浙江南麂岛真蛸网箱和水泥池养殖试验

2005年11月至2006年1月,分别在传统网箱和室内水泥池投放真蛸(Octopus vulgaris)野生苗种22062头,进行了养殖初步试验。主要结果为,55口传统网箱共放养10912头,平均体重233.6g,经过40d养殖,平均体重达660.9g,生长速度快,日增重率高达2.389%,养殖成活率62.8%,饵料系数为8.08。18口室内水泥池共放养11150头,平均体重220.5g,第一阶段经过33d养殖,平均体重达364.5g,生长速度不如传统网箱,日增重率1.402%,养殖成活率70.9%,饵料系数为6.04;第二阶段进入越冬期,生长更慢,经过53d养殖,平均体重达489.5g,日增重率只有0.552%,死亡较严重,养殖成活率仅44.3%,饵料系数为8.97。传统网箱养殖经济效益高于室内水泥池,投入产出比前者为11.210,后者为11.105。此外,还对影响真蛸生长和成活的各种因素、互残和自残行为等方面内容进行了分析探讨。     

蛸类渔业概况及增养殖研究现状与展望

蛸类具有对养殖环境高度的适应性,且分布广、生长迅速、养殖周期短、营养价值高等特性,已成为头足类中最受关注的养殖对象和研究热点。此文概括地介绍了蛸类在海洋渔业中的地位,系统地阐述了蛸类渔业概况及增养殖研究现状,并对发展前景和方向进行了分析。     

Effects of a dry pelleted diet on growth and survival of the Yucatan octopus, Octopus maya

The effect of a dry pelleted diet on growth of the Yucatan octopus (Octopus maya) was determined and compared with crab diet (Callinectes spp). Two groups of 15 wild collected animals were used. Octopuses were placed in isolation, in a flow‐through system composed of 30 circular tanks (80 L), with a bottom of 40 cm in diameter and a water depth of 80 cm. Experiment lasted 40 days, and octopuses were weighed every 10 days to determine growth rates. Octopuses were fed between 7% and 10% body weight (BW) per day, twice a day at 9:00 h and 17:00 h. Uneaten food was removed after 4 h in the tanks and weighed, to determine food ingestion and conversion. No mortality as a result of natural causes was observed. The 15 octopuses fed on frozen crabs and the 15 fed on the artificial diet had similar weights (P > 0.05) at the start of the experiment, of 486.2 ± 214.8 and 472.5 ± 228.3 g, respectively. At the end of the experiment, octopuses fed on frozen crabs weighed 1466.5 ± 484.0 g, and were significantly larger (P < 0.05), than octopuses fed on artificial diets (438.9 ± 202.6 g). Growth rates for the experiment were of 3.3 ± 0.2 and –0.0 ± 0.3% BW per day, for octopuses fed frozen crabs and the artificial diet, respectively. The artificial diet did not promote growth, but animals did not loose weight and more important, ate regularly all the food supplied, with feeding rates higher than reported in the literature for prepared diets. This makes O. maya a good research animal for the development of artificial diets for cephalopods.     

Nucleic acids and fatty acids of the common octopus, Octopus vulgaris, in relation to the growth rate

