中国南极磷虾渔业发展的微观解析与对策研究——以辽渔集团有限公司为例

为探讨中国南极磷虾渔业全产业链发展模式,采用Thomson Innovation数据库、CCAMLR数据库等多源数据,分析辽渔集团南极磷虾渔业全产业链条发展特征。结果显示:1)自2009/2010年渔季以来,连续投入渔船参与南极磷虾捕捞生产;2)在南极磷虾油研发环节申请6项发明专利,储备了产业开发核心技术;3)开发10余种南极磷虾相关产品,通过互联网等方式建立了销售渠道,因此认为辽渔集团已经初步建立了全产业链发展模式。在探讨新时期辽渔集团南极磷虾渔业产业发展面临的机遇和挑战基础上,提出制定南极磷虾产业发展规划、统筹专利技术保护战略、构建南极磷虾信息平台、加强高端产品研发投入和推动新型南极磷虾捕捞加工船建设等相关对策建议,以进一步提升辽渔集团南极磷虾渔业产业国际竞争力。     

基于贝叶斯方法的FAO48.1区南极磷虾渔业资源评估

南极海域南极磷虾资源丰富,开发潜力已经得到世界范围的关注。由于南极海洋生物资源养护委员会（Commission for the Conservation of Antarctic Marine Living Resources, CCAMLR）多年来始终将联合国粮食及农业组织（Food and Agriculture Organization of the United Nations,FAO）在南极海域内设立的48.1区的捕捞限额控制在1.55×105 t,从而引发了众多争议,采用CCAMLR公布的2006-2015年生产统计数据,利用基于贝叶斯方法的非平衡剩余产量模型,对FAO 48.1区南极磷虾（Euphausia superba）的渔业资源进行评估,结果显示：当前48.1区南极磷虾资源的环境容纳量为（1.93～7.84）×107 t;渔业资源综合种群的内禀增长率为0.4～0.6;2016年48.1区南极磷虾的平均生物量为3.88×107 t;48.1区南极磷虾资源当前最大持续产量（MSY）为5.5×106 t;当前的触发产量远低于MSY的阈值,48.1区内南极磷虾资源几乎处于原始未开发状态。建议提高48.1区南极磷虾的触发产量至5.5×105t。     

南极磷虾木瓜蛋白酶酶解产物的营养学评价

分析了经1.5%木瓜蛋白酶55℃酶解3 h后的南极磷虾(Euphausia superba)蛋白酶解产物(上清和沉淀)的营养组成。结果显示:南极磷虾水解度为44.24%;上清冻干物(FDS)中粗蛋白和总糖含量分别为67.13%和13.91%,其必需氨基酸总量(ΣEAA)、鲜味氨基酸总量(ΣDAA)、牛磺酸Tau含量及F值(支链氨基酸/芳香族氨基酸)较酶解前分别提高了8.96%、6.06%、39.10%和16.67%,表明其氨基酸营养价值较酶解前要高。沉淀冻干物(FDP)中粗蛋白和总糖含量分别为44.49%和10.40%,而粗脂肪含量高达33.28%。FDP中总氨基酸含量(ΣAA)、ΣEAA、ΣDAA、Tau含量及F值均下降,但其ΣEAA在ΣAA中的比例高于40%,且8种EAA含量评分均高于FAO/WHO评分模式要求。脂肪酸分析结果表明,FDP中含有饱和脂肪酸(SFA)8种(44.81%),单不饱和脂肪酸(MUFA)6种(27.55%),多不饱和脂肪酸(PUFA)7种(27.64%),二十碳五烯酸EPA和二十二碳六烯酸DHA含量较丰富。研究认为在本实验条件下通过木瓜蛋白酶酶解南极磷虾得到的FDS和FDP具有较高的利用价值,可开发为人类重要的蛋白来源。     

南极磷虾粉营养成分的分析与比较

对两种不同来源的南极磷虾粉营养成分进行了分析和评价,并与进口鱼粉的营养成分进行了比较。结果显示,上海开创远洋渔业有限公司开利轮产南极磷虾粉(磷虾粉S)粗蛋白含量为62.89%,高于辽宁远洋渔业有限公司安兴海轮产南极磷虾粉(磷虾粉D)和进口鱼粉的粗蛋白含量,两种磷虾粉粗蛋白质含量分别达到一级品和二级品指标。磷虾粉S、磷虾粉D和进口鱼粉18种氨基酸总量分别为66.36%、57.19%、67.24%,鲜味氨基酸含量较高分别为24.65%、20.69%和25.25%,8种必需氨基酸含量分别为31.43%、21.74%、25.62%,且磷虾粉S必需氨基酸含量明显高于磷虾粉D和鱼粉,磷虾粉S、磷虾粉D和进口鱼粉三种样品必需氨基酸指数(EAAI)分别为57.83、49.89、57.07;磷虾粉S、磷虾粉D和进口鱼粉三种样品脂肪酸中,多不饱和脂肪酸含量较高分别为43.28%、40.25%、46.58%,且磷虾粉S的EPA与DHA的总量(36.14%)高于磷虾粉D(31.30%)及鱼粉(27.65%)。分析结果表明,南极磷虾粉蛋白含量高,且氨基酸组成符合FAO/WHO推荐的蛋白质理想模式,含有丰富的多不饱和脂肪酸,营养价值较高,具有较大的开发利用前景。     

