Abstract
The kelp Saccharina japonica var. ochotensis is the most
important algal
resource in northern Hokkaido, Japan. The species is biennial, and fishing
of the kelp is
limited solely to second year sporophytes. Annual change of monthly mean
surface water
temperature and catch of the kelp S. japonica. var. ochotensis
in northern Hokkaido,
Japan, from 1980 to 2016 were compiled based on data from public
organizations. Over
this period, increasing water temperatures in each month contrasted with a
decreasing
catch of kelp. Statistical analysis using Pearson Correlation Analysis
Method was conducted
between mean monthly water temperature and catch of S. japonica
var. ochotensis
in each year. A significant correlation was found between water temperature
from
September to December one year prior to the fishing year and the catch of
the kelp. In
general, fewer individuals of the kelp transit from first year sporophyte to
second year
sporophyte during from October to November, and this decreased rate of
transition
impacts the catch. The present study suggests that lower temperatures during
September
to December would lead to a higher transition rate from first year
sporophytes to second
year sporophytes, which in turn would lead to a higher catch of kelp the
following year.
