Target strength estimation of black porgy Acanthopagrus schlegeli using acoustic measurements and a scattering model

ABSTRACT:   Black porgy are hatched and released in marine ranching areas in Japan, Korea and Taiwan to maintain fisheries resources in coastal areas. If acoustic methods are used for field surveys, target strength ( TS ) information on the species is needed to convert acoustic data to biomass density. Target strength of black porgy ( Acanthopagrus schlegeli ) 15.5–32.9 cm fork length (nine individuals) was measured at 38 and 120 kHz (split beam) by ex situ measurements (cage and fishhook methods) of living fish, a tethered method with shock-frozen fish, and an acoustic scattering model, the Kirchhoff ray mode (KRM) model based on fish morphology. The ex situ TS -to-fork length ( FL , cm) relationships were TS _38kHz = 20log₁₀ FL  − 64.6 ( r  = 0.77) and TS _120kHz = 20log₁₀ FL  − 65.2 ( r  = 0.70). The values for the KRM model were TS _38kHz = 20log₁₀ FL  − 64.8 ( r  = 0.88) and TS _120kHz = 20log₁₀ FL  − 65.4 ( r  = 0.80). The agreement between the ex situ measurements and the KRM model for the mean TS was very good. In contrast, the results for the tethered method ( TS _38kHz = 20log₁₀ FL  − 69.3 [ r  = 0.42]) differed markedly from the other two methods, perhaps because of the effects of the shock-freezing procedure in air. The results of the ex situ measurements and scattering model provide basic information for studying TS and conducting acoustic surveys of black porgy, even though the tethered method must be modified.     

Density and sound-speed contrasts,and target strength of Japanese sandeel <Emphasis Type="Italic">Ammodytes personatus</Emphasis>

Sound-speed and density contrasts (h and g, respectively), important acoustic material properties, of Japanese sandeel Ammodytes personatus were measured to estimate theoretical target strength (TS). The measured sound-speed contrast of adult fish varied between 1.016 and 1.023 (mean 1.020), and showed temperature dependence. The measured density contrast differed significantly between juvenile and adult. The density contrast of juvenile varied between 1.017 and 1.024 (1.021), and that of adult varied between 1.026 and 1.038 (1.032). Using these results, TS at 38 and 120 kHz in the fishing season were estimated by an empirical sound scattering model. TS of an individual fish varied significantly with change of tilt angle. TS of near-dorsal aspect (TS_max) and tilt-averaged TS (TS_ave) differed by up to 7 dB. At both frequencies, two different TS_ave−length relationships (TS_ave = a log L + b) were obtained for adult and juvenile. The coefficients of log L of adult were close to 20, suggesting that backscattering strength was proportional to square of body length. These values were larger in juvenile (34.0 at 120 kHz, 56.5 at 38 kHz), suggesting that backscattering strength varied drastically with the cube or fifth power of body length.     

鸢乌贼目标强度绳系控制法测量

2017年9月在南海北部(18°42.9′N,113°05.5′E)附近的深海海域,利用Simrad EY60型便携式分裂波束科学探鱼仪(120 kHz)和自制的鸢乌贼绳系控制装置对25尾鸢乌贼逐尾进行了单体目标强度(TS/dB)的测量,探讨了鸢乌贼单体目标探测中脉冲长度决定水平(PLDL/dB)、最小标准脉宽(min NPL)、最大标准脉宽(max NPL)和短轴角度最大标准偏差(MIA)等参数的变化对鸢乌贼单体目标强度测量的影响,分析了鸢乌贼单体TS的变化规律,并归纳了鸢乌贼TS与胴长的关系。结果显示,①随着PLDL增大,所探测鸢乌贼单体目标的数量呈先增加后减少的特征,并在PLDL=6 dB时达到峰值,而平均TS则呈单调增加趋势;随着min NPL增大,鸢乌贼单体目标的数量减少,在min NPL0.7范围内,平均TS呈明显的上升趋势;当max NPL1.2时,鸢乌贼单体目标的数量随max NPL的增大而增加,但平均TS却随之减小,当1.2max NPL1.8时,鸢乌贼单体目标的数量呈缓慢增加趋势,但平均TS则基本保持稳定;鸢乌贼单体目标数量随MIA的增大而增加,但平均TS则随之减小。②本研究中鸢乌贼单体目标探测参数的优化组合为PLDL=6.00dB,min NPL=0.7 dB,max NPL=1.8 dB,MIA=0.8°。③活体鸢乌贼单体平均TS的最大值和最小值分别为-48.6 dB和-63.63 dB,其对应鸢乌贼的胴长(ML/cm)分别为25.2 cm和12.4 cm,鸢乌贼TS与其ML的关系为TS=34.22 lg ML–98.23 (N=16,R2=0.603)。本实验首次尝试利用绳系控制法海上现场测量活体鸢乌贼的目标强度,为今后继续深入研究鸢乌贼声学散射特性积累了资料,亦能为其他头足类或鱼类目标强度的海上现场测量提供参考。     

