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1.
蓝圆鲹(Decapterus maruadsi)属暖水性中上层鱼类,是中国近海重要的渔业资源。本文根据2015-2018年浙江南部海域(120.5°E~123.5°E,27°N~29°N)底拖网季度调查数据,运用线性混合效应模型等方法,研究了蓝圆鲹的叉长-体重关系和生长异质性,并估算其自然死亡系数。结果显示,蓝圆鲹样本叉长(L)范围为45.0~247.0 mm,平均叉长为126.1 mm;体重(W)范围为0.7~206.6 g,平均体重为29.1 g;叉长-体重关系式为:W=5.01×10-6L3.17。线性混合效应模型结果显示,同时考虑季节、性别和年份差异的模型对蓝圆鲹叉长-体重关系的拟合效果最佳。在相同叉长条件下,体重在秋季最大,其次是春季,而夏季最小;从不同年份来看,体重在2018年最大,其次是2016年,在2017年最小;从不同性别来看,雄性和雌性的差异不明显。这说明时间因素对于浙江南部海域蓝圆鲹的生长特征具有显著影响,2018年秋季蓝圆鲹的长势最佳。依据"Pauly"、"Pauly update"、"Jensen"、"Hoenig"和"Lorenzen"等不同的经验方程估算的蓝圆鲹自然死亡系数在0.36~1.41之间。本研究通过混合效应模型分析了年份、季节、性别对蓝圆鲹叉长-体重的影响,这对蓝圆鲹生活史特征及资源评估具有重要的参考意义。  相似文献   

2.
石永闯  陈新军 《海洋渔业》2019,41(1):118-128
小型中上层海洋鱼类是重要的渔业资源,目前其捕捞产量约占到全球海洋渔获量二分之一。小型中上层海洋鱼类具有生命周期短、生长速度快、分布不均匀、易受环境因素影响等生物学特点,近年来,一些小型中上层海洋鱼类渔获量出现下降趋势,为保证其资源的可持续利用,对其进行准确的资源评估研究和制定合理有效的管理策略显得尤为重要。以文献计量统计分析为基础,对20多年来应用于小型中上层海洋鱼类资源评估的模型方法以及所需数据类型进行归纳与回顾,同时对模型中重要的参数估计、不确定性来源进行总结。分析认为,由于缺乏完整、准确的生物学信息导致无法对小型中上层海洋鱼类使用传统的资源评估方法进行评估,因此,其资源评估研究仍处在发展阶段。建议今后研究中应开展以下工作:1)努力提高现有模型的评估精度,尽可能考虑更多影响因素; 2)要进行长期系统的渔业资源独立调查; 3)充分利用体长等易获得数据,开发体长结构模型和基于生态系统的评估模型,降低模型选择的局限性。  相似文献   

3.
基于 2012?2016 年和 2017?2021 年每年 8 月渤海渔业资源底拖网调查数据, 根据休渔期延长前后各 5 年游泳生物优势种, 主要渔业种群(类别)单位个体重和资源密度等指标的变化, 从个体、种群与群落 3 方面评价延长伏季休渔期对渤海渔业资源的养护效果。结果显示: (1) 休渔期延长前游泳生物年间平均单位数量个体重为 4.35 g/ind, 延长后为 3.77 g/ind; 延长后年间平均单位数量个体重的下降, 主要是大部分种群的年平均数量密度增幅远高于其年平均资源密度增幅, 补充群体数量增加明显, 可能是繁殖亲体资源量增加或繁殖力提升所致。(2) 延长休渔期后的前期游泳生物优势种主要是鳀(Engraulis japonicus)、口虾蛄(Oratosquilla oratoria)和黄鲫(Setipinna taty), 与延长前基本一致, 后期增加了蓝点马鲛(Scomberomorus niphonius)和矛尾虾虎鱼(Chaemrichthys stigmatias)等种类, 但出现频率低; 延长休渔期前后游泳生物优势种组成波动较大, 但延长后游泳生物优势种存在向大个体及凶猛性高营养级种类转换的趋势。(3) 休渔期延长后游泳生物、中上层鱼类、底层鱼和虾蟹类等年度资源密度普遍高于延长前, 特别是延长当年更远高于上年, 年间平均资源密度延长后较延长前增幅分别为 186.38%、178.26%、357.63%和 132.89%; 底层生物对中上层生物资源密度年度占比延长后基本处于增长态势; 高营养级层次生物资源密度延长后剧增, 且基本呈上升趋势, 年间平均增幅达 493.67%。综上所述, 延长休渔期后渤海生态系统鳀等中上层鱼类、 底层生物和高低营养级生物资源密度及其补充群体资源量的大幅增加, 夯实了生态系统的能量基础, 优化了渔业资源群落结构, 生态系统逐步稳态演替, 表明延长休渔期这种投入控制措施在渤海有较好的生态效果。  相似文献   

