PRINCIPLE 1: Sustainable fish stock
A fishery must be conducted in a manner that does not lead to over-fishing or depletion of the exploited populations and, for those populations that are depleted, the fishery must be conducted in a manner that demonstrably leads to their recovery
PRINCIPLE 2: Minimizing environmental effect
Fishing operations should allow for the maintenance of the structure, productivity, function and diversity of the ecosystem (including habitat and associated dependent and ecologically related species) on which the fishery depends.
2. Principle of fishing
PRINCIPLE 1: Sustainable fish stock
A fishery must be conducted in a manner that does
not lead to over-fishing or depletion of the
exploited populations and, for those populations
that are depleted, the fishery must be conducted in
a manner that demonstrably leads to their
recovery
PRINCIPLE 2: Minimizing environmental effect
Fishing operations should allow for the maintenance
of the structure, productivity, function and
diversity of the ecosystem (including habitat and
associated dependent and ecologically related
species) on which the fishery depends.
3. PRINCIPLE 3: Effective management
The fishery is subject to an effective
management system that respects local,
national and international laws and
standards and incorporates institutional
and operational frameworks that require
use of the resource to be responsible and
sustainable.
4. Criteria for fishing
• it can be continued indefinitely at a reasonable level;
• it maintains and seeks to maximize, ecological health and
abundance,
• it maintains the diversity, structure and function of the
ecosystem on which it depends as well as the quality of
its habitat, minimizing the adverse effects that it causes;
• it is managed and operated in a responsible manner, in
conformity with local, national and international laws and
regulations;
• it maintains present and future economic and social
options and benefits;
• it is conducted in a socially and economically fair and
responsible manner.
5. Why this principle of fishing?
• Appropriate fishing gear should be used
• Fishing crafts should only be used when it is
necessary
• To maintain sustainable fish harvesting
• To have a good catch avoiding over fishing
• To maintain minimum effort and maximum catch
• To select/find out new fishing ground
• Fishing during a definite season and ban on
spawning season
• To maintain a balance between the number of fish
caught and the number of young fish entering into
the population
• Less wastes during fishing
8. Theory of fishing
• Fishing is a complex problem for the fishery scientist
• A given population or community should be
exploited and the fishing activity should be adjusted
to obtain the best results
• The best results point to the maximum sustainable
yield
• That is the way to consume fish year to year without
depleting the fish stock
The different methods to solve this problem are:
1. Empirical method
2. Analytical method
9. Empirical method
• This method considers the maximum sustainable
yield
• This method takes in account by the yield and the
fishing effort
The fishing effort is measured by:
-the number and size of fishing gears and crafts
-the amount of time spent in fishing and yield
Criticisms:
-it provides no means of judging the condition of
getting MSY
-this condition may not give the best yield in future
-in some cases the population couldn’t be exploited to
give the better result
10. Analytical method:
• This method investigate the cause of
change in population size and yield
• It also investigates the cause of fish
mortality due to predation, diseases,
salinity, etc.
• The criticism of empirical method can
be solved by this method
11. Theoretical model:
The following parameters are need to be
studied to obtain MSY:
i) Recruitment (R): the number of a single
year group entering the exploitable phase of
a stock in a given period by growth of
smaller individuals
ii) Growth (G): increase in size (length and
weight). Fish growth curve is S shaped.
iii)Natural Mortality (M): mortality due to
predation, diseases, salinity, etc
iv)Fishing Mortality (F): mortality by fishing
13. Maximum Sustainable Yield (MSY)
• MSY is such amount of fish stock which are caught
from a certain area without causing any harm
• MSY is such amount of fish stock which are
captured from a certain water body without
depleting or hampering the actual stock
• By increasing fishing effort, total catch will be
increased but at a position of increasing fishing
effort, total catch will be maximum and after that
total catch will be decreased by increasing fishing
effort.
In case of MSY,
R+G=M+F