夏季西南大西洋阿根廷无须鳕异尖线虫幼虫感染情况研究

阿根廷无须鳕(Merlucciushubbsi)是西南大西洋最主要的捕捞物种之一,近年来其捕捞产量持续上升,异尖线虫幼虫(Anisakidlarvae)是寄生于阿根廷无须鳕最常见的寄生虫之一,本研究为了解西南大西洋阿根廷无须鳕感染异尖线虫幼虫的情况,于2022年10月至2023年2月夏季阿根廷及马尔维纳斯群岛(福克兰群岛)专属经济区外的公海海域共捕获435尾阿根廷无须鳕,对其进行生物学实验,采集寄生虫进行形态学鉴别,最后记录数据并进行分析。结果显示, 99.08%的阿根廷无须鳕均感染异尖线虫幼虫,平均感染强度为(19.56±24.76)条/尾, 44.37%的样本鱼感染异尖线虫幼虫的数量在1～10条之间。性腺成熟度为I～IV的样本鱼感染异尖线虫幼虫的平均感染强度分别为(9.89±10.67)条/尾、(13.83±14.74)条/尾、(25.86±22.17)条/尾、(50.61±56.78)条/尾;样本鱼腹腔、肝脏和胃感染异尖线虫幼虫的平均感染强度分别为(9.20±10.01)条/尾、(8.61±13.74)条/尾、(4.34±5.10)条/尾。统计分析结果显示,性腺成熟度为IV期的样...     

进镜海水鱼类感染异尖科线虫检疫情况初报

从1997年1-12月份,对从沙头角口岸进境的香港地区捕挥的冰鲜海水鱼类进行检查,发现带有大量异尖科线虫,主要为异尖属和对盲目囊属。在不同季节、不同种类的鱼类内,其数量变化呈现出一定的规律性。本文就其规律性进行了探讨。     

大连近海鱼类异尖线虫感染研究简报

近年，笔者在大连近海名贵鱼类生态调查中发现，包括走俏于大小酒家，广泛用于生鱼片料理和鱼杂料理，俗称先生鱼或疥疤鱼，通称绒杜父鱼在内的为数不少鱼种均见可能引起人体异尖线虫病的异尖线虫亚科Anisakinae幼虫大量寄生。     

西白令海夏季狭鳕个体肌肉组织能量密度及其影响因素分析

为了解白令海海域狭鳕(Gadus chalcogrammus)生长发育过程中肌肉组织的能量变化状况,利用2019年和2020年于西白令海拖网采集的112尾狭鳕样本,对其肌肉组织能量密度进行了测量,利用广义加性模型(generalized additive model, GAM)分析了夏季狭鳕个体肌肉组织的能量积累及变化情况,并探究了其影响因素。研究结果显示,体长范围为23.8～60.5 cm的狭鳕肌肉组织的能量密度为(21.10±0.89) kJ·g^-1,2019和2020年间狭鳕肌肉组织能量密度不存在显著的年际差异(P>0.05)。GAM结果对狭鳕肌肉组织能量密度的解释偏差为46.1%,仅性腺质量和捕捞月份是影响肌肉组织能量密度的两个显著因素,而体长、性腺成熟度等其他指标未对肌肉组织能量密度造成显著影响。相对于性腺成熟度,性腺质量更适于作为生长发育指标来分析狭鳕肌肉能量密度的影响因素。建议应采用多元统计手段开展生物能量累积与能量密度影响分析,以更好地揭示影响能量密度的主要因素。     

