrate sometime one
EEZ to an other EEZ.
 Tuna migrate some time 10,000
km.

Highly migratory species (HMS):
 The term highly migratory species (HMS) has its origins in Article 64 of the United Nations Convention
on the Law of the Sea (UNCLOS).
 The list includes: tuna and tuna-like species (albacore, bluefin, bigeye tuna, skipjack, yellowfin,
blackfin, little tunny, southern bluefin and bullet tuna), Pomfret, Marlin, Sailfish, Swordfish, dolphins
and other cetaceans.
 These species are found both inside the 200 mile exclusive economic zones and in the high seas outside
these zones.
Advantages or significance of migration-:
 Help in successful reproduction.
 Better egg and larvae survival.
 Have separate spawning , nursery and feeding grounds.
 To find suitable feeding and spawning ground.
 For protection from predators.
 Increases genetic diversity.

FACTOR INFLUENCING AND CONTROLLING MIGRATION-:
Physical factors
1. Bottom materials
2. Depth of water
3. temperature
4. light intensity
5. Photoperiod
6. Current turbidity
Chemical factor
1.salinity
2.pH
3. Smell and taste of water.
Biological factors:
1. Food
2. Physiological clock
3. The endocrine glands
4. Presence or absence of the predators
and competitors

Methods for studying fish migration
MARKING AND TAGGING
Physical method External Internal
Methods of marking & tagging
Some tags are used
in this methods
Make tattoo in
surface of body with
the help of marker
Some markers &
dye introduced in
body

1. By clipping method
2. By tattoed & metal tools
3. By tagging
4. By spray with a fluoresent dye
5. By markers
6. By permanenent marker

Different types of tag which are use in fishes

Diifferent markers and dies used in fishes

Life history of freshwater eel – Anguilla spp.

Leptocephalus larva:
 Lepto – small
 Cephalus – head
 Eggs rise towards the surface.
 Hatching take place at about 50cm.
 larvae called leptocephalus.
 Flat, transparent, leaf like tiny creature
 Have long needle like teeth.
 Eyes – large
 Alimentary canal – straight tube.
 They grow rapidly during the few months.
 Take 2 year to reach the coast of europe.
 Now, larvae – 5 to 18 cm. long.
 During metamorphosis – feeding stop,
 Needle like larval teeth are lost.
 Body – Cylindrical shape.
 Young one – transparent called elver or glass eel.
 Now, develop e teeth.
elver or glasseel:
 Start migration, after 3 year finally reached to the feeding area
Leptocephalus larva
Elver or Glass eel

Life history of Salmon spp.
Eggs of salmon:
 The cycle begins in freshwater, when
a redd, or a female's nest of eggs, is
fertilized
 These eggs remain in the gravel
throughout the winter, and the embryos
develop. In the spring, the eggs hatch
into alevins.

Alevin: (Lavae)
 These are tiny fish with the yolk sac of
the egg attached to their bellies.
When they have consumed all of the
yolk sac and grown in size, these fish
emerge from the gravel, and are then
considered fry.
Fry:
Fry swim to the surface of the water, fill
up their swim bladders with oxygen, and
begin to feed.
Spending 1-2 years before migrating to
sea.

Smolt:
 A young salmon or sea trout about two years old that
is at the stage of development when it assumes the
silvery color of the adult and is ready to migrate to the
sea.
 4 – 6 inch long.
Parr:
A young salmon that is older than a fry and younger than
a smolt, having dark marks on the sides.
Smolt

Ocean Life ( Spend in sea):
 Migrate to feedings grounds.
 Salmon may spend one to seven years in the
ocean.
Spawning Migration:
 Once the salmon reach freshwater, they stop feeding.
During the course of the journey, their bodies instinctively prepare
for spawning.
 The taxing journey draws energy from their fat storage, muscles,
and organs, except for the reproductive organs.
 Males develop hooked noses in order to fight for dominance.

Spawning & Death
 After reaching in freshwater, females build nests, or
redds.
 Salmon dies soon after spawning.
Eventually, both the males and females die.
The seeds of the next generation that will someday
return to continue the cycle.
After spawning salmon dies

Reference:
 Khanna S.S., A text book of fish biology &
Fisheries management , Migration of fish,
Narendra publishing House Dehli – 110006
(INDIA), 2017, Page no. 320 – 333
 Wikkipedia ( Fish Migration ).

Migration of fishes and their importance of spawning migration

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