Diet of late larval Japanese anchovy Engraulis japonicus in the Kii Channel, Japan

The diet of late larval (standard length 17.0–24.9 mm) Japanese anchovy Engraulis japonicus collected from the Kii Channel between April 2007 and March 2008 was analyzed. The main prey items found in the gut were copepods, and the composition of the gut contents changed on a monthly basis. The most important prey items were Calanoida (unidentified) from June to August and in October–November, Oncaea in March, April, and September, and Oithona in December and January. The prey selectivity analysis demonstrated that the selectivity for a particular prey category was not consistent throughout the months. It was considered that late larval anchovy may actually have no preference for a particular prey category. The major size (body width) of the prey items consumed fell within the range of 0.10–0.40 mm throughout almost the whole year. Late larvae tended to select relatively larger prey items from the environment. The relationship between the seasonal variabilities in diet and the fishery catch of anchovy “shirasu” (larvae of anchovy) is also discussed.     

Simulation of the impact of climate change on the egg and larval transport of Japanese anchovy (Engraulis japonicus) off Kyushu Island,the western coast of Japan

In order to investigate the impact of climate change on egg and larval transport of Japanese anchovy (Engraulis japonicus) off Kyushu Island western Japan, we conducted particle‐tracking simulations on transport success/failure to fishing grounds from 1960 to 2007. The modeled transport success since the mid‐1990s increased and decreased in the offshore and coastal zones, respectively, compared with the 1960s and 1970s. The estimated northward shift of the spawning ground and weakened Tsushima Warm Current contributed to increase in modeled transport success to the offshore zone. Conversely, the weakening trend of the modeled onshore current in the Goto‐Nada Sea combined with the northward shift of the spawning ground resulted in unsuccessful larval transport. These results suggest that fluctuations in juvenile and subadult anchovy catches in this area may be attributable to changes in the physical environment. The present study showed that changes in transport success induced by oceanographic fluctuations related to climate change, have the potential to affect anchovy recruitment off the western coast of Japan.     

Complete mitochondrial DNA sequence of the Japanese anchovy Engraulis japonicus

ABSTRACT: The complete nucleotide sequence of the mitochondrial genome for the Japanese anchovy Engraulis japonicus (Teleostei: Clupeiformes) was determined. The entire genome was purified by gene amplification using the long polymerase chain reaction (PCR) technique, and products were subsequently used as templates for PCR with 56 fish-versatile primers that amplify contiguous, overlapping segments of the entire genome. Direct sequencing of the PCR products demonstrated that the genome (16 675 base pairs [bp]) contained the same 37 mitochondrial genes (two ribosomal RNA, 22 transfer RNA and 13 protein-coding genes) as those found in other vertebrates, with the gene order being identical to that in typical vertebrates. A major non-coding region between the tRNA^Pro and tRNA^Phe genes (1024 bp) was considered to be the control (D-loop) region, as it has several conservative blocks characteristic to this region.     

Grouped, stacked rods and tapeta lucida in the retina of Japanese anchovy Engraulis japonicus

ABSTRACT: Morphology of the photoreceptor cells and tapetum of the Japanese anchovy Engraulis japonicus was studied by histologically and by chemical analysis. The Japanese anchovy has a duplex retina. The cones form parallel rows consisting of alternately placed long cones and bifid cones. Both types of cones are intimately associated and form triple units that are regularly spaced along the row of cones. The rods are grouped and stacked. This fish has a retinal tapetum lucidum composed of guanine and hypoxanthine. Three structures of the tapetum lucidum were recognized: platelet, diamond and rod types. Photomechanical changes include movements of the photoreceptor cells and the retinal tapetum. The retina of the Japanese anchovy is thought to be highly sensitive and well adapted to a dim light environment.     

Growth of larval and early juvenile Japanese anchovy, Engraulis japonicus, in the Kuroshio-Oyashio transition region

Larvae, juveniles, and adults of Japanese anchovy, Engraulis japonicus , were distributed throughout the Kuroshio-Oyashio transition region off northern Japan as far offshore as 170°E in 1996 and 1997. The growth trajectories of individual larvae and early juveniles were backcalculated using the biological intercept method based on the allometric relationship between otolith radius and somatic length. Mean larval growth rates ranged from 0.49 to 0.71 mm day^–1 in the transition region, and were comparable to those reported from the Pacific coastal waters of central Japan, which is the principal distribution range of E. japonicus . In terms of growth, the Kuroshio-Oyashio transition region seemed to be a favourable nursery area for larval E. japonicus . Larval growth tended to decline from the inshore to the offshore waters in the transition region. Thermal conditions did not show an inshore–offshore trend in the survey area and did not explain the longitudinal trend in growth rates.     