Verification of mean volume backscattering strength obtained from acoustic Doppler current profiler by using sound scattering layer

ABSTRACT:   Acoustic Doppler current profilers (ADCPs) have recently been used to estimate the dynamic characteristics and biomass of sound scattering layers (SSLs) or swimming speed of fish schools and to analyze SSL spatial distribution or various behavior patterns. This paper shows that it is necessary to verify mean volume backscattering strength (MVBS, dB) values acquired from each beam for quantitative analysis of the spatial distribution or the biomass estimates of such specific targets as SSL or a fish school when using an ADCP. In this study, the SSL was selected to be a homogeneous density layer over a large area and two methods were used to verify the MVBS values from each beam of the ADCP. First, a mutual comparison among four beams was conducted after calculating MVBS from the measured echo intensity. Second, the MVBS values were verified using comparison between the calculated MVBS from the 153.6 kHz ADCP and MVBS from three frequencies of a well-calibrated scientific echosounder. Moreover, the dominant scatterers (euphausiids) were collected by a framed midwater trawl. From these samples, biological data were used to identify the different frequency characteristics between two systems, using a distorted-wave Born approximation (DWBA) theoretical backscattering model in order to assess the averaged target strength and target strength TS differences for the three frequencies.     

Application of acoustic Doppler current profiler combined with a scientific echo sounder for krill Euphausia pacifica density estimation

ABSTRACT:   An application of the acoustic Doppler current profiler (ADCP, 153.6 kHz) in combination with a scientific echo sounder (EK60, 38 and 200 kHz) was investigated to estimate the density of krill Euphausia pacifica . The acoustic backscattering strength from sound scattering layers was compared with biomass estimates from midwater trawls. Euphausia pacifica was targeted among mixed species populations in the sound scattering layer in the offshore Funka Bay area of Hokkaido, Japan. The frequency characteristics of acoustic backscattering by krill were calculated using a distorted wave Born approximation scattering model at three frequencies. Krill aggregations identified from the EK60 data were extracted as the mean volume backscattering strength difference between two frequencies. They were then used to identify similar aggregations in the ADCP data by matching observation times and depths for the two methods, which were applied simultaneously. Results from the comparison of the mean volume backscattering strength and the density calculated from the ADCP and EK60 showed that ADCP can be used to measure density and spatial–temporal distribution of krill aggregations. Current speed and direction at the study site were found to be 16.1 cm/s and 187.0°, respectively, and krill speed and direction (including the current component) were found to be 19.8 cm/s and 172.2°, respectively. Based on the ADCP data, the net speed and direction of the krill aggregations were found to be 5.9 cm/s and 128.0°, respectively.     

Target strength measurements of suspended live ommastrephid squid, <Emphasis Type="Italic">Todarodes pacificus</Emphasis>, and its application in density estimations

ABSTRACT:   Average target strength (TS) measurements of free-swimming Todarodes pacificus are required for calculating abundance estimations using the echo integration method. In this study, 31 live T. pacificus (18.0–28.4 cm dorsal mantle length; [ML]) were suspended with mantle tilt angles horizontally similar to free-swimming orientation, and their TS were measured using a 38 kHz split-beam echo sounder. Normalized TS by squared ML of T. pacificus ML was calculated as −73.1 dB: TS = 20 log ML −73.1 dB. The density of T. pacificus at their fishing ground off the northern Sanriku coast, Japan, was then estimated first using the echo integration method with the obtained normalized TS measurements, and then using commercial purse seine fishery CPUE (catch (tons) of squid per haul of purse seine) data. The density of T. pacificus aggregations near the continental shelf edge and upper continental slope was estimated as approximately 50–400 individuals/100 m² using both the echo integration method and CPUE data, both density results were similar. It was considered feasible therefore, to assess T. pacificus biomass directly using the echo integration method.     

