Swimbladder Shape Research Articles

Early ontogenetic development of Cynodon gibbus (Characiformes: Cynodontidae) in the Amazon River basin

Abstract Knowledge regarding the early life history of neotropical fish, although incipient, is crucial for the accurate identification of larvae collected from the natural environment. Such details are important for defining spawning, drift, and nursery areas as well as the reproductive periods of species. Herein, the larval development of Cynodon gibbus was described using morphological, meristic, and morphometric characteristics. Specimens were collected from open water limnetic zones and under macrophyte stands in the Amazon basin from 2010 to 2023. Forty-eight larvae with standard lengths ranging from 5.73 to 21.57 mm were studied. The larvae have a long to very long body, small eyes, and a small head, which progresses to a moderate size in the preflexion stage. Furthermore, the larvae had ample mouths with numerous conical teeth, an oval-triangular swim bladder, overlapping dorsal and anal fins, and the tip of the pectoral fin not reaching the swim bladder. Pigmentation pattern comprised two punctate pigments above the fontanelle, the rectum, and at the lower and upper ends of the caudal peduncle. Various body parts exhibited predominant allometric relationships, reflecting differential developmental rates among them in response to fundamental ecological requirements for survival. The C. gibbus larvae can be identified by a combination of the position of dorsal, anal and pectoral fins, pigmentation pattern, swim bladder shape, and the total number of myomeres (51 to 53).

Diving into dual functionality: Swim bladder muscles in lionfish for buoyancy and sonic capabilities.

Although the primary function of the swim bladder is buoyancy, it is also involved in hearing, and it can be associated with sonic muscles for voluntary sound production. The use of the swim bladder and associated muscles in sound production could be an exaptation since this is not its first function. We however lack models showing that the same muscles can be used in both movement and sound production. In this study, we investigate the functions of the muscles associated with the swim bladder in different Pteroinae (lionfish) species. Our results indicate that Pterois volitans, P. radiata and Dendrochirus zebra are able to produce long low-frequency hums when disturbed. The deliberate movements of the fin spines during sound production suggest that these sounds may serve as aposematic signals. In P. volitans and P. radiata, hums can be punctuated by intermittent louder pulses called knocks. Analysis of sonic features, morphology, electromyography and histology strongly suggest that these sounds are most likely produced by muscles closely associated with the swim bladder. These muscles originate from the neurocranium and insert on the posterior part of the swim bladder. Additionally, cineradiography supports the hypothesis that these same muscles are involved in altering the swim bladder's length and angle, thereby influencing the pitch of the fish body and participating in manoeuvring and locomotion movements. Fast contraction of the muscle should be related to sound production whereas sustained contractions allows modifications in swim bladder shape and body pitch.

Influence of fish backbone model geometrical features on the numerical target strength of swimbladdered fish

Abstract The method of fundamental solutions has been applied to evaluate the influence of fish models geometrical features on the target strength (TS) directivity and TS frequency response of swimbladdered fish. Simplified models were considered for two fish species: gilt-head sea bream (Sparus aurata, Linnaeus 1758) and Atlantic salmon (Salmo salar, Linnaeus 1758), and different geometrical details of their morphology were studied, such as backbone presence, and its curvature or the inclusion of vertebrae modulation. Swimbladder shape and tilt, together with the inclusion of backbone (and its realistic curvature) for dorsal measurements were the most important features for proper estimation of mean TS. The estimation of mean TS is considered including the effect of fish tilt, the echosounder frequency, and the fish-to-transducer distance.