4.
2019年10月24日至26日,使用便携式Simrad EY60科学探鱼仪对珠海桂山岛海上风电场水域的渔业资源进行了声学调查,研究了该水域的渔业资源组成、数量密度、资源量密度及其空间分布。本次调查共捕获游泳生物和底栖无脊椎动物72种,其中34种参与声学评估。扫海面积法估算的鱼类平均数量密度与资源量密度分别为1.09×104尾/km2,227.48 kg/km2;声学方法估算的鱼类数量密度与资源量密度分别为5.97×105尾/km2,15.13 t/km2。风电场水域鱼类聚集性分布明显,在风电场西北与东南外围水域密度较高,中间水域的密度较低。鱼类单体目标强度(TS)分布范围为-68~-41dB,其中-68~-58 dB的单体TS占主要部分(79.12%),对应鱼类的体长范围为3~8 cm;随着水深的增加,单体平均TS先减小后增大。本研究是桂山风电场水域渔业资源的首次声学调查,结果较准确地反映了风电场水域多种鱼类的资源量及其分布信息,可为科学评价海上风电场建成运营后对渔业资源的长期影响提供基础数据。  相似文献   

5.
沙丁鱼属鱼类(Sardina)是一种具有重要生态价值和经济价值的中上层鱼类,其资源补充量极易受栖息地海洋环境因子影响。基于关键环境因子的沙丁鱼亲体量和补充量变动机制研究,有助于沙丁鱼资源的合理开发利用。根据1996—2015年沙丁鱼太平洋群系在142°~165°E、35°~40°N海域的渔业调查数据,结合沙丁鱼产卵场栖息地的海表面温度(sea surface temperature, SST)和太平洋十年涛动(Pacific decadal oscillation, PDO)数据,利用Ricker模型,构建多种基于关键环境因子的沙丁鱼亲体量补充量关系模型。结果表明,沙丁鱼产卵场平均SST和PDO对其补充量均有正向显著性的影响,且SST的影响强于PDO的影响。建议今后的沙丁鱼资源开发与管理中应考虑这两种环境因子的综合作用。  相似文献   

6.
为了解长江口盐沼湿地优势鱼类群落结构及其种间关系,采用插网调查,利用2019年5—10月的调查数据,基于生态位宽度和生态位重叠度指数对长江口崇明东滩(31°27''N,121°56''E)和九段沙盐沼湿地(31°10''N,121°57''E)鱼类群落的优势种生态位进行研究。研究结果表明,春、夏、秋3个季节共采获10个优势种,其中鮻(Liza haematocheila)、花鲈(Lateolabrax maculatus)和拉氏狼牙虾虎鱼(Odontamblyopus rubicundus)在3个季节中均为优势种。在10个优势种中,时间生态位宽度值变化范围为0.11~1.70,其中拉氏狼牙虾虎鱼时间生态位宽度值最大,小黄鱼(Larimichthys polyactis)值最小;空间生态位宽度值变化范围为0.57~1.53,其中棱鮻(Liza carinatus)空间生态位宽度值最大,小黄鱼值最小。长江口盐沼湿地鱼类优势种生态位宽度呈现显著的季节性变化趋势。长江口盐沼湿地鱼类优势种的时空生态位重叠值较高,其中具重叠意义的鱼种对(species pairs)高达73.33%,具有显著重叠意义的鱼种对高达48.89%。结论认为,长江口盐沼湿地鱼类优势种的时空分布具有相似性,存在明显的竞争关系。  相似文献   

