The hearing abilities of the silver carp (Hypopthalmichthys molitrix) and bighead carp (Aristichthys nobilis)

Concern regarding the spread of silver carp (Hypopthalmichthys molitrix) and bighead carp (Aristichthys nobilis) through the Illinois River has prompted the development of a Bio-acoustic Fish Fence (BAFF) to act as an acoustic fish deterrent. The application of this technology has resulted in a need to understand the auditory physiology of the target species, in order to maximise the effect of the barrier in preventing the migration of the non-indigenous carp species into Lake Michigan, whilst minimising the effect on indigenous fish populations. Therefore, the hearing thresholds of 12 H. molitrix and 12 A. nobilis were defined using the Auditory Brainstem Response (ABR) technique, in a pressure-dominated sound field generated by submerged transducers of the type used in the construction of the BAFF system. The results clearly show that these fish are most sensitive to sounds in a frequency bandwidth of between 750 Hz and 1500 Hz, with higher thresholds below 300 Hz and above 2000 Hz.     

Field hearing measurements of the Atlantic sharpnose shark Rhizoprionodon terraenovae

Field measurements of hearing thresholds were obtained from the Atlantic sharpnose shark Rhizoprionodon terraenovae using the auditory evoked potential method (AEP). The fish had most sensitive hearing at 20 Hz, the lowest frequency tested, with decreasing sensitivity at higher frequencies. Hearing thresholds were lower than AEP thresholds previously measured for the nurse shark Ginglymostoma cirratum and yellow stingray Urobatis jamaicensis at frequencies <200 Hz, and similar at 200 Hz and above. Rhizoprionodon terraenovae represents the closest comparison in terms of pelagic lifestyle to the sharks which have been observed in acoustic field attraction experiments. The sound pressure levels that would be equivalent to the particle acceleration thresholds of R. terraenovae were much higher than the sound levels which attracted closely related sharks suggesting a discrepancy between the hearing threshold experiments and the field attraction experiments.     

A proposed mechanism for the observed ontogenetic improvement in the hearing ability of hapuka (Polyprion oxygeneios)

Swim bladder extensions and hearing ability were examined in the temperate reef fish Polyprion oxygeneios (hapuka). Using the auditory evoked potential (AEP) technique, hearing thresholds were determined in four age-classes of hapuka, from larvae to juveniles. The youngest age-class had poor hearing abilities, with lowest thresholds of 132 dB re 1 μPa, and a narrow auditory bandwidth (100–800 Hz). Hearing ability improved significantly throughout the remainder of their first year, including decreases in thresholds of up to 27 dB, and an increase in auditory bandwidth (up to 1,000 Hz). Magnetic resonance imaging (MRI) was used to investigate structural mechanisms that may account for this ontogenetic improvement in hearing. These showed rostral extensions of the swim bladder developing early in the juvenile stage, and extending with increasing age closer to the otic capsule. It is suggested that this indirect connection between the swim bladder and the otic capsule could impart pressure sensitivity closer to the inner ear, accounting for the increase in sensitivity seen during development, although further investigation of older fish is required for conclusive evidence. The improvement in hearing ability in hapuka could be potentially related to a unique life history of extended pelagic durations up to 4 years.     

Study of the haemoglobin content of a single erythrocyte (M index) in various cultured fish species

Investigations of the erythrocyte count, haemoglobin content and M index of 7 fish species were performed under equivalent environmental conditions in the same period of the year. The species were: bighead Hypophthalmichthys nobilis (Richardson), carp Cyprinus carpio L., silver carp Hypophthalmichthys molitrix (Val.), grass carp Ctenopharyngodon idella (Val.), sheat-fish Silurus glanis L. , pike Esox Indus L., pike-perch Lucioperca lucioperca (L.). Bighead and carp are carnivorous and omnivorous, silver carp and grass carp are herbivorous and sheat-fish, pike and pike-perch are predatory. Significant differences were demonstrable between M values of fish living on different type of food, where the M index is: It is concluded that M index values are useful as one parameter differentiating between fish with distinctly different food habits.     