Differences in swimbladder volume between Baltic and Norwegian spring-spawning herring: Consequences for mean target strength

Fish swimbladders, where present, contribute most to the scattering of sound by fish, as measured by the target strength (TS). The volumes of the swimbladders of two different European stocks of Atlantic herring were compared to consider the effect on estimates of TS. Swimbladder volumes of Baltic and Norwegian spring-spawning herring (Clupea harengus) were measured, together with individual herring fat content. Swimbladder volumes were found to differ significantly between the two herring stocks. Baltic herring have a larger swimbladder volume, which is suggested to be associated with the fish's low fat content, which in turn may be linked to its specific energy budget and the low salinity of the Baltic Sea. A buoyancy model that considered the different salinity conditions and fat proportions was used to evaluate the observed differences in swimbladder volume. The swimbladder volume data were subsequently used to model the mean target strength as a function of depth and growth pattern. Backscattering of the swimbladder was modelled using the modal-series-based deformed-cylinder model (MSB-DCM), describing the swimbladder as a gas-filled, elongated prolate spheroid. The fish body component was modelled as a fluid-filled ellipsoid using the distorted wave Born approximation (DWBA). Modelling results support a different TS-to-size relationship for Baltic herring, with a stronger echo, due to the larger swimbladder. Depth- and length-dependent TS relationships based on the model results are suggested.     

基于网箱控制法和模型法的长江4种淡水鱼目标强度研究

目标强度(target strength,TS)是将回波积分值转换成绝对资源量的关键参数,同时也是渔业声学技术的热点研究内容。2012年12月及2013年6―7月,在三峡水库中华鲟基地网箱内使用BioSonics DT-X(199 kHz)分裂波式科学回声仪测定了4种共计31尾不同鳔室构造和体型的长江淡水鱼类背腹方向的目标强度,并将此结果与基尔霍夫近似模型法测定结果进行比较。实验鱼包括鳊(Parabramis pekinensis) 6尾、鲢(Hypophthalmichthys molitrix) 8尾、鲇(Silurus asotus)10尾及长江鲟(Acipenser dabryanus)7尾。结果表明,模型法测定结果与网箱控制法所测结果无显著性差异。构建4种鱼TS值(dB)与体长(BL, cm)的标准方程分别为鳊:TS=20lg(BL)-70.1 (R~2=0.94);鲢:TS=20lg(BL)-67.0 (R~2=0.80);鲇:TS=20lg(BL)-74.5 (R~2=0.80)及长江鲟:TS=20lg(BL)-66.1 (R~2=0.94)。模型法获得实验鱼目标强度的分布表明,鱼类不同的形态学特征及鳔室数量会影响目标强度的大小与分布特征。低频(38 kHz)下鳊、鲇及长江鲟目标强度最大值对应的姿态倾角出现在-10°～0°,而鲢目标强度最大值出现在-20°～-10°,且不同种类鱼的目标强度最大值所对应姿态倾角的位置各不相同。本研究通过网箱控制法和模型法测定了4种不同鳔室构造和体型的长江淡水鱼类目标强度,可为长江淡水鱼类目标强度研究提供有益借鉴,为采用渔业声学方法进行长江淡水鱼类垂直原位监测评估资源量提供相关参数。     

Changes in meat texture of three varieties of squid in the early stage of cold storage

ABSTRACT: The present study examined the changes in texture and protein components during cold storage of different squid varieties. Raw oval squid, Japanese common squid and arrow squid were sliced fresh and the muscles were stored at 4°C for 0, 4, 8, 12, 18, 24, 48 and 120 h. The rheological measurements, protein components and amounts of collagen were examined. The adhesiveness of each squid increased significantly in the early stage of cold storage. In all varieties, penetration decreased at 4 h, which is considered to be rigor mortis, then increased. The amounts of total collagen, 20°C water-soluble collagen and 70°C water-soluble collagen did not change significantly in each variety during cold storage. Sodium dodecylsulfate–polyacrylamide gel electrophoresis (SDS-PAGE) pattern showed that the 580 kDa component gradually disappeared up to 48 h. The correlations between the amounts of 580 kDa component and adhesiveness or firmness were high. Models of fit based on chemical kinetics accurately expressed the behavior of adhesiveness, firmness and penetration showing that 63.2% of adhesiveness changes occurred in 13–19 h and that 63.2% of firmness changes occurred in 18–24 h.     

