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Ultraviolet colors in fishing lures

Rapala VMC Corporation manufactures and sells artificial fishing lures with the ultraviolet (UV) finishes that combine fluorescent paints, reflective surfaces and optical brighteners (see http://rapala.fishing/lure-finishes). Lures with theses finishes are marked by signs “UV BRIGHT” or simply “UV”. However, Rapala does not understand the abilities of ultraviolet (with the wavelength below 400 nm) vision in fish and its role in their responses to UV reflected objects in the nature and fishing.

 

Fig. 1. The sigh used by Rapala (brands Rapala, Storm, Blue Fox and Luhr Jenssen) to mark the lures with the UV finishes.

 

UV finishes in mafacturing fishing lures are also used by other companies like Lakeland Inc., USA (see http://lakelandinc.com/UFI/UFI_vibrant.html).

Ultraviolet vision

Freshwater fish

Numerous freshwater small-sized fish like three-spined stickleback, Gasterosteus aculeatus, reflect (Rick et al., 2004) radiation in the ultraviolet part of the electromagnetic spectrum and have UV vision. In particular, three-spined stickleback use UV vision in schooling (Modarressie et al., 2006), sexual (Rick & Bakker, 2008) and foraging (Rick et al., 2012) behavioural responses. The similar results are found for guppy, Poecilia reticulata (Smith et al., 2002), sailfin molly, P. latipinna (Palmer & Hankison, 2015), and other freshwater small-sized fish in the adult age.

However, UV reflection by some body does not provide the success per se. For example, during the nest decoration in artificial conditions males of three-spined stickleback choose rather red foil strips which absorb UV radiation than silvery or blue foil strips which reflect UV radiation (Östlund-Nilsson & Holmlund, 2003).

In turn, yearlings of predatory brown trout, Salmo trutta, use UV reflection of three-spined stickleback to hunt these prey (Modarressie et al., 2013). However, only young trout are sensitive to UV (see data by Bowmaker & Kunz, 1987, for Salmo trutta; Hawryshyn et al., 1989, for Salmo gairdneri), while older (over two years) fish lose this ability.

The same ontogeny of UV vision is typical for other freshwater predatory fish like perch and others (see Bowmaker, 1990). With the age, the ocular structures change radically and do not allow the fish to perceive UV radiation.

Saltwater fish

Great care must be taken in relation to marine fish and invertebrates (like crustaceans) many of which have UV vision (Losey & Cronin, 1997; Siebeck & Marshall, 2001; Losey et al., 2003).

According to Fritsches et al. (2000), marine predatory fish of the younger age groups and medium-sized fish (like slimy mackerel, Scomber australasicus, and others) are sensitive to UV, while marine predatory fish of the older age groups and large-sized fish (like blue marlin, Makaira nigricans, black marlin, Makaira indica, sailfish, Istiophorus platypterus, and others) are UV blind.

In general, UV signals are mainly used by small-sized and juvenile fish (both freshwater and saltwater) to form private communuication channels that are relatively inaccessible for potential predators (Siebeck, 2014).

Thus, UV finishes of Rapala’s lures and lures of other companies are useless for freshwater and saltwater predatory fish of the older age groups which lose UV vision with the age.

Optical brighteners

In addition to reflective surfaces, Rapala uses optical brighteners. The use of optical brighteners  complicates the description of the optical properties of UV fishishes.

It is well known that optical brighteners are fluorescent substances which absorb UV radiation and immediately re-emit it in the visible part of the spectrum with the maximun of re-emission in violet and blue parts of the spectrum. White covers with optical brightners reflect partly the falling sun light which is mixed with the light of fluorescence, so the human’s eye perceives these covers as “more bright” and “more white” (well known as “snow white”) than white covers without optical brighteners.

In the pure form, fluorescent white finishes are used, for example, by Lakeland Inc. to cover its metal spoons and spinners (see http://www.lakelandinc.com/finishes.html).

In general, white and fluorescent white colors are most visible in the freshwater and saltwater environments (Kenney et al., 1967, 1968). But the great visibility of white and fluorescent white colors does not guarantee their attractiveness for fish.

For example, Dooley (1989) has studied using trolling technique the responses of rainbow trout, Salmo gairdneri, to wobblers, spoons and spinners of various colors and found that lures of the solid white color were less effective than lures of blue, green, yellow and red colors. Moraga et al. (2015) have studied using sink-and-retrieving technique the responses of largemouth bass, Micropterus salmoides, to soft plastic worms (of 12.7 cm length) of various colors and found that worms of the “pearl white” color were less effective than worms of natural and dark colors.

The same results were obtained in marine fishing. For example, according to Hsieh et al. (2001), in mackerel longline fishing white lures were slightly more effective than blue, purple and transparent lures (cryptic on the background of marine column) but less effective than black and red lures.

Psychological perception of white objects

It is known that relatively large objects of white color may scare fish. So, Moraga et al. (2015) have found that white soft plastic worms of 12.7 cm length allow to catch largemouth bass of greater sizes than the same worms of darker colors. It means that white lures warn of danger or scare largemouth bass of smaller sizes.

