462
M. Leopold
as
well as the effectiveness of table carp production. The growth rate of carp
stocking material (4.35 %, Fig. 1) was much higher than that of table fish
production (1 Z), even taking into account the non—significant
linear appro—
ximation. When the last years are added the slope of the straight
line does
not
change so the conclusion on the decreasing effectiveness of carp produc—
tion seems to be correct…
This trend, similar to the former conclusion on decreasing effectiveness
of carp feeding, seems to reflect a continuing process… This would confirm
the hypothesis of the negative, increasing impact of some external factor on
pond culture. The same conclusion can be drawn concerning the trend of K2
production (see item 3 in Material) in the three—year production cycle. The
rate
of pond stocking with Kl to produce K2 was characterized by a growing
trend with an average annual increment of 7.49 % compared to the multi—year
average.
At the same time, K2 production increased by only 4.80 %. We can also
say that the effectiveness of stocking decreased… As shown earlier, the pro—
duction of this fraction (K2) was strongly intensified with
feeding so the
problem is of economic importance. It should be stressed that these negative
trends occur in spite of improved methods of management. That State Pond Fish
Farms
improve their management methods is demonstrated by the fact that K2
production increased 4.80 % annually compared to the multi—year average, whe—
reas
the rate of K2 stocking in the fattening ponds (to produce table fish)
increased by 5.2 % annually. Thus, we are dealing here with the decreasing
mortality of the stocking material during wintering and/or increasing fish
husbandry (lower weight loss during winter).
That management is satisfactory, at least as regards stocking material,
is even more evident if we take into account that two—year old fish (K2) cons—
titued 83.8 % of the stocking material used in the finishing ponds to produce
table carp and that in reality, these fish determined the level of table carp
production. Multiple correlation between table production (y5) and stocking
rate
in fattening ponds with K1 (21) and K2 (zz) revealed that the coefficient
of determination (R2
) amounted to :
y5.zlzZ
R;5_zlzz
=
0.037121
+
0.5489ZZ
=
0.5859
Consequently, variability in table carp production is explained in
54.9 % by rate of stocking with K2
and in only 3.7 % by rate of stocking with
Kl°
When the use of feeds (y3) is also taken into account as another indepen—
deËt
variable in the multiple correlation, the coefficient of determination
(Ry5.zlz2y3)
amounts
to
:
=
0.0315zl
+
0.449222 + 0.1080y3
=
0.5887
on
the role of K
in explaining variation in table carp production decreases
to
3.2 %. Partial determination of the variation in this production due to
feeds amounts to 10.8 %, suggesting that the use of feeds is essentially rela—
ted with the production of carp stocking material. This confirm the earlier
conclusion on
higher f69d Use to produce one unit of carp stocking
compared to table fish.
'
'
correlation and regression indicate that the effectiveness of K1
stock1ng to produce table fish in the two—year cycle is really very low. It
would seem advisable to use carp fry-(Kl) to produce two—year olds (K2)
Which
can
then be used for the production of table fish; in other words the three—
year cycle
ShOU1d be used.
This assumption can be easily checked by the proper
calculations.
M. Leopold
as
well as the effectiveness of table carp production. The growth rate of carp
stocking material (4.35 %, Fig. 1) was much higher than that of table fish
production (1 Z), even taking into account the non—significant
linear appro—
ximation. When the last years are added the slope of the straight
line does
not
change so the conclusion on the decreasing effectiveness of carp produc—
tion seems to be correct…
This trend, similar to the former conclusion on decreasing effectiveness
of carp feeding, seems to reflect a continuing process… This would confirm
the hypothesis of the negative, increasing impact of some external factor on
pond culture. The same conclusion can be drawn concerning the trend of K2
production (see item 3 in Material) in the three—year production cycle. The
rate
of pond stocking with Kl to produce K2 was characterized by a growing
trend with an average annual increment of 7.49 % compared to the multi—year
average.
At the same time, K2 production increased by only 4.80 %. We can also
say that the effectiveness of stocking decreased… As shown earlier, the pro—
duction of this fraction (K2) was strongly intensified with
feeding so the
problem is of economic importance. It should be stressed that these negative
trends occur in spite of improved methods of management. That State Pond Fish
Farms
improve their management methods is demonstrated by the fact that K2
production increased 4.80 % annually compared to the multi—year average, whe—
reas
the rate of K2 stocking in the fattening ponds (to produce table fish)
increased by 5.2 % annually. Thus, we are dealing here with the decreasing
mortality of the stocking material during wintering and/or increasing fish
husbandry (lower weight loss during winter).
That management is satisfactory, at least as regards stocking material,
is even more evident if we take into account that two—year old fish (K2) cons—
titued 83.8 % of the stocking material used in the finishing ponds to produce
table carp and that in reality, these fish determined the level of table carp
production. Multiple correlation between table production (y5) and stocking
rate
in fattening ponds with K1 (21) and K2 (zz) revealed that the coefficient
of determination (R2
) amounted to :
y5.zlzZ
R;5_zlzz
=
0.037121
+
0.5489ZZ
=
0.5859
Consequently, variability in table carp production is explained in
54.9 % by rate of stocking with K2
and in only 3.7 % by rate of stocking with
Kl°
When the use of feeds (y3) is also taken into account as another indepen—
deËt
variable in the multiple correlation, the coefficient of determination
(Ry5.zlz2y3)
amounts
to
:
=
0.0315zl
+
0.449222 + 0.1080y3
=
0.5887
on
the role of K
in explaining variation in table carp production decreases
to
3.2 %. Partial determination of the variation in this production due to
feeds amounts to 10.8 %, suggesting that the use of feeds is essentially rela—
ted with the production of carp stocking material. This confirm the earlier
conclusion on
higher f69d Use to produce one unit of carp stocking
compared to table fish.
'
'
correlation and regression indicate that the effectiveness of K1
stock1ng to produce table fish in the two—year cycle is really very low. It
would seem advisable to use carp fry-(Kl) to produce two—year olds (K2)
Which
can
then be used for the production of table fish; in other words the three—
year cycle
ShOU1d be used.
This assumption can be easily checked by the proper
calculations.