Bilirubin-binding protein in the serum of spawning-migrating chum salmon,Oncorhynchus keta: Its identity with carotenoid-carrying lipoprotein

The serum carotenoid level gradually increased during the spawning migration of chum salmon (Oncorhynchus keta). Zeaxanthin, a yellowish carotenoid, was detected in the serum of spent males, while astaxanthin was a main carotenoid in the serum of males and females at other developmental stages. A high bilirubin level was found in the serum of spent males; the serum of spent male was yellow in colour due to the presence of zeaxanthin and bilirubin, although the serum of the other fish was bright orange.Three types of carotenoid-carrying lipoprotein such as low density lipoprotein, high density lipoprotein (HDL) and very high density lipoprotein fractions were present in the serum. Carotenoid-carrying lipoprotein from the HDL fraction became a main component during spawning migration. The serum bilirubin from the spent male salmon was distributed in the HDL fraction. Because bilirubin, as well as carotenoids, were present in the HDL fraction, the carotenoid-carrying lipoprotein from the HDL fraction was identical with bilirubin-binding protein in the serum of spent males. This carrier lipoprotein had two subunits (molecular weight 24,000 and 12,000); no disulfide bond was detected between the two subunits.     

Ecological effects of regime shifts in the Bering Sea and eastern North Pacific Ocean

Large‐scale shifts occurred in climatic and oceanic conditions in 1925, 1947, 1977, 1989 and possibly 1998. These shifts affected the mix and abundance of suites of coexisting species during each period of relative environmental stability—from primary producers to apex predators. However, the 1989 regime shift was not a simple reversal of the 1977 shift. The regime shifts occurred abruptly and were neither random variations nor simple reversals to the previous conditions. Timing of these anomalous environmental events in the North Pacific Ocean appears to be linked to physical and biological responses in other oceanic regions of the world. Changes in the atmospheric pressure can alter wind patterns that affect oceanic circulation and physical properties such as salinity and depth of the thermocline. This, in turn, affects primary and secondary production. Data from the North Pacific indicate that regime shifts can have opposite effects on species living in different domains, or can affect similar species living within a single domain in opposite ways. Climatic forcing appears to indirectly affect fish and marine mammal populations through changes in the distribution and abundance of their predators and prey. Effects of regime shifts on marine ecosystems are also manifested faster at lower trophic levels. Natural variability in the productivity of fish stocks in association with regime shifts indicates that new approaches to managing fisheries should incorporate climatic as well as fisheries effects.     

Changes in plasma prolactin and growth hormone concentrations during freshwater adaptation of juvenile chum salmon (Oncorhynchus keta) reared in seawater for a prolonged period

Freshwater adaptability of chum salmon was examined in juvenile fish reared in seawater for 4 months. The fish, weighing about 40g, were transferred directly to fresh water in October, when their cohorts are migrating in the North Pacific Ocean. Plasma sodium concentration decreased from 167 mM in seawater to about 130 mM during the first 24h, and increased gradually during 2–7 days after the transfer. No immunoreactive prolactin (PRL) was detected in the plasma of the seawater-adapted fish nor during the first 24h in fresh water. Significant levels of PRL were detected after 2–3 days. The maximal level (2.6 ng/ml) was observed after 5 days and became undetectable again after 7 days; no significant correlation was seen between the changes in plasma sodium and PRL levels during the transfer. Plasma growth hormone levels were relatively constant, except for a significant decrease 12h after the transfer. Although plasma thyroxine levels were highly variable during the experiment, a significant decrease and an increase were observed 12h and 5 days after the transfer, respectively. The present study indicates that juvenile chum salmon retain hyperosmoregulatory ability even after prolonged rearing in seawater. Examination of turnover rates, rather than changes in plasma levels, seems to be essential to clarify the osmoregulatory roles of the hormones.     

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.     

基于贝叶斯Schaefer模型的西北太平洋柔鱼资源评估与管理

利用基于贝叶斯统计方法的Schaefer模型分均匀分布、正态分布和随机分布3种方案,对西北太平洋柔鱼资源量进行评估,并对其管理策略做了风险分析。研究认为,在均匀分布的基准方案下,参数r、K和q的后验概率分布与先验概率分布存在较大差异,这表明本研究采用的年渔获量和CPUE数据为贝叶斯资源评估模型提供了足够多的信息。正态分布和随机分布2种方案下模型参数的预测值及估算的最大可持续产量较接近,但小于基准方案。研究认为,3种方案下,1996—2004年捕捞死亡率都远低于限制参考点F_0.1,1996—2004年渔获量也小于最大可持续产量,这表明目前西北太平洋柔鱼资源处于良好状况,没有遭受过度捕捞。决策分析表明,在相同的收获率情况下,基准方案得到的2019年资源量和渔获量均大于其它2种方案,但是资源崩溃的概率最大。保守的管理策略应将收获率控制在0.3左右,持续渔获量在13万t左右。     

