Size selectivity of a trammel net for oval squid Sepioteuthis lessoniana

ABSTRACT:   The size selectivity of a trammel net for herded oval squid Sepioteuthis lessoniana in Tateyama Bay, Chiba Prefecture, was estimated by comparison between the mantle length frequency distributions of oval squid caught by a trammel net and by a set net. The measured mesh sizes of the inner net of the trammel net and of the final section of the set net were 85.3 and 11.3 mm, respectively. In the trammel net fishery where oval squid are herded into the net, most of the oval squid are caught in the bag-shaped inner net. Hence, the logistic function was employed for the size selectivity curve of the trammel net. The 'share each length's catch total' (SELECT) model was implemented for the estimation of the selectivity curve. The size selectivity r ( l ) of the trammel net for the oval squid was expressed as a logistic function of the mantle length l : r ( l ) = exp(−18.57 + 0.88  l )/[1 + exp(−18.57 + 0.88  l )]. From these logistic parameter estimates, the 50% selection mantle length and selection range ( L ₇₅– L ₂₅) were calculated as 21.07 and 2.49 cm, respectively. The selection probability of oval squid whose mantle girth was equivalent to the mesh perimeter of the inner net was 0.09. Accordingly, oval squid of a girth smaller than the mesh perimeter were likely to pass through the mesh to escape from the net.     

Feeding habits of Baird's beaked whale Berardius bairdii, in the western North Pacific and Sea of Okhotsk off Japan

ABSTRACT:   We examined the stomach contents of 26 Baird's beaked whales caught off the coast of Japan by small-type coastal whalers. The main prey for these whales was rat-tails and hakes in the western North Pacific. Pollock and squids were also important food in the whales collected from the southern Sea of Okhotsk. The prey species found in the stomachs of the whales were almost identical to those caught in bottom-trawl nets at depths greater than about 1000 m in the western North Pacific, which suggests that the Baird's beaked whale forages for prey at depths of about 1000 m or more. Baird's beaked whales in the western North Pacific migrate to waters of 1000–3000 m in depth, where demersal fish are abundant. This implies that Baird's beaked whales migrate to waters where demersal fish, especially rat-tails and hakes, are abundant. Although there is limited information on the feeding habits of ziphiid whales, they are generally thought to prefer squid. The present data suggest that demersal fish are also important prey for ziphiid whales.     

Oxidative stability of lipids from squid tissues

ABSTRACT: Oxidative stability of lipids from squid tissues was compared with those of other marine lipids. On the basis of peroxide formation, total lipids (TL) from squid viscera or squid muscle with skin were most oxidatively stable, followed by squid eye TL, trout egg TL, bonito oil, and tuna orbital TL, respectively. This tendency in oxidative stabilities was also confirmed by the decrease in unoxidized polyunsaturated fatty acids during oxidation. Analyses of tocopherol contents and lipid compositions suggested that the higher oxidative stabilities of three kinds of squid tissue TL and trout egg TL compared to those of bonito oil and tuna orbital TL would be mainly because of the presence of phospholipids (PL) in squid tissue lipids and trout egg TL. However, the oxidative stability of lipids containing PL did not always decrease with increasing PL contents and stability was strongly influenced by PL composition. As squid viscera contained more than 25% of TL and these lipids were oxidatively stable, squid viscera may be used as a good resource of functional lipids rich in eicosapentaenoic acid and docosahexaenoic acid.     

柔鱼加工中酶法去皮工艺条件的研究

使用Ａ．Ｓ１．３９８蛋白酶除去北平洋柔鱼表皮，操作简便，快速，成品色白，完整，试验结果表明，较为合适的柔鱼酶法去皮工艺条件是：ｐＨ６．５－７．５、酶液浓度１．５－２．０％，料液比１：４ｇ／ｍｌ，酶液温度５０－５３℃，氯化钙添加量０．０５－０．１０％。     

哥斯达黎加外海茎柔鱼个体与耳石间生长关系研究

根据2009年7-8月哥斯达黎加外海采集的茎柔鱼样本,利用多种统计方法分析了茎柔鱼耳石与个体生长之间的关系。研究认为,耳石各形态参数与胴长(ML)关系显著(P<0.01),其中背侧区间长(DDL)、耳石总长(TSL)与其相关性最大。耳石生长存在两个阶段,当ML小于26～30 cm时,其耳石生长迅速,之后耳石生长减慢。在生长过程中,耳石背区长(DL)、吻区内长(RIL)、DDL生长快于TSL,背侧区夹角(DDA)、吻侧区夹角(RDA)、吻区夹角(RA)则随着ML的增大出现减小趋势,侧区、吻区形态变化显著(P<0.05)。耳石形态先于生长速度发生显著性变化,同时各形态参量发生显著性变化时间不同,但形态特征变化主要发生在ML为23～29 cm个体中,之后趋于稳定。耳石生长及形态显著性变化与茎柔鱼栖息水层改变相关,茎柔鱼与中上层头足类耳石特征相符。     

