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| An overview of fish bioacoustics and the impacts of anthropogenic sounds on fishes |
An overview of fish bioacoustics and the impacts of anthropogenic sounds on fishes
We (Protasov and Romanenko, 1962) experimentally established a connection between sound and spawning of some aquarium fish - Betta splendens, Macropodus opercularis, Lebistes reticulatus, etc. By adjusting the temperature and light conditions of the aquarium, we repeatedly changed the rate of fish maturation. In this case, when the fish entered the pre-spawning and spawning states, a sharp increase in their sound activity was always observed. Sounds related to courtship of males for females, sounds of threat of rival males, sounds of nest defense and protection of offspring were added to the sounds of food.
Sounds of danger arise in fish before spawning and when males compete for a female. By their nature, they do not differ from the sounds of threats issued in connection with the protection of offspring.
This phenomenon is especially clearly observed in sticklebacks (Protasov, Romanenko and Podlipalin, 1965). Male sticklebacks arrange spawning nests before spawning and invite females to the bottom with a characteristic dance. When rivals between males appear, the battle begins. Demonstrating the characteristic poses of the threat to one another, the males simultaneously squeak and cod, which obviously means threat signals. The sounds of the stickleback threat are very weak (tenths of a bar). Therefore, we could not experimentally verify their signal value.
The sounds of the threat made by the males in the fight for the female are easy to observe on aquarium fish; cocks (Betta splendens), various cichlids, etc.
Sounds of danger arise in fish before spawning and when males compete for a female. By their nature, they do not differ from the sounds of threats issued in connection with the protection of offspring.
This phenomenon is especially clearly observed in sticklebacks (Protasov, Romanenko and Podlipalin, 1965). Male sticklebacks arrange spawning nests before spawning and invite females to the bottom with a characteristic dance. When rivals between males appear, the battle begins. Demonstrating the characteristic poses of the threat to one another, the males simultaneously squeak and cod, which obviously means threat signals. The sounds of the stickleback threat are very weak (tenths of a bar). Therefore, we could not experimentally verify their signal value.
The sounds of the threat made by the males in the fight for the female are easy to observe on aquarium fish; cocks (Betta splendens), various cichlids, etc.
Cocks are typical in this regard. As the spawning period approaches, the aggressive behavior of this fish increases significantly. It is enough at this time to show the cock its image in the mirror, as the male assumes an aggressive pose and, making single clicks, rushes to the "enemy".
A large number of threat sounds in fish are associated with territorial behavior. Many fish, leading a solitary, paired or group lifestyle, live in a reservoir in a certain area, which is usually protected. Threat sounds in this case have not only intraspecific, but also interspecific signaling significance.
Inhabiting Thailand, Malaya, and the islands of the Indo-Australian archipelago, freshwater fish Botia hymenophisa, unlike other fish of the genus Botia, leads a solitary life (Clausewitz, 1958). In ponds, these fish live in small areas up to 1 meter in diameter, which protect against invasion. Before attacking the fish, they make a sharp jerky sound. This sound scares the invading fish, warns them of a possible attack. One demonstration of the species B. hymenophisa, without sound, does not frighten fish.
The most clear meaning of shock sounds as threat signals in connection with the defense of our territory was obtained by us (Protasov and Romanenko, 1962) on aquarium fish scalars.
In aquariums, these fish are usually divided into pairs (male and female), capturing certain areas. The invasion of other fish, especially the same species, leads to fights. Males from a distance of 15 - 30 centimeters take a menacing pose and make intense sound beats. Small fish at the same time sink to the bottom and freeze.
A large number of threat sounds in fish are associated with territorial behavior. Many fish, leading a solitary, paired or group lifestyle, live in a reservoir in a certain area, which is usually protected. Threat sounds in this case have not only intraspecific, but also interspecific signaling significance.
Inhabiting Thailand, Malaya, and the islands of the Indo-Australian archipelago, freshwater fish Botia hymenophisa, unlike other fish of the genus Botia, leads a solitary life (Clausewitz, 1958). In ponds, these fish live in small areas up to 1 meter in diameter, which protect against invasion. Before attacking the fish, they make a sharp jerky sound. This sound scares the invading fish, warns them of a possible attack. One demonstration of the species B. hymenophisa, without sound, does not frighten fish.
The most clear meaning of shock sounds as threat signals in connection with the defense of our territory was obtained by us (Protasov and Romanenko, 1962) on aquarium fish scalars.
In aquariums, these fish are usually divided into pairs (male and female), capturing certain areas. The invasion of other fish, especially the same species, leads to fights. Males from a distance of 15 - 30 centimeters take a menacing pose and make intense sound beats. Small fish at the same time sink to the bottom and freeze.
As can be seen from experiments with the separation of fish by opaque sound-conducting partitions, the appearance of shock sounds excites other fish. At the same time, flight as an expression of a clear defensive reaction manifests itself from a distance of less than 10 centimeters from the sound source. The most defensive reaction is manifested with the simultaneous action of sound and optical threat signals.
The sounds of fish also serve as danger signals.
We set up our first experiments on two individuals of a killer whale (Protasov, Romanenko, 1962). Frightening one of the fish, we observed the characteristic sharp creaks published by this fish, and the flight of both fish from this place in the aquarium.
