BREEDING [FISH SEED PRODUCTION]

 

CHAPTER FOUR

                BREEDING (FISH SEED PRODUCTION)

 

Definition of fish feed production

Fish feed production is specially formulated to contain all the essential nutrients they need to keep them healthy and growing and maintain the human health benefits of sea food consumption. The ingredients are formed into pellets. Categories of essential nutrient include vitamins, dietary mineral, essential fatty acid and amino acid. These are provided by a number of feed ingredients including fish, plant, and processing waste meals and oils

4.1                                       BREEDING CONCEPT

Breeding is the reproduction that is producing of offrings usually animals or plant . in fishing practice, it is an act of raising young fish.

TERMS IN FISH BREEDING

SPAWNING:- This is the process of releasing the eggs and sperm usually into water by fish. The process of spawning typically involves females releasing ova(unfertilized eggs) into the water often in large quantities while males simultaneously or sequentially release spermatozoa (milt) to fertilize the eggs

GAMETE:- This is a reproductive cell or sex cell that contains sperm cell (milt) and egg cell covum of a mature fish

LETENCY PERIOD:- This is the time interval between injection of the female fish and stripping of eggs

FISH SEED:This is reffered to  as milt or soft roe

EXTERNAL FERTILIZATION:- In fish is the process where female fish lay eggs outside and the male release sperm cell (milt) to fertilize the eggs

HATCHABLITY:- Is a process by which young fish emerge from the egg as by brooding .

HYPOPHIZATION:- Is the practice of injecting fish with substance derived from the pituitary gland for the purpose of including reproduction (such as ovulation) when condition are not favourable for successful natural spawning in ponds

        Hypophization is the technique of breeding the fish by administering pituitary gland extract injection is known as induced breeding

BROODSTOCK:- A group of sexually mature individuals of a culture species that is kept separate for breeding purpose

 

4.2                                       TYPES OF REPRODUCTION IN FISH

There are two main reproductive methods or breeding strategies in fish, these include

1.         Live bearing or livebearers

2.         Egg laying or egg layers

LIVE BEARNING :- These are fish that bear live young, there are two types of live bearing;

        i.            OVOVIPARIOUS:- The development of an embryo inside an egg within the mother’s body until it hatches within the female before birth e.g. rock fish

      ii.            VIVIPAROUS:- The development and nourishment of an embryo within the mother’s body and give birth to live young ones

        The male fish uses its rod-like anal fin called gonopodium to transmit sperm into the female fish and fertilize the fish egg internally later the female gives live birth to her fry.

EGG LAYING:-They are also called OVIPARIOUS. In egg laying, the female fish lays egg either on the sea floor or on the leaves of an aquatic plant. A male fish fertilizes the eggs and both them work together to protect the eggs or babies from danger until they can defend themselves.

The majority of aquarium fish are egg-layer with external fertilization. Egg-layer can be divided into five groups:

1.         Egg-scattered

2.         Egg –depositor

3.         Egg-burriers

4.         Nest-builders

5.         Mouth-brooders

1.         EGG-SCATTERER:-These species simply scatter their adhesive or non-adhesive eggs to fall the substrate, into plant, or float to the surface. These species do not look after their brood and even eat their own eggs

2.         EGG-DEPOSITORS:-Egg-depositor usually lay less eggs than scatters although the eggs are larger. The egg deposition their eggs on a substrate (tank glass, wood, rocks, plants). The eggs take a few days to hatch, and the fry are often guarded by the parents e.g catfish, killifish, cichlids etc. these species do not usually eat their eggs

3.         EGG-BURRIERS:-These species usually inhabit water that dry up at some time of the year. The majority of egg burriers are annual killifish which lay their egg in mud. The parents mature very quickly and lay their eggs before dying when the water dries up. The eggs remain in a dormant stage until rains stimulate hatching.

4.         MOUTH-BROODERS:-Are species that carry their eggs or larvae in their mouth. Mouth-brooders can be broken up into:

1.     OVOPHILES(Egg loving) e.g cichlids and some labyrinth

ii.     LARVOPHILES (larvae loving) e.g eartheaters fish.