从鱿鱼墨中精制黑色素

介绍了以鱿鱼墨为原料从中提取，精制黑色素的工艺。具体路线为：原料鱿鱼墨经水洗，酸洗，浓酸水解去除绝大多数杂质后，添加二甲亚砜（DMSO）使黑色素完全溶解，然后，加入丙酮改变溶液极性，减小黑色素的溶解度，从而使黑色素再次析出，经三次重结晶，以达到精制目的。在此基础上，测定了鱿鱼墨黑色素的一些物理和化学性制，精制所得黑色素呈黑褐色，不溶于水及通常的有机溶剂，但可溶于碱，浓硫酸，二甲亚砜等，紫外－可见光谱和红外光谱初步表明鱿鱼墨黑色素是以吲哚结构为主体的异聚物。     

西北太平洋柔鱼种群的聚类分析

根据沪渔公司鱿钓船于1999年10-11月在西北太平洋165℃E以西海域随机采集的柔鱼样本,测定其胴长、鳍长、鳍宽、眼径、右1腕长、右2腕长、右3腕长、右4腕长和右触腕穗长9个形态特征指标值。利用灰色系统理论中的变权聚类分析方法,对柔鱼种群结构进行初步划分。研究结果表明,在西北太平洋海域,柔鱼存在着两个明显的独立种群,其形态特征值有较大的差异。     

The giant squid Architeuthis: An emblematic invertebrate that can represent concern for the conservation of marine biodiversity

The current public perception is that there is little reason for concern for the conservation of marine invertebrates, in part due to the scarcity of emblematic species to represent that diverse group. This paper shows that giant squid can be considered an emblematic species to represent concern for the conservation of marine invertebrate biodiversity because it satisfies all the requirements of an emblematic species. It shows that Architeuthis attracts public interest and attention and can serve as an indicator of oceanographic conditions and ocean climate change. It asserts that Architeuthis can represent concerns for vulnerable marine ecosystems associated with submarine canyons and that it belongs to a broad diverse phylogenetic group of organisms associated with these canyons, sharing common concerns with that group with respect to vulnerability and conservation. This study also advocates that the giant squid can serve as an indicator of effects of ecosystem stress resulting from anthropogenic effects including ocean acidification and warming. It is also shown to be vulnerable to such anthropogenic effects as fishing, acoustic seismic exploration and, possibly, pollutants.     

超声波对鱿鱼墨黑色素成分和物理结构的影响

为了提高鱿鱼综合利用价值,以加工废弃物中的鱿鱼墨黑色素为原料,研究超声波处理对黑色素成分和物理结构的影响。采用超声功率15 W/mL、超声时间2 s、间歇时间1 s、总工作时间20 min的工作条件对黑色素进行处理。结果表明：鱿鱼墨黑色素在超声波处理后,波长为224 nm和267 nm附近的两个峰吸光值显著增加,黑色素在环己烷中的溶解性显著增加,样品中没有新的具有紫外可见吸收特性物质生成;黑色素中蛋白质在超声波处理后的没有发生显著变化,而脂质含量显著减少;超声波后Ca、Mg、Na、K、Fe、Cu、Cd和Pb等8种金属元素含量均显著降低;电镜图片显示黑色素微球颗粒在超声过程中发生了爆炸,产生更为细小的碎片和碎末。     

Influence of squid extracts on the triggering of secondary vitellogenesis in Penaeus vannamei

A series of five experiments were carried out to find an alternative to eyestalk ablation for inducing and controlling vitellogenesis in penaeid shrimps. Several extracts from squid were tested as supplements to a basal diet. Polar components of hydro-alcohol (ethanol/dicloromethane/water, 2:2:1:8) soluble and lipid squid fractions (Bligh & Dyer), when incorporated in formulated feed at low doses, trigger secondary vitellogenesis in 15–35 g female Penaeus vannamei , showing maturations of the same order of magnitude as the eyestalk-ablated controls. Achievement of vitellogenesis was estimated by a homologous ELISA-vitellogenin test. Even though the nature of the active molecules was not completely elucidated, the results obtained indicate that they may probably be steroid-like molecules of cephalopods, acting in a heterologous way.