Divided swim bladder maintains brooding cichlid mum's balance

When Astatotilapia burtoni females lay eggs, they don't simply turn their backs and make a quick exit. The soon-to-be mothers vacuum the eggs up into their mouths, where the youngsters develop and grow before they are ready to depart 14 days later. But the sudden weight shift, amounting to as much as 30% of the female's weight, could seriously destabilise brooding mums and the situation could become even more perilous as the larvae and fry become heavier and more negatively buoyant during development. Yet, the mothers seem to take the inconvenience in their stride and never topple forward. Knowing that the fish's swim bladder is divided into two compartments, Julie Butler, Prosanta Chakrabarty and Karen Maruska from Louisiana State University, USA, wondered whether the fish may adjust the distribution of gas between the two parts of the swim bladder to compensate when they become front heavy.Butler, Sarah Whitlow and Polly Gwan collected female A. burtoni that were ready to spawn large eggs, at various stages over the 14 day brooding period, and 1 and 3 weeks after the fry sallied forth, and then X-rayed the fish. Comparing the X-ray images, the team could see that the overall area of the swim bladder did not alter during the development of the offspring; however, the distribution of gas between the two compartments did shift. The front section expanded while the rear section deflated when the females slurped up their eggs and remained so until the youngsters left their mother's mouths 2 weeks later. Then, the front section of the swim bladder deflated and the rear section reinflated. The team also monitored the fish's swimming posture when the fry were liberated, and found that the unencumbered females’ heads bob upwards, so that the fish swam at an angle of 7 deg for 5 min until they resumed their pre-release almost-horizontal posture. And when the team attached a small bead weighing roughly the same as a mouthful of 7-day-old fry to the underside of the jaws of females that were not brooding, they saw the same shift in the swim bladder shape 4 h later.Considering the cichlid's rapid reaction to their sudden weight redistribution, the team suspects that the fish redistribute gas between the two parts of the swim bladder by opening and closing a ring of muscle in the diaphragm that separates the two. As tissue in the front section of the swim bladder produces gas, while tissue in the rear section removes gas from the swim bladder, the team suggests that the sphincter in the diaphragm closes when the fish suck the eggs into their mouths, allowing gas to inflate the front section to counteract the weight of the eggs. When the mothers release the fry, they can then restabilise their posture by rapidly opening the sphincter to drain gas into the rear compartment of the swim bladder. And the team suggests that a compartmentalised swim bladder could be an essential adaptation for fish that prefer to give their young a head start in their mouths.

Xenogenesis‐Production of Channel Catfish × Blue Catfish Hybrid Progeny by Fertilization of Channel Catfish Eggs with Sperm from Triploid Channel Catfish Males with Transplanted Blue Catfish Germ Cells

AbstractPutative spermatogonia A from a fresh‐cell isolate or a density‐gradient‐centrifuged isolate from the testes of Blue Catfish Ictalurus furcatus were transplanted into the gonads of triploid Channel Catfish I. punctatus. The cells were introduced into gonads of the host via catheterization (2 × 104–1.43 × 106 cells) or by surgically inserting the cells directly into the gonad (7 × 104–1.25 × 105 cells). Ten months after implantation, DNA was analyzed from biopsies of the gonads and seven of eight males were found to be xenogenic, having Blue Catfish cells in their gonads. The xenogenic males successfully courted normal Channel Catfish that had been induced with hormones to ovulate, but none of the eggs hatched, indicating inadequate sperm production, an inability to ejaculate, and/or low sperm quality. Male xenogenic catfish treated with luteinizing hormone releasing hormone analog had well‐developed testes, and sperm production was detected in three of seven xenogenic males examined 2 years after transplantation. Sperm were removed from a male that had been surgically transplanted with Blue Catfish cells and used to fertilize eggs from a hand‐stripped Channel Catfish female. One percent of these eggs hatched. All seven surviving 6‐month‐old progeny of this male had the external morphology, swim bladder shape, nuclear DNA profile, and mitochondrial DNA profile of female Channel Catfish × male Blue Catfish F1 hybrids, indicating that this triploid Channel Catfish male produced Blue Catfish sperm. This is the first report of successful production of xenogenic catfish and the first report of producing 100% hybrid progeny using xenogenesis in fish.

볼락의 형태학적 특징과 음향반사강도 특성

Morphological properties of dark banded rockfish (Sebastes inermis) were analysed to investigate its acoustic scattering characteristics. Total of 18 live samples was prepared for X-ray photos and collected morphological coordinates of their body and swim bladder shapes. Kirchhoff-ray mode model was used to calculate acoustic scattering pattern for broad-band frequency range. Inclination of swim bladder ranged from 17 to 30 and the averaged value was about (S.D.(standard deviation)

Modifications in call characteristics and sonic apparatus morphology during puberty in Ophidion rochei (actinopterygii: Ophidiidae)

