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ผู้เขียน หัวข้อ: Determining fish size and swimming speed in cages and tank  (อ่าน 2494 ครั้ง)
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« เมื่อ: มกราคม 16, 2010, 08:27:15 AM »

Determining fish size and swimming speed in cages and tanks using simple video techniques

R. J. Petrell”.“, X. Shi”, R. K. Ward”, A. Naiberg’, C. R. Savage”
 Aquacultural engineering 16(1997):63-84

Abstract
A video-based system which can he used to measure the average fish size in :I nob
intrusive fashion was developed. It performed well under a wide range of fish behaviours,
types, stocking densities, ages and water quality conditions in tanks and sea cages. The
design was based on principles of simple stereo geometry. incorporated fish dimensions,
weight relationships and took into consideration fish movement to lower system cost\. The
overall system is durable, cost effective and easy to use. No artificial lighting is reyuircd.
Approximately 20 min of continuous video footage are needed, and depending on the fishimage
density, 30-60 min of labour are required to select suitable fish images and detcrminc
accurately the average fish size of a population. On still fish. average tish mass wax
measured to within 05%. On moving fish in sea cages and tanks with known individual
salmonid masses, no significant difference was evident between measured and actual avcragc
mass. Testing the video system against the crowding/dip netting method in trout hatchq
tanks containing from 7000 to 20000 fry showed the video system to be as accurate as the
crowding/dip netting method for dctcrmining fish mass provided the cameras wcrc
positioned in apparently preferred fish swimming locations. The new video method can be
used to economically record and study hehaviour, swimming speed and size distributions
under a wide range of culture conditions.
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