合理利用近海水域养殖能力实现稳定持续生产

合理利用近海水域养殖能力实现稳定持续生产许洁（辽宁省海洋水产研究所，大连１１６０２３）苗振华（辽宁省大连渔政管理局，１１６０１３）赵丽敏（辽宁省海洋水产厅，沈阳）２１世纪是海洋的世纪，随着这一世纪的到来，人类对于海洋资源的开发利用将不断地加强。就海域...

Study on the Carry Capacity of Edible Jellyfish Fishery in Liaodong Bay

Jellyfish fishing is a special type of fishery that mainly exists in some countries of East and Southeast Asia. China has the largest jellyfish fishery yield in the world with an annual harvest of around 300 thousand tons. Liaodong Bay is the most important jellyfish fishery ground in China. However, due to the high benefits of jellyfish fishery, which leads to illegal and out-of-season jellyfish fishing occurring each year in Liaodong Bay. Illegal jellyfish fishery in Liaodong Bay is a typical example of the tragedy of the commons. The key problem is that fishermen seek to an illegally initiate jellyfish fishing as early as possible. In this paper, basing on the data of edible jellyfish's biology and ecology, we mainly analyzed the history of jellyfish fishery in China, especially in Liaodong bay, and then we calculated the carry capacity of edible jellyfish in Liaodong Bay which is about 300 thousand tons one year. This number is equal to the recent annual yield of edible jellyfish in China. Furthermore, basing on the carry capacity and reasonable quotas price analysis, we set up a Jellyfish fishing quotas and deficit quotas buyback system which could be a suitable and effective solution for jellyfish fishery management and development in Liaodong Bay at the underlying roots. Although China is the first country with edible jellyfish aquaculture, the annual yield of jellyfish aquaculture is only one fifth of jellyfish fishing. So, there is a very bright developing prospect about edible jellyfish aquaculture in China.

De-eutrophication of effluent wastewater from fish aquaculture by using marine green alga Ulva pertusa

The de-eutrophication abilities and characteristics of Ulva pertusa, a marine green alga, were investigated in Qingdao Yihai Hatchery Center from spring to summer in 2005 by analyzing the dynamic changes in NH4-, NO3-, NO2- as well as the total dissolved inorganic nitrogen （DIN）. The results show that the effluent wastewater produced by fish aquaculture had typical eutrophication levels with an average of 34.3 ~mol L-1 DIN. This level far exceeded the level IV quality of the national seawater standard and could easily lead to phytoplankton blooms in nature if discarded with no treatment. The de-eutrophication abilities of U. pertusa varied greatly and depended mainly on the original eutrophic level the U. pertusa material was derived from. U. pertusa used to living in low DIN conditions had poor DIN removal abilities, while materials cultured in DIN-enriched seawater showed strong de-eutrophication abilities. In other words, the de-eutrophication ability of U. pertusa was evidently induced by high DIN levels. The de-eutrophication capacity of U. pertusa seemed to also be light dependent, because it was weaker in darkness than under illumination. However, no further improvement in the de-eutrophication capacity of U. pertusa was observed once the light intensity exceeded 300 pmolM2 S1. Results of semi-continuous wastewater replacement experiments showed that U. pertusa permanently absorbed nutrients from eutrophicated wastewater at a mean rate of 299 mg/kg fresh weight per day （126 mg/kg DIN during the night, 173 mg/kg in daytime）. Based on the above results, engineered de-eutrophication of wastewater by using a U. pertusa filter system seems feasible. The algal quantity required to purify all the eutrophicated outflow wastewater from the Qingdao Yihai Hatchery Center into oligotrophic level I dean seawater was also estimated using the daily discharged wastewater, the average DIN concentration released and the de-eutrophication capacity of U. pertusa.

The Relationship Between Behavior with Some Productive Traits of Rabbits

This study aimed to obtain, by selection two lines of New Zealand white rabbits differing in total motor activity and to compare them for fertility, prolificacy, mortality and weight gains of young rabbits from birth until weaning. The emotional states of animals such as fear were analysed with the behavioural tests （open field, tonic immobility） and stress-induced hyperthermia （SIH）. These tests were the criterion for assigning animals to two experimental groups： group I, 10 males and 20 females with the highest total motor activity （A）; group II, 10 males and 20 females showing little or no motor activity （N）. Important differences were found in male and female fertility. During the first week, 80% of males mated in group I compared to only 20% in group II. Despite their normal breeding condition, passive males were timid and ponderous during mating, unlike active males which mated willingly and rapidly. Fertility was high in both groups （87.5% and 94.7% in group I and II）. Unlike females from group II, females from group I showed no tendency towards nest building. 40% of females from group I gave birth in different cage areas, while 90% of females from group II gave birth in nest boxes with down and straw bedding. No differences were found between the active and passive lines for body weight at birth or at 35 days of age.

Performance of Smallholder Dairy Farming in Nakuru County, Kenya

The Kenya dairy sub-sector has been undergoing developments since the 1980s in the areas of adoption of intensive dairy farming, especially zero grazing. There have been concerted efforts by the government and other development partners to commercialize the sub-sector so as to make it more profitable to farmers, especially smallholder farmers, but the profitability in the sector continues to be variable with some smallholder farmers making losses. The causes of the varying profits have not been empirically established, with the influence of institutional arrangements and financial factors contributing to this inconsistency not fully established. This study dwelt on establishing the critical institutional arrangements and financial factors that constrain the profitability of smallholder dairy farmers in Nakuru County. A multi-stage sampling procedure was used to select respondents. Data were collected by structured interviews at the farm level. Data Envelopment Analysis （DEA） was used to come up with profit efficiency rankings among the farmers, and the Frontier Model was used to establish the factors that constrain profit efficiency. The mean efficiency according to the results was 86%. The farm and farmer characteristics that were significant in explaining profitability efficiency according to the frontier results were： feeding system, breed type, and gender. The financial characteristics included debt amount and debt asset ratio. Additionally, issues of trust were also found to have an effect on profitability, and they included trust in local buyer price, trust in unit of measurement of institutional buyer, and trust in unit of measurement of middlemen.