不同尺寸网目与缩结系数对许氏平鲉的选择性

为探究不同尺寸网目及缩结系数对许氏平鲉(Sebastesschlegelii)的选择性,本研究基于实验水槽中的套网法试验,测得许氏平鲉的生物学特征参数,采用Logistic模型曲线拟合得到不同尺寸网目及缩结系数对许氏平鲉的选择性曲线,并用极大似然法估算选择性参数。结果表明:网目尺寸为63 mm、82 mm、93 mm时,许氏平鲉的50%选择性体长(L50)分别为18.49 cm、23.90 cm、25.12 cm,选择范围(SR)分别为3.18、3.6、3.85,选择因素(SF)分别为2.93、2.91、2.70,随着网目尺寸的增大,许氏平鲉的L50、SR逐渐增大, SF逐渐减小;当82 mm网目的缩结系数(Et)分别为0.5、0.6、0.707时,许氏平鲉的50%选择性体长(L50)分别为21.47 cm、23.90 cm、22.02 cm,选择范围(SR)分别为3.23、3.6、3.38,选择因素(SF)分别为2.65、2.91、2.68,随着网目缩结系数的增大,许氏平鲉的L50、SR、SF先增大后减小,在Et为0.6时均达到最大。为保护许氏平鲉幼鱼资源,建议在鱼礁区使用网目规格为70 mm, Et为0.6的笼壶渔具进行采捕。     

N and P budgets of Haliotis discus hanai,Apostichopus japonicas,and Sebastes schlegeli in a polyculture system

The viability of placing abalones (Haliotis discus hannai), sea cucumbers (Apostichopus japonicas) and rockfish (Sebastes schlegeli) in a polyculture system, the effect of this mixed species group on the system's nitrogen (N) and phosphorous (P) budgets, and the growth and food intake of the organisms in the system were examined using a recirculating aquaculture system. Four replicates were set up for each of three treatment groups (abalone only (C), abalone‐sea cucumber (AS) and abalone‐sea cucumber‐rockfish (ASF)) with an experimental period of 60 d. Compared with the C group, in the AS group the abalone survival rate and specific growth rate (SGR) of body weight increased and the harvested abalones from the polyculture system became the main source of N and P output of the polyculture system. However, the N and P output in the water layer did not differ significantly from that in the C group (p > 0.05), and the N utilization rate was significantly higher than that in the C and ASF groups (p < 0.05). Compared with the AS group, in the ASF treatment the SGR of body weight as well as the protease and amylase activities of sea cucumbers were significantly higher (p < 0.05), the water layer and faeces became the main sources of N and P output in the system. These results showed that the AS polyculture mode significantly improved the N and P utilization rates in the system and led to increased aquaculture production.     

Effects of 7,12-dimethylbenz(a)anthracene on growth and haematological parameters in Korean rockfish, Sebastes schlegeli (Hilgendorf)

The objectives of the present experiment were to determine the effects on growth factors and some haematological parameters in Korean rockfish, Sebastes schlegeil, after dietary 7,12‐dimethylbenz(a)anthracene (DMBA) exposure at 0.6, 1.2, 2.4 and 4.8 mg kg^?1 diet for 8 weeks. The specific growth rate of the fish exposed to DMBA (≥1.2 mg kg^?1) showed significantly lower performance than the control. Following 8 weeks of exposure, the DMBA‐exposed groups (2.4 and 4.8 mg kg^?1) had a significantly higher mean hepatosomatic index. Condition factor of the fish exposed to DMBA did not show any statistically significant deviation from the control (P>0.05), although the mean values were somewhat lower than those of the control group. Observations on haematological parameters indicated DMBA treatment induced a severe anaemia. Total protein, albumin and total cholesterol concentrations decreased following exposure to DMBA at 2.4 and 4.8 mg kg^?1. In contrast, serum bilirubin and blood urea nitrogen in fish exposed to DMBA increased. Significant decreases in serum electrolytes, chloride, phosphorus, magnesium and calcium, and osmolality were observed in all DMBA‐treatment groups. All DMBA‐treatment groups showed a significantly higher activity of lactate dehydrogenase and alkaline phosphatase. Serum transaminase activity after the highest level of 4.8 mg kg^?1 DMBA was significantly increased. The key finding from this study is that rockfish exposed to dietary DMBA at concentrations of 1.2 and 2.4 mg kg^?1 diet are likely to experience adverse impacts in growth and haematological property respectively.     

High abundance of larval rockfish over Cobb Seamount, an isolated seamount in the Northeast Pacific

The larval fish community in the region of Cobb Seamount (500 km west of Oregon) is dominated by myctophid species commonly encountered in the subarctic North Pacific. However, during a survey in June 1992, the ichthyoplankton community within 30 km of the seamount summit was almost completely dominated by larvae of various rockfish ( Sebastes ) species. Given their very small size (and hence very young age) and the fact that they occurred only rarely in samples collected > 30 km from the seamount summit, we conclude that these Sebastes larvae were produced locally over Cobb Seamount. Previous studies have shown that the Cobb fish fauna is dominated by various Sebastes spp. and that, unlike other fish present on the seamount, the rockfish populations may be self-recruiting. We suggest that a persistent clockwise (i.e. downwelling) eddy, consistent with a stratified Taylor cone, plays a critical role in retaining larval rockfish over Cobb Seamount and may contribute to the process of self-recruitment. The key to the success of rockfish on Cobb and other shallow Northeast Pacific seamounts seems to be linked to their viviparous life history.     

