Vegetation Survey Determines Effect of Fence

During the summer and autumn of 2012, a survey inside the fenced-off area measured things like the thickness and height of trees and the condition of seedlings that had naturally sprouted. The purpose of the survey was to see if seedlings were growing without being eaten by Sika deer and other wild animals, what effect the deer were having on nature, and how effective the fence was proving.

A comparison of the areas inside and outside the fence showed that for seedlings and small trees at least a year old, only about 70% of those outside the fence discovered in June remained by October. On the other hand, this figure was about 83% for those inside the fence. This shows that seedlings inside the fence are growing comparatively well.

Efforts Begun in Earnest to Return Iwaobetsu River to Its Original State

Human beings have altered the flow of the river and built embankments along the lower section of the Iwaobetsu River. Efforts have begun in earnest with the goal of returning the river to its natural state of river edges and meandering patterns and thus making it a suitable habitat for cherry salmon, char salt-water trout, and other fish to breed.

In July 2012, the river was returned to its original natural flow, and stones were placed in an approximately 100-meter stretch of the lower part of the river so that salmon and trout would have a place to breed. A survey in October discovered about 500 cherry salmon and char salt-water trout.

Besides surveying fish species, survey personnel recorded things like river width and depth, flow speed, and size of rocks on the river bottom. However, from late October when the survey finished until late November, there were record rainfalls that dramatically increased water volume and changed the environment of the river. Changes in the Iwaobetsu River caused by these rising water levels will be analyzed and this data will be used to help restore the river.

Surveys Conducted on River Birds and Small- and Medium-Sized Mammals

A survey was also conducted on wildlife around the Iwaobetsu River.

In June, bird species in an approximately 2.6-kilometer area along the river were surveyed. Besides black woodpeckers, a protected species, 16 other bird species were confirmed inhabiting the area.

Automatic cameras were also set up to survey small- and medium-sized mammals. In autumn, besides many raccoons, the camera captured many photos of the rarely spotted sable (related to the ferret). This shows that the habitat of the Iwaobetsu River is home to many animals.

43 Brown Bears, One of World's Largest Concentrations, Living in Rusha District

There are many brown bears living on the Shiretoko Penissula. And a dense population of brown bears is believed to be inhabiting the Rusha district on the west side of the peninsula. It's important to understand which bears are moving where so that they can be prevented from entering human habitats.

The Shiretoko Peninsula is closed off by snow for half the year, so outdoor surveys must take place during the short time between late spring and early autumn. While bears are hibernating in winter, humans are busy organizing and analyzing the data they have collected during the rest of the year.

One method used for obtaining DNA information uses biopsy darts. Researchers fire a special injection dart at the bears, and the skin and other tissue on the needle is used to take a DNA sample. The recent survey in Shiretoko is the first time that biopsy darts have been used successfully in Japan to collect brown bear samples.

A study of the DNA and hair color samples revealed that there are at least 43 brown bears living in the Rusha district. This is one of the highest concentrations of brown bears in the world.

Researchers plan to use the blood samples to determine the relationship among the brown bears in the Rusha district, verify this with information on brown bears from other areas, and thus determine the bears' pattern of movement.