Morphology of the sense organs of anchovy Engraulis japonicus

ABSTRACT:   The morphology of the lateral line system, the inner ear, the olfactory epithelium and the taste bud of the wild adult anchovy Engraulis japonicus was examined by photo microscopy and scanning electron microscopy. Hematoxylin solution was injected into the lateral line canals to show the arrangement of the lateral line system. The lateral line system has well-developed supraorbital, infraorbital and preoperculomandibular canals on the head, dense canal branches on the operculum, lateral line canals on the trunk, and no free neuromasts. The inner ear comprises three semicircular canals and three otholithic end organs: the sacculus, the lagena and the utriculus. The olfactory organs and taste buds were examined by scanning electron microscopy. The paired olfactory organs on the snout have rosettes of lamellae, whose sensory epithelium consists of receptor cells of both the ciliated and microvillous type. The taste buds are distributed only inside the mouth, and mostly between the teeth of the upper and lower jaws, and between the gill teeth on the gill rakers. Well-developed lateral lines on the head are advantageous for schooling, and the taste buds in the mouth and on the gill rakers are advantageous for filter-feeding on plankton.     

Distribution and settling of Japanese anchovy (Engraulis japonicus eggs at the spawning ground off Changjiang River in the East China Sea

Spatial patterns in the distribution and abundance of Japanese anchovy, Engraulis japonicus, eggs were studied from net surveys in the East China Sea in May 1991. Egg abundance was> 5 × 10³ eggs (100 m³)^?1 in the area off Changjiang River, where a large spawning ground was developed. The vertical distribution of living eggs showed a maximum concentration at the surface (40700 eggs (100 m³)^?1) and rapidly decreased to ～5000 eggs (100 m³)^?1 at 14 m. Newly spawned eggs (stage I) were found throughout the water column but were most abundant near surface. Some eggs were morphologically identified as dead owing to their abnormal development and physical damage. In contrast to living eggs, no dead eggs were found at the surface and the concentrations were low to 21 m depth (40–64 eggs (100 m³)^?1). The concentration increased markedly with increasing depth, reaching a maximum of 634 eggs (100 m³)^?1 near the bottom (35 m). Dead eggs accounted for less than 0.3% of the total caught within 7 m of the surface and increased exponentially to 12% near the bottom. The settling loss of dead anchovy eggs also was studied by employing sediment traps at the spawning ground. The downward flux of settling eggs was low (304–405 eggs m^?2 day^?1) at 15 and 20 m depths, but rapidly increased with increasing depth, reaching a maximum of 1622 eggs m^?2 day^?1 at 35 m (5 m above bottom). By comparing the egg flux at 20 m with the living eggs abundance in the upper 20 m, the settling loss of eggs was calculated as about 0.098 day^?1. This probably represents the natural mortality of anchovy eggs caused by genetic abnormalities and incomplete fertilization.     

Environmental determinants of growth rates for larval Japanese anchovy Engraulis japonicus in different waters

Do disparate mechanisms determine growth rates of fish larvae in the different regions? The relationship between growth rates and environmental factors (sea temperature and food availability) was examined for larval Japanese anchovy Engraulis japonicus in geographically and environmentally different waters, through sagittal otolith microstructure analysis. Recent 3‐day mean growth rates directly before capture were positively related with sea‐surface temperature (SST) but not with food availability (plankton density) for the larvae in the Kuroshio Extension and Kuroshio–Oyashio transition regions of the western North Pacific. On the contrary, variations in recent growth rates were attributed to food availability (plankton density) as well as SST for the larvae in the East China Sea. In the shirasu fishing ground in Sagami Bay, larval growth rates were variable under the influences of both SST and food availability (feeding incidence). On the surface, the growth–environment relationships seemed to differ among regions. However, a definite general pattern of the dome‐shaped relationship between recent growth rates and SST was observed when all the regions were combined. Growth rates were similar even among clearly different regions if at the same SST. Overall, growth rates roughly increased with SST until they reached the maximum at SST of 21–22°C (i.e. optimal growth temperature), and declined when SST went over 21–22°C. On the contrary, no clear relationship was observed between growth rate and plankton density or between SST and plankton density. Therefore, the apparent among‐region differences would be firstly caused by the differences in regional SST range. The systematic mechanism of growth determination for widespread pelagic fish species larvae would be run by primarily sea temperature and secondarily food availability, at the species level.     

