Calls of the Atlantic Cod: Does Captivity Restrict Their Vocal Repertoire?

Stress response to anthropogenic noise in Atlantic cod Gadus morhua L.

“…Luczkovich et al (2012) found that vocal fish of the Sciaenidae family produced fewer vocalizations when ambient noise increased due to vessel and ferry traffic, although this reduction happened only outside the reproductive season. In cod it is known that captivity does not inhibit reproduction while it may restrict the vocalisation repertoire (Midling et al, 2002;Finstad and Nordeide, 2004). While not an exhaustive examination, the recordings of grunts in the current study (in terms of peaks in activity, duration of grunts and frequency range) appeared comparable to that previously reported for captive cod broodstock (Finstad and Nordeide, 2004) and in agreement with the same authors we recorded no prolonged "knock" vocalisations which may be an effect of captive rearing as proposed by Midling et al (2002).…”

“…In cod it is known that captivity does not inhibit reproduction while it may restrict the vocalisation repertoire (Midling et al, 2002;Finstad and Nordeide, 2004). While not an exhaustive examination, the recordings of grunts in the current study (in terms of peaks in activity, duration of grunts and frequency range) appeared comparable to that previously reported for captive cod broodstock (Finstad and Nordeide, 2004) and in agreement with the same authors we recorded no prolonged "knock" vocalisations which may be an effect of captive rearing as proposed by Midling et al (2002). As grunts have been correlated to mating success Hutchings, 2006, 2008), even if the randomised noise in the current study did not always conflict with the vocalisation climax, hearing thresholds could have been adjusted, as previously shown in cyprinid species (Scholik and Yan, 2001;Smith et al, 2004a), reducing the communication success, mate choice process and subsequently fertilisation of egg batches.…”

A link between sound producing musculature and mating success in Atlantic cod

“…Accordingly, sound production peaks during the spawning period and although both sexes are capable of making sounds throughout the year, primarily males appear to do so during the spawning season (Brawn, 1961 b ). The acoustic displays usually consist of short ( c. 200 ms) ‘grunts’ with peak amplitudes ranging between 50 and 500 Hz (Brawn, 1961 b ; Hawkins & Rasmussen, 1978; Midling et al , 2002; Finstad & Nordeide, 2004; Rowe & Hutchings, 2006).…”

The function of sound production by Atlantic cod as inferred from patterns of variation in drumming muscle mass

“…Second, individual drumming muscle mass should be more consistent over time than the characteristics of the sounds they produce, thus making it a more reliable indicator of individual sound-producing ability. For example, sound characteristics, including sound pressure and frequency, have been shown to vary in relation to environmental conditions, particularly water temperature, on a day-to-day basis, making an individual's sounds difficult to measure and compare over time (Fine 1978;Brantley and Bass 1994;Connaughton et al 2000;Midling et al 2002).…”

“…Like many fishes, cod are capable of producing and detecting sound (Hawkins 1993). The calls of Atlantic cod are produced by three pairs of drumming muscles exterior to the swim bladder wall (Brawn 1961a) and consist of short "grunts" with peak sound amplitudes at frequencies ranging between about 50 and 500 Hz (Brawn 1961a;Hawkins and Rasmussen 1978;Midling et al 2002;Finstad and Nordeide 2004). Recent studies have shown that successful reproduction in Atlantic cod involves complex behaviour within and between sexes and it has been hypothesized that acoustic displays are used in mate competition (Brawn 1961a(Brawn , 1961bHutchings et al 1999).…”