The aim of this study was to investigate changes in the ribonucleic acid (RNA)/deoxyribonucleic acid (DNA) ratio and the fatty acid composition of cultured Octopus vulgaris (50–750 g) in relation to recent (last 30 days) specific growth rate (SGR). Wild animals (80–500 g), collected in the field throughout the year (Aegean Sea, Mediterranean), were also examined for the aforementioned biochemical parameters. Octopuses were reared in a closed seawater system at three different temperatures (15, 20 and 25 °C). The octopuses were fed on squid (Loligo vulgaris). The cultured animals showed a high n‐3 (33–52.9%) and n‐6 (3.3–13.7%) polyunsaturated fatty acid content, but with a high variation for 22:6n‐3 [docosahexaenoic acid (DHA)], 20:5n‐3 [eicosapentaenoic acid (EPA)] and 20:4n‐6 [arachidonic acid (AA)]. The proportion of these fatty acids (% total fatty acids) and the RNA/DNA ratio were linearly (P<0.0001) related to SGR. Specifically, RNA/DNA (0.5–1.9) and AA (2.7–10.7%) increased, while EPA (10.4–19.7%) and DHA (20.8–31.9%) decreased, with increasing SGR (0.4–1.7% day⁻¹). The highest levels of SGR, RNA/DNA and AA were detected in small (50–150 g) octopuses reared at 20 and 25 °C and in large (500–750 g) animals reared at 15 °C. Similar RNA/DNA levels and fatty acid percentages were found in wild octopuses. It is concluded that RNA/DNA, DHA, EPA and AA could be used as biochemical indices for predicting the growth rate of O. vulgaris.     

Growth and mortality of common octopus Octopus vulgaris reared at different stocking densities in Mediterranean offshore cages

Four ongrowing cycles of common octopus ( Octopus vulgaris ), each with two stocking densities, were carried out in an offshore area in order to evaluate the effect of the following variables on growth ( G , % body weight day⁻¹) and mortality ( M , % day⁻¹): weight ( W , 0.5–3.0 kg), temperature ( T , 14–26 °C), stocking density (SD, 6–46 kg m⁻³), size dispersion, expressed as coefficient of variation (CV, 13–42%) and significant wave height (SWH: 0.4–1.2 m). The assays were performed in an 8 m³ stainless-steel floating cage divided into two compartments of 4 m³ each. For the range of temperatures considered (14–26 °C), G depended significantly on T and SWH, with maximum G values being obtained at 18.5 °C and with an important negative effect of SWH. M depended significantly on T, W and CV, mortality being minimal at 18 °C. The two other variables had an antagonistic effect, mortality increasing with greater size dispersion – suggesting that animals should be graded throughout the process – although the effect diminished as the sizes increased. The results point towards two alternatives for the commercial ongrowing of octopus under the particular conditions of the present study: (A) two ongrowing cycles of 3.5 months to reach a final weight of 2.5 kg or (B) one 5-month cycle to reach a final weight of 3.5 kg.     

Changes in lipid composition of different tissues of common octopus (Octopus vulgaris) during short‐term starvation

In this work, we study the variations in concentration (mg 100 g^?1 dry weight) and total content (mg individual^?1) of different lipid classes in muscle and the digestive gland of Octopus vulgaris during an 8‐day starvation period. In all the samples analysed, polar lipids (PL) predominated in muscle (267.3–337.2 mg 100 g^?1) compared with neutral lipids (66.9–104.7 mg 100 g^?1). A significant positive tendency was observed in muscle for the content and concentration of monoglycerides as a consequence of starvation (P < 0.05). Furthermore, a higher cholesterol (CHO) content was detected in this tissue after the fourth day of starvation compared with the fed animals (P < 0.05). Neutral lipids predominated in the digestive gland (12 958–14 151 mg 100 g^?1) compared with PL (3157–6517 mg 100 g^?1), with triglycerides, free fatty acids and monoglycerides being the major lipid classes. The concentration of PL and monoglycerides showed a positive trend with starvation, while the triacylglycerol showed a negative tendency (P < 0.05). The results suggest that triglycerides and CHO are transported simultaneously from the digestive gland to the muscular tissues during starvation and the preferential use of PL and CHO during growth phases. It was estimated that lipids contributed 26% of the energy costs of the animals during starvation, mainly in the form of triglycerides from the digestive gland.     

