浙江北部沿岸春夏季长蛸时空分布及其与海洋环境的关系

根据2014—2016年春夏季浙江北部沿岸拖网调查数据,选取时空因子(年、月、经纬度)和环境因子(底层温度SBT、底层盐度SBS、深度Depth和溶解氧DO),分析长蛸(Octopus minor)资源的时空分布情况,并利用提升回归树(boosted regression tree, BRT)模型研究各因子对长蛸资源丰度(以渔获量g/h表示)的影响程度。结果表明:2014年的平均渔获量明显高于2015和2016年,同一年中4月份的渔获量均高于其他月份;主要渔获量分布在122.75°E～123.25°E,30°N～30.5°N之间;2015年的渔场重心较其他年份略向北移动,4月至6月间渔场重心向东北方向移动,但变化不明显;选择以学习率(learning rate,lr)为0.001和复杂度(tree complexity,tc)为4的模型来建立时空环境因子与渔获量的关系,发现溶解氧对渔获量的影响最大,占所有影响因子的45.5%;其次为年和盐度,随后依次为深度(10.7%)、底层温度(7.3%)、纬度(4.7%)、月(4.7%)以及经度(2.3%)。相比较时空因子而言,环境因子对长蛸的渔获量影响更大。溶解氧是直接影响长蛸活动的重要因素,后续研究应该对此因子提高关注。     

短蛸消化系统和部分器官中μ受体的免疫组织化学定位

采用免疫组织化学SABC法对短蛸（Octopus ocellatus）消化系统和部分器官中μ受体（mu opioid receptor）进行定位研究。结果表明,短蛸腕、漏斗、外套膜腹面、口球、嗉囊、胃盲囊、肠、直肠、前唾液腺、后唾液腺、肝胰脏均呈μ受体阴性,但食道内上皮、外膜、结缔组织和胃角质层有μ受体分布,外套膜背面、腕间膜的上皮或近上皮部位呈μ受体阳性。μ受体在短蛸不同部位分布密度的不同,可能与各器官的功能不同有关。     

Effective use of glucose rather than starch in formulated semimoist diets of common octopus (Octopus vulgaris)

The aim of the present work was to test the capacity of O. vulgaris to use carbohydrates supplied in three diets: a diet without added carbohydrates (diet C0: 500 g kg^?1 water, 200 g kg^?1 gelatine, 100 g kg^?1 egg yolk powder, 50 g kg^?1 freeze‐dried Sardinella aurita and 150 g kg^?1 freeze‐dried Todarodes sagittatus), and two obtained by substituting 50 g kg^?1 of T. sagittatus by glucose (diet GLU50) or by starch (diet STA50). The most stable and best accepted diet was STA50 (SFR 1.26%BW day^?1), although there were no significant differences in the growth rates obtained with the three diets: 10.1 g day^?1, 9.4 g day^?1 and 11.2 g day^?1 for C0, GLU50 and STA50, respectively (P > 0.05). The feed efficiency indices were better for GLU50, of particular note being the protein productive value of 72% and a feed conversion ratio lower than 1. Protein and lipid digestibility were similar in all three diets (96–98% for proteins and 85–94% for lipids), whereas carbohydrate digestibility was higher in GLU50 (98%) than in C0 (84%) and STA50 (0.33%). The content of carbohydrates increased in muscle and the digestive gland as a consequence of the increased carbohydrates intake.     

Preliminary trials on the use of large outdoor tanks for the ongrowing of Octopus maya juveniles

Octopus maya has high growth rates, direct embryonic development and high hatchling survival, making it a good candidate for aquaculture diversification. The present study was designed to evaluate growth rate, survival and food conversion of O. maya juveniles cultured in outdoor tanks. Octopuses were captured from the wild during the fishing season, and fed discarded fish heads and whole crabs. Three trials were conducted between 23 and 32 days, in September (trial 1), October (trial 2) and November (trial 3) where a decrease in sea water temperature was registered (29–24 °C, from September to November respectively). Octopuses were held in three outdoor tanks of 5 m² of bottom area and 0.5 m deep, aerated sea water and water flow allowing 10% of water exchange per day. Initial density was between 2.9 and 3.8 kg m^?3 with different initial mean weight of 542.3 ± 18.8, 493 ± 11.9 and 321 ± 7.8 g, for trials 1, 2 and 3 respectively. Specific growth rate varied between 1.8 and 2.7% BW day^?1 with no apparent relation with the culture temperature. These results put in evidence that tanks used are adequate for the ongrowing of O. maya juveniles, with commercial size being attained in a few weeks.     

The effects of fish hydrolysate (CPSP) level on Octopus maya (Voss and Solis) diet: Digestive enzyme activity, blood metabolites, and energy balance