Amphibious auditory responses of the American alligator (Alligator mississipiensis)

Animals that thrive both on land and underwater are faced with the task of interpreting stimuli in different media. This becomes a challenge to the sensory receptors in that stimuli (e.g., sound, motion) may convey the same type of information but are transmitted with different physical characteristics. We used auditory brainstem responses to examine hearing abilities of a species that makes full use of these two environments, the American alligator (Alligator mississipiensis). In water, alligators responded to tones from 100 Hz to 2,000 Hz, with peak sensitivity at 800 Hz. In air, they responded to tones from 100 Hz to 8,000 Hz, with peak sensitivity around 1,000 Hz. We also examined the contribution to hearing of an air bubble that becomes trapped in the middle ear as the animal submerges. This bubble has been previously implicated in underwater hearing. Our studies show that the trapped air bubble has no affect on auditory thresholds, suggesting the bubble is not an important adaptation for underwater hearing in this species.     

Effects of saccular otolith removal on hearing sensitivity of the sleeper goby (<Emphasis Type="Italic">Dormitator latifrons</Emphasis>)

It is not known to what extent the entire saccule contributes to overall hearing sensitivity in any fish species. Here we report directional and frequency sensitivity in a teleost fish (Dormitator latifrons) and effects of unilateral and bilateral removal of saccular otoliths on its hearing sensitivity. The fish had different hearing thresholds in the horizontal (-54.4 to -50.3 dB re: 1 micro m) and mid-sagittal (-58.6 to -53.1 dB) planes. At 100 Hz, unilateral otolith removal did not significantly change hearing sensitivity in the mid-sagittal plane, but caused selective reductions of auditory sensitivity by 3-7 dB in the azimuthal axes that are consistent with the longitudinal axis of the damaged saccule. Along the fish's longitudinal axis, unilateral otolith removal significantly decreased auditory sensitivity at 50 Hz and 400 Hz, but not at 100 Hz, 200 Hz, and 345 Hz. At 100 Hz, bilateral otolith removal resulted in robust hearing loss of 27-35 dB at different axes in both horizontal and mid-sagittal planes. Along the fish's longitudinal axis, the bilateral removal reduced auditory sensitivity by 13-27 dB at the different frequencies. Therefore, these results demonstrate that the saccule plays important roles in directional hearing and frequency responses.     

Ontogenetic development of auditory sensitivity and sound production in the squeaker catfish <Emphasis Type="Italic">Synodontis schoutedeni</Emphasis>

Background  

Surveys of ontogenetic development of hearing and sound production in fish are scarce, and the ontogenetic development of acoustic communication has been investigated in only two fish species so far. Studies on the labyrinth fish Trichopsis vittata and the toadfish Halobatrachus didactylus show that the ability to detect conspecific sounds develops during growth. In otophysine fish, which are characterized by Weberian ossicles and improved hearing sensitivities, the ontogenetic development of sound communication has never been investigated. We analysed the ontogeny of the auditory sensitivity and vocalizations in the mochokid catfish Synodontis schoutedeni. Mochokid catfishes of the genus Synodontis are commonly called squeakers because they produce broadband stridulation sounds during abduction and adduction of pectoral fin spines. Fish from six different size groups - from 22 mm standard length to 126 mm - were studied. Hearing thresholds were measured between 50 Hz and 6 kHz using the auditory evoked potentials recording technique; stridulation sounds were recorded and their sound pressure levels determined. Finally, absolute sound power spectra were compared to auditory sensitivity curves within each size group.     

Evoked Potential Audiograms of the Nurse Shark (Ginglymostoma cirratum) and the Yellow Stingray (Urobatis jamaicensis)

The hearing thresholds of the nurse shark, Ginglymostoma cirratum, and the yellow stingray, Urobatis jamaicensis, were measured using auditory evoked potentials (AEP). Stimuli were calibrated using a pressure-velocity probe so that the acoustic field could be completely characterized. The results show similar hearing thresholds for both species and similar hearing thresholds to previously measured audiograms for the lemon shark, Negaprion brevirostris, and the horn shark, Heterodontis francisi. All of these audiograms suggest poor hearing abilities, raising questions about field studies showing attraction of sharks to acoustic signals. By extrapolating the particle acceleration thresholds into estimates of their equivalent far-field sound pressure levels, it appears that these sharks cannot likely detect most of the sounds that have attracted sharks in the field.     