真蛸早期发育形态特征及生长规律研究

为了探究真蛸(Octopus vulgaris)早期幼体生长发育特征,在室内水泥池育苗条件下,研究了孵化后1~100日龄真蛸的形态变化特征,并对1~49日龄真蛸的全长、腕长、胴长、胴宽、体重及最长腕的吸盘个数进行了测量。结果显示,在盐度为30~32,水温为18.6℃~26.0℃条件下,初孵仔蛸平均全长为(3.05±0.11) mm,大部分初孵仔蛸外卵黄囊在出膜前已吸收完毕,1日龄仔蛸已开口摄食,17日龄稚蛸开始摄食糠虾,35日龄稚蛸开始营底栖生活,60日龄体色由透明发育为乳白色,80日龄体色已与成体相同,100日龄除性腺外,各器官发育成熟,形态特征与成体基本一致。研究表明,真蛸早期(1~49日龄)发育过程中,体重与全长呈立方函数关系,为y=5×10–5x3– 0.0009x2+0.0072x–0.0132;全长与腕长呈立方函数关系,为y=–0.0012x3+0.0492x2+0.0243x+0.2179;全长、体重、腕长、胴长、胴宽分别与日龄呈立方函数关系,为y=–0.0001x3+0.0105x2–0.0122x+3.0562、y=–2×10–7x3+4×10–5x2–0.0004x+0.0034、y=–0.0004x3+0.0247x2–0.1037x+0.8214、y=–0.0004x3+0.0124x2 +0.0749x+1.4757、y=–3×10–5x3+0.0025x2+0.0354x+1.4026。依据营养类型、形态和生物学特征等参数,将真蛸早期发育分为仔蛸期、稚蛸浮游期、稚蛸底栖期和幼蛸期4个时期。     

Evaluation of relationship between Chilean octopus (Octopus mimus Gould, 1852) egg health condition and the egg bacterial community

The objective of this study was to evaluate how bacterial community associated with Chilean octopus (Octopus mimus) egg was related to egg health condition using a culture dependent method and PCR‐DGGE fingerprinting technique. Total heterotrophic bacterial number of fresh egg was much lower than infected egg. However, biodiversity of culturable bacterial community associated with the fresh egg exhibited a higher diversity than the infected egg. Result of a culture dependent method showed that Roseobacter clade was predominant in the fresh egg, while predominant species in the infected egg was γ‐proteobacteria. DGGE fingerprinting technique showed that fresh egg associated unculturable bacterial community was constituted of Roseobacter clade and Bacteroidetes, whereas Bacteroidetes was predominant bacteria in the infected egg. These results suggest that there might be some sort of relationship between octopus eggs associated bacterial community and egg health condition. Moreover, Roseobacter clade and Bacteroidetes might be potential symbiotic bacteria associated with the octopus egg, and some γ‐proteobacteria might be involved in octopus egg disease. In particular, Roseobacter clade may play an important role in octopus egg health and it raises the possibility that this clade can be utilized as potential probiotics for octopus aquaculture.     

真蛸亲体培育、产卵及孵化试验

2005~2007年春、夏期间,在浙江南麂岛开展了真蛸亲体培育、产卵及孵化的试验研究。结果表明:亲蛸培育成活率为77.5%~95.5%,平均产卵率为68.0%~83.3%。不搭配雄体产卵率为65.0%,搭配一定比例的雄体后产卵率达92.5%,最高达100%。不同附卵器附卵效果以方形鲍鱼箱为最好,圆形鲍鱼皮桶次之,扇贝笼最差。在南麂海域暂养在网箱中的真蛸当水温上升到13.5℃以上时就开始有少量产卵,多数开始产卵在16.0℃左右,主要产卵期在4~6月。不同个体真蛸的产卵量变化很大,少者只有22 632粒,多者达170 684粒,平均102 665粒,平均每颗卵粒重量在1.670~2.207 mg之间,大小为长2.8~3.1 mm、宽0.915~0.950 mm。在水温13.5~28.0℃范围内,真蛸卵可以正常孵化,孵化率达60.0%~80.0%,超过28℃时孵化率明显下降。真蛸卵的孵化时间较长,至少需要20 d以上。孵化时间长短与水温关系密切,水温越高,孵化时间越短。孵化期间平均水温16.5℃,整个孵化时间长达47 d。当孵化期间平均水温为21.6℃时,从产卵到稚蛸出膜大致需要25 d左右。此外,还发现亲蛸护卵可以减少疾病,提高孵化率,本文也论述了有关其对疾病防治方面的探索。     

