Diel and seasonal variations of sound production in captive grey gurnards Eutrigla gurnardus(In English)

摘要

I investigated diel and seasonal patterns of sound production in captive grey gurnards subject to natural variations in water temperature and photoperiod. I also examined daily variations in activity (number of fish swimming). Diel rhythms of sound production concerned routine levels of acoustic activity (i.e. outside feeding periods), but monthly recordings (seasonal patterns) were carried out during feeding sessions, when sound production increases, because routine acoustic activity was infrequent. Fish were of both genders and were less than mature size. Grey gurnards produced more sounds during the day when they were also more active. Sounds were produced in bouts (bursts) and occurred infrequently (mean = 0.04 sounds min^-1 per fish at day time). Fish showed minimum acoustic activity at night, intermediate at dawn/dusk (with sound bursts being emitted more often but with fewer sounds), and maximum during the day (with sound bursts becoming both more frequent and containing a higher number of sounds). Sound production rate during competitive feeding did not present seasonal variations (mean = 3.98 sounds min^-1 per fish) and was not correlated with temperature, suggesting that sounds are emitted in a maximum rate in this context. Several acoustic features of the knocks and grunts were temperature dependent, particularly the grunt pulse period, which strongly decreased at higher temperatures. Most seasonal variations in the acoustic parameters of knocks and grunts can be explained by the effect of temperature on sonic muscles and central vocal control circuits [ Acta Zoologica Sinica 51(6): 1013–1022, 2005].