In general, white objects are perceived greater in size than the same dark objects (e.g., Kremkow et al., 2014).

On the other hand, because the natural sun light contains all the chromatic colors, which may be detected with the assistance of Newton’s lens, we perceive the sun light as “white”. In the same manner, we perceive any white surfaces (like white clouds, snow, paper, etc.) as “white” because these surfaces reflect more or less evently all components of the sun light.

However, our perceptions can not be automatically transferred to fish perceptions!

It is known that fresh water absorbs short-wavelength rays and transmits long-wavelength rays, so the maximum of spectral sensitivity of eyes of freshwater fish is shifted to the orange and red parts of the optical spectrum (e.g., Tamura & Niwa, 1967). Therefore, the “white light” for freshwater fish is enriched with the long-wavelength rays (we name this light as “worm light” or “warm white”). In contrast, marine water absorbs long-wavelength rays and transmits short-wavelength rays, so the maximum of spectral sensitivity of eyes of saltwater fish is shifted to the blue and green parts of the optical spectrum (Tamura & Niwa, 1967). Therefore, the “white light” for saltwater fish is enriched with the short-wavelength rays (we name this light as “cool light” or “cool white”).

How fish perceive colors, see Vorobyev et al. (2001).

In addition, for small-sized and juvenile freshwater and salwater fish the “white light” is enriched with UV rays (see above), which are invisible for the human’s eye.

Numerous freshwater and saltwater fish have white or whitish with the different tints belly (or the lower side in flat fish) that masks them on the backgrounds of the bright water surface illuminated with the sun light. Subjected to the conditions of crypsis in the water environment, boldly white fish (like arctic animals in winter) are absent in this environment, excepting white morphs.

In order to estimate roughly the composition of the underwater li ... Read more »

Category: Lures | Views: 308 | Added by: nickyurchenko | Date: 2016-12-24

Already in the 19th century Sabaneev (1960) reported that piscivorous visually guided zanders, Stizostedion lucioperca, which eat only live food can nonetheless be caught on dead fish cut into stripes with the skin and silver scale. Like other visually guided predatory fish, namely pike, Esox lucius, and perch, Perca fluviatilis, zanders never eat decaying fish. According to the modern knowledge, zanders could respond in addition to visual cues to alarm pheromone that released in the water from the injured skin of fish or from dead fish without injuring their skin (Malyukina et al., 1980).

Indeed, dead fish in trolling and other rigs may be used to fish big pike and zander (Sabaneev, 1960).

In the undirect winter experiments carried out in the USA by Wisenden & Thiel (2001), predatory fish active in cold season such as pike, E. lucius, walleye, S. vitreum, largemouth bass, Micropterus salmoides, and yellow perch, P. flavescens, colud be attracted by the skin extract of fathead minnow, Pimephales promelas (Cyprinidae).

In the direct field experiments (Dnipro river in Ukraine, in June) described below, we found that S. lucioperca could be attracted by alarm pheromone of roach, Rutilus ruitlus.

Chemical stimulus of one type was prepared by squashing 30 g of roach skin together with the scale in the rough clay mortar and diluted with the 0,3 liter of river water, without further filtration. Chemical stimulus of another type was prepared of 30 g of roach flesh without skin in the foregoing way (according to Malyukina et al., 1980, standard extract of fish skin contains 1g of skin per 1 liter of water).

To compare both chemical stimuli, artificial soft lures made of high quality white foam rubber were used. Lures were in the form of stripes (0,5 x 0,5 x 5,0 cm) attached at one end to the single hooks (VMC live bait hooks #1/0, short shank). For more buoyancy, one white styrofoam olive was dressed similar to sabiki on the line leader in front of each lure.

In the field, two units of the typical feeder rods with reels, main lines, simple sinkers and two line leaders, 30 and 40 cm length, with the attached lures were used. In one rig, lures attached to 30 and 40 cm leaders was soaked with the skin and flesh extracts, respectively, vice versa in another rig.

Lures of both types were compared in the typical zander location with the depth of 2,0- 2,5 m at the distance of 15-20 meters from the shore, with the middle flow. Tests were carried out during two nights from 1000 of evening until 1200 of midnight, skin and flesh extracts in rubber bodies of lures were resoaked every thirty minutes.

In total, within two nights 21 bites were obtained. Potential predators, in addition to zander, were large individuals of chub, Leuciscus cephalus, ide, L. idus, and wels catfish, Silurus glanis, all with the nocturnal type of feeding activity. Among potential predators, 9 individuals of zander (from 0,8 to 1,2 kg) were caugh, all for lures soaked with the skin extract (sign test, n = 9, z = 9, p < 0,01). Also, single 3 kg wels was caught for the same lure.

These data show the preference of zanders to alarm pheromone of cyprinid fish. According to Valentinčič (2004), for wild zanders an odor of the fish flech extract must be indifferent.

... Read more »

Category: Attractants | Views: 1474 | Added by: nickyurchenko | Date: 2013-06-30

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