Paralarval rearing of Octopus vulgaris (Cuvier) in Tuscany,Italy

This paper describes the research work carried out on Octopus vulgaris reproduction at Maricoltura di Rosignano Solvay, Italy, during the period 2002–2007. Already in the first few years, it was possible to establish healthy broodstock groups, starting from subadults captured in the wild. Obtaining numerous viable eggs was not difficult and paralarval rearing up to around 40 days was successful. In 2007, the first juveniles were produced and the oldest juvenile reached the age of 160 days. During the initial stages, careful attention was paid to work as closely as possible with standard aquaculture procedures for live food production (mainly the use of Artemia and rotifers as live prey) and paralarval rearing techniques, in order to facilitate the step towards industrialization later on.     

人工养殖条件下真蛸的生物学特性及胚胎发育

对人工养殖条件下真蛸(Octopus vulgaris)的生物学特性和胚胎发育进行了初步研究.结果表明,真蛸喜栖息于阴暗的场所,隐居,主要捕食一些活体甲壳类和贝类,也能很好的适应死鱼、蟹和贝类等饵料,夜间或傍晚摄食较为活跃.繁殖季节,雌、雄个体间存在交配行为,临产时亲蛸(♀)藏入巢穴,受精卵分批产出,呈穗状悬挂于巢穴顶部或四壁,亲蛸(♀)具有护卵行为.人工养殖条件下亲蛸不能全部产出其所怀的卵,产卵量为7×104～20×104粒,单位体重产卵量为42～71粒·g-1.受精卵为盘状卵裂,经过肉眼可见的红珠期、黑珠期、胚胎的逆转,水温18.2～22.1℃时,真蛸幼体经过35～42 d孵化出膜;22.3～26.9℃时,真蛸幼体经过24～37 d孵化出膜;24.6～28.3℃时,真蛸幼体经过23～33 d孵化出膜.     

Evaluation of two anaesthetic agents and the passive integrated transponder tagging system in Octopus vulgaris (Cuvier 1797)

Octopus vulgaris is a species of demand in the market with the potential to diversify European aquaculture. However, this species develops complex social interactions under culture conditions, which may have negative effects on its growth, survival and profitability. In order to understand its behaviour under such conditions, individual tagging systems allow a careful evaluation of biological parameters, such as growth and longevity. The present work describes a combined protocol (anaesthetic and tagging) for implanting subcutaneous passive integrated transponder tags (PIT). The effect of two anaesthetic agents in facilitating octopus handling is assessed: clove oil at 20–40–100 mg L^?1 and ethanol (96%) at 1–1.5–2%. The most suitable body location of PIT tags, its effect on growth and mortality, the addition of a stitch and the PIT retention rate after 2 months in floating cages were evaluated. It was concluded that immersion in seawater with 1.5% of ethanol at 22.3±0.5 °C is a suitable anaesthetic for this species. The results showed that the best‐selected PIT body location was the upper left arm III. No effect of the PIT tagging system was found on growth and survival when tagged and untagged octopuses were compared. It was observed after 2 months that the stitch did not induce an increase in the retention rate and 81–100% tag retention regardless of the dietary treatment.     