7.
灯笼鱼科鱼类种类繁多, 且同属鱼类形态学相近, 因此利用分子标记对灯笼鱼进行准确的物种鉴定具有重要价值。为探讨线粒体细胞色素 b 基因(Cyt b)和 12S rRNA 基因在灯笼鱼科物种鉴定中的适用性, 对西北太平洋采集的 56 尾灯笼鱼进行扩增, 并进行序列对比与系统发育分析。研究表明, 采集的样本包括 6 种灯笼鱼, 分别为瓦氏角灯鱼(Ceratoscopelus warmingii)、长体标灯鱼(Symbolophorus californiensis)、粗鳞灯笼鱼(Myctophum asperum)、 细泰勒灯鱼(Tarletonbeania crenularis)、日本背灯鱼(Notoscopelus japonicus)以及某背灯鱼属鱼类(Notoscopelus sp.)。 核苷酸多态性分析显示, 基于 Cyt b 基因的种内与种间遗传距离比基于 12S rRNA 基因的更大。比较灯笼鱼科 2 种基因序列的结构特征, 发现 Cyt b 基因的种间平均遗传距离是种内平均遗传距离的 25 倍, 12S rRNA 基因的种间平均遗传距离是种内平均遗传距离的 26 倍, 均符合作为 DNA 条形码的基本要求。系统进化分析显示, 每种灯笼鱼均能形成独立分支, 2 个基因均能对 6 种灯笼鱼类进行鉴别; 但在 Cyt b 基因构建的进化树中, 每种鱼类能更好与数据库中已有的序列进行聚类。综上所述, Cyt b 和 12S rRNA 作为 DNA 条形码可以有效地对灯笼鱼科鱼类物种进行鉴定, 且 Cyt b 基因在系统进化关系的研究上具有更高的适用性。  相似文献   

8.
本研究首次对西藏雅鲁藏布江大峡谷墨脱江段鱼类群落结构及多样性的空间分布特征进行分析。根据 2015 年春季(4 月), 2017 年春季(3—4 月)和秋季(11 月)在雅鲁藏布江大峡谷墨脱江段及其附属湖泊布裙湖进行的渔业资源调查数据, 对墨脱江段鱼类群落结构特征及多样性的空间变化进行了分析。结果表明, 春、秋季墨脱江段及布裙湖共捕获鱼类 18 种, 隶属于 2 目 4 科 13 属, 其中外来鱼类 2 种, 分别为鲤(Cyprinus carpio)和麦穗鱼(Pseudorasbora parva)。通过形态和分子生物学鉴定发现新物种 3 种, 分别属于裂腹鱼属(Schizothorax)、墨头属(Garra)和鰋属(Exostoma), 暂时命名为裂腹鱼属待定名种(Schizothorax sp.)、墨头鱼属待定名种(Garra sp.)和鰋属待定名种(Exostoma sp.)。春季墨脱江段干流和支流的鱼类种类组成存在显著差异, 干流主要由大中型鱼类组成, 支流主要为小型鱼类。优势种组成也存在差异, 仅弧唇裂腹鱼(Schizothorax curvilabiatus)为干流和支流的共有优势种。相对资源量最高的鱼类为弧唇裂腹鱼(S. curvilabiatus), 在干流中平均每小时电捕获鱼类重量为 9844.7 g; 平均每组网捕获鱼类重量 446.0 g, 支流平均每小时电捕获鱼类重量为 486.4 g。物种多样性指数(H?)变化范围为 0.95~1.77, 丰富度指数(D?)变化范围为 0.58~1.13, 均匀度指数(J?)变化范围为 0.37~0.77, 其中干流物种的多样性指数、丰富度指数和均匀度指数均低于支流, 表明春季墨脱江段干流鱼类物种多样性明显低于支流。  相似文献   

