190
WILLIAM N. TAVOLGA
by Richard (1968) demonstrated the feasibility of attracting a variety
of predatory fishes by means of low frequency sound. For the successful
development of these techniques, it is clear that more basic information
is still required on the hearing range of many of the commercially important species, as well as more information on the behavioral significance
of sounds produced by these fishes.
Although the technique of listening for sounds produced by fishes is
known as an art among fishermen in several areas of the world (Moulton,
1963), the use of this method in major commercial fisheries has yet to be
tested. Some preliminary studies have been attempted, using a combination of sonobuoy and telemetry equipment ( Hashimoto et al., 1960). Considering the technology now available, it should be feasible to detect
and identify fish sounds electronically, although much needed information
on identifying characteristics of commercially desirable species is still
lacking.
It is no longer sufficient to present another instance of a fish making
sounds, and such information needs to be correlated with the behavioral
context of the sound. Long-term recordings and observations, like those
supplied by the acoustic-video installation of the Institute of Marine
Science at Bimini, Bahamas (Kronengold et al., 1964), will be increasingly necessary. Bioacoustic observations by small submersibles hold
much promise for the future of the field (Backus et al., 1968)) and some
scuba divers are already becoming equipped with listening devices. In
this connection, the identification of many hitherto unspecified field
contacts will become possible. Behavioral studies, however, will have to
be supplemented by laboratory observations and experiments where
environmental conditions can be controlled.
A problem that has troubled both field and laboratory investigators
has been the exact specification and description of the acoustic stimulus.
Watkins (1967) pointed out the pitfalls of analyzing equipment, but,
further, it is extremely difFicult to separate the two forms of energy that
usually exist together in an underwater sound field: pressure and displacement. Most hydrophones are basically pressure transducers and will
detect pressure changes produced by a near field as well as those of a
far field. The needs of biologists for a small, but sensitive, displacement
transducer have not yet been satisfied (Tavolga, 1967cj, and this is
another area in which an interdisciplinary approach to the problem is
necessary.
The problem of frequency discrimination by fish is an intriguing one.
If future evidence demonstrates the applicability of a place theory to
fish hearing, it may necessitate a reexamination of the concept of the
critical band.
WILLIAM N. TAVOLGA
by Richard (1968) demonstrated the feasibility of attracting a variety
of predatory fishes by means of low frequency sound. For the successful
development of these techniques, it is clear that more basic information
is still required on the hearing range of many of the commercially important species, as well as more information on the behavioral significance
of sounds produced by these fishes.
Although the technique of listening for sounds produced by fishes is
known as an art among fishermen in several areas of the world (Moulton,
1963), the use of this method in major commercial fisheries has yet to be
tested. Some preliminary studies have been attempted, using a combination of sonobuoy and telemetry equipment ( Hashimoto et al., 1960). Considering the technology now available, it should be feasible to detect
and identify fish sounds electronically, although much needed information
on identifying characteristics of commercially desirable species is still
lacking.
It is no longer sufficient to present another instance of a fish making
sounds, and such information needs to be correlated with the behavioral
context of the sound. Long-term recordings and observations, like those
supplied by the acoustic-video installation of the Institute of Marine
Science at Bimini, Bahamas (Kronengold et al., 1964), will be increasingly necessary. Bioacoustic observations by small submersibles hold
much promise for the future of the field (Backus et al., 1968)) and some
scuba divers are already becoming equipped with listening devices. In
this connection, the identification of many hitherto unspecified field
contacts will become possible. Behavioral studies, however, will have to
be supplemented by laboratory observations and experiments where
environmental conditions can be controlled.
A problem that has troubled both field and laboratory investigators
has been the exact specification and description of the acoustic stimulus.
Watkins (1967) pointed out the pitfalls of analyzing equipment, but,
further, it is extremely difFicult to separate the two forms of energy that
usually exist together in an underwater sound field: pressure and displacement. Most hydrophones are basically pressure transducers and will
detect pressure changes produced by a near field as well as those of a
far field. The needs of biologists for a small, but sensitive, displacement
transducer have not yet been satisfied (Tavolga, 1967cj, and this is
another area in which an interdisciplinary approach to the problem is
necessary.
The problem of frequency discrimination by fish is an intriguing one.
If future evidence demonstrates the applicability of a place theory to
fish hearing, it may necessitate a reexamination of the concept of the
critical band.