For decades, many companies offer rattling woblers, like Rapala Rattlin’ Rap, Bill Lewis Rat-L-Trap, Cotton Cordell Super Spot and other, positioning these lures as more attractive than usuals.

In particular, Bill Lewis Co. writes that today’s Rat-L-Trap lures are proven by leading experts to produce sound qualities nearly identical to those of schooling baitfish under attack. These sounds are the "dinner bell” for predatory fish. According to scientific research, Rat-L-Trap and schooling fish emit really similar sounds (Fig.1), but this does not confirm the benefits of Rat-L-Trap lures in the practice.

Figure 1. According to Joseph Olson (Cetacean Research)

An objective of tests described below was to compare two types of Rat-L-Traps, noisy and quiet, using the common perch, Perca fluviatilis, in the capacity of test objects. Tiny Traps of 3,5 gr with Smokey Joe color were used. Some lures, marked TTN, were intact, whereas in other lures, marked TTQ, the rattling balls were glued over the thin holes drilled in the body, sealed finally.

At each estimated locality of perch, 12 presentations (cast and retrieving) of lures were made: 3 with TTN, 3 with TTQ, 3 with TTN and 3 with TTQ. Then an experimentator moved to the other locality, where 12 presentations of the compared lures were made in the reverse order. 180 lure presentatations per 1 day were made, null and pair results for TTN and TTQ lures were canceled. In total, 33 perch were included in the calculation, the number of fish (landed and released) were group per each 6 lure (for TTN and TTQ) presentations.

Lures were tested in the presense of small windy waves, but without rain.

Some landed and released Northern pike, Esox lucius, were no included in the calculation.

An estimation of mean difference for findings obtained in field for TTN and TTQ lures with the assistance of Student’s t-test have confirmed that perch have shown preference for neither of lure types. Similar results (the absence of preference) have been obtained in other 5 sessions with the same Tiny Traps and 3 sessions with alike Rapala Rattlin’ Raps (4 cm, Shad color) carried out in the different fishing conditions.

There are several reasons that allow to explain why perch ignore sounds of the foregoing lures.

Acoustic signals of three types induce the most clear responses, including motor responses, in perch (and other fish with the developed acoustically guided behaviour). Feeding sounds of conspecific individuals and cohabiting fish (like roach, Rutilus rutilus) that have the noise nature in the frequency band up to 5000 Hz (Protasov, 1965). Secondly, threat sounds listened in the water as the powerful single pulses with the main frequency of 1000 Hz. And finally, courtship and spawning sounds that have the most clear rhythmic nature in the band of low frequencies. Furthermore (Protasov, 1965), perch can move towards the source of rhythmic signals, if these signals are even overlapped (4:1) by wideband noise. Unlike the foregoing signals, wideband high frequency noises induce in perch only orientation responses (that quickly fade due to the so called habituation).

Sounds made by Rat-L-Traps belong to the wideband high frequency noises (Fig. 1), unattractive for perch.

Noise sounds emited by small lures may be very weak.  For example, they can be overlapped by noises of windy waves and rain. However, perch ignore sounds of larger lures (like Mini Trap).

In addition, perch are mainly visually guided predatory fish. Therefore, they may ignore weak noises in the complex muitimodal signals.

Finally, it is well known that tuna and other sea fish are attracted to areas on the water surface disturbed by the falling drops of the ship sprinklers. These "boiling spots” perfectly mimic schools of baitfish pursued by predators. According to our experiments, perch are attracted to "boiling spots” created by jets of an autonomous pump. In these cases, however, acoustic, vibrating and visual parts of complex stimuli are much more powerful than those of small lures.

Basic References

Protasov V.R. 1965. The bioacoustics of fishes. Moscow, Science