基于贝叶斯概率的印度洋大眼金枪鱼渔场预报

本文采用贝叶斯概率为模型基础框架,利用来自印度洋金枪鱼管理委员会(IOTC)的大眼金枪鱼延绳钓历史渔获统计数据和美国国家海洋大气管理局(NOAA)的海温最优插值再分析数据,进行适用于印度洋金枪鱼延绳钓渔场的模型参数估算与预报模型构建。模型回报精度验证结果表明,印度洋大眼金枪鱼延绳钓渔场综合预报的准确率达到了65.96%。模型预报结果用概率百分比来表示,符合渔业资源分布的客观特点。利用中分辨率成像光谱仪MODIS提供的SST产品进行业务化运行的渔场预报,利用模型结果每周生成印度洋大眼金枪鱼延绳钓渔场概率预报图,用不同大小的圆形来表示渔场概率的高低,可以为印度洋区域的远洋渔业生产提供信息支持。     

东太平洋金枪鱼延绳钓兼捕鲨鱼种类及其渔获量分析

2003年7月-11月份期间,对东太平洋公海海域(03°S~17°S,96°W~146°W)的超低温金枪鱼延绳钓兼捕鲨鱼进行调查。发现共兼捕到9种鲨鱼,分别是尖吻鲭鲨、长鳍鲭鲨、鳄鲨、人眼长尾鲨、路氏双鲨、长鳍真鲨、镰状真鲨、大青鲨和黑异鳞鲨,隶属于3目6科。共钓获鲨鱼24 711 kg,其中大青鲨是优势种类,占鲨鱼渔获尾数的50.4%,占鲨鱼渔获总重量的76.5%,平均个体重量达到64.9 kg。调查获得9种大洋性鲨鱼的渔获率,其中以大青鲨的最高,达到0.964尾数/千钩,鳄鲨次之为0.497尾数/千钩,其它鲨鱼的CPUE均在0.200尾数/千钩以下,此外估计了东太平洋海域金枪鱼延绳钓兼捕鲨鱼总渔获量,约在4.0~5.9万吨。     

Age‐dependent distribution of juvenile southern bluefin tuna (Thunnus maccoyii) on the continental shelf off southwest Australia determined by acoustic monitoring

Juvenile southern bluefin tuna (Thunnus maccoyii, SBT) were monitored in nearshore waters off southwest Australia using acoustic tagging and monitoring over five austral summers (2002/2003–2006/2007) to determine patterns in age‐based distribution of SBT. A total of 20–70 receivers were deployed in early December along one to three cross‐shelf transects and at three inshore topographic features (lumps) where SBT are known to occur; and a total of 59–84 juvenile SBT (41–90 cm fork length) were tagged and released each year. After several months, receivers were recovered, and data extracted. In 2002/2003 and 2003/2004, 2‐yr‐old SBT were detected more frequently in nearshore areas than did 1‐yr old fish. Similarly in 2004/2005 and 2006/2007, it was the larger 1‐yr‐old SBT that were detected more frequently at inshore lumps (>85% of detections) while small 1‐yr‐old SBT were detected more widely over the study area. In 2005/2006, although large 1‐yr‐old SBT were still detected more frequently at inshore lumps than small 1‐yr old SBT, the percentage of all detections at lumps was lower at 31.5%, indicating wider distribution of both small and large age‐1 fish. The observed age‐dependent distribution pattern may be enhanced by the distribution of prey, which disperse or concentrate depending on the local oceanography.     

The cause of death of juvenile Pacific bluefin tuna (Thunnus orientalis) reared in sea net cages

Although the survival rate of juvenile Pacific bluefin tuna Thunnus orientalis (PBT) during 30 days after stocking in sea net cages has been as low as approximately 50%, the reason for this high mortality is not clear. The dead fish were collected and counted during 30 days after stocking in a sea net cage, and the growth performance, stomach contents, and bone injury were investigated. Nearly half (47.9%) had died within the first 4 days. The total length and body weight of the dead fish were significantly smaller than those of the live fish, and the weight of the dead fish did not increase during the first 7 days. Approximately one-third of the dead fish (21.9–42.9% per day) had ingested inorganic matter such as wood or Styrofoam waste during the first 7 days, and 25.0–45.0% of the dead fish sampled per day showed poor growth. The daily ingestion rate of inorganic matter decreased dramatically from the eighth day, when the daily mortality rate decreased. The percentage of dead fish with bone injuries due to collision or contact was low (less than 15%). These results suggest that one of the causes of high mortality during several days after stocking in a sea cage was accidental ingestion of inorganic matter by juvenile PBT. Improvement in feeding method can increase the survival rate of juveniles in sea net cages.     

