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Migratory Restlessness and the Role of Androgen for Increasing Behavioral Drive in the Spawning Migration of the Japanese eel.

Sudo R, Tsukamoto K - Sci Rep (2015)

Bottom Line: This behavior is primarily known in birds, where it is considered to be an indicator of the urge for migration.To confirm migratory restlessness in a fish, we measured the locomotor activity of the Japanese eel, Anguilla japonica during its migration season.Silver eels had higher levels of the androgen hormone 11-ketotestosterone at the end of experiment than yellow eels.

View Article: PubMed Central - PubMed

Affiliation: Aquaculture Systems Division, National Research Institute of Aquaculture, Fisheries Research Agency, 422-1 Nakatsuhamaura Minami-Ise, Mie 516-0193, Japan.

ABSTRACT
Migratory restlessness refers to a type of locomotor activity observed just before the onset of a migration. This behavior is primarily known in birds, where it is considered to be an indicator of the urge for migration. In contrast, little is known about migratory restlessness in fishes. To confirm migratory restlessness in a fish, we measured the locomotor activity of the Japanese eel, Anguilla japonica during its migration season. Migratory-phase silver eels showed higher locomotor activity in aquaria than yellow eels at the non-migratiory growth-phase. Silver eels stayed outside of their shelters for longer durations in dark periods than yellow eels and were active even in light periods when yellow eels were inactive in the shelters. Silver eels had higher levels of the androgen hormone 11-ketotestosterone at the end of experiment than yellow eels. Administration of 11-ketotesosterone to yellow eels induced higher levels of locomotor activity than that observed in non-treated controls. These findings suggest that anguillid eels exhibit migratory restlessness just before their spawning migration and that 11-ketotestosterone may be involved in the onset of this behavior.

No MeSH data available.


Related in: MedlinePlus

Movements of yellow and silver eels outside their shelters showing locomotorybout frequency (A,C) and locomotory bout duration(B,D) in the two experiments. Asterisks indicatesignificant differences between the indicated groups of eels.
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f3: Movements of yellow and silver eels outside their shelters showing locomotorybout frequency (A,C) and locomotory bout duration(B,D) in the two experiments. Asterisks indicatesignificant differences between the indicated groups of eels.

Mentions: Besides the difference between silver eels and yellow eels in their absolute levelsof activity as shown in Fig. 1a, there were differences withrespect to the other types of activity measurements. During the dark period, yelloweels moved in and out of the shelters more frequently than did the silver eels.Consequently, the locomotory bout frequencies were statistically higher in yelloweels (U-test, p < 0.05; Fig.3A), but they moved in and out of the shelters much less frequently duringthe light period than during the dark period. Although, during the light period,there was no statistical difference between yellow and silver eels in locomotorybout frequency, yellow eels remained outside the shelters for statistically lesstime on each occasion (U-tests, p < 0.05). Thelocomotory bout duration in silver eels was significantly higher than in yellow eelsduring the dark period (U-test, p < 0.05) (Fig. 3B). The locomotory bout frequency and duration differedbetween light and dark periods in yellow eels (U-test,p < 0.05), whereas they did not in silver eels (Fig. 3A,B).


Migratory Restlessness and the Role of Androgen for Increasing Behavioral Drive in the Spawning Migration of the Japanese eel.

Sudo R, Tsukamoto K - Sci Rep (2015)

Movements of yellow and silver eels outside their shelters showing locomotorybout frequency (A,C) and locomotory bout duration(B,D) in the two experiments. Asterisks indicatesignificant differences between the indicated groups of eels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663494&req=5

f3: Movements of yellow and silver eels outside their shelters showing locomotorybout frequency (A,C) and locomotory bout duration(B,D) in the two experiments. Asterisks indicatesignificant differences between the indicated groups of eels.
Mentions: Besides the difference between silver eels and yellow eels in their absolute levelsof activity as shown in Fig. 1a, there were differences withrespect to the other types of activity measurements. During the dark period, yelloweels moved in and out of the shelters more frequently than did the silver eels.Consequently, the locomotory bout frequencies were statistically higher in yelloweels (U-test, p < 0.05; Fig.3A), but they moved in and out of the shelters much less frequently duringthe light period than during the dark period. Although, during the light period,there was no statistical difference between yellow and silver eels in locomotorybout frequency, yellow eels remained outside the shelters for statistically lesstime on each occasion (U-tests, p < 0.05). Thelocomotory bout duration in silver eels was significantly higher than in yellow eelsduring the dark period (U-test, p < 0.05) (Fig. 3B). The locomotory bout frequency and duration differedbetween light and dark periods in yellow eels (U-test,p < 0.05), whereas they did not in silver eels (Fig. 3A,B).

Bottom Line: This behavior is primarily known in birds, where it is considered to be an indicator of the urge for migration.To confirm migratory restlessness in a fish, we measured the locomotor activity of the Japanese eel, Anguilla japonica during its migration season.Silver eels had higher levels of the androgen hormone 11-ketotestosterone at the end of experiment than yellow eels.

View Article: PubMed Central - PubMed

Affiliation: Aquaculture Systems Division, National Research Institute of Aquaculture, Fisheries Research Agency, 422-1 Nakatsuhamaura Minami-Ise, Mie 516-0193, Japan.

ABSTRACT
Migratory restlessness refers to a type of locomotor activity observed just before the onset of a migration. This behavior is primarily known in birds, where it is considered to be an indicator of the urge for migration. In contrast, little is known about migratory restlessness in fishes. To confirm migratory restlessness in a fish, we measured the locomotor activity of the Japanese eel, Anguilla japonica during its migration season. Migratory-phase silver eels showed higher locomotor activity in aquaria than yellow eels at the non-migratiory growth-phase. Silver eels stayed outside of their shelters for longer durations in dark periods than yellow eels and were active even in light periods when yellow eels were inactive in the shelters. Silver eels had higher levels of the androgen hormone 11-ketotestosterone at the end of experiment than yellow eels. Administration of 11-ketotesosterone to yellow eels induced higher levels of locomotor activity than that observed in non-treated controls. These findings suggest that anguillid eels exhibit migratory restlessness just before their spawning migration and that 11-ketotestosterone may be involved in the onset of this behavior.

No MeSH data available.


Related in: MedlinePlus