Vol. 60, 2021

(update: 2021.08.18; 11.03)
 

Acoustic Properties of the Otolith of the Large Yellow Croaker Larimichthys crocea (Perciformes: Sciaenidae)

Xin-Hai Zhang¹, Yi Tao^1,*, Yang-Liang Zhou¹, Li-Guo Tang¹, Min Liu², and Xiao-Mei Xu¹

¹Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian Province, China. *Correspondence: E-mail: taoyi@xmu.edu.cn (Tao).
E-mails: xhzhang@stu.xmu.edu.cn (Zhang); zhouyangliang@stu.xmu.edu.cn (Zhou); liguotang@xmu.edu.cn (Tang); xmxu@xmu.edu.cn (Xu).
²Dongshan Swire Marine Station, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian Province, China. E-mails: minliuxm@xmu.edu.cn (Liu)

Received 11 March 2021 / Accepted 28 July 2021
Communicated by Benny K.K. Chan

The inner ears of fish contain three pairs of otoliths—lapilli, asterisci and sagittae—which play important roles in hearing and balance. However, acoustic properties and dynamic responses of fish otoliths are poorly understood. The large yellow croaker (Larimichthys crocea), like many species in the family Sciaenidae, is extremely sensitive to sound. The present study used L. crocea sagittae as the research subject and examined the variation in shear stress on sagittae under different acoustic stimuli. For the first time, the sound speed of the sagitta was measured using ultrasonic pulse-echo techniques, and the acoustic impedance and natural frequency of the sagitta were calculated. Larimichthys crocea adults (20–22 cm standard length, n = 10) had a sagitta density of 2781.5 ± 28.06 kg/m³, sound speed of 4828–6000 m/s and acoustic impedance range of 13.4–16.7 MPa·s/m, approximately 9–11 times that of seawater (1.48 MPa·s/m). The natural frequency of the sagitta was 76.4–95.5 kHz. The shape and structural details of sagittae were reconstructed by 3D scanner and the shear stress responses of sagittae under different acoustic stimulus were investigated based on a finite element model. The simulation results showed that the shear stress responses tended to increase and then decrease in the range of sciaenid hearing frequency from 200 to 1300 Hz, peaking at 800 Hz. The shear stress responses varied with the direction of acoustic stimulus and peaked when the incident direction was perpendicular to the inner surface of the otolith. These results provide important parameters that may be used to protect L. crocea from possible underwater noise damage, particularly during their spawning aggregations and over-wintering aggregations.

Key words: Sciaenidae, Otolith, Acoustic properties, Sound speed, Finite element modeling.

Citation: Zhang XH, Tao Y, Zhou YL, Tang LG, Liu M, Xu XM. 2021. Acoustic properties of the otolith of the large yellow croaker Larimichthys crocea (Perciformes: Sciaenidae). Zool Stud 60:64. doi:10.6620/ZS.2021.60-64.