Relationships between the daily growth rate of Japanese anchovy Engraulis japonicus larvae and environmental factors in Osaka Bay,Seto Inland Sea,Japan

Fisheries Science - Seasonal changes in the growth rate of larval Japanese anchovy Engraulis japonicus collected by shirasu seine net boats in Osaka Bay in 2008 were estimated using otolith daily...     

黄海鳀鱼的卵巢发育

采用组织切片方法和常规目测法对黄海鯷鱼的卵巢发育特征进行了研究,描述了卵巢各发育期的特征,对不同发育期卵巢内卵母细胞的发育时相组成、卵径分布、卵巢两叶及其前、中、后部发育的差异情况进行了分析。结果表明,鯷鱼卵母细胞发育不同步;Ⅱ期卵巢由1～3时相卵母细胞组成,2时相卵母细胞在数量上占优势（66．39／6）;Ⅲ、Ⅳ和Ⅵ期卵巢均由1～4时相卵母细胞组成,其主要区别在于4时相卵母细胞所占比例不同,其中Ⅳ期卵巢中最高（34．8％）,Ⅲ期次之（28．69／6）,Ⅵ期最低（17．8％）;Ⅴ期卵巢由1～5时相卵母细胞组成,已发育成熟的5时相细胞所占比例最高（29．8％）;卵巢由Ⅲ期到Ⅴ期的发育过程中,主要是3、4时相卵母细胞向4、5时相的发育,1、2时相细胞所占比例基本不变。卵母细胞的粒径分布呈明显的峰、谷特征,这与以前对该问题的“浅锯齿状分布”认知有明显不同;Ⅲ和Ⅵ期卵巢内的卵径（长径）呈单峰分布,优势粒径组均为0．5～0．6mm;Ⅳ和Ⅴ期卵巢呈双峰分布,优势粒径组分别为0．2～0．3mm、0．7～0．8mm和0．5～0．6mm、1．1～1．2mm;V期卵巢两个优势卵母细胞群在粒径分布上彼此分离,粒径较大的群内均为水合卵母细胞,呈现出明显的分批产卵特征。鯷鱼卵巢左叶大、右叶小,右／左重量比值为0．71,95％置信区间为（0．67,0．75）;卵巢叶间和叶内部位间卵母细胞的发育状态无显著差异（P〉0．05）。     

Basin-scale distribution pattern and biomass estimation of Japanese anchovy Engraulis japonicus in the western North Pacific

The distribution pattern and biomass of the Japanese anchovy Engraulis japonicus in the offshore region of the western North Pacific (north of 35°N and west of 170°E) were studied using a quantitative echosounder. This is the first attempt at such a study in this region. Data were collected in summer from 2004 to 2007. The biomass was estimated using data collected at 38?kHz. Species compositions in the backscatterings from pelagic fish were assigned based on the results of trawl hauls taking account of sea surface temperature (SST). Japanese anchovy tended to be high density to the west of 153°E and were distributed in an SST range of 9?C24?°C. Although the temporal and spatial coverage of the survey differed each year, at least 1.5?C3.4 million tons of Japanese anchovy were present in the survey area between 2004 and 2007. To take account of the spatial coverage of the survey each year, the most reliable biomass estimate for this region in the time period was 3.4 million tons (coefficient of variation?0.22).     

Daily growth rate model of Japanese anchovy larvae Engraulis japonicus in Hiuchi-nada Sea, central Seto Inland Sea

In the present study, we developed a larval anchovy growth model in relation to sea temperature and food availability via food consumption and metabolic process terms, based on biological data from previous laboratory experiments and field surveys from 2003 to 2006 in Hiuchi-nada Sea, central part of Seto Inland Sea, Japan. To investigate when food shortage for larval anchovy and then recruitment failure occur in Hiuchi-nada Sea, anchovy food requirements were estimated by using the growth model, and we compared the food requirement with anchovy food availability. We applied an estimation method for growth model parameters, Hewett?CJohnson p and Q ₁₀, by minimizing the sum of squares of difference between mass-specific growth rates estimated by the models and those by otolith growth analysis. Parameter p was 0.86, slightly higher than typical values, and Q ₁₀ was 2.11, close to the value used for the biological model of larval northern anchovy. Food shortage for anchovy larvae did not occur in Hiuchi-nada Sea, although it was indicated that low food availability led to a low reproductive success rate. The newly developed growth model is considered optimal at present and useful to link environmental conditions and larval growth.     

