The fishes of the family Sciaenidae have been known to vocalize during the reproductive season, and it is known that in most species only the male calls. Sounds are produced by vibration of the sonic muscles, which set the swim bladder into resonance. In addition, they also emit sounds by the same mechanism while being disturbed. The large yellow croaker, Larimichthys crocea (Perciformes, Sciaenidae) is one of the important commercial fish species distributed in South China Sea, East China Sea and southern Yellow Sea. In the past years, they have been overfished because of their high fishery value. Many aquatic farms started to culture economically important sciaenids because of the established artificial propagation technique. Now large yellow croakers have been successfully cultured in Fuchien Province, China. Unlike most sciaenids, the sonic muscles are only possessed by male, both male and female large yellow croakers have sonic muscles. This species provides the best opportunity to investigate the characteristics of sounds produced by different genders. The aims of this study were 1) to describe the hand-held disturbance sounds in large yellow croakers, 2) to describe the sounds produced during courtship and spawning in large yellow croakers being injected hormone (LHRH-A3), 3) to investigate the phylogenetic position of large yellow croaker in relation to other sciaenid fishes, and 4) to understand the evolutionary path of swim bladder morphology in the family Sciaenidae. The results show that 1) the pulse numbers of hand-held disturbance sounds in large yellow croaker can reach 23; 2) The reproductive sounds consisted of 1 to 7 pulses which started at about 1400 hr, and both vocal activity (no. sounds/min) and pulse numbers per call would increase with time. However, spawning occupied at the time slot when pulse numbers per call reached 7 in the unisex pond. The sounds in the ponds with only males or females can only recorded the sounds with 1 to 2 pulses; 3) The genus Collichthys was the sister taxon of large yellow croaker. Morphology of the swim bladder in Collichthys is similar to large yellow croaker; 4) Morphology of swim bladder evolved from simple to complex forms. Finally, Larimichthys, Collichthys, and other sciaenid genera distributed in the Indo-western Pacific Ocean including Miichthys, Boesemania, Bahaba, Panna, Atrobucca, Otolithes, Pterotolithus, Chrysochir, Paranebris, Protonibea, Pennahia, Nibea, Dendrophysa and Johnius form a monophyletic group with a bootstrap value of 100. Most of the members have the complex swim bladders with many appendages except Boesemania, Bahaba and Paranebris. Presence of simple form of the swim bladder in these three genera is inferred as a result of morphological reversal.

The swim bladder of Glaucosoma hebracium is specialized by having two side membranes extending dorsally from the side to the vertebrae. This characteristic supports the morphology of the Glaucosomatidae. There is a pair of reddish muscles connecting the skull and the swim bladder of the Glaucosoma hebracium. This type of muscle is likely to involve with sound production. However, vocalization has not been reported in the Glaucosomatids. As direct recordings for sound production in live specimens of this species could not easily be carried out, function of these swim bladder muscles was assessed by means of biochemical assay. Activities of Citrate synthase (CS) and L-lactate dehydrogenase (LDH), known to involve with energy supply during muscle contraction were assessed. Two-dimensional gels for the white muscle, tail region red muscle and swim bladder muscles were compared to reveal difference of protein expression. Results show that CS activity of the swim bladder muscle was higher than the white muscle. But LDH activities in these two types of muscles were not significant different. As high activities in CS reflecting aerobic nature of the tissue, the present dataset suggests that the swim bladder muscles should involve with sound production. Proteomics analyzes identified 14 proteins from the swim bladder muscle, one of them are related to energy production (ATP synthase beta chain). Two-dimensional gels show some different spots from these three type muscles. These results help us to find some different proteins in these three types of muscles of this fish. In conclusions base on these evidence in morphology, histology, enzyme activity assay and two-dimensional gels, the swim bladder muscles should involve with sound production in G. hebracium.

Basioccipital foramen (bof) is found in four acropomatid species, including Apogonops anomalus, Doederleinia berycoides, Neoscombrops annectens, and Synagrops japonicus belonging to four genera. This structure is just near the fish¡¦s inner ear and to which the anterior diverticulae of the swim bladder in the species protrudes. This configuration is though to be closely related to enhance hearing capabilities and an important synapomorphic system to the phylogeny of acropomatids. The structural parameters of the sagittae (i.e., otolith area, otolith sulcus area, ratio of sulcus to area, otolith weight, hair cell density in otolithic macula, and the stereocilia number per hair cell bundle) were estimated, measured, and analyzed. The data of the parameters from the ¡¥bof-possessing¡¦ acropomatids are lower than that of the ¡¥non-bof¡¦ acropomatids. These values infer a probable poorer auditory capability of the ¡¥bof-possessing¡¦ acropomatids. COI, cytochrome b, and rhodopsin sequences of 12 species in five acropomatid genera (i.e., Acropoma, Doederleinia, Malakichthys, Neoscombrops, Synagrops) were analyzed to resolve the issue whether the configuration between ¡¥bof¡¦ and anterior diverticulae of swim bladder representing synapomorphic characters. The constructed Bayesian and maximum parsimony trees indicate that the ¡¥bof-possessing¡¦ acrpomatids do not form a clade. These results suggest that thses specialized structures (¡¥bof¡¦ and anterior swim bladder diverticulae) have developed more than once in Acropomatidae (i.e., a case of convergence).

Work on sound production of deep-sea fishes has been limited to anatomy, and no sounds from identified species have been recorded on the continental slope. Here I examined the sonic muscles of six species in the family Macrouridae by depth (Coelorhincus carminatus, Nezumia bairdii, Coryphaenoides rupestris, Nezumia equalis, Coryphaenoides armatus, Coryphaenoides carapinus,). Due to increasingly limited food with depth, I hypothesized that sonic muscle development would decrease with depth. Sonic muscles were intrinsic and occurred in males and females. Swimbladder and sonic muscle dimensions increased linearly with fish size, but there were no clear differences with depth suggesting sound production remains important in deeper species.