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排序方式: 共有1318条查询结果,搜索用时 31 毫秒
91.
1992年,在50m^3水体中,太平洋牡蛎控温育苗量为20.2万粒/m^3。当年筏式殖6个月,亩产5670kg,利税6400元平均亮高8cm以上,个体重97.4g,比常温育苗,可缩短养殖周期近1年,专家鉴定认为:本研究属国内首创,居国内领先水平。 相似文献
92.
The relationships between fishing ground locations of Pacific saury (Cololabis saira) and the two Oyashio fronts, the offshore front between 146oE and 155oE and the coastal Oyashio intrusion, before the saury fishing season, were examined using data from 1971 to 1991. Interannual geographical shifts of both the offshore Oyashio front and saury fishing grounds had a dominant interdecadal fluctuation. In years when the offshore front shifted north (south), the fishing grounds were formed relatively nearshore (offshore). When the offshore front shifted north, the fishing grounds were formed further nearshore in years the coastal Oyashio intrusion extended south. When the offshore front shifted south, on the other hand, the southward extension of the coastal intrusion did not necessarily cause formation of coastal fishing grounds. These results showed that locations of the fishing grounds depend not only on local and instantaneous oceanographic environments around the fishing grounds, but also on oceanographic conditions over an extensive range of the Oyashio area. This might indicate that the ecology of the saury's northward migration, through mixed water regions between the Kuroshio and Oyashio fronts in spring and summer, has a close relation to the shift of the offshore Oyashio front over a time range of months. A practical forecasting method for locations of saury fishing grounds is proposed based on the oceanography before the fishing season. 相似文献
93.
94.
The optimal stability `window': a mechanism underlying decadal fluctuations in North Pacific salmon stocks? 总被引:2,自引:0,他引:2
ANN E. GARGETT 《Fisheries Oceanography》1997,6(2):109-117
While recent evidence suggests that North Pacific salmon stocks are influenced by decadal variability in atmospheric forcing of the ocean, the actual combination of physical and biological processes that determines this linkage has not been identified. This paper describes a possible scenario in which water column stability is the primary factor by which the physical environment influences phytoplankton production, the basis for production at higher trophic levels. Variation in the strength of the wintertime Aleutian Low pressure area affects water column stabilities, hence primary production, along the entire eastern boundary of the North Pacific. The `optimal stability window' explains the qualitative relationship between fish stocks and the strength of the winter Aleutian Low, as well as the observed out-of-phase variation between northern and southern salmon stocks. 相似文献
95.
Patterns of stable carbon and nitrogen isotopes in the baleen of common minke whale Balaenoptera acutorostrata from the western North Pacific 总被引:3,自引:0,他引:3
ABSTRACT: Stable carbon and nitrogen isotope ratios were determined in the baleen plates of 17 common minke whales Balaenoptera acutorostrata from the north-western Pacific Ocean off Japan, as well as prey species (krill Euphausia pacifica , Japanese anchovy Engraulis japonicus and Pacific saury Cololabis saira ) collected in the stomach contents, to investigate the trophic relationship between the minke whales and their prey. A few δ15 N-depleted peaks occurred along the length of baleen plates for 10 males irrespective of stomach content (anchovies and sauries). Similar δ15 N-depleted peaks were also found for one female and two immature individuals. It was likely that these δ15 N-depleted peaks formed in early summer. The stable nitrogen isotope ratio (δ15 N) values in Pacific saury (9.3 ± 1.4‰) did not differ significantly from that in Japanese anchovy (8.8 ± 0.9‰). In contrast, δ15 N in krill (7.2 ± 0.5‰ in July and 8.0 ± 0.2‰ in September) were significantly lower than in the Pacific saury. Thus, these peaks may reflect the dietary change from krill to fishes in the feeding migration of the whales. Growth rate of the baleen plate was estimated to be 129 mm/y, and it appeared that a dietary record of about 1.4 years remained in the baleen plate. For two immature whales, the maximum value of δ15 N occurred at the tip of baleen. This δ15 N enrichment may possibly be useful for discriminating weanlings and older whales. 相似文献
96.
