Sound production of Atlantic cod (Gadus morhua) in relation to environmental factors

• Main Author: Michl, Stéphanie Céline, 1988-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: Líffræði; Þorskur; Umhverfisáhrif; Hljóðmælingar; Skjálfandi; atlantic cod; Gadus morhua
• Online Access: http://hdl.handle.net/1946/7569

In September 2008 to January 2009, two Ecological acoustic recorders (EARs) were placed in Skjálfandi Bay in order to record marine sounds. In total 14381 single Atlantic cod sounds were detected in the recordings. Cod sounds in general consist of various numbers of grunts. The grunts in this study start usually at a frequency of around 5 Hz and go up to 200 Hz. They consist of pulses, which are very short in duration and only visible on an oscillogram. The highest amplitude was in all examined cases reached at a frequency level of 40 to 60 Hz and the grunts reached amplitudes with a power of 2000 mV. The Atlantic cod sound’s characteristics are similar but not identical to those described in earlier studies. The amount of recorded sounds between both EARs is different, they are however highly correlated (rs=0.45, p<0.001) and follow the same trend in activity in the course of the whole period. The data was divided into five research periods and a comparison of their means showed significant differences between single research periods. Pearson’s correlation was highly significant (p<0.001, rP=0.3533, n=87) for the relationship between sound production activity and intertidal changes in Skjálfandi Bay. Additionally a correlation between acoustic activity and other environmental factors such as wind speed (p< 0.001, rp=0.123, n=2088) and cloud cover (p<0.001, rp=0.428, n=87) was found. The frequency of sound production increased strongly in October and decreased again in November and December. Further increase in January had also been observed. In addition no differences in the activity during the course of a day were found in this study. Frá september 2008 til janúar 2009 voru tveir hljóðnemar (Ecological acoustic recorders, EARs) staðsettir í Skjálfandaflóa til að nema hljóð í sjónum. Alls reyndust 14381 einstök hljóð þorsks vera á upptökunum. Þorskhljóð samanstanda almennt úr mismunandi fjölda af rýtum. Í þessari rannsókn hófust rýtin venjulega á um 5 Hz sveiflutíðni og fóru upp í 200 Hz. Þau ...