大麻哈鱼繁殖特征及呼玛河原始产卵场生境功能验证

大麻哈鱼 (Oncorhynchus keta) 是重要的洄游性经济鱼类,在中国分布于黑龙江、乌苏里江、绥芬河和图们江水域。为保护大麻哈鱼种质资源,恢复图们江流域野外种群数量,该研究基于微卫星标记技术,利用10对微卫星标记,对355尾回捕子代和91尾繁殖亲本开展了亲子关系鉴定研究。结果表明,检测等位基因数 (N_a) 201个,观测杂合度 (H_o) 为0.617~0.895,平均0.744;期望杂合度 (H_e) 为0.676~0.909,平均0.824;多态信息含量 (PIC) 为0.628~0.900,平均0.805。利用Cervus 3.0软件计算10个微卫星座位的累积非亲排除率 (CEP) 达99.95%。5个回捕样本与繁殖亲本存在亲子关系,确定为增殖放流的大麻哈鱼。该研究成功利用微卫星标记技术明确回捕大麻哈鱼归属地,为巩固中国鱼源国地位提供有力证据,同时为评估大麻哈鱼的增殖放流效果提供技术支撑。

     

Population structure of bigeye tuna (Thunnus obesus) in the Indian Ocean inferred from mitochondrial DNA

Population structure of bigeye tuna (Thunnus obesus) in the Indian Ocean, Western Pacific Ocean and Eastern Atlantic Ocean were investigated using mitochondrial (mt) DNA sequence data. A total of 380 specimens were sampled from four regions in the Indian Ocean (Cocos Islands, Southeastern Indian Ocean, Southwestern Indian Ocean and Seychelles), and one region each from the Atlantic (Guinea) and the Western Pacific Oceans, respectively. The reconstructed neighbor-joining phylogeny based on the first hypervariable region (HVR-1) of the mitochondrial control region sequence data showed that haplotypes from the Indian and the Western Pacific Oceans could be grouped into two clades (Clades I and III), whereas in the Atlantic Ocean, two divergent clades (Clades I and II) coexisted. A single stock of bigeye tuna in the Indian Ocean was supported by hierarchical AMOVA tests and pairwise Φ_ST analyses. Clade I was the dominant population in the Indian and the Western Pacific Oceans which consisted of more than 96% of the specimens and Clade II was a specific group exclusively restricted to the Atlantic Ocean which made up 77% of its specimens. A new minor Clade, Clade III was discovered in the Indian and the Western Pacific Ocean. Overall, these analyses indicated that bigeye tuna of the Indian Ocean constituted a single panmictic population.     

西北太平洋鸢乌贼种群遗传结构

为检测西北太平洋鸢乌贼种群遗传结构,采用线粒体DNA细胞色素b基因(Cytb)序列分析方法对鸢乌贼东海群体、南海群体与菲律宾海群体进行遗传变异分析。结果显示,(1)所有群体总的单倍型多样度与核苷酸多样度分别为0.982±0.006、0.012±0.006;菲律宾海群体对应的遗传多样度均最高,分别为0.973±0.014、0.015±0.008;南海群体与东海群体的单倍型多样度分别为0.959±0.026、0.943±0.031,核苷酸多样度均为0.006±0.003。3个地理群体均具有较高的遗传多样性水平。(2)分子方差分析结果显示,34.6%的遗传变异来自于群体间,群体间遗传分化极显著。两两群体间Fst分析表明,西北太平洋鸢乌贼群体间均具有极显著的遗传分化。构建的单倍型邻接系统树和最小跨度树显示,西北太平洋鸢乌贼群体存在明显的系统发育谱系结构(谱系A、B、C),3个谱系单倍型类群间也存在极显著的遗传分化(Fst=0.735~0.805)。(3)中性检验和核苷酸不配对分析结果均表明,谱系B可能经历过近期群体扩张事件,发生群体扩张的时间在10.3~12.5万年前。综合分析认为,西北太平洋鸢乌贼的种群遗传结构模式及系统发育地理格局模式是由其栖息地海洋环境与更新世气候变化共同塑造的。建议在渔业管理上将3个地理群体划分为3个独立的管理单元。     