白令海阿留申海盆区夏季理化环境特征及其与狭鳕分布和移动的关系

１９９３年６～８月，“北斗”号渔业资源调查船在白令海阿留申海盆区进行了狭鳕资源声学调查及渔场环境调查。应用本航次调查资料，本文阐述了调查海区温度、盐度及溶解氧分布特征，并分析了狭鳕分布和移动与理化环境的关系。结果表明：（１）阿留申海盆区为大面积低温水所覆盖，水温在１０℃以下。温盐水平分布特征为公海区低温高盐，调查区的其余水域则为高温低盐。溶解氧水平分布比较均匀，表层溶氧含量在１０ｍｇ／Ｌ左右；（２）温跃层位于２５米和５０米之间，一强冷水团控制着１００米到２００米左右的水层，其水温在３℃以下。盐度随深度增加而增加，溶解氧随深度的增加而降低；（３）狭鳕当年生幼鱼主要分布在海盆水系和东大陆架水系的混合区内，１００米层幼鱼密集区水温在３～５℃，盐度在３２．９～３３．１，溶解氧在８～９ｍｇ／Ｌ；（４）夏季狭鳕成鱼主要在冷水团范围以内垂直移动，２００米层成鱼密集区水温为３～４℃，盐度为３３．２～３３．６，溶解氧为６～８ｍｇ／Ｌ。     

白令海阿留申海盆区狭鳕当年生幼鱼数量分布的调查研究

１９９３年夏季白令海狭鳕资源调查期间，作者等应用声学／拖网评估调查方法，首次发现阿留申海盆区有大量当年生狭鳕幼鱼分布。研究结果表明：（１）当年生幼鱼主要分布在海盆区东北部，密集区位于东白令海陆架斜坡与公海区之间，呈西北东南走向；（２）鱼群主要栖息于中上层８０—１２０米处，有明显的昼夜垂直移动现象；（３）７月份海盆区东北部幼鱼鱼体长度为２９—４７毫米，而南部波哥斯洛夫岛附近的鱼体长度仅为１１—１７毫米，系两个不同产卵期鱼群的子代；（４）幼鱼主要栖息层的水温为３—５℃，盐度为３２．９—３３．１，其分布与陆架斜坡地理环境和饵料生物关系较密切。     

尖吻鲈仔、稚鱼异速生长研究

以16日龄尖吻鲈(Lates calarifer)为仔、稚鱼发育的区分节点,采用Auto CAD 2014软件对尖吻鲈(孵化后1~36 d)关键器官进行测量和分析。研究发现,在尖吻鲈仔、稚鱼的感觉、呼吸、摄食和游泳等重要器官分化的过程中,均表现出异速生长现象。头部器官中,吻长、口宽在仔、稚鱼期表现出生长速率不同的正异速生长;眼径在仔鱼期为等速生长,稚鱼期转化为负异速生长;仔鱼期的头高为正异速生长,稚鱼期转为负异速生长。在躯干部分器官中,头长在仔、稚鱼阶段均为快速生长,体高及躯干长为等速生长。游泳器官中,仔鱼期,尖吻鲈胸鳍保持等速生长,稚鱼期转为正异速生长;尾鳍在仔鱼期为负异速生长,稚鱼期转化为等速生长,而稚鱼期起始分化的背鳍、臀鳍、腹鳍为快速生长。     

饲料中添加月桂酸单甘酯对尖吻鲈脂质代谢与肝脏功能的影响

为探讨月桂酸单甘酯(glycerol monolaurate, GML)对尖吻鲈(Lates calcarifer)脂质代谢、消化能力及肝脏组织形态、抗氧化能力和血清生化指标等的影响,实验分别在饲料中添加0 g·kg^-1(G0组、对照组)、1 g·kg^-1(G1组)、2 g·kg^-1(G2组)和4 g·kg^-1(G4组)的GML饲喂尖吻鲈[体质量(442.727±54.423)g,体长(28.438±1.493)cm],实验进行8周。结果显示,饲料中添加2 g·kg^-1 GML显著提高了尖吻鲈脏器系数、脂质代谢酶活性和血清脂质代谢指标的含量,同时改善了肝细胞空泡化现象,减少了脂质在肝细胞中的沉积。添加GML还可以提高肝脏抗氧化酶和血清谷丙转移酶的活性,促进机体的免疫作用。此外,饲料中添加GML显著提高了肠道内消化酶的活性,有利于机体从饲料中吸收营养和能量。结果表明,饲料中拌喂GML可有效促进尖吻鲈脂质代谢和消化能力,改善肝脏组织形态和生理功能,增强免疫水平,调节机体健康。在该实...     