Juveniles, females, and males of Ophidion rochei share similar external morphology, probably because they are mainly active in the dark, which reduces the role of visual cues. Their internal sonic apparatuses, however, are complex: three pairs of sonic muscles, and highly modified vertebrae and ribs are involved in sound production. The sonic apparatus of males differs from juveniles and females in having larger swimbladder plates (modified ribs associate with the swimbladder wall) and sonic muscles, a modified swimbladder shape and a mineralized structure called the "rocker bone" in front of the swimbladder. All of these male traits appear at the onset of sexual maturation. This article investigates the relationship between morphology and sounds in male O. rochei of different sizes. Despite their small size range total length (133-170 mm TL), the five specimens showed pronounced differences in sound-production apparatus morphology, especially in terms of swimbladder shape and rocker bone development. This observation was reinforced by the positive allometry measured for the rocker bone and the internal tube of the swimbladder. The differences in morphology were related to marked differences in sound characteristics (especially frequency and pulse duration). These results suggest that male calls carry information about the degree of maturity. Deprived of most visual cues, ophidiids probably have invested in other mechanisms to recognize and distinguish among individual conspecifics and between ophidiid species. As a result, their phenotypes are externally similar but internally very different. In these taxa, the great variability of the sound production apparatus means this complex system is a main target of environmental constraints.

Boarfish (Capros aper) target strength modelled from magnetic resonance imaging (MRI) scans of its swimbladder

Abstract Fässler, S. M. M., O'Donnell, C., and Jech, J.M. 2013. Boarfish (Capros aper) target strength modelled from magnetic resonance imaging (MRI) scans of its swimbladder. – ICES Journal of Marine Science, 70: . Boarfish (Capros aper) abundance has increased dramatically in the Northeast Atlantic from the early 1970s after successive years of good recruitment attributed to an increase in sea surface temperature. Due to increased commercial fishing over recent years, an acoustic boarfish survey funded by the Killybegs Fishermen's Organisation was initiated by the Marine Institute to establish a baseline for the future management of this stock. In the absence of any species-specific boarfish target strength (TS), acoustic backscatter was estimated by a Kirchhoff-ray mode model using reconstructed three-dimensional swimbladder shapes which were computed from magnetic resonance imaging scans of whole fish. The model predicted TS as a function of size, fish tilt angle, and operating frequency. Standardized directivity patterns revealed the increasing importance of changes in the inclination of the dorsal swimbladder surface at higher frequencies (120 and 200 kHz) and a less directive response at lower frequencies (18 and 38 kHz). The model predicted a TS-to-total fish length relationship of TS = 20 log10(L) − 66.2. The intercept is ∼1 dB higher than in the general physoclist relationship, potentially reflecting the bulky nature of the boarfish swimbladder with its relatively large circumference.

이론모델을 이용한 멸치의 음향산란강도의 검토 및 적용

Acoustical backscattering characteristics of Japanese anchovy can be estimated by Kirchhoffray mode model (KRM model) due to estimate exact body and swim-bladder shape of the fish, the samples were rapidly frozen by dry-ice and alcohol. X-ray photos for ventral and lateral direction for 6 samples were taken and the 3D coordinates of the body swim-bladder were estimated by digitizing from the photos. The angles between the axis of body and swim-bladder were about at 38kHz and at 120kHz, 200kHz. General formula of TS and BL estimated were >

Classification of three tuna species in enclosures by using target strength spectra measured by a broadband split-beam system

The selective capture of tunas; bigeye tuna (Thunnus obesus), skip jack tuna (Katsuwonus pelamis) and yellow fin tuna ((Thunnus albacares) is important for Japanese seine net fisheries. Classification of the species composition by using acoustic information before catching them will significantly contribute for the selective catch. Target strength spectra (TSSP) of each species were measured by a broadband split beam system. Each tuna species was separately kept in a enclosure, which sized 8 × 8 m square and approximately 5 m in depth. This system was able to measure not only TSSP but also a swimming track of individual in 3D. The differences of TSSP among three species were confirmed. For example, the target strength value of begeye whose tilt angle was 0 degree about 10 dB higher than skip jack tuna one. Swimbladder sizes were measured for each species by soft X-ray because skip jack tuna are physoclist species, and others are physostome species. There were differences of the swimbladder shape between bigeye tuna and yellow fin tuna. The TSSP seemed to be depend on not only body size (fork length), but also swimbladder shape. The TSSP could be useful information to classify among tunas.

