Fishermen Advocates: Disclosing Forgery in Fishing Industries




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In the expeiments described below, artificial tube lures decorated with the periodic gratings, eye-spots and longitudinal stripes, named amimetic stimuli, were tested in the field. As known, the effectiveness of amimetic (non-simulative) stimuli is determined by the neuroethological mechanisms that are common for the different sensory guided behavioural responses, both in animal and human.

For more information bout amimetic stimuli, please see these articles:

The testing lures were made of hard plastic tubes with the diameter of 3-4 mm and the length of 22-24 mm. The tubes were moved to the single or duble slightly decorated hooks. The tubes were white, amimetic stimuli were made of black sticky paper (WTP Inc., # 414). Periodic gratings had 2 mm bands with 2 mm spaces (5 bands, in total). The diameter of bilateral black eye-spots was 3,0-3,5 mm. Bilateral longitudinal stripes had the width of 2 mm and the length of 18 mm. In the experiments, lures of the same size with and without black decorations (see Fig) were compared pairwise.

Two compared lures, with and without black decorations, were attached to the two arms of an umbrella rig. Its arms of 10 cm long were made of high quality stainless wire diameter of 0,3 mm. Umbrella rig was equipped with the low-centered weight of 10-15 gr (neutral grey color). When retrieving, both compared lures moved in the horizontal plane at the distance of 6-7 cm each from other.

Perch, Perca fluviatilis, were used as the fish model.

Note, adult perch and other visually guided fish can distinguish 1,5-2,0 mm details at an attack distance up to 15-20 cm under the day light (Richmond et al., 2004).

Compared lures were presented with the assistance of light spinning rods in the wide (5-10 m) aisles between the coastal aquatic plants, where perch located mainly at the border of vegetation and clear water. In this case, perch could attack the nearest lure. To avoid this systematic mistake, compared lures were presented the same number of times near the left wall of vegetation and, correspondingly, near the right wall (at the distance of 0,3-0,8 m from the wall).

Aquatic plants included mainly yellow water lily (Nuphar lutea) and numerous pondweeds.

Within one of the typical sessions of lure presentations, the following results were obtained. Out of 100 lure presentations, 58 were empty, 10 perch were landed pairwise. These data were no used in calculation. The remaining 32 perch were distributed in the following way. 24 perch (marked by sign +) took the lure with the banded tube. Whereas only 8 perch (marked by sign ) took the lure without bands. According to the sign test statistical method, n =32, z fact =24, z standard = 24, p < 0.01. It means that in these tests perch preferred authentically the lure with the bands.

Similarly, perch preferred lures with the bilateral eye-spots and lures with the bilateral longitudinal stripes (see Fig.) to simple lures. ... Read more »

Category: Lures | Views: 641 | Added by: nickyurchenko | Date: 2013-03-12



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