阿根廷滑柔鱼（Illex argentinus）适宜栖息地模型比较及其在渔场预报中的应用

根据2003–2007年1–5月西南大西洋阿根廷滑柔鱼生产统计数据以及表温(SST)、海面高度(SSH)等海洋遥感数据,以作业次数为基础采用外包络法建立SST、SSH的适应性指数模型。分别采用算术平均法(AMM)和几何平均法(GMM)建立栖息地指数(HSI)模型,并对2003–2007年1–5月的HSI值与实际产量和作业次数作比较。研究结果显示,AMM和GMM均拟合较好,HSI>0.6时,AMM的产量和作业次数比例分别为86.75%和89.82%;GMM的产量和作业次数比例分别为84.30%和85.80%,AMM稍优于GMM。利用2008年1–5月的阿根廷滑柔鱼生产数据进行实证分析,结果显示,作业渔场主要分布在HIS>0.6的海域,其产量占总产量的64%以上,作业次数占总作业次数的68%以上;基于SST和SSH的AMM 栖息地指数模型可用于阿根廷滑柔鱼中心渔场的实时动态预报,为该资源的高效开发提供科学依据。     

北斗船位数据提取拖网捕捞努力量算法研究

传统的捕捞努力量统计耗时费力,并且存在延时,不能及时了解宏观的捕捞强度,本研究以象山港拖网渔船为研究对象,选择安装北斗终端的1 508艘渔船,对北斗卫星船位监控系统所获取的渔船船位、航向、航速等信息进行分析挖掘,获得捕捞强度。根据航速统计获得每艘渔船处于捕捞状态的航速阈值,如拖网船300791捕捞状态船位点阈值的航向差最小和最大分别是-50和52°,航速最小和最大分别是0.9和2.0 m/s,两者结合判断捕捞状态点,再采用过滤窗修正,在各渔区格网计算一段时间内渔船捕捞状态点的累计捕捞时间,其值与渔船功率的乘积获得捕捞努力量,物理单位为kW·h,并制作累计捕捞kW·h的格点图和插值图。该方法具有实时、大范围、快速、分辨率高的特点,能够很好地服务于渔业资源保护。     

闽南地区近海定置,拖,围网渔业最适捕捞力量及其管理措施

采用 Schaefer 剩余产量模式估算了闽南近海三大作业——定置网、拖网和灯光围网的渔业资源可捕量和最适捕捞力量,结果定置网的 MSY为5.55万 t,f_(opt)为33745张;拖网的 MSY 为15.92万 t,f_(opt)为2222艘;灯光围网的 MSY 为10.12万 t,f_(opt)为472组。根据评估结果就现有捕捞船(网)数量,提出了削减定置网和拖网作业的捕捞力量,发展灯光围网渔船的调整方案,以及合理利用和科学管理近海渔业资源的具体措施。     

闽南、台湾浅滩渔场单拖作业渔获物组成分析

根据2000~2001年单拖作业渔获物调查资料,着重对渔获物种类组成、个体大小进行分析。结果表明:闽南、台湾浅滩渔场单拖网作业渔获物品种繁多、个体小,优势种数量多、比重小,占周年总渔获量1%以上的品种有19种,鱼类、甲壳类、头足类渔获个体平均体重仅为11.4g/ind,周年中,5~6月个体最小,建议将该渔场单拖作业伏季休渔时间调整为5月1日至7月15日。     

渔船发展动向及节能型渔船

本文分析了我国渔船发展的动向,报道了8170、8171两型拖网渔船采用的节能措施及其船池试验结果。     

闽南、台湾浅滩渔场中上层鱼类资源监测

本文根据闽南、台浅渔场1987～1995年间灯围渔业逐年各月生产统计资料,以及渔获物组成、生殖群体结构和幼鱼发生量对中上层鱼类进行监测和研究。结果表明,80年代末期以来,福建闽南地区灯围作业船组不断减少,但平均单产逐年上升,从而保持了渔业质量在下降中相对稳定。中上层鱼类种群结构非常稳定,蓝圆鲹和金色小沙丁鱼一直是最重要的渔获对象,占灯围产量约2/3。其生殖群体几乎是一成不变,该两个鱼种叉长优势组均为180～200mm,各占60～80％,1龄鱼补充群体数量雄厚,且其幼鱼发生量连年增长,闽中、闽东沿海小型灯围和夏缯等作业夏汛产量逐年迅速上升,由此认为,90年代以来,闽南、台浅渔场中上层鱼类资源利用不足,建议扶持灯围作业,加大对中上层鱼类资源的开发力度。     

Cluster analysis of linear model coefficients under contiguity constraints for identifying spatial and temporal fishing effort patterns