南极磷虾拖网的性能优化分析

针对一顶中国目前正在使用的南极磷虾(Euphausia superba)拖网进行网具优化试验,设计了调整参数为浮沉比、上下手纲(等长)和叉纲的三因子L9(34)正交实验,并在3组L/S(水平扩张比)和5级拖速下完成了135次拖曳试验。结果表明:(1)随着拖速和L/S的增加,网具阻力增加,网口高度降低;(2)流速为3 kn情况下,L/S=0.45时,对阻力(Fs)和网具功率消耗(Ps)影响的主次顺序均为沉力(A)>叉纲(C)>手纲(B),对网口高度(Hs)影响的主次顺序为A>B>C,对能耗系数(Ce)影响的主次顺序为C>A>B,水动力性能的最优组合为A3B3C1;L/S=0.5时,对Fs、Hs和Ps影响的主次顺序均为C>A>B,对Ce影响的主次顺序为B>C>A,最优组合为A2B3C3;L/S=0.55时,对Fs和Ps影响的主次顺序均为C>A>B,对Hs影响的主次顺序为B>A>C,对Ce影响的主次顺序为B>C>A,最优组合为A2B3C3;(3)当L/S极低为0.2时,网口的水平扩张约为23 m,虽然此时网口高度有一定的提高,但网具的综合性能却显著下降,能耗系数增加;(4)增加沉力,适当放长手纲和叉纲可以有效提高已定型网具的性能。为确保在低拖速下达到网具的高扩张性能,应考虑改进网板性能,建议采用低拖速高扩张性网板。     

2012/2013渔季CAMLR 48区南极磷虾(Euphausia superba)资源时空分布

根据2013年1–9月辽宁远洋渔业有限公司“福荣海”轮南极磷虾拖网调查数据,以3n mile/h拖曳获得的产量作为CPUE指标,对南极磷虾资源时空分布进行了分析。结果显示,1–6月的月均CPUE值相对稳定,7–9月逐月下降。各渔区中平均CPUE值以48.1区最高,为(25.12±31.04) t/h;48.3区最低,为(11.49±12.06) t/h;CPUE值的波动幅度48.1区大于48.2和48.3区。48.1区的南极磷虾群主要分布于0 –100 m水层,CPUE值以25–50 m水层为最高;48.2区虾群主要分布于50–150 m水层,CPUE值以100–150 m水层最高;48.3区虾群主要分布于100–250 m水层,CPUE值以200– 250 m水层最高。海底深度<500 m的近岸海域是磷虾主要集群分布区和商业捕捞渔场,以水深<250 m的浅水区渔场虾群密度最大,平均CPUE值为(17.54±35.26) t/h,水深250–1500 m的深水区渔场平均CPUE值变化较小,在12.0–14.0 t/h之间波动,但水深>1500 m时,平均CPUE值降到(9.62±9.54) t/h。作业渔场的表温SST主要集中在－1–2℃,当SST为－1–0℃时,平均CPUE值最高。探捕调查发现了5个主要的磷虾集群,集群时间可达30 d以上,但集群密度随时间发生变化。调查结果可为研究南极磷虾渔场形成机制和渔业管理提供基础数据,并为商业捕捞提供参考。     

Effect of krill phospholipids versus soybean lecithin in microdiets for gilthead seabream (Sparus aurata) larvae on molecular markers of antioxidative metabolism and bone development