Observation and explanation of systematic split-beam angle measurement errors

Experiments conducted at the Qualark Creek acoustic site on the Fraser River have shown unexpected systematic errors in the split-beam angle measurement. A tethered dead salmon with a target strength of approximately –30 dB was used as a target at 3.7 m range. A signal-to-noise ratio of ∼12 dB was observed. This target strength and signal-to-noise ratio are typical in some rivers where migrating adult salmon are observed. The target's location was measured both from the frame used to position the target in the beam and from the acoustic data. Comparison of these two sets of measurements demonstrated a bias that increased with the target's distance off the beam axis. The acoustically measured target locations were closer to the beam axis than the actual locations. Each acoustic estimate represented the mean location obtained after 3 000 pings. Results from a simulation model that includes the effects of random noise on the split-beam angle measurement reproduce the systematic underestimate of these angles. This bias increases rapidly with increasing off-axis target location and decreasing signal-to-noise ratio. The bias has been observed for circular and elliptical beams and the model accurately predicts the magnitude and direction of the systematic part of the angle measurement error in both cases. Results for a circular transducer are used here to illustrate the situation. The presence of this bias can affect measurements of fish density and migration speed. At the low signal-to-noise ratios often obtained in riverine environments, those who use a split-beam system for observation or estimation of fish should be aware of this phenomenon.     

Hydroacoustic differentiation of adult Atlantic salmon and aquatic macrophytes in the River Wye,Wales

Split-beam hydroacoustic techniques have been used to enumerate adult Atlantic salmon (Salmo salar) passage on the River Wye since 1994. Aggregations of aquatic macrophytes, principally Ranunculus fluitans, are seasonally present at the monitoring site. At high densities, these macrophytes return target strength (TS) values similar to those of adult salmon. Target direction-of-movement information readily resolves upstream-migrant salmon from static- or downstream-traveling macrophytes. However, Atlantic salmon are iteroparous, and downstream-migrant kelts must be factored into the acoustic estimates. Net upstream target movement and/or TS were not reliable indicators of salmon passage at the River Wye site when aquatic macrophyte aggregations were present. In 1995, a subset of data (n = 71) was selected from the ongoing monitoring program to determine the feasibility of resolving salmon from macrophytes using acoustic parameters other than target direction-of-movement or mean TS. Individual targets were visually identified as either salmon or macrophytes based on concurrent video records. Distributions of available acoustic parameters were statistically compared between the two target-types using a two-tailed t-test assuming equal variance (P = 0.05). Available acoustic parameters included echo position, pulse width (at –6, –12, and –18 dB power points), amplitude, beam pattern factor and target strength. Pulse width standard deviation (PWSD) measurements were determined to be the most effective individual parameters for discriminating macrophytes from salmon. Based on PWSD at the –6 dB echo power points, 77% of all macrophyte targets were removed from the mixed data set. Multiple selection criteria increased total target discrimination. Applying a combination of –6 and –12 dB PWSD, and Y–axis target slope criteria rejected 94% of all macrophytes, retaining all salmon targets.     

Hydroacoustic in situ target strength of smelt (Osmerus eperlanus (L.))

Dependence of the in situ acoustic target strength (TS) of smelt (Osmerus eperlanus (L.)) on the total fish length (L) was estimated from TS measurements made with a split-beam 120 kHz echo sounder with reference to fish length–frequency distributions in trawl catches. The studies were conducted in the eutrophic and turbid Lake Hiidenvesi in southern Finland. Smelt dominated the catches-in-number with proportions at different sampling stations ranging from 91.8 to 100%. A TS–length equation of the form TS = alog L − b was fitted through the modes in the TS-distributions and in the respective fish length distributions. The estimated model (±parameter standard error) was TS = 23.4 (±2.24)log₁₀ L − 68.7 (±1.82). With a pre-defined slope of 20, the fitted equation was TS = 20 log₁₀ L − 65.9 (±0.23). The estimated day–night difference in TS–length relationship was not significant (t-test, p = 0.37).     