永州市黄鳝体内胃瘤线虫和新棘衣棘头虫的感染情况调查

2021年3～8月对永州市4个地区黄鳝体内胃瘤线虫和新棘衣棘头虫进行流行病学调查研究。结果显示,黄鳝胃瘤线虫新田县感染率最高(45.61%),冷水滩区次之(36.74%),东安县第3(36.11%),宁远县最低(21.43%);平均感染强度(条/尾)以冷水滩区最高(3.74),东安县次之(1.75),新田县第3(1.69),宁远县最低(1.00)。黄鳝新棘衣棘头虫冷水滩区感染率最高(1.96%),东安县次之(1.67%),新田县和宁远县未发现感染;平均感染强度(条/尾)东安县最高(2.00),冷水滩区次之(1.44)。根据统计可以得出永州黄鳝胃瘤线虫感染率为36.99%,感染强度为3.02条/尾;单尾黄鳝感染胃瘤线虫最多为54条,结果表明永州黄鳝胃瘤线虫感染较严重。而永州黄鳝新棘衣棘头虫的感染率为1.69%,感染强度为1.58条/尾;单尾黄鳝感染新棘衣棘头虫最多也只有4条,结果表明永州黄鳝感染新棘衣棘头虫的数目较少,感染不太严重。     

日输华水产发现活寄生虫

据《每日经济新闻》消息：近期，上海出入境检验检疫局多次从日本输华冰鲜竹荚鱼和真鲷中检出活的异尖线虫。由于这些水产品在口岸被检验中含有异尖线虫，因此未进入流通领域。     

Mass mortality of short-tailed shearwaters in the south-eastern Bering Sea during summer 1997

During summer 1997, hundreds of thousands of emaciated short-tailed shearwaters ( Puffinus tenuirostris ) died in the south-eastern Bering Sea. Using strip transect methodology, we documented the distribution and abundance of short-tailed shearwaters during cruises conducted prior to, during, and after the die-off, as well as the distributions and abundances of floating carcasses. The distributions and abundances of short-tailed shearwaters in 1997 were similar to those found during the 1970s and early 1980s. In August–September 1997, we observed 163 floating shearwater carcasses, most of which were between St Paul Island and Nunivak Island. We estimated ≈ 190 000 carcasses were afloat in the study area, about 11% of the surveyed population. Between spring (June) and autumn (August/September), mean net body mass of shearwaters decreased by 19%, mean pectoral muscle mass decreased by 14%, and mean percentage body lipid content decreased by 46%, from 15.6% in spring to 8.4% in autumn. Compared with spring, short-tailed shearwater diets broadened in autumn 1997, to include, in addition to adult euphausiids Thysanoessa raschii, juveniles of T. inermis, T. raschii and T. spinifera, crab megalops, fish and squid. We discuss how the ecosystem anomalies in the south-eastern Bering Sea during spring and summer 1997 relate to the mortality event and suggest possible implications of long-term climate change for populations of apex predators in the south-eastern Bering Sea.     