西北太平洋公海秋刀鱼渔场分布与海表温度锋的相关关系

西北太平洋公海秋刀鱼渔业是我国重要的经济渔业之一,其渔场分布与海表温度及温度变化息息相关。本研究通过海表温度（SST）的遥感数据计算海表水平温度梯度（SSTG）,根据2013—2015年中国（不含中国台湾省）北太平洋公海秋刀鱼渔业生产数据,分析海表温度锋与秋刀鱼资源丰度和渔场时空分布的关系。结果显示,秋刀鱼作业渔场主要分布于37°~49°N,145°~165°E;SST为10~14 ℃时,单位捕捞渔获量（CPUE）与SST呈负相关,SST为14~17 ℃时呈正相关,最适宜SST为12.5~14.5 ℃。当SSTG为0.01~0.06 ℃/km时,CPUE与SSTG呈显著线性正相关,最适宜SSTG为0.01~0.05 ℃/km。作业海域温度锋与CPUE呈显著正相关,相关系数为0.81;CPUE作业点到锋面的距离（DIST）表现出明显的季节特征,在夏季6—8月,当DIST为0~100 km范围内时,CPUE与DIST呈线性正相关,在秋季9—11月,CPUE与DIST呈对数负相关,90%以上的作业点出现在DIST为0~50 km范围内。研究表明,海表温度影响着秋刀鱼洄游渔场分布,亲潮黑潮交汇区形成冷水楔,海表温度锋集聚,进而秋刀鱼鱼群集群,形成高产渔场。     

北太平洋秋刀鱼生活史和资源渔场研究进展

北太平洋秋刀鱼(Cololabis saira)是中国重要的远洋渔业鱼种,被北太平洋渔业委员会列为优先管理的种类之一。本文回顾和概述了秋刀鱼生活史、种群动力、资源渔场和栖息地适宜性等方面的研究进展,分析和展望了秋刀鱼生长生物学、繁殖生物学、洄游、资源波动和栖息地适宜性等研究现状和未来的发展趋势。主要建议包括:基于耳石微化学信息和最适环境参数的时空分布变动,探索秋刀鱼潜在的洄游路径和模式;建立繁殖栖息地适应性指数模型,分析海洋气候对秋刀鱼补充群体潜在栖息地的影响;建立秋刀鱼集群栖息地适宜性指数模型,开发秋刀鱼渔场渔情速报系统。本文的概述和分析旨在为秋刀鱼渔业资源等相关研究提供参考。     

西北太平洋北方拟黵乌贼耳石外部形态特性分析

根据2018年9—11月我国鱿钓船在西北太平洋采集的339尾北方拟黵乌贼样本,对其耳石外形生长特征进行了研究。结果发现,北方拟黵乌贼具有长窄的吻区和宽大的翼区。主成分分析表明,耳石总长(TSL)、吻侧区长(RLL)、侧区长(LDL)、翼区长(WL)和最大宽度(MW)可以作为北方拟黵乌贼耳石外形变化的特征因子。协方差分析表明,MW、LDL和WL与胴长的关系存在性别间显著性差异,TSL和RLL则不存在显著性差异;MW、RLL、TSL、LDL和WL与体质量的关系均存在性别间显著性差异。AIC (Akaike’s information criterion)分析表明,TSL、RLL与胴长的生长关系最适合用线性函数表示,雄性个体的MW、LDL和雌雄个体的WL与胴长的关系最适合用幂函数表示,而雌性个体的LDL则最适合用指数函数表示。雄性个体的LDL和MW与体质量的关系最适合用指数函数表示,雌性个体的LDL、MW和TSL最适合用线性函数表示,而其余特征参数则均最适合用幂函数表示。随着胴长增加,耳石绝对尺寸都逐渐增大,但耳石的形态结构比例基本不变:背区、侧区、吻侧区、翼区的长度与耳石总长之比基本保持一...     

利用鳍条研究北太平洋长鳍金枪鱼的年龄与生长

根据2013—2014年在大连远洋渔业金枪鱼钓有限公司的超低温金枪钓渔船“天祥”16号船上采集的258个鳍条样品为基础(从845尾长鳍金枪鱼样本中随机选取了258个鳍条样本),研究了北太平洋长鳍金枪鱼的年龄和生长情况。研究首次采用了3个不同的切割位置(鳍条全长的10%、20%、50%标记段)对鳍条截面进行处理,利用线性函数、指数函数和幂函数分别拟合长鳍金枪鱼叉长和鳍条截面半径之间的关系,采用赤池信息准则(AIC)来获得最优化的函数,并计算其逆算叉长,最后得到北太平洋长鳍金枪鱼的生长方程、生长拐点以及生长率和生长指标。研究表明,北太平洋长鳍金枪鱼的主要年龄段集中在4~6龄,不分雌雄的生长方程为L_t=112.231×[1-e^{-0.277 132×(t+1.435)}],拐点年龄为2.53,生长率和生长指标随着年龄的增长呈递减的趋势,且年龄越大变化越小。本研究可为北太平洋长鳍金枪鱼的资源状况评估及渔业可持续发展提供生物学信息。     