Bioacoustic variation of swimbladder disturbance sounds in Neotropical doradoid catfishes (Siluriformes: Doradidae, Auchenipteridae): Potential morphological correlates

Abstract Swimbladder disturbance sounds of doradoid catfishes (Doradidae and Auchenipteridae) demonstrated striking waveform and spectrographic variation. We surveyed sounds of 25 doradoid species in 20 genera comparing these to sounds of four vocal outgroup catfish families. Sounds were either continuous waveforms (lacking interpulses) or pulsed (groups of pulses repeated at fixed temporal intervals). This is the first evidence for swimbladder calls with fixed interpulse patterns in catfishes. Vocal mechanism components that were similar between doradids and auchenipterids included: swimbladder shape, swimbladder dimensions and sonic muscle-somatic index. Morphological traits that showed variation among taxa and were evaluated for potential correlates of call diversity are: 1) diverticula (marginal outpocketings of the swimbladder with no connection to inner ear) and 2) elastic spring apparatus Müllerian rami (ESA-Mr). Within the doradid subfamilies and within the Auchenipteridae most species differed significantly in dominant frequency with frequency ranges overlapping to some extent for most. Doradid swim-bladder diverticula did not explain dominant frequency variation within the doradoid superfamily. Some doradids with conical ESA-Mr had the highest dominant frequency sounds. Auchenipterids included both relatively lower and higher dominant frequency sound producers but lacked diverticula and had discoidal ESA-Mr. Comparing a phylogeny of doradoid genera with out-group taxa, we infer that complex diverticula and conical ESA-Mr are derived characters within the Doradidae. Species representing outgroup families produced either continuous lower dominant frequency sounds (aspredinids, mochokids and pseu-dopimelodids) or pulsed higher dominant frequency sounds (pimelodids).

Basis of acoustic discrimination of chinook salmon from other salmons by echolocating Orcinus orca

The "resident" ecotype of killer whales (Orcinus orca) in the waters of British Columbia and Washington State have a strong preference for Chinook salmon even in months when Chinook comprise less than about 10% of the salmon population. The foraging behavior of killer whales suggests that they depend on echolocation to detect and recognize their prey. In order to determine possible cues in echoes from salmon species, a series of backscatter measurements were made at the Applied Physics Laboratory (Univ. of Wash.) Facility on Lake Union, on three different salmon species using simulated killer whale echolocation signals. The fish were attached to a monofilament net panel and rotated while echoes were collected, digitized and stored on a laptop computer. Three transducer depths were used; same depth, 22° and 45° above the horizontal plane of the fish. Echoes were collected from five Chinook, three coho and one sockeye salmon. Radiograph images of all specimens were obtained to examine the swimbladder shape and orientation. The results show that echo structure from similar length but different species of salmon were different and probably recognizable by foraging killer whales.

Swimbladders under pressure: anatomical and acoustic responses by walleye pollock

Abstract Horne, J. K., Sawada, K., Abe, K., Kreisberg, R. B., Barbee, D. H., and Sadayasu, K. 2009. Swimbladders under pressure: anatomical and acoustic responses by walleye pollock. – ICES Journal of Marine Science, 66: 1162–1168. Pressure influences echo intensities from fish through changes in swimbladder volumes and surface areas. Volume reduction is expected to correspond to Boyle’s law (volume α pressure−1), but the effects of deforming the dorsal-aspect surface area of the swimbladder on the target strength (TS) of a physoclist have not been quantified at geometric scattering frequencies. Dorsal and lateral radiographs of three juvenile walleye pollock (Theragra chalcogramma) in a pressure chamber were used to image swimbladders from ambient to a maximum of 4.9 × 105 Pa (i.e. 5 atm). Radiographs from an additional 16 0-group, 21 juvenile, and 28 adult fish were used to compare swimbladder sizes and shapes across life-history stages. The directional elliptical eccentricity, which describes the relative compression in dorsal and lateral planes, was formulated to define swimbladder shapes and their variation. As pressure increased, dorsal-aspect surface areas of the swimbladder decreased at a constant rate. Swimbladder-volume reductions were similar among individuals, but less than those predicted by Boyle’s law. Compression was greatest in the dorsal–ventral plane and asymmetric anterior to posterior. The Kirchhoff-ray mode backscatter model predicted that TS at 38 and 120 kHz decreased by ∼4 dB as pressure increased from ambient to 4.9 × 105 Pa.