许氏平鲉微卫星标记的开发及评价

采用磁珠富集法筛选具多态性的许氏平鲉微卫星标记,并用一个野生群体对其多态性进行了评价。三引物PCR法筛选出58个阳性克隆进行了测序,共得到47个含微卫星核心的DNA序列,筛选出15对具有多态性的微卫星引物。所有位点上共得到66个等位基因片段,每个位点的观测等位基因数(A)为2~14个,平均等位基因数为4.4,观测杂合度(Ho)、期望杂合度(He)范围分别为0.062 5~0.968 8、0.061 5~0.929 1。每个位点的多态信息含量(PIC)显示,有6个位点表现出高度或中度多态。经Bonferroni校正后,HJ2-32、HJ4-27、HJ4-45和HJ4-47四个位点的等位基因频率显著偏离了Hardy-Weinberg平衡。连锁不平衡检测表明,各位点间无连锁不平衡现象。     

The role of environmental conditions and exploitation in determining dynamics of redfish (Sebastes species) in the Northwest Atlantic

The six stocks of redfish (Sebastes spp.) in the Northwest Atlantic have been fished for the past 60 years, during which time they have also experienced considerable variability in environmental conditions. Despite their close proximity and with life‐history features characteristic of many deep‐sea fishes (long‐lived, slow‐growing, late‐maturing, relatively low fecundity), each redfish stock has displayed quite different dynamics. Some have been able to support apparently sustainable fisheries, whereas others have been forced to close. The causes of such differences are unclear. We used dynamic factor analysis to determine the relative impacts of exploitation (days fishing for redfish, days fishing for shrimp, days fished by all fisheries, catch in the redfish fishery, total redfish catch) and environment (North Atlantic Oscillation, surface temperature, salinity, shallow, middle, and deep bottom temperatures) on trends of abundance in each stock over the years 1960–2004. The results showed that a mix of exploitation and environmental variability, with various and different lag times, accounted for observed trends. The Gulf of St. Lawrence stock was affected most by exploitation. Flemish Cap and northern Newfoundland‐Labrador stocks were mostly affected by environmental factors with longer time lags than more southerly stocks. We conclude that management of redfish must take into account individual responses to exploitation and environment over the time periods during which such factors operate, often decades or more, as opposed to the usual practice of reviewing only dynamics of the past few years. Deep‐sea populations cannot be managed on the same scales as shelf fisheries.     

人工选育池蝶蚌的EST和MDH同工酶分析

采用聚丙烯酰胺梯度凝胶电泳的方法, 对人工选育池蝶蚌的3 个世代的8 种组织( 心、肝、肾、外套膜、性腺、鳃、斧足、闭壳肌) 的酯酶( EST)和苹果酸脱氢酶(MDH )进行研究, 比较了不同组织的相对迁移率及酶活性大小。结果表明, 池蝶蚌的EST 和MDH 同工酶具有明显的组织差异性, 不同世代间没有明显的差异性, 表明其经人工选育后已初步成为一个纯系, 遗传性状趋于稳定。     

许氏平鲉消化管上皮细胞及消化腺组织学和组织化学

对许氏平鲉Sebastes schlegeli(Hilgendorf)消化管中的上皮细胞及消化腺进行了组织学及组织化学的研究.经光学显微镜和扫描电镜观察,口咽腔、舌和食道黏膜表面为复层扁平细胞,含有杯状细胞和味蕾,上皮细胞表面具微脊(微皱襞).食道下段复层扁平细胞中夹有单层柱状细胞.胃黏膜表面为单层柱状细胞,细胞表面具顶板.胃贲门和盲囊部有丰富胃腺,盲囊底部和幽门部无胃腺.肠黏膜表面为单层柱状细胞,小肠段杯状细胞丰富,幽门盲囊上皮细胞结构同小肠.另外,还研究了肝脏、胰腺和胆囊的结构.     

Diel vertical distribution of postflexion larval Citharichthys spp. and Sebastes spp. off central California

The diel and spatial distributions of postflexion larval Citharichthys spp. and Sebastes spp. at 67 stations off central California were examined during March 1994 with a 10 m² MOCNESS during 24 h sampling operations. At each station, a CTD profiler with an attached PAR sensor was deployed to measure temperature, salinity, σ_t, dynamic height, and ambient light levels at depth. Catches of C. sordidus, C. stigmaeus, unidentified Sebastes spp., and S. jordani were larger at night than during the day and crepuscular periods, probably because of net avoidance during the day and crepuscular periods, and (for Citharichthys spp.) vertical migration into the upper water column at night. C. sordidus and C. stigmaeus migrated vertically through the pycnocline on a diurnal cycle, while Sebastes spp. apparently remained in the mixed layer above the pycnocline at all times. No definitive patterns were observed between horizontal contours of temperature, salinity, and σ_t at depth and catches of any larvae. This was attributed to the relatively homogeneous spatial pattern in the water column above the pycnocline, where the majority of the fish occurred.