Analysis on the value of CPUE [Catch Per Unit Effort] by each river form in the mountainous stream: Case study of the Wasadagawa River in Tohoku region [Japan]
2002
Watanabe, K. (Iwate Univ., Morioka (Japan)) | Okubo, H. | Maekawa, K.
Angling pressure to fishes (O.masou, S.leucomaenis) in the mountainous stream was studied using CPUE (Catch Per Unit Effort) based on 12 times survey. CPUE was calculated as the whole total length per one hour and as a number of capture per one hour. The study area, 1.6km-length, was divided into the 19 units. The ratio of the water surface area became lower in order of fast rapids, flat riffle, step and pool. The average density of the point, which a angler throws worms into with fishing rod, of flat riffle was 2-3 times higher than other river forms. In pool, it was lowest values. In the seasonal variation of CPUE, any river form was low in summer where the water temperature rose to 15 degrees or more. The CPUE became higher in spring and autumn. Average CPUE in the whole investigations showed low value 25cm/h at the flat riffle and high result 97crn/h at pod. Fast rapid and pod were accounted for about 80% in the number and the amount of total capture. And especially highest pressure was brought to fish of the average type (16-20cm). As for flat riffle and step, the tendency with a high pressure to a small type of fish (16cm or less) was analyzed compared with pod and fast rapids. As mentioned above, the feature of angling pressure to fishes and the point in each river form became clear. Therefore, some important findings will be useful for making a countermeasure plan to angling pressure in the mountainous stream.
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