Size selectivity of a trammel net for oval squid Sepioteuthis lessoniana

ABSTRACT:   The size selectivity of a trammel net for herded oval squid Sepioteuthis lessoniana in Tateyama Bay, Chiba Prefecture, was estimated by comparison between the mantle length frequency distributions of oval squid caught by a trammel net and by a set net. The measured mesh sizes of the inner net of the trammel net and of the final section of the set net were 85.3 and 11.3 mm, respectively. In the trammel net fishery where oval squid are herded into the net, most of the oval squid are caught in the bag-shaped inner net. Hence, the logistic function was employed for the size selectivity curve of the trammel net. The 'share each length's catch total' (SELECT) model was implemented for the estimation of the selectivity curve. The size selectivity r ( l ) of the trammel net for the oval squid was expressed as a logistic function of the mantle length l : r ( l ) = exp(−18.57 + 0.88  l )/[1 + exp(−18.57 + 0.88  l )]. From these logistic parameter estimates, the 50% selection mantle length and selection range ( L ₇₅– L ₂₅) were calculated as 21.07 and 2.49 cm, respectively. The selection probability of oval squid whose mantle girth was equivalent to the mesh perimeter of the inner net was 0.09. Accordingly, oval squid of a girth smaller than the mesh perimeter were likely to pass through the mesh to escape from the net.     

4种常见淡水养殖鱼类目标强度测定与差异分析

鱼类目标强度(target strength)的测量是渔业声学技术研究和应用的核心内容之一。2015年6―10月,在小型水槽内使用Bio Sonics DT-X(199kHz)科学探鱼仪发射水平声波,测量了4种共29尾不同鳔室结构的淡水养殖鱼类体侧向及背腹向(180°范围)的目标强度,并拍摄X光影像以了解鱼体鳔室结构及特征。其中瓦氏黄颡鱼(Pelteobagrus vachelli)7尾、鳜鱼(Siniperca chuatsi)9尾、鲫鱼(Carassius auratus)6尾、草鱼(Ctenopharyngodon idellus)7尾。结果显示,单体鱼目标强度与声波入射角度具有cos三次方函数关系,体侧向与背腹向上最大目标强度均出现于鱼体主轴垂直于入射声波时,最小目标强度出现于头尾方向朝向声波时,与最大目标强度相差10dB。不同种鱼类体侧向平均目标强度略大于背腹向0.5~5dB。单室鳔鱼类目标强度比相近体长的两室鳔鱼类小。对4种鱼类的目标强度与鱼体相关生物学指标进行主成分分析,体侧向与背腹向目标强度主要受体长、鳔长和鳔长/鳔高值的影响较大。通过目标强度与实验鱼全长、体长、体重的线性回归,获得体侧和背腹入射方向目标强度与3个生物学参数的关系式。本研究通过分析不同鳔室形态鱼种的回波特征差异,辅助判别长江内常见鱼类(如瓦氏黄颡鱼、鱖鱼、鲫鱼等)的声学信号,结果对于淡水水域水平原位监测时分析评估资源量相关参数具有参考意义。     

轻量化神经网络在远洋鱿钓检测技术中的应用

中国远洋鱿鱼捕捞技术比较单一,智能化的鱿鱼捕捞技术对远洋渔业资源统计至关重要。在智能化鱿鱼捕捞作业过程中,以YOLOV3算法检测时,其特征提取网络Darknet53模型参数量较大,模型输出权重存储量较高,降低了检测速度。为此,建立轻量化MobileNetV3网络作为特征提取网络,进行初步有效特征提取,再设计CSP瓶颈层作为逆瓶颈结构,提高特征提取能力;最后通过CIoU模型建立网络模型的损失函数。在实验室环境下,使用Squid数据集验证轻量化网络模型的有效性,并对其主干网络与损失函数的性能进行分析。通过训练目标数据集,将轻量型网络模型与YOLOV3网络模型结构做消融试验,验证轻量化网络应用在远洋捕捞技术上的准确性以及实用性。结果显示,轻量化网络结构的性能明显优于YOLOV3网络模型结构,可以大幅度降低参数量,提高检测速度,缩短检测时间,提高检测率,提高了鱿鱼实时检测的工作效率。本研究成果为远洋渔业资源调查提供重要依据。     

轻量化神经网络在远洋鱿钓检测技术中的应用

中国远洋鱿鱼捕捞技术比较单一,智能化的鱿鱼捕捞技术对远洋渔业资源统计至关重要。在智能化鱿鱼捕捞作业过程中,以YOLOV3算法检测时,其特征提取网络Darknet53模型参数量较大,模型输出权重存储量较高,降低了检测速度。为此,建立轻量化MobileNetV3网络作为特征提取网络,进行初步有效特征提取,再设计CSP瓶颈层作为逆瓶颈结构,提高特征提取能力;最后通过CIoU模型建立网络模型的损失函数。在实验室环境下,使用Squid数据集验证轻量化网络模型的有效性,并对其主干网络与损失函数的性能进行分析。通过训练目标数据集,将轻量型网络模型与YOLOV3网络模型结构做消融试验,验证轻量化网络应用在远洋捕捞技术上的准确性以及实用性。结果显示,轻量化网络结构的性能明显优于YOLOV3网络模型结构,可以大幅度降低参数量,提高检测速度,缩短检测时间,提高检测率,提高了鱿鱼实时检测的工作效率。本研究成果为远洋渔业资源调查提供重要依据。     