Copepod dynamics across warm and cold periods in the eastern Bering Sea: Implications for walleye pollock (Gadus chalcogrammus) and the Oscillating Control Hypothesis

Differences in zooplankton populations in relation to climate have been explored extensively on the southeastern Bering Sea shelf, specifically in relation to recruitment of the commercially important species walleye pollock (Gadus chalcogrammus). We addressed two research questions in this study: (i) Does the relative abundance of individual copepod species life history stages differ across warm and cold periods and (ii) Do estimated secondary production rates for copepods differ across warm and cold periods? For most copepod species, warmer conditions resulted in increased abundances in May, the opposite was observed in colder conditions. Abundances of smaller‐sized copepod species did not differ significantly between the warm and cold periods, whereas abundances of larger‐sized Calanus spp. increased during the cold period during July and September. Estimated secondary production rates in the warm period were highest in May for smaller‐sized copepods; production in the cold period was dominated by the larger‐sized Calanus spp. in July and September. We hypothesize that these observed patterns are a function of temperature‐driven changes in phenology combined with shifts in size‐based trophic relationships with primary producers. Based on this hypothesis, we present a conceptual model that builds upon the Oscillating Control Hypothesis to explain how variability in copepod production links to pollock variability. Specifically, fluctuations in spring sea‐ice drive regime‐dependent copepod production over the southeastern Bering Sea, but greatest impacts to upper trophic levels are driven by cascading July/September differences in copepod production.     

Effects of spawning temperature on the reproductive characteristics of walleye pollock Gadus chalcogrammus

Fisheries Science - Reproductive characteristics under different water temperature regimes were examined in hatchery-reared walleye pollock Gadus chalcogrammus. The fish had been cultured for...     

Body size trends along vertical and thermal gradients of chum salmon in the Bering Sea during summer

Relationships between the vertical distribution and thermal habitat, and body size of chum salmon Oncorhynchus keta were studied in the Bering Sea in summer using trawl surveys at various depths. Chum salmon abundance decreased with increasing depth, but the patterns of decrease differed between size groups. The abundance of small salmon fell rapidly with depth, whereas that of large salmon decreased gradually to 40 m depth, and abruptly below that. The average fork length of chum salmon collected from each trawl correlated positively with trawl net depth and negatively with water temperature. Since the optimal temperature for growth decreases with body size in this species, the observed body size‐related vertical habitat use by chum salmon may indicate size‐dependent thermal preferences.     

Chum salmon (Oncorhynchus keta) growth and temperature indices as indicators of the year–class strength of age‐1 walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea

Ecosystem‐based fisheries management requires the development of physical and biological time series that index ocean productivity for stock assessment and recruitment forecasts for commercially important species. As recruitment in marine fish is related to ocean condition, we developed proxies for ocean conditions based on sea surface temperature (SST) and biometric measurements of chum salmon (Oncorhynchus keta) captured in the walleye pollock (Gadus chalcogrammus) fishery in the eastern Bering Sea in three periods (July 16–30, September 1–15 and September 16–30). The main purpose of this paper was to evaluate Pacific salmon (Oncorhynchus spp.) growth as a possible indicator of ocean conditions that, in turn, may affect age‐1 walleye pollock recruitment. Marine growth rates of Pacific salmon are the result of a complex interplay of physical, biological and population‐based factors that fish experience as they range through oceanic habitats. These growth rates can, therefore, be viewed as indicators of recent ocean productivity. Thus, our hypothesis was that estimated intra‐annual growth in body weight of immature and maturing age‐4 male and female chum salmon may be used as a biological indicator of variations in rearing conditions also experienced by age‐0 walleye pollock; consequently, they may be used to predict the recruitment to age‐1 in walleye pollock. Summer SSTs and chum salmon growth at the end of July and September explained the largest amount of variability in walleye pollock recruitment indicating that physical and biological indices of ocean productivity can index fish recruitment.     