Pacific herring, Clupea pallasi, recruitment in the Bering Sea and north-east Pacific Ocean, I: relationships among different populations

We examined recruitment and average weight-at-age time series for Pacific herring ( Clupea pallasi ) populations from the Bering Sea and north-east Pacific Ocean to determine similarities. Statistical correlation and multivariate clustering methods indicated Pacific herring populations form large-scale groups. Large year classes occur synchronously among several Pacific herring populations. Multivariate cluster analyses of recruitment and weight-at-age data indicated that Bering Sea herring populations are distinct from north-east Pacific Ocean populations. Within the NE Pacific Ocean, there appear to be three groups of herring populations: a British Columbia group, a south-east Alaska coastal group, and an outer Gulf of Alaska group. Jackknife and randomization tests indicate these groups are robust and not the result of random chance. Deviations from observed herring population groups were examined for indications of anthropogenic perturbations. The Prince William Sound herring populations did not show any strong deviations corresponding to the oil spill of 1989. There might not yet be enough data since the spill to detect changes in the recruitment or weight-at-age data since that time, particularly if oil spill effects were concentrated on the early life history stages.     

中西太平洋鲣卵巢发育特征

根据2007年10月-2008年1月在中西太平洋采集的140个卵巢样本,利用组织学分析方法,研究了鲣卵巢的发育过程,详细描述了鲣卵巢、卵细胞的发育阶段。结果表明:(1) 组织学上,鲣的卵细胞发育过程分为6个时相,与之对应的,卵巢发育过程分为6个时期。(2) 鲣属于不同步产卵类型,卵巢内会同时出现不同时相的卵细胞。(3) 传统鉴定方法用于鲣卵巢发育状况时,存在不足之处,与组织学分析的结果差别较大,尤其是Ⅵ期的差别最大。(4) 调查海域的鲣至少有两个产卵高峰期,一个高峰期是11月底(12月初),另一个高峰期是12月底(1月初)。     

基于线粒体COⅠ和Cytb基因序列的北太平洋柔鱼种群遗传结构研究

为准确掌握柔鱼的种群遗传结构,拟通过线粒体DNA的COI和Cytb基因序列分析方法对柔鱼不同产卵季节群体的遗传多样性和遗传结构进行研究。经PCR扩增与测序分别获得600 bp COI与481 bp Cytb基因序列。基于COI基因序列分析得到的单倍型数、单倍型多样性指数、核苷酸多样性指数及平均核苷酸差异数分别为24、(0.729 ±0.033)、(0.005 70 ± 0.003 25)和3.421。基于Cytb基因序列分析得到的单倍型数、单倍型多样性指数、核苷酸多样性指数及平均核苷酸差异数分别为28、(0.852 ± 0.016)、(0.006 45 ± 0.003 73)和3.101。分析认为, 北太平洋柔鱼2个产卵季节群体均具有较高的单倍型多样性指数和较低的核苷酸多样性指数。单倍型邻接树、两两群体间的F_st值以及AMOVA分析结果均表明, 北太平洋柔鱼2个产卵季节群体间的遗传差异不显著, 不存在显著的群体遗传结构。初步认为, 该海域因缺乏地理上的障碍, 加之北太平洋海流的作用以及柔鱼个体较强的游泳能力, 使得群体之间具有较强的基因流。     

应用贝叶斯生物量动态模型评估印度洋黄鳍金枪鱼资源

利用贝叶斯生物量动态模型对印度洋黄鳍金枪鱼(Thunnus albacares)资源进行了评估,并分析了不同标准化单位捕捞努力渔获量(catch per unit effort,CPUE)、内禀增长率(r)先验分布对评估结果的影响。结果表明:(1)模型能较好拟合日本延绳钓渔业的标准化CPUE,但对中国台湾延绳钓渔业的标准化CPUE拟合较差;当模型单独使用日本标准化CPUE时,评估结果显示印度洋黄鳍金枪鱼被过度捕捞;若模型单独使用中国台湾标准化CPUE,则结果相反,显示印度洋黄鳍金枪鱼未被过度捕捞;而当同时使用两个标准化CPUE时,日本标准化CPUE数据获得更大估计权重,因此,评估结果与单独使用日本标准化CPUE的结果类似。(2)当r采用无信息先验时,r估计偏小,而环境容纳量(K)估计则偏大,参数估计不合理;当r采用信息先验时,r与K的后验分布估计相对合理;由于r与K存在显著的负相关关系,生物量动态模型难于同时有效估计这两个参数,特别是在数据质量较差情况下,因而采用信息先验能提高生物量动态模型参数估计的质量。(3)本研究利用偏差信息准则(Deviance Information Criterion,DIC)与均方误差(Mean Square Error,MSE)统计量对模型进行了比较,并选择模型S8用于评价印度洋黄鳍金枪鱼的资源状态。评估结果认为印度洋黄鳍金枪鱼被过度捕捞,既存在捕捞型过度捕捞,也存在资源型过度捕捞,这与资源合成(Stock synthesis version 3,SS3)等模型的评价结果一致。     