For fisheries management purposes, it is essential to take into account spatial and seasonal characteristics of fishing activities to allow a reliable assessment of fishing impact on resource. This paper presents a novel technique for describing spatial and temporal patterns in fishing effort. The spatial and seasonal fishing activity patterns of the French trawler fleet in the Celtic Sea during the period 1991–1998 were analysed by modelling fishing effort (fishing time) with generalised linear models. The linear model for fishing effort included fixed effects for both spatial (statistical rectangles) and temporal units (months). In addition, spatial correlations in any given month were modelled by an exponentially decreasing function. Temporal correlations were included using the previous month's fishing effort for a given spatial unit as predictor. A method based on cluster analysis of estimated model coefficients of spatial or temporal fixed effects is proposed for identifying groups of similar spatial and temporal units. A contiguity constraint is imposed in the clustering algorithm, ensuring that only neighbouring spatial units or consecutive temporal units are grouped. The cluster analysis identified 22 spatial and 9 temporal groups. Winter and spring months stood out as being more variable than the remaining months. Spatial groups were of varying size, and generally larger offshore. The proposed method is generic and could for example be used to analyse temporal and spatial patterns in catch or catch rate data.     

Habitat of endangered white abalone, Haliotis sorenseni

Surveys with a submersible at offshore islands and banks in southern California found that white abalone were most abundant at depths between 43 and 60 m. This is deeper than estimates taken when white abalone were more abundant. Densities were highest at sites far from fishing ports. Controlling for depth and site found that white abalone were significantly more abundant in areas with Laminaria farlowii (an alga) but abalone were not associated with areas high in the cover of other algae (Pelagophycus porra or Eisenia arborea) or the amount of sand in the habitat (except that abalone always occurred on rock). Within an area with abalone, the particular rock they occurred on was significantly larger than unoccupied neighboring rocks. Occupied rocks were not significantly different in algal cover or in sea urchin density than unoccupied neighboring rocks. The position of abalone on a rock was nearer to the rock-sand interface than would be expected based on a random distribution. More white abalone were feeding when in association with red urchins, perhaps because both grazers capture drift algae to eat. These data may aid future efforts to locate white abalone brood stock and identify locations for outplanting.     

3个杨桃品种茎次生木质部导管分子结构研究

[目的]为杨桃的品种鉴定及果树栽培提供理论依据。[方法]运用细胞图象分析系统及显微照相方法,对3个杨桃品种(秤锤杨桃、蜜丝杨桃、红杨桃)茎次生木质部导管分子结构进行研究。[结果]杨桃茎次生木质部导管分子有两端具尾、一端具尾和无尾3种类型;导管分子平均长度为328.88~366.09μm,平均宽度为44.61~52.43μm;端壁多数为单穿孔板;壁上纹孔式以互列-对列混合纹孔式为主。[结论]杨桃导管分子的多数特征表现为导管分子系统演化过程中较为进化的特征,但也存在导管两端或一端有尾、端壁倾斜等较为原始的性状;杨桃导管分子的结构与其生态适应性相一致,不同品种的生长特性也与导管分子结构差异相一致。     

Dynamics of Iron Oxides in Two Benchmark Inland Valley Soils and Rice Grain Yields in Nigeria

An investigation was conducted on two contrasting inland valley soils (Fluvauents and Tropaquents) over two cropping seasons (1993, 1994, and 1995) in two benchmark wetlands in Nigeria, and the contents and dynamics of iron (Fe) forms (active and organic) were examined when two different rice (Oryza sativa L) cultivars (‘ITA 212’ and ‘Suakoko 8’) were planted. Results showed that active Fe ranged between 0.96 and 3.16% on Fluvaquents and between 1.57 and 4.73% on Tropaquents; organic Fe, on the other hand, ranged between 0.05 and 2.84% (Fluvaquent) and between 0.60 and 2.38% (Tropaquents). Dynamics of the two Fe forms did not follow any clear pattern in the two cropping seasons on both soil types. On Fluvaquents, grain yields (GY) ranged between 2.40 and 3.46 t/ha (‘ITA 212’) and between 2.35 and 3.15t/ha (‘Suakoko 8’). Similarly, on Tropaquents, the GY ranged between 0.68 and 2.13 t/ha (‘ITA 212’) and between 0.61 and 2.11 t/ha (‘Suakoko 8’). Generally, the GY on Fluvaquents was higher than on Tropaquents and declined in the second cropping seasons. Results further showed that active Fe is significantly negatively correlated with GYs of rice. Critical active Fe and organic Fe contents for lowland rice on these soils were 2.90 and 1.80%, respectively.