growth and survival, searanching

1. Unit - IV
Estimation of Growth and survival
Estimation of Primary productivity
&
Sea ranching

2. Estimation of Growth and survival

3. Percentage weight gain
Final weight (g) – Initial weight (g)
• Percentage weight gain = ------------------------------------------------ X 100
Initial weight (g)

4. Specific Growth Rate
(ln Final weight – ln Initial weight)
• SGR / day (%) = ---------------------------------------------- X 100
Number of days

5. Feed conversion Ratio
Feed given (dry weight)
• Feed conversion ratio = ----------------------------------------
Body weight gain (wet weight)

6. Feed efficiency ratio
Body weight gain (wet weight)
• Feed efficiency ratio = --------------------------------------------
Feed given (dry weight)

7. Protein Efficiency ratio
Body weight gain (wet weight)
• Protein Efficiency Ratio = ------------------------------------------
Crude Protein fed

8. Mean Growth rate
• Mean growth rate (mg /day) = 1000x (W2-W1)
-----------------------
0.5X(W1+W2)Xt
• Where, W1= Initial body weight (g), W2= Final body weight (g) and T=
Culture duration (days)

9. Survival Rate
Total number of animal harvested
• Survival (%) = ----------------------------------------------- x 100
Total number stocked

10. Estimation of Primary productivity

11. Why there is a need for primary
production?
Microscopic algae are food for microscopic
animal plankton.
Animal plankton are food for small fish and
animals (clams, worms, crabs).
Small fish and animals are eaten by larger
and larger fish, by birds, or by humans.

12. Primary productivity
• Primary productivity, is defined as the rate at which energy is
stored by photosynthetic activity of producer organisms
(chlorophyll bearing organisms, mainly plants and
phytoplankton) in the form of organic substances which can
be used as food substances.

13. Types of Primary producers
• In marine environments
the two principal
categories of producers
are pelagic phytoplankton,
which float freely in
the ocean, and
benthic algae, which live
at or near the ocean’s
floor.

14. Contd..
• Primary productivity is usually determined by measuring
the uptake of carbon dioxide or the output of oxygen.
• Production rates are usually expressed as grams of organic
carbon per unit area per unit time.

15. Photosynthesis
• The first products of photosynthesis are phosphorylated sugars which converted,
rapidly into other metabolites (carbohydrates, proteins, nucleic acids, etc.) if the
cells are in condition favouring growth.
• Besides CO2, water and energy all other essential cell constituents such as N, P, S,
Fe, etc. must also be present.
• The familiar formula of photosynthesis is:
6 CO2 + 12 H2O --------------- C6H12O6 + 6O2 + 6 H2O

16. Light and Dark bottle method
• Primary productivity can be measured from
the amount of oxygen consumed by a volume
of water in a fixed period of time;enclosed in
sealed white and dark bottles (bottle painted
dark so light would not enter).
• Dissolved oxygen measurement of water is
made at the beginning of the immersion
period.

17. Contd..
• The two bottles are then immersed
in the water body concerned at the
level from which the water is taken.
• The phytoplankton and other
elements in the water produce
oxygen in the water bottle, but some
oxygen disappears due to
respiration.

18. Contd..
• The latter is measured from the readings of dark bottle,
where only respiration takes place.
• However this oxygen production indicates net
primary productivity only.

19. Contd..
• From the DO difference in dark bottle oxygen consumed by
the enclosed organisms can be obtained and when this
respiration value is added to the oxygen production in the
white bottle, a value for gross primary productivity is
obtained.

20. Gross Primary Production
• The amount of plant substance produced per unit of time and space is
defined as Gross Primary Production (GP).
• Gross Primary Production measurement is essentially a statement of
growth.
LB-DB 0.375
T PQ
GPP= × × 1000
LB = DO concentration in light bottle
after incubation.
DB = DO concentration in Dark bottle
after incubation.
PQ = photosynthetic quotient
0.375 = numerical value ; to express the
value in carbon.
1000 = To convert litre to m3
Expressed in mg C /m3
/ hr

21. Net primary production
• Actual plant growth is represented by an amount of energy equal to the
total carbohydrate formed minus the respiration and is termed as Net
Primary Production.
• The rate of net primary production represents the rate at which organic
matter is stored.
IB-DB 0.375
T PQ
NPP= × × 1000
Expressed in mg C/m3
/hr
IB = initial DO concentration.
DB = DO concentration in Dark bottle
after incubation.
PQ = photosynthetic quotient
0.375 = numerical value ; to express the
value in carbon.
1000 = To convert litre to m3

22. Tertiary productivity
• Tertiary production is the amount of fish biomass.
• It is measured
• y converting mg C/m3
/hr (primary productivity) to kg/ha/yr
primary productivity
10,00,000 10,000 12 365
Tertiary productivity = × ×
×
Expressed in kg/ha/yr

23. C14 method
• The most accurate method
• The method of using radioactive carbon (C14) added as carbonate.
• Labelled carbonate is added into a bottle containing water with the
phytoplankton and other organisms.
• After a short period of time the plankton is separated, dried and
planchetted and the radioactive carbon fixed can be measured from
the radioactive counts made.
• The productivity measured thus is net primary productivity as the
carbon fixed in the tissues only are measured here.

24. Sea Ranching
• Sea ranching involves introducing juveniles
(either hatchery-produced or wild-caught)
into the natural environment where they are
allowed to grow without containment
structures.
• Sea ranching or artificial recruitment of
aquatic organisms into their natural habitat
for stock improvement or enhancing the
production or for conservation of resources.

25. Two types of Techniques
• The sea ranching technique involves
• (1) brood stock development,
• (2) breeding,
• (3) larval rearing on large scale,
• (4) nursery rearing,
• (5) release of seed at suitable sites and
• (6) monitoring of the released and natural stocks to assess the
impact. Ranching is advantageously carried out in bays, lagoons,
shallow water bodies and in the protected ecosystems.

26. Types of species involved
• Marine prawn, Pearl oyster, and clams,
seacucumber, scallop etc…

27. Advantages
• The exploitation of natural population though
energy saving, is dependent on biomass
availability and its abundance.
• The cultured population could produce the
biomass for commercial requirements, but entails
much energy, feed, labour and capital investment.
• Artificially recruitted population, on the other
hand, permits to raise the population in the
natural environment without spending much
energy, feed or labour

28. Thank you