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Use
economic concepts to relate catch and effort
Resources
Background
information
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Graph 1
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Graph
1 shows that as effort increases, catch also increases
until a maximum is reached. Any increase in effort
beyond this point results in a reduced total catch.
The point of maximum catch is called MSY (Maximum
Sustainable Yield).
The
management of fish is based on the concept of
MSY. This is the largest average annual catch
that can be taken over time without reducing the
stock's productive potential. Natural mortality
and exploitation by fishing are balanced by recruitment
and growth of individuals in the fish stock.
Graph
2 |
Graph
2 assumes that the price of fish is constant (therefore
the total revenue curve is a direct translation
of the sustained yield curve) and that each additional
unit of fishing effort is available at a fixed
cost (therefore the TC curve has a constant slope).
E1
is the open-access equilibrium. Fishers expand
their effort as long as total revenue is greater
than total cost, ie, until total profit falls
to zero at E1. The economic rent is dissipated,
because the same total revenue (R1) is obtainable
at effort E2. If total catch is restricted to
MSY (E3), economic rent is returned to the fishery,
ie, there is an increase in total revenue and
a decrease in total cost. However, profit is maximised
at the effort corresponding to the Maximum Economic
Yield - MEY (E4), where marginal cost equals marginal
revenue (ie, the slopes of the total cost and
total revenue curves are equal).
Activities
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| 1 |
Why
is the concept of MSY used in fisheries management? |
| 2 |
Explain
why MEY is the greatest level of profit which
can be achieved. |
| 3 |
Show
graphically, and explain in words, what happens
if: |
| a |
the
price of fish increases; |
| b |
the costs go up, but the price of fish stays
the same. |
| 4 |
The
"three" elements in the Quota Management System
(QMS) are the Total Allowable Catch (TAC),
the Total Allowable Commercial Catch (TACC),
which sets a limit on the amount of fish caught
commercially, and Individual Transferable
Quota (ITQ), which gives individuals harvest
rights. From a commercial fisher's point of
view what are the advantages of the QMS? Consider
the investment they need to make in boats,
fishing gear, technology, etc. |
| 5 |
Some
fisheries overseas use a competitive TACC
system, where the fishery is closed when the
TACC is reached. What advantages and disadvantages
does this system have for fishers? Consider
the investment fishers need to make in boats,
fishing gear and technology. |
| 6 |
Which
system do you think is better for fishers,
the QMS or the competitive TACC system? Which
is better for society? Give reasons for your
answers. The needs of commercial, recreational
and Maori fishers. |
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