Spatial and temporal patterns in summer ichthyoplankton assemblages on the eastern Bering Sea shelf 1996–2000

Larval and early juvenile fishes were sampled from the eastern Bering Sea (EBS) shelf during summer from 1996 to 2000. Data from these collections were used to examine spatial and temporal patterns in species assemblage structure and abundance. Cluster analyses based on Bray–Curtis dissimilarity coefficients were used to group species and stations according to similar abundance and species composition. Ordination techniques were used to verify groupings, and a non‐parametric stepwise procedure using a Spearman correlation coefficient (BIO‐ENV) was used to relate groupings to predominant environmental variables. These approaches revealed a pattern of station groupings that were generally related to bathymetry in 1996, 1997, 1999, and 2000, although no obvious relationship to geographic boundaries was observed in 1998. Significant differences in species associations were observed in 1997 and 1998, and depressions in abundance were also noted among many species between 1997 and 1999. A regional, full primitive equation model was used to simulate float trajectories on the EBS shelf in each year to better relate fish distributional observations to prevailing current patterns. Model results indicated general variations in flow in several years, although 1998 stood out with stronger northeast flow than in any of the other years examined. Observed disruptions of larval and early juvenile fish assemblages could be related to the strong El‐Niño event of 1997–98 in the EBS. If this idea is confirmed, our study suggests that larval and juvenile fish are sensitive and respond relatively quickly (1–2 yr) to environmental perturbations, and as such, may be timely indicators of environmental change.     

Spatial and temporal patterns in summer ichthyoplankton assemblages on the eastern Bering Sea shelf 1996–2007

Larval and early juvenile fishes were sampled from the eastern Bering Sea (EBS) shelf from 2001 to 2005, and in 2007. Data from these collections were used to examine spatial and temporal patterns in species assemblage structure and abundance. The years 2001–2005 were unusual because the EBS water temperature was ‘warm’ compared with the long‐term mean temperature. In contrast, 2007 was a ‘cold’ year. The abundance of the five most numerous taxa at 12 stations common to all years sampled (1996–2005, 2007) were significantly different among years. Larval and early juvenile stage Theragra chalcogramma (walleye pollock), a commercially important gadid, were by far the most abundant fish in all years. Bottom depth alone best explained assemblage structure in most years, but in others, bottom depth and water column temperature combined and percent sea‐ice coverage were most important. Abundance of T. chalcogramma larvae increases with water column temperature until 5°C and then becomes level. Higher abundances of Gadus macrocephalus (Pacific cod) larvae occur in years with the greatest percent sea‐ice cover as indicated by GAM analysis. Larvae of Lepidopsetta polyxystra (northern rock sole) increase in abundance with increasing maximum wind speed, but decrease at a later date during the last winter storm. The data are consistent with the hypothesis that oceanographic conditions, specifically water temperature and sea‐ice coverage, affect the spatial and temporal pattern of larval abundances. In general, ichthyoplankton species assemblages can be important early indicators of environmental change in the Bering Sea and potentially other subarctic seas as well.     

2006年夏秋季东海群系澳洲鲐数量分布特征

利用2006年7~11月大型机轮灯光围网在东海外海的生产资料,并结合生物学测定数据以及水温遥感数据,对夏秋季东海群系澳洲鲐数量分布时空变化特征进行了研究,并探讨了它们与海洋环境条件的关系。结果表明:夏秋季东海外海海域的澳洲鲐主要为索饵群体,它们的高度集群期主要在7~9月份,其中以8月份较为明显;10月份以后,由于鱼群开始进行越冬洄游,移动速度明显加快,虽然有偶尔的高度集群现象,但是持续时间较短。在地理分布上,7~8月份,澳洲鲐索饵群体的主要分布在125°00′E以西、28°00′N以南海域;9月份,鱼群重心向东北方向转移,范围为125°00′~126°00′E、28°00′~28°30′N海域;10月份相对于9月份鱼群重心向东转移50 n mile,群体向北移动达150 n mile左右;11月份以后,澳洲鲐群体向东北方向的对马海峡转移且可能至日本海越冬。群体结构分析表明,夏秋季澳洲鲐的个体逐月迅速增大,且增长量以7~8月份较大,以后逐渐下降。根据澳洲鲐的群体移动规律以及海洋环境条件的变化,认为东海群系澳洲鲐属于黑潮边缘种,其中心渔场的变动和黑潮的强弱具有密切的关系。