        Fertilization occurs with the help of egg-spots, which are colourful spots on the anal fin of the male, when the females sees these spots she tries to pick up the egg-spots, but instead gets a mouthful of sperm fertilizing the eggs in her mouth

5.         NET-BUILDERS:-Nest –builders some sort of nest for their eggs. The nest is usually in the form of bubble-nest formed with plant debris and saliva coated bubbles(catfish, labyrinth fish ) or a excavated pit in the substrate (cichlids). Nest builders practice brood care

 

4.3                                                   DIADROMOUS FISH

Diadromous fish refers to all fishes that migrate between the sea and fresh water for reproduction purpose. Diadromous fishes have been classified into several categories:

1.         ANADROMOUS:-Fish are born in fresh water, then migrate to the ocean as juveniles  where they grow into adult before migrate back into fresh water to spawn. E.g salmon, smelt, bass, gulf sturgeon etc.

2.         CATADROMOUS:-Fish are born in fresh water as juveniles where they grow into adults before migrating back into ocean to spawn e.g American eel, European eel, inanga

3.         AMPHIDROMOUS:-Fish are born in freshwater / estuaries, then drift into the ocean as larvae before migrating back into freshwater to grow into adult and spawn e.g. bigmouth sleeper, mountain mullet, river goby, torrent fish etc

4.         POTAMODROMOUS:-Fish are born in upstream fresh water habitats, then migrate downstream (still in freshwater) as juveniles to grow into adults before migrating back upstream to spawn e.g lake sturgeon, flathead catfish robust red horse etc

5.         OCEANODROMOUS:-Fish are born near spawning ground then drift on ocean currents as larvae before settling as juveniles to grow into adults before migrating back to spawning grounds. Examples; black groupers, goliath grouper, mutton snapper

ADVANTAGES OF LIVE BEARING OVER EGG LAYING FISH.

1.         The mother’s body provides the developing young protection.

2.         Live bearing fish start life as miniature version of the adult one

3.         It allows more mobility during development while lay-eggs are usually stuck whenever they landed

                                            DISADVANTAGES OF LIVE BEARING

1.         Female live-bearers usually have smaller broods their egg laying counterparts.

STRUCTURE QUESTIONS

1.      The following are characteristics of a culturable fish species except (a) adaptation to artificial feed (b) exhibition of high mortality rate (c) capability to reproduce in captivity (d) exhibition of high survive rate (e) resistance to parasite and infestation.

2.      Spawning in fishery means (a) breeding fingerlings (b) milting (c) laying of eggs (d) camouflaging (e) swimming zigzag.

3.      In fishery “milt” is a term which means (a) egg (b) fed (c) sperm (d) waste (e)harvest

4.      A suitable place where fish lay egg is known as (a) brooding spot (b) labour ground (c) egg hatching spot (d) nesting area (e) spawning ground.

5.      Pick one fish from the list that is anadromous (a) eel (b) river goby (c) salmon (d) mutton snapper (e) catfish

6.      In order to work out sustainable yields, scientist need to understand what factors? (a) birth rate (b) mortality (c) breeding age size (d) all of the above

7.      Males and females kept for the purpose of breeding is referred to as (a) fish seed (b) brood stock (c) viviparous (d) gaining

8.      The time interval between injection of the female fish and stripping of eggs is known as (a) ovulation (b) latency period (c) spawning (d) hypophization

9.      Which of the following is not an example of egg layers in fish (a) mouth brooders (b) egg depositor (c) egg scattered (d) viviparous

10.    The migration of fish between the sea and freshwater for the purpose of reproduction is known as (a) catoparous (b) diadromous (c) oceanic (d) phatodromies

                         

          THEORY

1a.    Briefly explain the type of reproduction in fish.

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

     b. Give two example each of the type mention in (la)

          ___________________________________________________________

          ___________________________________________________________

          __________________________________________________________

1.          Briefly explain the following:

        i.             Brood stock

______________________________________________________________________________________________________________________________________________________________________II. Oceanodromous

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

      iiI.            Anadromous

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

    iV.            Spawning

______________________________________________________________________________________________________________________