120
moves upwardly along a thallus, similar to the action of a conveyor belt. Therefore,
by marking a hole with a cork borer at an appropriate position on the blade and tracing the temporal movement of the hole on the thallus, it is possible to estimate the
new growth of the blade or the number of newly formed lateral blades in the case of
Ecklonia and Eisenia,within a given period. Kurashima (2010) and Sakanishi (2010)
describe the method of measuring the production of these kelps by this punch-hole
marking method in their reviews.
Both warm- and cold- temperate kelps also show clear seasonal fluctuations, and
the thallus size and biomass are generally maximized in late spring to summer.
From summer onward, senescence and withering of blade tissues rapidly progress
at the tip of thalli (called Sue-gare), and the biomass decreases. Formation of new
blade tissue is activated again in seasons with lower water temperature. At the Iki
Islands in Nagasaki Prefecture, the production of Ecklonia kurome is extremely
small in the summer, when the water temperature can reach a maximum of 28 °C,
but it recovers rapidly as the water temperature declines after autumn (Yatsuya et al.
2014a).
Reported annual production of Ecklonia species was 2.8 kg dry weight/m
2
/year
at Izu peninsula, Pacific Honshu region (Yokohama et al. 1987); 2.7 kg dry weight/
m
2
/year at Tosa Bay, Shikoku region (Tominaga et al. 2004); and 2.8 kg dry weight/m
2
/year at Iki Islands, Kyushyu region (Yatsuya et al. 2014a). In addition, we obtained
a similar value (2.5 kg dry weight/m
2
/year) in Iyo-nada, Seto Inland Sea region
(Yoshida et al. unpublished). Reported production of species of Eisenia was 3.0 kg
dry weight/m
2
/year at Matsushima Bay, Pacific Tohoku region (Yoshida 1970) and
3.6 kg dry weight/m
2
/year at Miura Peninsula, Pacific Honshu region (Terawaki
et al. 1991; converted to dry weight as 15% of wet weight). The annual production
of Ecklonia and Eisenia in Japan ranged from 1.4 to 3.6 kg dry weight/m
2
/year
regardless of region (Kurashima 2010; Yatsuya et al. 2014a).
Cold-temperate kelps in Japan, mostly species belonging to genus Saccharina
and called Kombu in general, are commercially very important. Kombu fisheries in
Japan are almost dependent on harvest of natural resources. However, whereas
many data about catch statistics are available, information on the biomass and production of natural kelp beds has been scarce. Even with this small amount of
information, some studies have reported the biomass and production of some species at some locations. In S. japonica, the maximum biomass was 2.6 kg dry weight/
m
2
in Tsugaru Peninsula (Pacific Tohoku region) and 0.8 kg dry weight/m
2
in
Onagawa Bay (Pacific Tohoku region). In S. japonica var. religiosa, it was 1.0 kg
dry weight/m
2
in Otaru (Hokkaido region) and 4–18.4 kg dry weight/m
2
in
Kadonohama Bay (Pacific Tohoku region). On the northern coast of Hokkaido such
as in Rausu and Akkeshi, S. japonica var. diabolica showed biomass values of <1 to
8.7 kg dry weight/m
2
(Onitsuka and Hasegawa 2013; converted to dry weight as
20% of the wet weight). Although data on annual production are quite limited, it
was recorded as 1.3 kg dry weight/m
2
/year for S. japonica in Onagawa Bay and
1.4 kg dry weight/m
2
/year for S. angustata in Urakawa Town in Hokkaido. In addition, production of 20 kg dry weight/m
2
/year or more has been reported for S. japonica var. diabolica in the eastern coast of Hokkaido (Sakanishi 2010; Onitsuka and
Hasegawa 2013).
G. Yoshida et al.
moves upwardly along a thallus, similar to the action of a conveyor belt. Therefore,
by marking a hole with a cork borer at an appropriate position on the blade and tracing the temporal movement of the hole on the thallus, it is possible to estimate the
new growth of the blade or the number of newly formed lateral blades in the case of
Ecklonia and Eisenia,within a given period. Kurashima (2010) and Sakanishi (2010)
describe the method of measuring the production of these kelps by this punch-hole
marking method in their reviews.
Both warm- and cold- temperate kelps also show clear seasonal fluctuations, and
the thallus size and biomass are generally maximized in late spring to summer.
From summer onward, senescence and withering of blade tissues rapidly progress
at the tip of thalli (called Sue-gare), and the biomass decreases. Formation of new
blade tissue is activated again in seasons with lower water temperature. At the Iki
Islands in Nagasaki Prefecture, the production of Ecklonia kurome is extremely
small in the summer, when the water temperature can reach a maximum of 28 °C,
but it recovers rapidly as the water temperature declines after autumn (Yatsuya et al.
2014a).
Reported annual production of Ecklonia species was 2.8 kg dry weight/m
2
/year
at Izu peninsula, Pacific Honshu region (Yokohama et al. 1987); 2.7 kg dry weight/
m
2
/year at Tosa Bay, Shikoku region (Tominaga et al. 2004); and 2.8 kg dry weight/m
2
/year at Iki Islands, Kyushyu region (Yatsuya et al. 2014a). In addition, we obtained
a similar value (2.5 kg dry weight/m
2
/year) in Iyo-nada, Seto Inland Sea region
(Yoshida et al. unpublished). Reported production of species of Eisenia was 3.0 kg
dry weight/m
2
/year at Matsushima Bay, Pacific Tohoku region (Yoshida 1970) and
3.6 kg dry weight/m
2
/year at Miura Peninsula, Pacific Honshu region (Terawaki
et al. 1991; converted to dry weight as 15% of wet weight). The annual production
of Ecklonia and Eisenia in Japan ranged from 1.4 to 3.6 kg dry weight/m
2
/year
regardless of region (Kurashima 2010; Yatsuya et al. 2014a).
Cold-temperate kelps in Japan, mostly species belonging to genus Saccharina
and called Kombu in general, are commercially very important. Kombu fisheries in
Japan are almost dependent on harvest of natural resources. However, whereas
many data about catch statistics are available, information on the biomass and production of natural kelp beds has been scarce. Even with this small amount of
information, some studies have reported the biomass and production of some species at some locations. In S. japonica, the maximum biomass was 2.6 kg dry weight/
m
2
in Tsugaru Peninsula (Pacific Tohoku region) and 0.8 kg dry weight/m
2
in
Onagawa Bay (Pacific Tohoku region). In S. japonica var. religiosa, it was 1.0 kg
dry weight/m
2
in Otaru (Hokkaido region) and 4–18.4 kg dry weight/m
2
in
Kadonohama Bay (Pacific Tohoku region). On the northern coast of Hokkaido such
as in Rausu and Akkeshi, S. japonica var. diabolica showed biomass values of <1 to
8.7 kg dry weight/m
2
(Onitsuka and Hasegawa 2013; converted to dry weight as
20% of the wet weight). Although data on annual production are quite limited, it
was recorded as 1.3 kg dry weight/m
2
/year for S. japonica in Onagawa Bay and
1.4 kg dry weight/m
2
/year for S. angustata in Urakawa Town in Hokkaido. In addition, production of 20 kg dry weight/m
2
/year or more has been reported for S. japonica var. diabolica in the eastern coast of Hokkaido (Sakanishi 2010; Onitsuka and
Hasegawa 2013).
G. Yoshida et al.