基于鱼鳞明胶的可食性保鲜膜对金枪鱼肉的保鲜作用研究

为分析不同复合保鲜膜处理对金枪鱼的保鲜效果,以鱼鳞明胶为主料,添加桔子/柠檬精油和薄荷制备可食性保鲜膜,用于金枪鱼肉的冷藏保鲜,检测冷藏过程中金枪鱼肉的TVB-N值、pH值、菌落总数、肌红蛋白与高铁肌红蛋白含量、a^*值、TBA值的变化,并对金枪鱼的品质进行感官评价分析。结果表明,鱼鳞明胶膜中添加薄荷、桔子精油和柠檬精油均能不同程度地抑制金枪鱼肉中的微生物繁殖,减缓TVB-N值、TBA值和高铁肌红蛋白含量的升高,抑制鱼肉色泽的衰变,且薄荷与桔子/柠檬精油的复合有协同增效保鲜金枪鱼肉的作用。明胶膜中复合2%浓度的桔子/柠檬精油对金枪鱼肉风味略有覆盖,低浓度桔子/柠檬精油(1%)有优化金枪鱼鱼肉气味的作用,且以柠檬精油的效果更优,1%薄荷-1%桔子精油-鱼鳞明胶复合膜和1%薄荷-1%柠檬精油-鱼鳞明胶复合膜保鲜处理的金枪鱼肉的货架期可分别延长至 7 d 和8 d。本研究结果为制备高品质水产品可食性保鲜膜材料提供了理论依据和技术支持。     

Influence of Amino Acid Compositions and Peptide Profiles on Antioxidant Capacities of Two Protein Hydrolysates from Skipjack Tuna (Katsuwonus pelamis) Dark Muscle

Influence of amino acid compositions and peptide profiles on antioxidant capacities of two protein hydrolysates from skipjack tuna (Katsuwonus pelamis) dark muscle was investigated. Dark muscles from skipjack tuna were hydrolyzed using five separate proteases, including pepsin, trypsin, Neutrase, papain and Alcalase. Two hydrolysates, ATH and NTH, prepared using Alcalase and Neutrase, respectively, showed the strongest antioxidant capacities and were further fractionated using ultrafiltration and gel filtration chromatography. Two fractions, Fr.A3 and Fr.B2, isolated from ATH and NTH, respectively, showed strong radical scavenging activities toward 2,2-diphenyl-1-picrylhydrazyl radicals (EC₅₀ 1.08% ± 0.08% and 0.98% ± 0.07%), hydroxyl radicals (EC₅₀ 0.22% ± 0.03% and 0.48% ± 0.05%), and superoxide anion radicals (EC₅₀ 1.31% ± 0.11% and 1.56% ± 1.03%) and effectively inhibited lipid peroxidation. Eighteen peptides from Fr.A3 and 13 peptides from Fr.B2 were isolated by reversed-phase high performance liquid chromatography, and their amino acid sequences were determined. The elevated antioxidant activity of Fr.A3 might be due to its high content of hydrophobic and aromatic amino acid residues (181.1 and 469.9 residues/1000 residues, respectively), small molecular sizes (3–6 peptides), low molecular weights (524.78 kDa), and amino acid sequences (antioxidant score 6.11). This study confirmed that a smaller molecular size, the presence of hydrophobic and aromatic amino acid residues, and the amino acid sequences were the key factors that determined the antioxidant activities of the proteins, hydrolysates and peptides. The results also demonstrated that the derived hydrolysates and fractions from skipjack tuna (K. pelamis) dark muscles could prevent oxidative reactions and might be useful for food preservation and medicinal purposes.     

Dynamic simulation of tuna longline gear using numerical methods

ABSTRACT:   The underwater shape and hook depth of tuna longline gear are important factors determining fishing performance. In this study, how the shape of tuna longline gear changes in response to sea conditions and gear rigging is explained. Physical models of underwater gear shape were made to simulate fishing gear and analyzed according to the direction and velocity of currents. Then experiments with small-scale models were conducted in a flume tank to confirm the accuracy of the simulation analysis. Finally, the simulation was examined relative to actual longline fishing gear. This approach provided an improvement over previous analytical methods that did not consider fishing gear shape in response to different sea conditions. A useful result is an improved understanding of the relationship between ocean currents and the configuration of longline gear (the shortening ratio, and number of hooks per basket). These factors affect hook depth which, in turn, affects selectivity. Application of these results could lead to more effective and efficient fishing under different sea conditions.     

金枪鱼延绳钓捕捞作业状态的数值模拟

一种基于有限元原理的非线性混合法被用于预测捕捞作业中的金枪鱼延绳钓的形状与张力,为渔具设计提供理论方法,并以期在设计阶段能替代传统的水槽模型试验,为实际渔业生产作业调整提供有益的技术参数。构成延绳钓渔具的绳索可以被一系列绝对柔软的被称为绳索要素的单元所模拟,因此,整个延绳钓渔具可以被看作为一系列绳索要素在其两端点通过无摩擦铰接连接而成的集合体。根据最小位能原理,可以导出描述系统平衡状态的非线性基本平衡方程式。利用Newton-Raphson方法,通过一系列的负荷-形状迭代法求解基本平衡方程式,可以获得海流作用下延绳钓渔具作业时的形状和张力分布的数值解。简化模型的回流水槽试验验证表明,本方法具有较好的计算精度和解的收束性与稳定性。     

深冷型远洋金枪鱼延绳钓船的技术经济分析

在掌握大量相关资料的基础上，用系统分析的方法，对深冷型远洋金枪鱼延绳钓船的技术经济特征进行了分析，首先建立目标函数的数学模型，并对该数学模型的特性进行分析。在此基础上，采用SA算法（模拟退火算法）与单纯形加速法相结合的方式，在单目标下对最优船型进行了论证，并对最优船型参数的稳定性予以分析。其结论可供船舶选型时参考。