Takashi Kitagawa Shingo Kimura Hideaki Nakata Harumi Yamada 《Fisheries Oceanography》2004,13(3):161-180
Twenty‐four archival tags were recovered from Pacific bluefin tuna previously released off Tsushima Island in the East China Sea. By analysis of the time‐series data of the pressure and the ambient and internal temperature from the 24 tags, we examined the relationship between the tuna's pattern of diving and the thermocline depth. In the East China Sea, diving and feeding events occurred throughout almost the entire day in both winter and summer, suggesting that the purpose of diving is for feeding. In summer, the feeding frequency was greater than that in winter, which corresponds to the fact that growth is more rapid in summer than in winter. During summer in the Kuroshio–Oyashio transition region, on the other hand, feeding events were much more frequent than those in the East China Sea, in spite of a lower diving frequency. The mean horizontal distance traveled was also significantly higher and it seems that in this area they may move horizontally to feed on prey accumulated at the surface. We conclude that, in addition to the ambient temperature structure, the vertical and horizontal distribution of prey species plays an important role in the feeding behavior of Pacific bluefin tuna. One bluefin tuna migrated to the Oyashio frontal area, where both the horizontal and the vertical thermal gradients are much steeper. The fish spent most of the time on the warmer side of the front and often traveled horizontally to the colder side during the day, perhaps to feed. This implies that there is a thermal barrier effect, in this case from the Oyashio front, on their behavior. The frequency of feeding events was low, although all the monitored fish dived every dawn and dusk, irrespective of the seasons or location. It is possible that these twice‐daily diving patterns occurred in response to the change in ambient light at sunrise and sunset. 相似文献
97.
陈新军 《上海海洋大学学报》1999,(3)
本文根据1997年6月~7月北太平洋(16°E~170°E)海域柔鱼探捕调查的资料,对渔场形成的海洋环境条件进行了初步分析。160°E~170°E海域的大型柔鱼渔场主要由亲潮策3和第4分支与黑潮的第4和第5分支交汇形成,特别是在深层(100米水层)的暖水域前端形成。其表层水温一般为11~13°,100米水层水温约为9~10℃。其中167°E~170°E海域的渔场较为稳定,可供北太平洋鱿钓船的前期生产。中心渔场形成时常有浮游生物层。浮游生物层越厚实,渔获量越高,但有关浮游生物层的形成原因需作进一步的研究与探讨。 相似文献
98.
以鲜葡萄和北虫草菌丝体为主要原料,经正交试验得出北虫草—葡萄补酒的最佳发酵条件为温度25℃,酵母菌种添加量为2%,北虫草菌丝体的添加量为30%,糖度15%,偏重亚硫酸钠添加量为140mg.L-1。北虫草菌丝体在后发酵中加入,得到营养丰富、酒香醇厚、风味独具,具有保健功效的北虫草—葡萄酒补酒。 相似文献
99.
100.
Peter S. Homann Mark Harmon Suzanne Remillard Erica A.H. Smithwick 《Forest Ecology and Management》2005,220(1-3):270-283
How much organic C can a region naturally store in its ecosystems? How can this be determined, when land management has altered the vegetation of the landscape substantially? The answers may lie in the soil: this study synthesized the spatial distribution of soil properties derived from the state soils geographic database with empirical measurements of old-growth forest ecosystem C to yield a regional distribution of potential maximum total-ecosystem organic C stores. The region under consideration is 179,000 square kilometers extending from the southern Oregon border to the northern Washington border, and from the Pacific Ocean to the east side of the Cascade Mountains. Total ecosystem organic C (TEC) was measured in 16 diverse old-growth forests encompassing 35 stands and 79 pedons to a depth of 100 cm. The TEC ranged between 185 and 1200 Mg C ha−1. On an average, 63% of TEC was in the vegetation, 13% in woody detritus, 3% in the forest floor, 7% in the 0–20 cm mineral soil, and 13% in 20–100 cm mineral soil. The TEC was strongly related to soil organic C (SOC) in the 0–20 cm mineral soil, yielding a monotonically increasing, curvilinear relation. To apply this relation to estimate the TEC distribution throughout the region, 211 map units of the state soils geographic database (STATSGO) were used. The SOC in the 0–20 cm mineral soil of the map units was consistent with values from previously measured pedons distributed throughout the region. Resampling of 13 second-growth forests 25 years after initial sampling indicated no regional change in mineral SOC, and supported the use of a static state soils map. The SOC spatial distribution combined with the quantitative old-growth TEC–SOC relation yielded an estimate of potential TEC storage throughout the region under the hypothetical condition of old-growth forest coverage. The area-weighted TEC was 760 Mg C ha−1. This is 100 Mg C ha−1 more than a previous estimate based on a coarser resolution of six physiographic provinces, and 400 Mg C ha−1 more than current regional stores. The map of potential TEC may be useful in forecasting regional C dynamics and in land-management decisions related to C sequestration. 相似文献