279
production of sardines which was maintained at
a high level (from the first half of the 1980s to
the first half of the 1990s) (Year book of Annual
statistics on Fisheries and Aquaculture production 2013). The huge amount of sardines had
been used as feed fish for both these two carnivorous species. The market price of sardines has
been very low. The price of feed is a significant
problem for aquaculture production because carnivorous fish requires much feed fish. Although
depending on the species and aquaculture conditions such as the number of fish in a unit volume,
feed requirement of both fishes ranged from 6 to
8 times the amount of production as wet weight
(Furuya 1999). In order to estimate energy conversion efficiency of typical aquaculture species,
such as yellowtail and sea bream in Japan, a preliminary calculation was conducted based on
food calorie database. In the calculation, common baitfish feed used in Japan aquaculture, that
is, sardines, mackerels, pacific saury and
Japanese sand lance, etc., was selected. Actually,
the mean value (197 kcal per 100 g weight; converted energy 197 × 10
3
× 4.184 J) obtained for
the aforementioned baitfish was used, and the
value of feed requirement was assumed as 6
times the amount of production as wet weight.
The estimated energy conversion efficiency for
yellowtails is 0.21 and for red sea bream 0.16.
Here, these values are underestimated because
actually almost all feeds used are made from fish
meal, and therefore, there is a production loss in
the course of processing. In the calculation, production loss was written off. Both species productions have been maintained at around
2.0 × 10
5
tons level in the recent two decades.
When focusing on the recent 6 years from 2006
to 2011, a difference in the degree of decrease
can be seen, with yellowtail production indicating a gradual decrease (see Fig. 6) and red sea
bream showing rapid reduction.
Recently, carnivore fish aquaculture production was badly affected by increased feed price
due to reduced baitfish production (Demura
2010). In addition, as pointed by FAO, 80 % of
natural resources as human food are already
overexploited, indicating that considering the
natural resource condition, there is no place for
sufficient allowance to pass on to roundabout
production such as carnivore fish aquaculture
production. Of course, new feed has been developing without animal protein, but it is still unpredictable and uncertain elements still remain.
There is a need to address the urgent task of
reconsidering optimum fishery production system
and about the balance between capture fishery
and aquaculture production for maintaining and
developing the fishery. To avoid the depletion of
a finite natural fishery resource, people have to
stop and reconsider about the amount of optimum
production process and the system of carnivore
fish aquaculture. Socioeconomic activities, such
as production of popular foodstuffs, should be
considered within the bounds of nature. In the
case of aquaculture, we have been getting huge
amounts of living organisms as feed for carnivore
fish from the sea. And even in the processing
stage of feed, there is release of and output of
garbage. The roundabout method of production
such as aquaculture of high-priced fish exists in
combination with risks involved. The aquaculture production throughout its production process
needs a large amount of natural resources such as
living organisms. On the other hand, natural
resources are finite, and we could not overuse
these organisms’ sustainable self-recovery.
For example, imported nonfood use was
1.15 × 10
6
tons in 2011; on the other hand, fish
meal was imported from Chili (34,642 tons),
Peru (101,494 tons), Russia (585 tons), and the
USA (8,018 tons) reaching a total of 247,045
tons (Year book of Annual statistics on foreign
trade statistics 2011).
Domestic production of nonfood use was
4.8 × 10
5
tons, and although the specific items are
unknown, almost of all them might be directed to
feed of farmed fish.
In February 2014, the Japanese government
instituted a guideline for optimum production of
carnivorous species such as red sea bream and
yellowtails for supplying adequate aquaculture
production to meet demand (production volume
is 7.2 × 10
4
tons and 14 × 10
4
tons, respectively) in
the 2014 fishing period.
Capture Fisheries and Aquaculture in Japan and the World: Current Status and Future Concern
production of sardines which was maintained at
a high level (from the first half of the 1980s to
the first half of the 1990s) (Year book of Annual
statistics on Fisheries and Aquaculture production 2013). The huge amount of sardines had
been used as feed fish for both these two carnivorous species. The market price of sardines has
been very low. The price of feed is a significant
problem for aquaculture production because carnivorous fish requires much feed fish. Although
depending on the species and aquaculture conditions such as the number of fish in a unit volume,
feed requirement of both fishes ranged from 6 to
8 times the amount of production as wet weight
(Furuya 1999). In order to estimate energy conversion efficiency of typical aquaculture species,
such as yellowtail and sea bream in Japan, a preliminary calculation was conducted based on
food calorie database. In the calculation, common baitfish feed used in Japan aquaculture, that
is, sardines, mackerels, pacific saury and
Japanese sand lance, etc., was selected. Actually,
the mean value (197 kcal per 100 g weight; converted energy 197 × 10
3
× 4.184 J) obtained for
the aforementioned baitfish was used, and the
value of feed requirement was assumed as 6
times the amount of production as wet weight.
The estimated energy conversion efficiency for
yellowtails is 0.21 and for red sea bream 0.16.
Here, these values are underestimated because
actually almost all feeds used are made from fish
meal, and therefore, there is a production loss in
the course of processing. In the calculation, production loss was written off. Both species productions have been maintained at around
2.0 × 10
5
tons level in the recent two decades.
When focusing on the recent 6 years from 2006
to 2011, a difference in the degree of decrease
can be seen, with yellowtail production indicating a gradual decrease (see Fig. 6) and red sea
bream showing rapid reduction.
Recently, carnivore fish aquaculture production was badly affected by increased feed price
due to reduced baitfish production (Demura
2010). In addition, as pointed by FAO, 80 % of
natural resources as human food are already
overexploited, indicating that considering the
natural resource condition, there is no place for
sufficient allowance to pass on to roundabout
production such as carnivore fish aquaculture
production. Of course, new feed has been developing without animal protein, but it is still unpredictable and uncertain elements still remain.
There is a need to address the urgent task of
reconsidering optimum fishery production system
and about the balance between capture fishery
and aquaculture production for maintaining and
developing the fishery. To avoid the depletion of
a finite natural fishery resource, people have to
stop and reconsider about the amount of optimum
production process and the system of carnivore
fish aquaculture. Socioeconomic activities, such
as production of popular foodstuffs, should be
considered within the bounds of nature. In the
case of aquaculture, we have been getting huge
amounts of living organisms as feed for carnivore
fish from the sea. And even in the processing
stage of feed, there is release of and output of
garbage. The roundabout method of production
such as aquaculture of high-priced fish exists in
combination with risks involved. The aquaculture production throughout its production process
needs a large amount of natural resources such as
living organisms. On the other hand, natural
resources are finite, and we could not overuse
these organisms’ sustainable self-recovery.
For example, imported nonfood use was
1.15 × 10
6
tons in 2011; on the other hand, fish
meal was imported from Chili (34,642 tons),
Peru (101,494 tons), Russia (585 tons), and the
USA (8,018 tons) reaching a total of 247,045
tons (Year book of Annual statistics on foreign
trade statistics 2011).
Domestic production of nonfood use was
4.8 × 10
5
tons, and although the specific items are
unknown, almost of all them might be directed to
feed of farmed fish.
In February 2014, the Japanese government
instituted a guideline for optimum production of
carnivorous species such as red sea bream and
yellowtails for supplying adequate aquaculture
production to meet demand (production volume
is 7.2 × 10
4
tons and 14 × 10
4
tons, respectively) in
the 2014 fishing period.
Capture Fisheries and Aquaculture in Japan and the World: Current Status and Future Concern