The sounds of fish also serve as danger signals.
We set up our first experiments on two individuals of a killer whale (Protasov, Romanenko, 1962). Frightening one of the fish, we observed the characteristic sharp creaks published by this fish, and the flight of both fish from this place in the aquarium.
Subsequently, experiments were conducted with a group of killer whales sitting in an aquarium with macro pods. The frightened killer whale also makes a sharp creak, floating away from a dangerous place.
Other killer whales located close to her joined her, also emitting characteristic creaks. It should be noted that macropods do not pay attention to the sounds of killer whales and do not leave their places. It can therefore be assumed that the squeaks of killer whales have the value of an intraspecific hazard warning signal. Similarly, the killer whale behaves in a similar way in natural conditions. According to the observations of the Amur fishermen,
Fish that have formed spawning pairs, due to the maturation asynchrony, do not immediately begin reproduction. Gametogenesis in males, as a rule, is ahead of the process of maturation of oocytes in females. By the time of spawning, males already have matured spermatozoa (and therefore, as a rule, there are always flowing males in spawning grounds), females have ovaries at stages IV - V at this time, the ovulation process in them has not yet begun (Meyen, 1944; Kulaev, 1939; Dryagin, 1949).
At present, it has been established that for the transition of the female ovaries to a fluid state, certain external conditions are necessary, the impact of which on the endocrine system leads to ovulation. It was also established that in the complex of factors that lead the ovaries of females to ovulation, the behavioral reactions of the male are of great importance (Noble, 1938; Aronson, 1945). In this regard, the sounds made by the male during courtship of the female are of particular importance. Along with optical signals, the sounds of males caring for a female have a stimulating value, involving the female in the reproduction process and synchronizing it with its own maturation in time.
In many paired and family-territorial fish, the male plays an active role in stimulation. Usually it begins with the pursuit of the female. At the same time, males make complex stereotypical movements using optical signaling and reinforcing it with sounds and bites or a blow to the genital area of the abdomen. Males, macropods, angelfish, acaras, gourami and others produce weak percussion sounds (single or double).
Fish that have formed spawning pairs, due to the maturation asynchrony, do not immediately begin reproduction. Gametogenesis in males, as a rule, is ahead of the process of maturation of oocytes in females. By the time of spawning, males already have matured spermatozoa (and therefore, as a rule, there are always flowing males in spawning grounds), females have ovaries at stages IV - V at this time, the ovulation process in them has not yet begun (Meyen, 1944; Kulaev, 1939; Dryagin, 1949).
At present, it has been established that for the transition of the female ovaries to a fluid state, certain external conditions are necessary, the impact of which on the endocrine system leads to ovulation. It was also established that in the complex of factors that lead the ovaries of females to ovulation, the behavioral reactions of the male are of great importance (Noble, 1938; Aronson, 1945). In this regard, the sounds made by the male during courtship of the female are of particular importance. Along with optical signals, the sounds of males caring for a female have a stimulating value, involving the female in the reproduction process and synchronizing it with its own maturation in time.
In many paired and family-territorial fish, the male plays an active role in stimulation. Usually it begins with the pursuit of the female. At the same time, males make complex stereotypical movements using optical signaling and reinforcing it with sounds and bites or a blow to the genital area of the abdomen. Males, macropods, angelfish, acaras, gourami and others produce weak percussion sounds (single or double).
Characteristic in this respect is the acoustic behavior of macropods and swordsmen (unpublished data by Tsvetkov). The male stimulation of the female takes place in parallel with the construction of the nest.
By the time its construction is completed, the stimulation process is accelerating. This is manifested both in a faster change of the poses and circular movements demonstrated by the male, and in an increase in intensity and an increase in the rhythms of sounds. Before laying eggs, male stimulation of the female reaches the highest value. Single or double beats merge into a drum trill. Publishing them, the male swims in front of the female, spreading its fins and trembling with his whole body.
The same sounds are observed during stimulation of females in seahorses and needles (Hardenburg, 1934; Noble, 1938). Stimulating sounds synchronize the maturation process in male and female. Therefore, if during the courtship of a male scalar, indiscriminate tapping is made on the glass of the aquarium, disorienting the female, spawning games of these fish are interrupted. Such phenomena are not unique, all aquarium enthusiasts are well aware of them.
The same sounds are observed during stimulation of females in seahorses and needles (Hardenburg, 1934; Noble, 1938). Stimulating sounds synchronize the maturation process in male and female. Therefore, if during the courtship of a male scalar, indiscriminate tapping is made on the glass of the aquarium, disorienting the female, spawning games of these fish are interrupted.
Such phenomena are not unique, all aquarium enthusiasts are well aware of them. The same sounds are observed during stimulation of females in seahorses and needles (Hardenburg, 1934; Noble, 1938).
Stimulating sounds synchronize the maturation process in male and female. Therefore, if during the courtship of a male scalar, indiscriminate tapping is made on the glass of the aquarium, disorienting the female, spawning games of these fish are interrupted. Such phenomena are not unique, all aquarium enthusiasts are well aware of them.
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