1995 Fiscal Year Final Research Report Summary
Development of the Size Selectivity Theory of Angling Gear
| Project/Area Number |
05806025
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
General fisheries
|
|---|
| Research Institution | Hokkaido University |
|---|
Principal Investigator |
SHIMIZU Susumu Hokkaido Univ., Fac.of Fish., Lecturer, 水産学部, 講師 (80226240)
|
|---|
| Project Period (FY) |
1993 – 1995
|
| Keywords | Angling Gear / Size Selectivity / Modeling / Hooking Process / Hook Size / Hook Shape / Bait Size |
|---|
| Research Abstract |
In this study, the influence of fish size and the influence of the characteristics of the main components of angling gear were investigated. A relation between those factors and size selectivity was found, so the size selectivity theory of angling gear was developed.
1) The entering process of a hook into the model of a mouth cavity occurred by fluid resistance. The maximum entering distance of a big hook or a big bait in the model was longer than a small one. But the ratio of entrance of a big hook was lower than for a small one. Considering the ratio of entrance, the total average of the maximum entering distance of the big hook was shorter than for the small one.
2) For the long type hook, the maximum entering distance changed when the shank touched the upper part of the entrance of the model. For the round type hook, it did not appear that the maximum entering distance changed when the shank touched the entrance. And this hook had an advantage for hooking because the hook point easily touched the upper inside of the model.
3) It was shown that a suitable bait size existed for a given fish size, according to the hard entering coefficient estimated by angling experiments. Bait size was related to the hard entering coefficient. Because there was not a simple relation, such as liner, it was difficoult to construct a mathematical model.
4) As the limit of entering distance was introduced in the stochastic model of the hooking mechanism, this model could be fit on many more cases of angling phenomenon. The relation between the limit of the entering distance and size or shape of a mouth cavity, a hook, and a bait will have to be investigated in the future.
|
