For the most part, trials with baited samples of armored cable in 

 tensile frames have been unsuccessful, although in one case Prionace glauca 

 punctured samples of polyethylene and polycarbonate in trials conducted 

 off the southeast coast of Massachusetts (Stimson and Prindle, 1967). 

 Studies of this kind cannot be considered realistic since they fail to 

 stimulate the stratification of the moorings' physio-chemical and biological 

 environment. 



It has been theorized that sharks usually do not exert maximum biting 

 strength on cables because they are attracted to foreign objects on or in 

 the immediate vicinity of the cables, rather than to the cables themselves. 

 Walden and Panicker (1973) ascribe the "dental floss effect" to a slashing 

 phenomenon. This may occur when the shark is casually searching for food, 

 and the cable is rapidly drawn across the tip of one or more teeth as a 

 result of whip-lash motion mediated by fluctuating currents or by movement 

 of surface or sub-surface buoys. From an operational standpoint, slashing 

 at any depth may expose one or more conductors, interrupting data collection, 

 decreasing tensile strength, and contributing to the premature loss of an 

 entire system. For these reasons various studies are being conducted to 

 develop armor for multiple-conductor cables so that they will be resistant 

 to attack by sharks and other fishes but still possess the tensile strength 

 and characteristics (including diameter, weight, flexibility, etc.) necessary 

 for deep-sea deployment of navigational buoys as well as instrument packages 

 (Hartman, 1972; Preston, et al., 1973). 



Concurrent interest has developed in investigating factors attracting 

 sharks, and countermeasures suitable for use in shallow and deep-water 

 applications. One factor under consideration is low-frequency sound 

 generated by cable movement, generally referred to as "strumming", which 

 may be similar to the low frequency vibrations that are known to attract 

 sharks (Myrberg et al. , 1969 a & b, 1972b; Nelson and Gruber, 1963; Nelson 

 and Johnson, 1972; Nelson et al. , 1969). Various types of ant i- strumming 

 devices are currently in use or undergoing evaluation to determine their 

 effectiveness. The simplest involves the application of polyethylene ribbons 

 at regular intervals along the length of the cable. Quantitative data are 

 not available to confirm the efficacy of this method. 



Based on examination of recovered deep-sea moorings it has also been 

 hypothesized that sharks may be attracted to cables by visual clues elicited 

 by an assortment of bioluminescent organisms accumulating on the cables' 

 surface (Turner, 1965). Flashes of light would be triggered by mechanical 

 stimuli as the cable strums, possibly evoking a positive phototropic 

 response. 



The high frequency of biting reported near the permanent thermocline 

 suggests that a higher concentration of food organisms may exist there. 

 This could increase the incidence of random encounters and expression of 

 the "dental floss" effect. 



Olfactory clues from chemical messengers cannot be discounted, since 

 recovered moorings are often covered with a variety of unidentifiable decayir 

 biological materials. This is generally referred to as "Sea Snot" and is 

 frequently seen in the Bermuda area (Gifford, 1973). Garbage is also found 

 on deep-sea mooring cables, and similarly could be expected to attract 

 sharks and smaller fishes as aromatic degradation products are continuously 



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