北日本海域におけるハダカイワシ科魚類の鰾形態とターゲットストレングス

Swimbladder shapes of 5 myctophid species captured around northern Japan were measured using an X-ray method. The species were classified into swimbladder and swimbladderless fishes according to the presence of gas. All specimens of Lampanyctus jordani had a well-inflated swimbladder. Notoscopelus japonicus and Stenobrachius nannochir had no swimbladder in any body size range examined. Diaphus theta and Symbolophorus californiensis contained swimbladder and swimbladderless fishes in relation to growth. Based on several morphological parameters of the body or swimbladder, the relationships between body length and target strength at 38 and 120 kHz were estimated using theoretical acoustical backscattering models. The estimated values of the target strength showed 10-dB or more differences between bladder and bladderless fishes, even when the fish were of equivalent size. The target strength values of most fishes did not grow proportionally to the square of the body length at both frequencies because of swimbladder allometric growth or the effect of Rayleigh scattering. Our result suggests the importance of swimbladder observation for target strength study of myctophid fishes, because they have various swimbladder conditions, and the characteristics of acoustic backscattering change dramatically with the swimbladder conditions.

Swimbladders under pressure: Anatomical and acoustic responses by walleye pollock

Pressure influences echo intensities of swimbladdered fish through changes in swimbladder volumes and surface areas. Volume reduction is expected to correspond to Boyle’s law (volume ∝pressure−1) but the resulting deformation in swimbladder surface area will largely determine target strength at geometric scattering frequencies. Dorsal and lateral radiographs of juvenile walleye pollock (Theragra chalcogramma) in a pressure chamber were used to image swimbladders from ambient to a maximum of 5‐atm pressure. As pressure increased, dorsal swimbladder surface areas decreased at a constant rate among the three individuals. Swimbladder volume reduction rates were similar among individuals but less than that predicted by Boyle’s law. Compression of swimbladders occurred dorsal‐ventral, anterior‐posterior, and laterally. Resulting swimbladder shapes became more spindlelike as pressure increased. KRM predicted target strengths at 38 and 120 kHz decreased more rapidly at 3 atm above ambient than at lower pressures. [Work supported by ONR and NRIFE.]

Swimbladder morphology and target strength of myctophid fish of the northwestern Pacific

Swimbladder shapes of fish from 14 myctophid species captured around Japan were measured using an x‐ray method to estimate the theoretical target strength. Using those x‐ray images, the fish were classified into bladder species and nonbladder species according to the presence of the gas. Five species had no swimbladder in any body size range examined. Others contained bladder and nonbladder fishes in relation to growth. The growth of swimbladder length was not proportional to that of body length (allometric growth) in some bladder fishes. Based on morphological parameters of the body and swimbladder, the relationships between body length and target strength from 38 to 200 kHz were estimated using theoretical acoustical backscattering models. Estimated values of target strength showed greater than 10‐dB differences between bladder and nonbladder fishes, even when the fish were of equivalent size. Because of the allometric growth of the swimbladder, values of the target strength were not proportional to the square of the body length in most bladder species. In addition, larger fishes (over 60 mm) of Myctophum asperum showed regressive growth of the swimbladder (or target strength), suggesting that the use of the 20 log relationship is inappropriate for bladder species of myctophid.

Comparing predictions from backscatter models to in situ measurements of a dual-chambered, swimbladdered fish

Most acoustic backscatter models predict echo amplitudes of single or aggregations of fish with single-chambered swimbladders. Lavnun (Acanthobrama terraesanctae), a planktivorous fish in Lake Kinneret, Israel, possesses a dual-chambered swimbladder. Target strength, length, frequency, or aspect relationships do not exist for this commercially important species. What is the most appropriate way to model backscatter amplitudes from single and aggregations of fish with multi-chambered swimbladders? Carrier frequency, organism length, organism aspect, and swimbladder shape all influence amplitudes of returned echoes. Predicted backscatter amplitudes and intra-species variance predictions from an anatomically-based Kirchhoff-ray mode model were compared to in situ measures of lavnun backscatter at 120 and 420 kHz. The lavnun swimbladder was modeled as a single chamber (with equivalent volume of both chambers), as two independent chambers, and as two acoustically interacting chambers. Wider application and comparison of theoretical models to field measurements increases understanding of factors influencing backscatter amplitude and variability for all fish species, and should improve methods for identifying organisms. [Work supported by ONR and US–Israel BSF.]

