August 4th our class did a bio survey near a river near Lake Toro in Kushiro. We observed the river by getting into the water. We looked at the structure of the river, the vegetation and fished to find animal and bug species in and near the river. We caught fish, shrimp and crayfish. At the end of our survey, we were required to kill the crayfish that were caught. The crayfish species was the Signal crayfish or the “Uchida-zarigani” in Japanese. Despite having a typical Japanese name in its species name, it is an invasive species to Japan.
In a trip before to the upper course of the river, forest rangers explained to us that most crayfish in Japan are invasive species and in Kushiro, to preserve the natural species of the Japanese crayfish, the signal crayfish and American crayfish are considered to be a designated invasive species in the area. Therefore, a law proposes any signal crayfish caught must not be put back in the water, but be killed.
Just hearing about such law, I understood it had the purpose of protecting the ecosystem and the native species. However, when it came to kill the crayfish I was flushed with mixed feeling, both sad and having a feeling that I have done something for the environment. It was not the crayfish`s fault that it was in that river as an invasive species.
Human beings were the ones who brought the signal crayfish and because the invasive species was introduced, it caused the decrease of the native species and an embalance in the ecosystem. Therefore, humans are the ones who have the responsibility to take care of such issues. In this case the issue was taken care of by a law where they would kill the crayfish. However, these crayfish never chose to live in the environment of Japan. It is the humans that are of fault but we had to kill the crayfish.
Through this experience I questioned the level of value humans put on living things and also felt strongly that we must think more of our social and economic actions and look to see the possible environmental risks beforehand to prevent any issues in our future.