As has been demonstrated in previous studies, Octopus maya can be fed on artificial diets. In the present study six different diets were assayed. Five diets were designed to test the effect of percentage of inclusion of fish protein concentrate (CPSP: 0, 5, 10, 15, and 20%) and were offered to octopuses as a specifically designed artificial diet. The sixth diet consisted of frozen crab (Callinectes spp) and was used as control diet. Blood metabolites and energy budget of octopuses were evaluated to determine how CPSP levels modulate the digestive capacity and allow retaining energy for growth. Wild animals (316.4 ± 9.8 g) were used in the study. Results showed that CPSP produced a positive specific growth rate (SGR, % day^− 1) with high value in octopuses fed 15% CPSP level. A maximum growth rate of 0.86% day^− 1 was recorded in these animals, a value that is extremely low when compared with the SGR obtained when animals were fed fresh crab (3.7% day^− 1). In general, blood metabolites were affected by diet composition, indicating that some metabolites could reflect the nutritional and/or physiological status of octopus. Preliminary reference values for O. maya fed crab were found for glucose (0.09 ±0.02 mg/ml), lactate (0.004 ± 0.002 mg/ml), cholesterol (0.16 ± 0.02 mg/ml), acylglycerol (0.14 ± 0.01 mg/ml), protein (0.37 ± 0.04 mg/ml), hemocyanin (1.85 ± 0.04 mmol/l), and digestive gland glycogen (1.86 ± 0.3 mg/g). Total energy content can be used as an indicator of tissue metabolic reserves. In the present study, higher energy content in the digestive gland and muscle was observed in octopuses fed crab, followed by animals fed 15% CPSP. Results from the digestive gland indicated that the retained energy derived from glycogen, suggesting that lipids and protein were the main sources of variation linked with energy content. In general, digestive gland proteases activity and trypsin were induced in octopuses fed 15% CPSP. The capacity of O. maya juveniles to adjust their digestive enzymes to different types of food was evidenced. Essential amino acid content (EAA) of the diet was not a limiting factor. When dietary EAA profiles were compared with O. maya EAA profiles, all dietary EAA resulted in a higher concentration than whole body octopus composition. In the present study, all experimental groups ingested between 3300 and 4106 kJ wk^− 1 kg^− 1 without statistical differences among treatments, indicating that experimental diets were as attractive as crab. Differences were recorded in the proportion of absorbed energy (Ab, %) between CPSP-based and crab meat diets, suggesting digestion limitations associated with artificial diets. The present results indicate that the 15% CPSP diet had characteristics that stimulate digestive enzymes and reduce energetic costs associated with its digestion (HiE or SDA), channeling more biomass production than the other experimental diets.     

First feeding of Octopus vulgaris Cuvier, 1797 paralarvae using Artemia: Effect of prey size, prey density and feeding frequency

Different assays related to the first feeding of Octopus vulgaris Cuvier, 1797 are compiled in this paper. They include: age at initial feeding age, prey size selection and optimal density, attack timing after feeding, and effect of dose number on the number of captures. Prey capture and ingestion processes were also analysed. Food supplied was cultured Artemia sp. Each assay lasted 15 min.Although paralarvae already start to feed on the hatching day (day 0), it is during day 2 when a greater number of attacks is recorded (81.7 ± 14.7% paralarvae attack). They mainly prefer (significance level α = 0.05) large Artemia, 1.4 ± 0.4 mm (77.0 ± 5.6% of the total attacks) than small Artemia, 0.8 ± 0.1 mm (23.0 ± 5.6%). There is also a slight predilection for the lowest Artemia concentration (33.3 ±12.6% paralarvae attack in a 0.1 Artemia ml^− 1 density, opposite 16.7 ± 7.6 and 18.3 ± 7.6% in densities of 0.5 and 1 Artemia ml^− 1 respectively). The greatest predatory activity is recorded during the first 5 min after food is supplied (72.2 ± 25.5%). An increase in the predatory activity was also observed when food was distributed in several doses instead of a single dose (75.0 ± 10.0% and 46.7 ± 17.6% respectively). It was proved for the first time that paralarvae completely ingest their preys (including their exoskeletons), in this case Artemia. Time needed for their total ingestion ranges between 4 and 10 min.     

短蛸神经系统和消化系统的形态解剖

采用传统的系统形态解剖学方法对短蛸神经系统和消化系统进行观察,并描述、绘图.结果表明,短蛸中枢神经系统由围绕着食道的脑神经节、足神经节和脏神经节组成,周围神经系统可见口球神经节、视神经节、胃神经节、鳃神经节、外套神经节和脑神经索;短蛸的消化管从前到后包括口、口球、食道、嗉囊、胃、胃盲囊、肠、直肠、肛门,消化腺包括1个肝脏及前唾液腺、后唾液腺和胰脏各1对.     

Marine gammarids (Crustacea: Amphipoda): a new live prey to culture Octopus maya hatchlings

The effects of feeding two alternative live prey Hyalella azteca (freshwater gammarids) and Hyale media (marine gammarids) to Octopus maya hatchlings were compared with feeding adult Artemia sp., traditionally used during the first weeks of the life cycle. Hatchlings were fed ad libitum these three live preys during the first 15 days, and a paste elaborated with fresh squid and shrimp during the next 15 days when hatchling can be fed prepared diets. Weight (g) and specific growth rates (% day^?1) were determined every 15 days. Octopus maya hatchlings fed with marine gammarids grew larger (6.9 ± 0.2% day^?1) compared with hatchlings fed Artemia sp. or freshwater gammarids (4.8 ± 0.2% and 5.0 ± 0.3% day^?1 respectively). Survival was also higher (92.2 ± 6.8%) for hatchlings fed marine gammarids, than for those fed Artemia sp. (74.5 ± 23.8%) or freshwater gammarids (41.2 ± 21.2%). The content of acylglycerides, cholesterol and proteins in O. maya fed marine gammarids suggested a better nutrient assimilation by the hatchlings. Also, polyunsaturated fatty acids levels (EPA and DHA) were more abundant in marine gammarids, possibly contributing to the higher growth rates observed. This is the first study revealing a successful use of marine gammarids as alternative prey for octopus hatchlings culture.