9.
于2011年5-10月对莱州湾渔业资源与栖息环境进行了6个航次的逐月大面调查,研究了春末至秋中网采浮游植物群落结构的演替,并利用广义可加模型分析了其与主要小型中上层鱼类资源密度的关系。共记录浮游植物33属78种,总丰度在春、秋季各出现1个峰值,分别为265×104 ind/m3和111×104ind/m3。春末夏初优势种主要为具槽帕拉藻(Coscinodiscus)、角毛藻()属逐渐形成优势。夏末至秋中,物种丰富度、多样性和均匀度皆呈现上升的趋势。将环境和浮游植物群落指标作为解释变量逐步优化后的广义可加终模型,对4种鱼类CPUE总偏差的累积解释率达到了76.5%,月份、海表温度、夜光藻丰度、圆筛藻丰度、甲/硅藻比5个预测变量皆达到显著水平以上,甲/硅藻比的升高对渔业资源密度分布表现出正向的作用。结果表明,莱州湾浮游植物群落长期演变后的类群结构和丰度水平,对鱼类群落结构及其资源量现状的可持续性有着积极的意义。本研究为深入探讨渔业种群关键栖息地早期补充和食物网过程的影响因素,从浮游植物饵料基础变动的角度提供了数据资料和科学依据。  相似文献   

10.
吴红岩 《水产学报》2008,32(4):621-627
试验以硫酸锌为锌源,评价不同锌水平对奥尼罗非鱼幼鱼(Oreochromis aureus×Oreochromis niloticus♀)生长和抗氧化能力的影响。体质量为(4.13±0.32)g罗非鱼随机分配在18个水族箱中,每箱20尾,每3个箱为1个处理组,分别以添加锌为0、20、40、80、160和320 mg•kg-1的6种饲料投喂,日投喂率为鱼体重5%~9%。8周的试验结果表明:20mg•kg-1锌饲料组的增重率和鱼体蛋白含量显著高于其它各组(P<0.05),蛋白质效率、饲料转化率也明显高于其它各组;全鱼脂肪含量随着饲料锌水平的升高而升高,但320mg•kg-1锌饲料组降低;20mg•kg-1锌饲料组,脊椎骨中锌离子浓度达到最大值且显著高于0mg•kg-1锌饲料组(P<0.05);20mg•kg-1与40mg•kg-1锌饲料组的血液中红细胞数量显著高于其它各添加组(P<0.05),20mg•kg-1锌饲料组的血液中血比容显著高于0mg•kg-1组(P<0.05),与其它各组没有显著差异;肌肉中,硫代巴比妥酸反应产物(TBARS)(Thiobarbituricacid reactive substances)的量,锌为0mg•kg-1饲料组显著高于其它各组(P<0.05)。综上所述,饲料中锌添加量为20mg•kg-1饲料促进了罗非鱼生长,使鱼体抗氧化功能增强。  相似文献   

11.
Decadal changes in northern fur seal (Callorhinus ursinus) diet were examined based on the stomach contents data collected off the Pacific coast of northeastern Japan from January to April, 1953–1988. Seventeen families of fish and seven families of squid were identified from the stomach contents. Dominant prey species in terms of percentage of occurrence and wet weight were Japanese sardine (Sardinops melanostictus), chub mackerel (Scomber japonicus), and myctophid fishes. Demersal fishes, sparkling enope squid (Watasenia scintillans), and oceanic squids were also preyed on at low incidences. Decadal‐scale diet composition of northern fur seals revealed shifts in the significance of Japanese sardine and chub mackerel in parallel with the decadal alternation in the dominance of these species within the pelagic fish community off the Pacific coast of northeastern Japan. These results suggest that northern fur seals can use a variety of prey resources in this wintering area by switching the diet according to the distribution and abundance of prey species.  相似文献   

