Possible Relationships between Fishermen's Perception and the Fractal Structure of Coastline—A Case Study of Oshika Peninsula

Fumio Yonechi¹ and Masatoshi Endo²

¹Institute of Geography, Faculty of Science, Tohoku University, Aobayama, Sendai 980, Japan
²Department of Geography, Faculty of Education, Iwate University, Ueda 3-18-33, Morioka 020, Japan

(Received October 22, 1988; Accepted December 20, 1988)

Keywords: Fractal, Coastline, Koch Curve, Fishermen, Perception

Abstract. Oshika Hanto is a small peninsula on the Pacific Coast of northeastern Honshu Island, Japan, where many conflicts concerning fishery occurred in the Edo era (1603-1868). The fifteen villages belonging to the "Kitsunezaki-gumi", a fishing cooperative, are located along the southwestern coast of the peninsula. They had a self arbitration system in cases of conflict between villages. In one of the Hiratsuka family documents (a representative lineage of the "Kitsunezaki-gumi"; Fig. 1), written in 1830, there is a curious grouping of villages; namely, 15 villages are divided into three groups and lined up from west to east along the coast as follows:

A C A B C B A B C B A C A B C.

In the usual grouping, they used a kind of scan like this:

a b c a b c a b c. . .(ex. 1798 document; Table 1).

Why did they change the grouping system to an apparently erratic arrangement?
The authors found some regularities in the arrangement of villages. "A" villages are arranged on promontories, except for a village located at the center of the bay. "B" villages are situated along both sides of the bay. "C" villages are located between two "A"s or two "B"s. (The "C" at the eastern end is the only exception because it is an island village.) In this way, fishermen in the Edo era grouped their villages to fit the coastline shape.
MANDELBROT (1983) claimed that a Koch curve is a rough but vigorous model of a coastline. The authors tried to modify the real coastline of the Oshika Peninsula (proto-landform; YONECHI, 1985), and got a "pseudo" triadic Koch curve as a meta-landform (YONECHI, 1985; Fig. 4).
The process of drawing this "pseudo" triadic Koch curve (Fig. 3) is a key to the understanding of the fishermen's arrangement of village groups. The fishermen would have had an intuitive perception of the coastline similar to a triadic Koch curve, a typical "fractal" curve.