General îrends in carp farming
459
on
more
refined
statistical methods, even though of an elementary type. Last
but not
least, it is often difficult to obtain wast, long—term data.
The main object of this paper is to give an example of how elementary
statistics can be used to make an analysis, what may be the conclusions and
how they can be interpreted from an economic viewpoint. I have taken advantage
of
the time—series approach and the relationships between the obtained trends
using the last—Squares method (linear and parabolic trends) and linear cor—
relation and regression.
MATERIAL
As already mentioned, this paper should be considered as an example of
the possibilities of the "benefit" approach. Nevertheless, it also gives a
picture of the development of carp farming in Poland. Data were obtained on
carp farming in the State Pond Fish Farms over a 20—year period (1963—1982).
The Farms are the main carp producers in Poland and include over 70 % of the
total carp production, while within the farms themselves, càrp production
represents 94 % and other fish species only 6 Z. We purposely used only
and not
economic, data in order to illustrate how economic con—
clusions can be obtained.
The data include the following.
1.
Total carp production during the period studied.
This production consisted of two fractions, the production of table
(commercial) carp and the production of carp stocking material.
2.
The production of table carp
These data necessitate some comment.
In Poland, two systems of carp far—
ming are in use, i.e. the two and the three—year cycle of production. In the
first, carp fry (K) produced the first year are stocked (after wintering)
directly in the finishing (fattening) ponds to produce table fish by the end
Of the second year.
In the three—year system, carp fry (Kl) produced the first
Year
are
stocked
(after wintering) in rearing ponds to produce two—year old
fiSh (K2) by the end of the second year. These are stocked (after another
wintering) in finishing (fattening) ponds to produce table fish by the end
of
the third year.
Consequently, table carp production each year includes fishes
Of different ages (2 and 3 years old); their share in this production 15
unknown.
3.
The production of carp stocking material
As can be concluded from the above, this production includes three frac— ’
tions, all of them being known: carp fry (K1) used to obtain K2 the next year
(three—year cycle), carp fry (K1) used to obtain table fish the next year
(tw0—year cycle), and two—year old carp (K2) used to obtain table fish the
next
year
(three—year cycle).
4. The level of carp stocking
It
includes the same thmee fractions as
item 3
(all known) bUt the data
refer to the numbers actually stocked in the P0ndS the next Spring (after
Wintering) and not to the production of stock1ng material.
5.
The area of
the car
ends in the
eriod studied
.
.
d
Four different sets of data were available. caâastraî pÎÏd ÎËîÊ’ îîÊmîreq
Pond area (or area of existing PondS, d1kes lnClude )’ ÊC uî ïnd actîall
underwater pond area. In this study only the dammed pon
ar
a
y
459
on
more
refined
statistical methods, even though of an elementary type. Last
but not
least, it is often difficult to obtain wast, long—term data.
The main object of this paper is to give an example of how elementary
statistics can be used to make an analysis, what may be the conclusions and
how they can be interpreted from an economic viewpoint. I have taken advantage
of
the time—series approach and the relationships between the obtained trends
using the last—Squares method (linear and parabolic trends) and linear cor—
relation and regression.
MATERIAL
As already mentioned, this paper should be considered as an example of
the possibilities of the "benefit" approach. Nevertheless, it also gives a
picture of the development of carp farming in Poland. Data were obtained on
carp farming in the State Pond Fish Farms over a 20—year period (1963—1982).
The Farms are the main carp producers in Poland and include over 70 % of the
total carp production, while within the farms themselves, càrp production
represents 94 % and other fish species only 6 Z. We purposely used only
and not
economic, data in order to illustrate how economic con—
clusions can be obtained.
The data include the following.
1.
Total carp production during the period studied.
This production consisted of two fractions, the production of table
(commercial) carp and the production of carp stocking material.
2.
The production of table carp
These data necessitate some comment.
In Poland, two systems of carp far—
ming are in use, i.e. the two and the three—year cycle of production. In the
first, carp fry (K) produced the first year are stocked (after wintering)
directly in the finishing (fattening) ponds to produce table fish by the end
Of the second year.
In the three—year system, carp fry (Kl) produced the first
Year
are
stocked
(after wintering) in rearing ponds to produce two—year old
fiSh (K2) by the end of the second year. These are stocked (after another
wintering) in finishing (fattening) ponds to produce table fish by the end
of
the third year.
Consequently, table carp production each year includes fishes
Of different ages (2 and 3 years old); their share in this production 15
unknown.
3.
The production of carp stocking material
As can be concluded from the above, this production includes three frac— ’
tions, all of them being known: carp fry (K1) used to obtain K2 the next year
(three—year cycle), carp fry (K1) used to obtain table fish the next year
(tw0—year cycle), and two—year old carp (K2) used to obtain table fish the
next
year
(three—year cycle).
4. The level of carp stocking
It
includes the same thmee fractions as
item 3
(all known) bUt the data
refer to the numbers actually stocked in the P0ndS the next Spring (after
Wintering) and not to the production of stock1ng material.
5.
The area of
the car
ends in the
eriod studied
.
.
d
Four different sets of data were available. caâastraî pÎÏd ÎËîÊ’ îîÊmîreq
Pond area (or area of existing PondS, d1kes lnClude )’ ÊC uî ïnd actîall
underwater pond area. In this study only the dammed pon
ar
a
y