Sensitivity of acoustic scattering models to fish morphometry

Current efforst to model fish backscatter (e.g., Kirchoff ray-mode model [C. S. Clay and J. K. Horne, J. Acoust. Soc. Am. 96, 1661–1668 (1994)] use digitized images of fish anatomy for a more realistic representation of swimbladder shape, volume, and aspect. However, the degree of image resolution necessary for acoustic characterization and improved predictions, and the variability associated with resolution has not been quantified. Does a more accurate and higher resolution image result in improved correlation between theory and empirical measurements? Backscatter amplitudes display strong relationships with carrier frequency, swimbladder shape, and swimbladder aspect at rather high frequencies. Are predictions of these relationships influenced by image resolution? X-ray images of Atlantic cod (Gadus morhua) and brook trout (Salvelinus fontinalis) were digitized at fine resolution, and sensitivity analyses were performed to quantify the effect of varying image resolution on predicted backscatter as a function of carrier frequency and swimbladder shape and aspect. Quantifying image resolution is a step towards determining morphometric effects on backscatter variability and estimating fish abundance using multi-frequency data and the inverse approach. [Work supported by ONR.]

Quantifying intraspecies variation in acoustic backscatter models

Fisheries researches are increasing the use of frequency-, length-, and aspect-dependent backscatter models in population abundance estimates of fish and zooplankton. Model predictions are often based on measurements from a single or a limited number of organisms. The resulting model parameters are used to predict backscatter for organisms of any length in the population. At rather high frequencies (i.e., length/wavelength ratios of 1 to 20), choice of carrier frequency, swimbladder shape, and swimbladder aspect influence amplitudes of returned echoes. Morphological differences among individuals will therefore determine the variance observed in amplitudes of echo ensembles. To quantify variance in predicted backscatter within species as a function of carrier frequency, fish length, and swimbladder aspect, we combined data from digitized x rays with Kirchhoff ray-mode backscattering models of brook trout (Salvelinus fontinalis) and Atlantic code (Gadus morhua). Quantifying backscatter variances within and between species allow us to examine the applicability of multi-frequency data and the inverse approach to estimate fish length abundances. [Work supported by ONR.]

Relationship of swim-bladder shape to the directionality pattern of underwater sound in the oyster toadfish

The swim bladder of the oyster toadfish, Opsanus tau, has a distinctive heart shape with two anterior protrusions separated by a midline cleft. The lateral surfaces contain intrinsic muscles that meet at the caudal midline, but the rostromedial surface is muscle-free. We hypothesize that swim-bladder design represents a compromise between opposing tendencies toward (i) an omnidirectional sound source that would optimize a male's opportunity to attract females from any direction, and (ii) a directional sound source that would shield the nearby ears during sound production. To determine if the directionality of toadfish sound is consistent with this hypothesis, boatwhistle advertisement calls of individually identified males were recorded in the York River, Virginia, by means of two calibrated hydrophones and a waterproof recording system: one hydrophone was fixed 1 m in front of the fish and the second was roving. Boatwhistles in the horizontal plane propagated in a modified omnidirectional pattern that was bilaterally symmetrical. The mean sound pressure was 126 dB re: 1 µPa at 0°. The sound pressure level decreased by approximately 1 dB at ±45°, after which levels increased to 180°, averaging 3-6 dB greater behind (mean 130 dB) than directly in front of the fish. This pattern is consistent with the hypothesis that sound energy is reduced at the fish's ears. The source level and fundamental frequency of the boatwhistle were highly stereotyped, with coefficients of variation averaging less than 1%, and duration was more variable, with a coefficient of variation of 8%. Grunt levels overlapped but were slightly lower than boatwhistle values.