长江鲟幼鱼的听觉阈值研究

试验采用室内噪声控制的方式模拟野外自然噪声环境,以长江鲟(Acipenser dabryanus Dumeril)幼鱼为实验对象,使用TDT听觉测试系统,在100—500 Hz的刺激频率下,通过听性脑干反应(Auditory Evoked Potential, AEP法)测定其听力阈值。结果显示,长江鲟的最敏感频率为300 Hz,声压为(133±0.5) dB,听力曲线呈“V”型,听觉阈值随着频率的不同而发生变化。总体看,长江鲟听觉阈值较高,听力较弱,不能听到500 Hz以上的声音,其中,长江鲟的听觉阈值与湖鲟和匙吻鲟等鲟鱼类基本相似,但比长江中常见的淡水鱼类的听觉阈值高、听频范围窄。研究结果将为长江鲟的野外放归和种群重建提供重要基础资料,为评价涉渔工程建设运行对长江鱼类的影响提供基础数据支撑。     

Biochemical genetic comparison of bighead (Hypophthalmichthys molitrix), silver carp (Aristichthys nobilis), and their hybrids reared in Czechoslovakia

Incidental and/or uncontrolled hybridization between silver carp ( Hypophthalmichthys molitrix ) and bighead ( Aristichthys nobilis ) represents a serious problem in Czechoslovak aquaculture. This fact affects fitness traits very negatively in successive generations of hybrids. To solve this problem, 1076 individuals in a total of both H. molitrix. A. nobilis , and their hybrids in 12 groups from six rearing facilities were analysed. Twelve protein systems representing 21 presumptive loci were studied to analyse the electrophoretic patterns of their products using horizontal starch gel electrophoresis of blood and tissue extracts. Both species displayed identical electrophoretic patterns in MYO-I* , LDH-A *, LDH-B *, sMDH-1 *, sIDHP-3*, GPI-1*, and CK-I * loci. For a reliable differentiation of both species products of the following nine loci are applicable ALB *, PA *, TF, sMDH-2 *, SOD *, NDH *, MYO-IF , MYO-III *, and CK-2 *. In addition, some polymorphic variants in slDHP-1 *, sIDHP-2 *, LDH-C *, EST-II *, and GPI-2 * loci are of use as auxillary markers while the other variants are common to both species. A high level of gene introgression was evident through hybridization between both species. All groups declared previously as ' H. molifrix ' were actually confirmed biochemically to be H. molitrix . However, all groups declared as ' A. nobilis ' were proved to be a mixture of A. nobilis and its hybrids of different level with H. molitrix . This suggests it is impossible to distinguish between A. nobilis and hybrids using their external morphology only.     

The hearing of the Atlantic Salmon, Salmo salar

The hearing of the salmon, Salmo salar L., was studied by means of a cardiac conditioning technique. Fish were trained to show a slowing of the heart, on hearing a sound, in anticipation of a mild electric shock applied later. The minimum sound level to which the fish would respond was determined for a range of pure tones, both in the sea, and in the laboratory. The fish responded only to low frequency tones (below 380 Hz), and particle motion, rather than sound pressure, proved to be the relevant stimulus. The sensitivity of the fish to sound was not affected by the level of sea noise under natural conditions but hearing is likely to be masked by ambient noise in a turbulent river. Sound measurements made in the River Dee, near Aberdeen, lead to the conclusion that salmon are unlikely to detect sounds originating in air, but that they are sensitive to substrate borne sounds. Compared with the carp and cod the hearing of the salmon is poor, and more like that of the perch and plaice.     