Relationship between daily survival rates of larval Japanese anchovy (Engraulis japonicus) and concentrations of copepod nauplii in the Seto Inland Sea, Japan

We attempted to estimate the survival rates of larval cohorts (3–15 mm in body length) of the Japanese anchovy Engraulis japonicus population in Hiuchi‐nada, Seto Inland Sea, Japan, and examined the relationship to their food availability. The survival rates were directly calculated from the change in larval density during the survey. The estimated daily survival rate ranged between 0 and 89% d⁻¹, but increased with the increase in the mean concentration of small‐sized copepod nauplii (<100 μm in body length) sampled at 10 m depth. When the food concentration was higher than about 5 nauplii L⁻¹, the daily survival rate of larval anchovy reached an asymptote of approximately 89% day⁻¹. It might be possible to provide a framework for the forecast for larval abundance immediately prior to recruitment size (10–15 mm SL), based on larval abundance of the monitored size (3–8 mm SL) and the survival rate which is estimated from the concentration of small‐sized nauplii.     

赤潮异弯藻对鳀鱼早期发育的影响

就赤潮异弯藻(Heterosigma akashiwo)藻液及各组分对鳀鱼(Engraulis ja ponicus)早期发育阶段的影响进行了研究。并就鳃鱼早期发育过程中对赤潮异弯藻的敏感性时期作了探讨。实验结果表明,原肠期前的发育卵和初孵仔鱼对赤潮异弯藻较其他发育阶段更为敏感。在同等条件下藻细胞内容物对鳃鱼早期发育各阶段的毒性最大,其次是藻细胞碎片和藻液,去藻过滤液的毒性最小。暴露在高浓度90000c／ml藻细胞内容物中,96h后仔鱼的存活率为4％;而在同浓度的去藻过滤液中,96h后仔鱼的存活率为75％。藻细胞内容物和藻细胞碎片对鳃鱼仔鱼96hI。C∞分别为2818、6760c／mL．     

黄海Ti鱼限额捕捞的研究

根据10多年在黄海中南部Ti鱼（Engraulis japonicus)越冬场进行的声学／拖网调查生物量评估结果，利用调谐有效种群分析方法（VPA）对黄海Ti鱼资源种群动态进行了分析。研究结果：提出了Ti鱼限额捕捞工作内容和程序框架。并根据2001年Ti鱼生物量情况推荐，F0．1为0．7时，Ti鱼总允许可捕量（TAC）不超过10万t。     

黄海鳀鱼鱼体能值的季节变化

根据2002年6月～2003年9月黄海中南部水域鳀鱼的调查资料,分析了产卵、索饵和越冬期鱼体能值的季节变化以及精巢和卵巢能值的变化情况。产卵期(5～7月)、索饵期(8～10月)和越冬期(11～1月)鳀鱼能值的变动情况反应了性腺发育状况。卵巢能值和精巢能值的季节变化趋势相似。幼鱼和成年鳀鱼能值的季节变化趋势相似,但各个月份幼鱼能值均比成鱼低。鱼体能值从越冬期到产卵前期变化很大,达40％～50％,这主要由脂肪含量变化引起。湿重丰满度系数比干重丰满度系数估算鱼体能值准确度差。     

低酶水解法提取无苦味鳀鱼水解蛋白

低酶水解法提取无苦味鳀鱼水解蛋白王长云，薛长湖，陈修白（青岛海洋大学水产学院，２６６００３）关键词鳀鱼，水解蛋白，无苦味，低酶水解法ＰＲＥＰＡＲＡＴＩＯＮＯＦＦＩＳＨＮＯＮ－ＢＩＴＴＥＲＨＹＤＲＯＬＹＳＡＴＥＦＲＯＭＡＮＣＨＯＶＹ（ＥＮＧＲＡＵＬＩＳ...     

黄海中南部鳀鱼的生殖力及其变化

根据2002～2004年在山东半岛南部鳀鱼(Engraulis japonicus)产卵场的调查资料和1985～1986年相关历史资料,分析鳀鱼在经过近20年的高强度捕捞过程中,资源衰退导致个体绝对生殖力与叉长、纯重和年龄之间关系的变化,并对两个时期相同个体鳀鱼的生殖力进行比较.结果表明,2002～2004年鳀鱼的个体绝对生殖力为(14 850±579)粒,个体绝对生殖力随叉长、纯重和年龄的变化显著;与1985～1986年同海区、相同叉长范围和纯重范围的鳀鱼相比,2002～2004年鳀鱼生殖力的增大显著.生殖力增加可能是鳀鱼对长期捕捞压力及外部环境变化的适应性的反应.