12.
In the present study, we assessed small fishes as potential feed fishes with the lowest mercury levels. The mercury levels of four small pelagic fishes and a benthic fish from the Pacific Ocean and the Sea of Japan, i.e., spotted chub mackerel Scomber australasicus, chub mackerel Scomber japonicus, horse mackerel Trachurus trachurus, round scad Decapterus punctatus, and bastard halibut Paralichthys olivaceus, were determined. Total mercury levels in fish muscle were measured using a reduction vaporizing atomic absorption method. There were no significant correlations between body weight and mercury levels for these species. However, significant differences were observed in the mercury levels of these species between the two catch locations, with fish caught in the Pacific Ocean having higher mercury levels. This difference may be due to the Pacific Ring of Fire, a highly seismically and volcanically active zone, which is located in the Pacific Ocean. Preference for these fishes for use in aquaculture should refer to the area where they are caught in addition to the species.  相似文献   

13.
Mangalore coast is well known for its multi‐species and multi‐gear fisheries and the fishery and oceanographic features of this region is a true representation of the Malabar upwelling system. Ten years of study (1995–2004) of oceanographic parameters has been carried out from the inshore waters off Mangalore to understand their seasonal and interannual variations and influences on the pelagic fishery of the region. Attempt has been also made to understand the influence of local and global environmental conditions on the alternating patterns of abundance between the Indian mackerel and oil sardine from the area. Field‐ and satellite‐derived oceanographic data have shown that coastal upwelling occurs during July–September with a peak in August resulting in high nutrient concentrations and biological productivity along the coast. Nearly 70% of the pelagic fish catch, dominated by oil sardine and mackerel, was obtained during September–December, during or immediately after the upwelling season. Catches of scombroid fishes were significantly related to cold Sea Surface Temperature, while such relationships were not observed for sardines and anchovies. Significant positive correlations were observed between the ENSO events (MEI) and seawater temperature from the study area. The extreme oceanographic events associated with the cold La Niña, which preceded the exceptional 1997–98 El Niño event, were responsible for the collapse of the pelagic fishery, especially the mackerel fishery along the southwest coast of India (Malabar upwelling system). Coinciding with the collapse of the mackerel fishery, oil sardine populations revived during 1999–2000 all along the southwest coast of India. Tolerance of oil sardine to El Niño / La Niña events and the low predatory pressure experienced by their eggs and larvae due to the collapse of mackerel population might have resulted in its population revival.  相似文献   

14.
We compared a wide range of environmental data with measures of recruitment and stock production for Japanese sardine Sardinops melanostictus and chub mackerel Scomber japonicus to examine factors potentially responsible for fishery regimes (periods of high or low recruitment and productivity). Environmental factors fall into two groups based on principal component analyses. The first principal component group was determined by the Pacific Decadal Oscillation Index and was dominated by variables associated with the Southern Oscillation Index and Kuroshio Sverdrup transport. The second was led by the Arctic Oscillation and dominated by variables associated with Kuroshio geostrophic transport. Instantaneous surplus production rates (ISPR) and log recruitment residuals (LNRR) changed within several years of environmental regime shifts and then stabilized due, we hypothesize, to rapid changes in carrying capacity and relaxation of density dependent effects. Like ISPR, LNRR appears more useful than fluctuation in commercial catch data for identifying the onset of fishery regime shifts. The extended Ricker models indicate spawning stock biomass and sea surface temperatures (SST) affect recruitment of sardine while spawning stock biomass, SST and sardine biomass affect recruitment of chub mackerel. Environmental conditions were favorable for sardine during 1969–87 and unfavorable during 1951–67 and after 1988. There were apparent shifts from favorable to unfavorable conditions for chub mackerel during 1976–77 and 1985–88, and from unfavorable to favorable during 1969–70 and 1988–92. Environmental effects on recruitment and surplus production are important but fishing effects are also influential. For example, chub mackerel may have shifted into a new favorable fishery regime in 1992 if fishing mortality had been lower. We suggest that managers consider to shift fishing effort in response to the changing stock productivity, and protect strong year classes by which we may detect new favorable regimes.  相似文献   