The objective of the present study was to compare the effectiveness of dietary marine phospholipids (MPL) obtained from krill and soybean lecithin (SBL) on the rearing performance and development of seabream (Sparus aurata) larvae. Larvae were fed from 16 to 44 day posthatching (dph) five formulated microdiets with three different levels (50, 70 and 90 g kg^–1) of phospholipids (PL) obtained either from an MPL or from a SBL source. Larvae‐fed MPL show a higher survival, stress resistance and growth than those‐fed SBL, regardless the dietary PL level. Overall, the increase in MPL up to 70 g kg^–1 total PL in diet was enough to improve larval gilthead seabream performance, whereas even the highest SBL inclusion level (90 g kg^–1 PL) was not able to provide a similar success in larval growth or survival. Inclusion of SBL markedly increased the peroxidation risk as denoted by the higher TBARs in larvae, as well as a higher expression of CAT, GPX and SOD genes. Moreover, SBL tends to produce larvae with a lower number of mineralized vertebrae and a lower expression of osteocalcin, osteopontin and BMP4 genes. Finally, increasing dietary MPL or SBL lead to a better assimilation of polyunsaturated fatty acids in the larvae, n‐3HUFA (especially 20:5n‐3) or n‐6 fatty acids (especially 18:2n‐6), respectively. In conclusion, MPL had a higher effectiveness in promoting survival, growth and skeletal mineralization of gilthead seabream larvae in comparison with SBL.     

Extracting Protein from Antarctic Krill (Euphausia superba)

ABSTRACT

The isoelectric solubilization/precipitation (ISP) process was applied to Antarctic krill protein extraction. The solubility of Antarctic krill proteins and their fluoride content were studied between pH 1.00–13.75. The previous krill protein extraction conditions using ISP were improved. Excess fluoride in Antarctic krill was removed using a water-washing method according to its solubility. To save water, a multistage countercurrent system was used to optimize the ISP method. The results showed that the solubility of Antarctic krill proteins reached a minimum at pH 4.5 and a maximum at pH 13.5, while the concentration of dissolved fluoride was relatively unchanged (16.78–20.50 mg/L), with pH 2.00–13.50. Water-washing 4 times could reduce fluoride 98.14 ± 0.01% from krill with about a 5.14 ± 0.21% protein loss. The reduction allows krill protein to meet the Chinese National Standard (GB 2762-2005) for fluoride. Meanwhile, the four-stage countercurrent system achieved almost the same high fluoride removal rate (98.58 ± 0.01%) using only 25% of the water.     

Optimum krill phospholipids content in microdiets for gilthead seabream (Sparus aurata) larvae

The aim of the present study was to determine the optimum dietary levels of krill phospholipids (KPL) for sea bream (Sparus aurata) larvae, and its influence on larval development and digestive enzymes activity. Larvae were fed five formulated microdiets with five different levels of KPL. Complete replacement of live preys with the experimental microdiets for seabream larvae produced high survival and growth rates, particularly in fish fed the highest levels of KPL. In the present study, increase in dietary KPL up to 120 g kg^?1 (100 g kg^?1 total PL) significantly improved larval survival and growth, whereas further increase did not improve those parameters. An increase in alkaline phosphatase, trypsin and lipase activity with the elevation of KPL up to 120 g kg^?1 was also found denoting a better functioning of digestive system. Besides, there was a linear substrate stimulatory effect of dietary KPL on phospholipase A2 activity. Finally, increasing dietary KPL lead to better assimilation of n‐3 HUFA especially eicosapentaenoic acid, reflected in the higher content of these fatty acids in both neutral and polar lipids of the larvae. In summary, KPL were found to be an excellent source of lipids for seabream larvae. Optimum inclusion levels of this ingredient in microdiets to completely substitute live preys at this larval age were found to be 120 g kg^?1 KPL.     

Decadal trends in abundance,size and condition of Antarctic toothfish in McMurdo Sound,Antarctica, 1972–2011

We report the analyses of a dataset spanning 39 years of near‐annual fishing for Dissostichus mawsoni in McMurdo Sound, Antarctica, 1972–2011. Data on total length, condition and catch per unit effort (CPUE) were derived from the > 5500 fish caught, the large majority of which were measured, tagged and released. Contrary to expectation, the length frequency of the McMurdo Sound catch was dominated by fish in the upper two‐thirds of the overall distribution exhibited in the industrial catch for the Ross Sea shelf. Fish length and condition increased from the early 1970s to the early 1990s and then decreased. Fish length positively correlated with Ross Sea ice extent in early spring, a relationship possibly caused by more ice encouraging larger fish to move farther south over the shelf and into the study area. Fish condition positively correlated with the amount of open water in the Ross Sea during the previous summer (Feb), perhaps reflecting greater availability of prey with the higher productivity that more open water brings. Decreasing fish size corresponds to the onset of the fishery, which targets the large individuals. CPUE was constant through 2001 and then decreased dramatically. We hypothesize that this decrease is related to the industrial fishery, which began in the 1996–97 austral summer, and concentrates effort over the ice‐free Ross Sea continental slope. As a result of limited prey choices and close coupling among mesopredators of the region, Antarctic toothfish included, the fishery appears to be dramatically altering the trophic structure of the Ross Sea.