Development of silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) genetic maps using microsatellite and AFLP markers and a pseudo-testcross strategy

Silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) are two of the four most important pond-cultured fish species inhabiting the major river basins of China. In the present study, genetic maps of silver carp and bighead carp were constructed using microsatellite and AFLP markers and a two-way pseudo-testcross strategy. To create the maps, 60 individuals were obtained from a cross of a single bighead carp (female) and a single silver carp (male). The silver carp map consisted of 271 markers (48 microsatellites and 223 AFLPs) that were assembled into 27 linkage groups, of which 22 contained at least four markers. The total length of the silver carp map was 952.2 cM, covering 82.8% of the estimated genome size. The bighead carp map consisted of 153 markers (27 microsatellites and 126 AFLPs) which were organized into 30 linkage groups, of which 19 contained at least four markers. The total length of the bighead carp map was 852.0 cM, covering 70.5% of the estimated genome size. Eighteen microsatellite markers were common to both maps. These maps will contribute to discovery of genes and genetic regions controlling traits in the two species of carp.     

Mortalities induced by the copepod Sinergasilus polycolpus in farmed silver and bighead carp in a reservoir

The frequency distributions of the parasitic copepod Sinergasilus polycolpus were examined in silver carp Hypophthalmichthys molitrix and bighead carp Aristichthys nobilis during a disease outbreak of the 2 species of fish in a reservoir in China. The mean abundance of the copepod was positively related with host length and age, and the overdispersion of the copepod in both silver and bighead carp was fitted well with negative binomial distribution. Although parasite-induced host mortality was observed, a peaked age-parasite abundance curve was not detected in the present parasite-host system. It is also proposed that this peaked age-abundance curve is unlikely to be observed in its natural host populations.     

Ship noise‐induced temporary hearing threshold shift in the Chinese sucker Myxocyprinus asiaticus (Bleeker, 1864)

The study objective was to explore the effects of noise generated by a 2000 hp containership on the reaction of Chinese sucker Myxocyprinus asiaticus. The noise was played back for various durations (1, 2, 4, 8, 24 h) at 142.8 dB re 1 μPa. Immediately after the noise exposure, hearing abilities of the fish were tested using the auditory evoked potential (AEP) protocol and compared with the response to a control group with no noise exposure. After 1 h noise exposure no significant differences were found compared to control fish; however, significant auditory threshold shifts began to occur at 800 Hz after 2 h of noise exposure. After 24 h of noise exposure, significant auditory threshold shifts were found at all tested frequencies (100–3000 Hz) when compared to control fish. Recoveries were also measured until the auditory thresholds returned to the hearing levels of the control fish. Auditory thresholds of all Chinese suckers fully returned to control levels within 96 h of recovery time. The results indicate that ship noise exposure can lead to threshold shifts in Chinese sucker and that these threshold shifts are temporary, referred to as temporary threshold shift (TTS).     

褐菖鲉的听觉阈值研究

利用听觉诱发电位记录技术研究了褐菖鲉(Sebasticus marmoratus)的听觉阈值。通过采用听觉生理系统记录和分析了8尾褐菖鲉对频率范围在100—1000 Hz的7种不同频率的声音刺激的诱发电位反应。结果表明, 褐菖鲉的听觉阈值在整体上随着频率增加而增加, 对100—300 Hz的低频声音信号敏感, 最敏感频率为150 Hz, 对应的听觉阈值为70 dB re 1 μPa。褐菖鲉的听觉敏感区间与其发声频率具有较高的匹配性, 表明其声讯交流的重要性。同时, 人为低频噪声可能对其声讯交流造成影响。     

A comparison of avoidance to acoustic stimuli in fish with different auditory capabilities: juvenile chum salmon (Oncorhynchus keta) and common carp (Cyprinus carpio)

This study compared the repulsive effects of sound playbacks of intermittent 30, 150, 300, 600 and 900 Hz tones on two fish with different auditory capabilities: juvenile chum salmon (Oncorhynchus keta) and common carp (Cyprinus carpio). When 150 and 300 Hz tones were emitted from an underwater speaker, O. keta exhibited a moderate repulse reaction. Conversely, C. carpio exhibited a moderate repulse reaction to a tone with a frequency of 30 Hz, which indicates that a low-frequency component in complex broadband sound may be important for inducing a repulse reaction in cyprinids.     