15.
We tested whether the predation dynamics of chub mackerel Scomber japonicus and spotted mackerel S. australasicus on young anchovy Engraulis japonicus relates to individual growth characteristics of the prey and could account for the growth-selective survival predicted by recruitment hypotheses. Juvenile and adult mackerel were sampled along with their young anchovy prey field in 2004 (juvenile mackerel and larval anchovy) and 2005 (adult mackerel and juvenile anchovy) off the Pacific coast of Honshu, Japan. The recent 5-day mean growth rate of larval and juvenile survivors and prey found in the stomach of mackerel was estimated from the otolith microstructure. No significant difference was found between the recent growth of larval or juvenile survivors and that of preyed individuals. We conclude that despite a relatively small body size, the high activity level and predation skills displayed by mackerel prevent fast-growing larvae and early juveniles from benefitting in terms of the expected survival advantage over slow-growers. Hence, growth-selective predation mortality of larval fish would depend on the feeding ecology of the predator rather than predator size. Selection for fast growth is more likely to occur under predation pressure from invertebrate organisms and small pelagic fish specialized on zooplankton, such as herring and anchovy.  相似文献   

16.
We used the average fork length of age‐3 returning coho (Oncorhynchus kisutch) and age‐3 ocean‐type and age‐4 stream‐type Chinook (Oncorhynchus tshawytscha) salmon along the northeast Pacific coast to assess the covariability between established oceanic environmental indices and growth. These indices included the Multivariate El Niño‐Southern Oscillation Index (MEI), Pacific Decadal Oscillation (PDO), Northern Oscillation Index, and Aleutian Low Pressure Index. Washington, Oregon, and California (WOC) salmon sizes were negatively correlated with the MEI values indicating that ultimate fish size was affected negatively by El Niño‐like events. Further, we show that the growth trajectory of WOC salmon was set following the first ocean winter. Returning ocean‐type British Columbia‐Puget Sound Chinook salmon average fork length was positively correlated with the MEI values during the summer and autumn of return year, which was possibly a result of a shallower mixed layer and improved food‐web productivity of subarctic Pacific waters. Size variation of coho salmon stocks south of Alaska was synchronous and negatively correlated with warm conditions (positive PDO) and weak North Pacific high pressure during ocean residence.  相似文献   

17.
The Chilean jack mackerel Trachurus murphyi, is a pelagic fish from the Carangidae family that is distributed in the South Pacific Ocean. Because this species constitutes an important economic resource across the South Pacific and plays an important ecological role in this ecosystem there is a growing interest in determining its population structure. In this study, we used molecular markers (mitochondrial DNA sequences and microsatellites) from Chilean jack mackerel samples to investigate its genetic population structure across the South Pacific Ocean. The mitochondrial DNA did not detect a genetic structure in T. murphyi populations in the Pacific Ocean, but revealed very low haplotype diversity and a short genealogy history compared to other small-pelagic species. The same general pattern of a lack of genetic structure was found with microsatellite loci; however, a large genetic diversity was revealed with microsatellite markers. The present results did not support the existence of different stock units for T. murphyi across the South Pacific Ocean but a more holistic approach will be necessary to determine an adequate management strategy for this fishery.  相似文献   