Mechanism of body cavity temperature regulation of chum salmon (Oncorhynchus keta) during homing migration in the North Pacific Ocean

Vertical movement patterns of five chum salmon (Oncorhynchus keta) during homing migration were examined using archival tags. The standard deviation of the depth and ambient and body cavity temperatures during daytime were larger than those during night‐time. Vertical movements through the thermocline with a periodicity of less than 1 h were observed during daytime in addition to the diel vertical movement patterns in the open ocean. During these periods of frequent short‐term vertical movements, the difference between the body cavity temperature and ambient temperature was large while the variance of the body cavity temperature was less than that of the ambient temperature. From the results of a random simulation, the variation of the body cavity temperature was shown to decrease due to these periodic high frequency movements in comparison with random vertical movements. The whole‐body heat‐transfer coefficient k (s^?1), which was estimated by a heat budget model, was 1.48 × 10^?3. The k of chum salmon was larger than that of bigeye tuna (Thunnus obesus) by about one order of magnitude for the cooling of the body. The k of chum salmon did not change like tuna, which are physiologically adapted to conserve body cavity temperature. This indicates that the regulation of body cavity temperature by chum salmon is dependent on the vertical movements only. The maintenance of the body cavity temperature is concluded to be advantageous for their maturation and growth from the relationship between energy input and output during their homing migration.     

Ribosomal DNA sequences indicate isolated populations of Ichthyophonus hoferi in geographic sympatry in the north-eastern Pacific Ocean

Infections of Ichthyophonus hoferi, a cosmopolitan parasite of marine fish, have recently been reported in rockfish, Sebastes spp., from the north‐eastern Pacific. Because I. hoferi also infects Pacific herring, Clupea pallasi Valenciennes, and salmonids in this region, we wanted to determine if Ichthyophonus parasites from rockfishes, Pacific herring and chinook salmon, Oncorhynchus tshawytscha (Walbaum), were the same. Small subunit ribosomal deoxyribonucleic acid sequence data revealed two haplotypes that were fixed among host species in geographic sympatry, one from rockfish and the other from both Pacific herring and salmon. These isolated populations of Ichthyophonus could be part of the same species that are ecologically separated because of host behaviours, or they could be distinct species that are host specific. Dietary patterns of the hosts indicate that ecological separation among hosts is possible, but the presence of distinct species may better explain the observed Ichthyophonus haplotype association with host species.     

东太平洋茎柔鱼耳石形态差异性分析

茎柔鱼是大洋性重要经济头足类,其耳石包含着重要的生态信息。根据2008年5月—2009年10月智利、哥斯达黎加、秘鲁外海采集的茎柔鱼耳石样本,分析三海区间耳石外部形态特征及生长模式差异。研究认为,不同海区间耳石形态特征差异显著(P<0.05),耳石长度指标均出现显著性差异,角度指标中仅背侧区夹角出现显著性差异。主成份分析认为,耳石总长(TSL)是表征耳石形态特征的最显著指标,吻区夹角是表征智利、秘鲁外海耳石的显著性角度指标,吻侧区夹角是表征哥斯达黎加外海耳石的显著性角度指标。在整个生长过程中三海区耳石各部分均异速生长,其形态变化趋势为整体变得狭长、背区逐渐宽大,耳石重心不断向背区转移,符合中上层头足类耳石特征。TSL为1 600μm时,三个海域耳石的长度指标RDL均出现显著变化。哥斯达黎加外海、秘鲁外海茎柔鱼耳石的TSL分别为2 000和1 800μm时,其角度指标吻区夹角出现显著变化,智利外海茎柔鱼耳石的吻区夹角则没有显著差异。由于角度变化迟于耳石形态长度变化,因此TSL为1 600μm时可作为茎柔鱼栖息水层变化的重要标志。