Development of a method for live octopus (Octopus vulgaris) transportation for long distance at high densities

The development of new octopus‐based products with a growing economic value ensures the commercial interest of this species, making live octopus export an activity of great interest. The aim of this study was to develop a method for long‐distance transportation of live octopus at high densities. The system was composed by 220‐L tanks with cooling and aeration, where the animals were kept separated from each others. The water temperature was maintained at 10°C, after a decreasing of 1°C/hr. Live octopus transportation was tested for 48 hr at two densities: 50 kg/m³ and 100 kg/m³. During this period, water parameters were monitored. Stress response was evaluated through the analysis of haemolymph, muscle and brain tissues. No mortality was registered after 48 hr for both treatments. In all trials, water quality remained within the normal limits in both densities; there was, however, a significative increase of ammonia levels in the water. Ammonia, dopamine and Hsp70 levels were analysed in the beginning and at the end of the experiment for both densities; however, no significant differences were found among them. In general, this system seems to be a viable solution for live octopus 48‐hr transportation at a density of 100 kg/m³.     

Enrichment of Artemia metanauplii in phospholipids and essential fatty acids as a diet for common octopus (Octopus vulgaris) paralarvae

Highly unsaturated fatty acids (HUFA), like the eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids and polar lipids (essentially phospholipids, PL) have been identified as essential nutrients for common octopus (Octopus vulgaris) paralarvae. However, they are not available in sufficient amounts in live preys as Artemia, making necessary a supplementation of these nutrients previous use. A commercial emulsion, soya liposomes, and marine and soya lecithins were used to supply HUFA and PL to Artemia metanauplii, those being regarded as suitable size preys for octopus paralarvae. Our results prove that a simultaneous enrichment in HUFA and PL is possible using enrichment diets combining HUFA‐ and PL‐rich products in short‐term (4 h) incubations. Particularly interesting was the enrichment efficiency shown by the marine lecithin, which enabled the enhancement of the PL fraction of Artemia metanauplii and, importantly, also their HUFA with a remarkable 13% DHA of total fatty acids. Marine lecithin arises as a novel enrichment diet for Artemia and more effective than some commercial products currently used in hatcheries worldwide.     

Investigation of the potential effect of diet,body mass and maturity on growth and feed performance of common octopus Octopus vulgaris: an information theory approach

The potential effect of body mass (m), maturity stage (ms), food type (ft), food protein (p) and lipid (li) content, and food protein‐to‐energy ratio, P/E (pe) on Specific Growth Rate (SGR, % day⁻¹), Absolute Feeding Rate (AFR, g day⁻¹), Feed Efficiency (FE, %), Assimilation Efficiency (AE, %), and Protein Retention Efficiency (PRE, %) in the common octopus was investigated. Six food types were provided ad libitum: shrimp, squid, hake, mussel, sardine and artificial one (gels made of hydrated squid flour agglutinated with sodium alginate). Estimated SGRs, AFRs, FEs, AEs and PREs were modelled with General Linear Models based on an information theory approach, using m, ms, ft, p, li and pe as potential predictor variables. SGR decreased when m increased; octopuses fed on shrimps showed the highest SGRs and the ones fed on mussels showed the lowest SGRs. AFR increased with m. Maximum and minimum FEs were observed, when food provided was shrimps and mussels, respectively. Maximum PRE was performed by octopuses fed on shrimps or sardines and minimum PRE by octopuses fed on mussels. Octopuses fed on artificial diet reached satisfactory levels of SGR (0.50% day⁻¹) and FE (12.3%).     

Variations in Weight and Proximate Composition of Newly Hatched Octopus vulgaris (Cuvier 1797) Paralarvae

Abstract

Survival and growth of juvenile octopi vary considerably. The objective of this research was to determine variations in weight, total lipids (TL), and total protein (TP) of newly hatched Octopus vulgaris paralarvae (0 days old) over the course of the spawning period. Newly hatched paralarvae dry weight from three females decreased throughout the spawning period. Similarly, newly hatched paralarvae TL percent decreased consistently (p < 0.05) in two of them and remained similar (p > 0.05) for the third female. Contrary, TP% did not vary regardless of the female or the time of hatching throughout paralarvae spawning. In conclusion, we believe that paralarvae used in O. vulgaris culture should be collected during the first 10 days of spawning, as they are larger and have higher lipid content; this increases the chances of a successful paralarvae culture, which is the major bottleneck in the culture of this species.