Potential effects of underwater noise from wind turbines on the marbled rockfish (Sebasticus marmoratus)

Environmental assessments of underwater noise on marine species must be based on species-specific hearing abilities. This study was to assess the potential impact of underwater noise from the East China Sea Bridge wind farm on the acoustic communication of the marbled rockfish. Here, the 1/3 octave frequency band of underwater noise was 125 Hz with the level range of 78–96 dB re 1 μPa, recorded at distances between 15-20m from the foundation at wind speed of 3–5 m/s. Auditory evoked potential (AEP) and passive acoustic techniques were used to determine the hearing abilities and sound production of the fish. The resultes showed the lowest auditory threshold of Sebastiscus marmoratus was 70 dB at 150 Hz matching the disturbance sound ranging 140–180 Hz, which indicating the acoustic communication used in this species. However, the frequency and level of turbine underwater noise overlapped the auditory sensitivity and vocalization of Sebastiscus marmoratus. The wind turbine noise could be detected by fish and may have a masking effect on their acoustic communication. This result can be applied for further to the assessent of fish species released into offshore wind farm marine ranch.     

清河水库鲢、鳙鱼种群动态研究Ⅰ.生产量的估计

本文根据Robson-Chapman公式估算了清河水库鲢、鳙可捕群体的残存率,计算了非捕捞群体的残存率和种群生产量。清河水库非捕捞群体平均年残存率约为0.25,可捕群体的平均年残存率鲢为0.32、鳙为0.38。鲢、鳙鱼种群生产量分别为141和110kg/ha,种群年P/B系数分别为1.15和1.09。鲢、鳙鱼获量仅为其生产量的33%和34%,库存生物量的36%。     

Digestive enzyme pattern of two stomachless filter feeders, silver carp, Hypophthalmichthys molitrix Val., and bighead carp, Aristichthys nobilis Rich.

Activities of digestive enzymes (trypsin and amylase) of microplanktophagous silver carp, Hypophthalmichthys molitrix , and macroplanktophagous bighead carp, Aristichthys nobilis , were investigated in relation to pH in 10 different segments of the gut. In addition, the possible existence of 'classical' lysozyme in both species and cellulase in silver carp were scrutinized, but no activities were detected. Tryptic and amylolytic activities decreased sharply from fore-gut to hind-gut indicating an efficient reabsorption mechanism. Trypsin and amylase of both species had a pH optimum at 8.3 and 7.0 respectively. The relatively low pH of 6.4 in the fore-gut of silver carp did not support an efficient operation of these enzymes, which was compensated by a higher enzyme concentration as compared to bighead carp. The latter, however, showed a higher pH of 7.3 in the fore-gut and thereby maintained similar activities as silver carp. The distinction of herbivorous and omnivorous fish in terms of digestion mechanisms is discussed.     

Acoustic intensity discrimination by the cichlid fish Astronotus ocellatus (Cuvier)

The acoustic intensity discrimination ability of the oscar (Astronotus ocellatus), a cichlid fish, was investigated using an automated positive reward method. Intensity discrimination thresholds (I, in dB) for 7-s continuous pure tone signals were measured both as functions of sound intensity above thresholds, i.e., sensation levels, (SL)(+10 dB, +20 dB and +30 dB) and frequency (200 Hz, 500 Hz, and 800 Hz). I at 500 Hz for +10 dB, +20 dB, and +30 dB SLs are 8.9, 5.5, and 3.3 dB, respectively. I (at+20 dB SL) for 200 Hz, 500 Hz, and 800 Hz are 4.5, 5.5, and 9.3 dB, respectively. Despite having poor auditory sensitivity (narrow frequency range and high thresholds), the intensity discrimination ability of the oscar follows the general trends of previously studied fish species, however, with higher thresholds.