基于灯光罩网法的南海鸢乌贼声学评估技术研究

南海中南部深水海域蕴藏着丰富的鸢乌贼资源,为推动南海外海渔业资源开发,实验探索了灯光罩网与声学手段相结合的鸢乌贼资源量评估方法。根据2011年4—5月在南沙群岛海域灯光罩网和Simrad EY60科学鱼探仪同步采集鸢乌贼生物学和声学数据,对鸢乌贼的趋光性行为、种群结构、声学映像和分布水层等特征进行分析。结果表明,灯光诱集结合罩网采样可确定南海鸢乌贼的单体回波,分布于0～100 m水层;通过背景噪声消除、鱼类和浮游动物目标限定、单体目标检测等处理,确定鸢乌贼现场目标强度-67～-52 dB;选择鸢乌贼渔获比例较大的网次,统计得到鸢乌贼胴长10.4～14.2 cm,对应目标强度-60.7～-58.0 dB,胴长与目标强度经验公式为TS=21.23LogML-82.48。研究认为,声学与灯光罩网相结合的调查方法可以作为南海今后开展鸢乌贼资源量评估的基本方法。     

Swimming angle and target strength of larval Japanese anchovy (<Emphasis Type="Italic">Engraulis japonicus</Emphasis>)

The swimming angle of larval Japanese anchovy (Engraulis japonicus) was measured in a tank, and target strength (TS) was calculated using a theoretical scattering model. The mean swimming angle was 12.8° (SD ±22.1). Increased speeds of flow led to increased mean swimming angles. The mean swimming angle at flow of 5 cm s⁻¹ was higher than at other speeds. TS values were estimated using a distorted-wave Born approximation model for two cases. Average values were 1–3 cm s⁻¹ (11.5° ± 22.1) and 5 cm s⁻¹ (16.6° ± 21.7) for cases 1 and 2, respectively. For case 1, TS ranged from −92.0 to −74.7 dB with a mean of −79.4 dB at 120 kHz. For case 2, TS ranged from −92.2 to −75.2 dB with a mean of −79.9 dB. The mean TS in case 2 was lower than that in case 1, with the maximum difference being 1.0 dB at 120 kHz (standard length 22.0 mm). However, there were no significant differences between the regression lines of cases 1 and 2. Thus, changes in flow speed altered the swimming angle of larval Japanese anchovy, but had little influence on TS.     

中国鱿鱼钓机装备研究现状及展望

鱿鱼钓机是远洋鱿钓渔业的重要生产工具。目前鱿鱼钓机装备发展面临的主要问题是机钓产量低。本文介绍了我国鱿鱼钓机装备的研究现状,对钓机运转速度、作业水深控制、抖动模式设置及结构设计等方面的研究趋势进行了探讨。最后,提出了我国鱿鱼钓机发展对策,研究指出需重点解决钓机结构优化设计、控制系统性能优化、运行参数优化等问题,为远洋鱿钓渔业的可持续发展提供参考依据。     

南海黄斑蓝子鱼的目标强度测量研究

2008年10月在大亚湾人工鱼礁海域的渔排上,使用鱼类目标强度测量装置,包括分裂波束式Simrad EY60便携式水声学测量系统(120 kHz),采用"绳系控制实验法"对16尾黄斑蓝子鱼(Siganus oramin)逐尾进行单体鱼的目标强度测量.样品鱼为在大亚湾海域现场采用渔笼捕捞的单体活鱼样品,其叉长范围为7.3～19.5 cm,平均叉长为11.3 cm,体质量范围为4.6～135 g,平均体质量为33.2 g.结果表明,南海黄斑蓝子鱼目标强度(TS)与其叉长的关系式采用常规的20lgL形式为TS=20lgL-74.1分贝.本研究采用"绳系控制实验法"对16尾黄斑蓝子鱼逐尾进行单体鱼的目标强度测量,旨在为提高渔业资源声学调查与评估的准确性提供数据支持.