18.
As a crucial step in developing a bioenergetics model for Pacific Chub Mackerel Scomber japonicus (hereafter chub mackerel), parameters related to metabolism, the largest dissipation term in bioenergetics modelling, were estimated. Swimming energetics and metabolic data for nine chub mackerel were collected at 14°C, a low temperature within the typical thermal range of this species, using variable‐speed swim‐tunnel respirometry. These new data were combined with previous speed‐dependent metabolic data at 18 and 24°C and single‐speed (1 fork length per second: FL/s) metabolic data at 15 and 20°C to estimate respiration parameters for model development. Based on the combined data, the optimal swimming speed (the swimming speed with the minimum cost of transport, Uopt) was 42.5 cm/s (1.5–3.0 FL/s or 2.1 ± 0.4 FL/s) and showed no significant dependence on temperature or fish size. The daily mass‐specific oxygen consumption rate (R, g O2 g fish?1 day?1) was expressed as a function of fish mass (W), temperature (T) and swimming speed (U): R = 0.0103W?0.490 e(0.0457T) e(0.0235U). Compared to other small pelagic fishes such as Pacific Herring Clupea harengus pallasii, Pacific Sardine Sardinops sagax and various anchovy species, chub mackerel respiration showed a lower dependence on fish mass, temperature and swimming speed, suggesting a greater swimming ability and lower sensitivity to environmental temperature variation.  相似文献   

19.
为了探讨气候变化对智利竹筴鱼(Trachurus murphyi)渔获量的长期影响, 采集 19002016 年北大西洋涛动
(North Atlantic Oscillation, NAO)、太平洋年代际涛动(Pacific Decadal Oscillation, PDO)、厄尔尼诺(El Ni?o)8
低频气候变化参数, 全球海气温度异常指标时间序列数据和 19702016 年东南太平洋智利竹筴鱼总渔获量数据,
在对其进行相关性分析的基础上, 运用 BP 神经网络模型构建了东南太平洋智利竹筴鱼渔获量预测模型, 并以效率
系数为评价规则对预测模型进行评价, 进而得到了最优预测模型。最后对最优预测模型进行了因子敏感性分析,
取了对东南太平洋智利竹筴鱼(Trachurus murphyi)影响较大的因子。最优预测模型拟合效果显示, 渔获量拟合值与
观测值有基本一致的变化趋势, 两个序列的线性相关系数为 0.745, 模型拟合效果良好。最优模型因子敏感性分析
表明, 在研究期间, 影响东南太平洋智利竹筴鱼渔获量的气候变化表征因子主要为北大西洋涛动、太平洋年代际涛
动和北太平洋指数。  相似文献   

20.
We report results from 28 yr of a midwater trawl survey of pelagic juvenile rockfish (Sebastes spp.) conducted off the central California coast. The fishery‐independent survey is designed to provide pre‐recruit indices of abundance for use in groundfish stock assessments. Standardized catch rate time series for 10 species were developed from delta‐generalized linear models that include main effects for year, station, and calendar date. Results show that interannual fluctuations of all 10 species are strongly coherent but highly variable, demonstrating both high‐ and low‐frequency components. A similarly coherent result is observed in the size composition of fish, with large fish associated with elevated catch rates. In contrast, spatial and seasonal patterns of abundance show greater species‐specific differences. A comparison of the shared common trend in pelagic juvenile rockfish abundance, derived from principal components analysis, with recruitments from five rockfish stock assessments shows that the time series are significantly correlated. An examination of oceanographic factors associated with year‐to‐year variability indicates that a signature of upwelled water at the time of the survey is only weakly related to abundance. Likewise, basin‐scale indices (the Multivariate El Niño‐Southern Oscillation Index, the Pacific Decadal Oscillation, the North Pacific Gyre Oscillation, and the Northern Oscillation Index) are poorly correlated with abundance. In contrast, sea level anomalies in the months preceding the survey are well correlated with reproductive success. In particular, equatorward anomalies in the alongshore flow field following the spawning season are associated with elevated survival and poleward anomalies with poor survival.  相似文献   

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