Depth‐dependent swimbladder compression in herring Clupea harengus observed using magnetic resonance imaging

Abstract

Changes in swimbladder morphology in an Atlantic herring Clupea harengus with pressure were examined by magnetic resonance imaging of a dead fish in a purpose-built pressure chamber. Swimbladder volume changed with pressure according to Boyle's Law, but compression in the lateral aspect was greater than in the dorsal aspect. This uneven compression has a reduced effect on acoustic backscattering than symmetrical compression and would elicit less pronounced effects of depth on acoustic biomass estimates of C. harengus.

Resonance classification of mixed assemblages of fish with swimbladders using a modified commercial broadband acoustic echosounder at 1–6 kHz

“…In that study, three-dimensional images of the swimbladder were formed in a laboratory using a magnetic resonance imaging system for a single dead herring (total length = 25.0 cm) for pressures up to the equivalent of 60 m depth. Our inferred volumes at depths of 55 and 82 m were about 70% higher than those predicted by Fässler et al (2009) at each of those depths. However, our inferred volume at 182 m was four times that predicted by Fässler et al (2009).…”

“…Our inferred volumes at depths of 55 and 82 m were about 70% higher than those predicted by Fässler et al (2009) at each of those depths. However, our inferred volume at 182 m was four times that predicted by Fässler et al (2009). Given how little information is available on the volumes of swimbladders at these depths, this remains a research question.…”

“…However, the inferred volume of the herring at this and the other depths are higher than those predicted by the regression equation in Fässler et al (2009). In that study, three-dimensional images of the swimbladder were formed in a laboratory using a magnetic resonance imaging system for a single dead herring (total length = 25.0 cm) for pressures up to the equivalent of 60 m depth.…”

Variations in killer whale food-associated calls produced during different prey behavioural contexts

“…Herring swimbladder volume is negatively related to depth and body fat content, but positively related to fish length (Løvik and Hovem, 1979;Ona, 1990;Nero et al, 2004;Fässler et al, 2008Fässler et al, , 2009. In turn, swimbladder volume is negatively related to its resonant frequency thus, increased depth or fat content will lead to higher resonant frequencies while increased body length will lead to lower resonant frequencies (Løvik and Hovem, 1979;Nero et al, 2004).…”

Broadband and statistical characterization of echoes from random scatterers : application to acoustic scattering by marine organisms

“…For example, as important as the swimbladder is in determining the scattering from fish, the depth-dependency of its geometry with respect to the behavior and life history stage of fish remains unclear (Diachok, 2005;Fässler et al, 2009a;Gorska and Ona, 2003b;Horne et al, 2009;Ona, 1990). This question is further complicated by the diversity in the anatomical features of fish swimbladders, among them the differences between physostomes (fish with a swimbladder connected to the stomach through a pneumatic duct) and physoclits (fish with a closed swimbladder) (as reviewed in Diachok, 2005).…”