银山种群生态学研究

银杉(Cathaya argyrophylla)是我国特有的珍贵植物，被认为处于濒危状态。本文结合前人的研究，通过大量的野外调查，弄清了银杉的种质资源现状，分析银杉的群落特征，在此基础上重点研究了银杉种群的主要特征。 研究表明，现存银杉间断分布于我国亚热带山地，形成4个集结地，资源总量（株高大于1米者）不占4000棵。现有银杉群落处于演替的早、中期阶段，到演替后期，银杉将被组成地带性植被的优势阔叶树种取代。 银杉种群的空间分布格局与银杉的生物学特性及微环境有关。在老龄种群内，容易产生林窗，银杉在林窗形成异龄群聚，以寻求充足的光照和营养支持，种群多表现为集群分布;在群落内微环境异质性较明显时，也导致集群分布。在各种银杉群落中，就银杉种群而言，光因子可能是影响其分布格局的主导因子。银杉种群集群分布的格局规模虽在和群落种群间有明显差异，但大多在面积小于16平方米的较小尺度下发生。 银杉各群落类型中银杉种群年龄化加剧的现象，有些种群在某些龄组出现断层。从年龄结构看，有些银杉种群处于被阔叶树种更替的境地。 林窗干扰对银杉种群的更新意义重大，在林窗内和非林窗银杉群落内，银杉种群的重要值均为最大;银杉幼树在林窗内的高生长量普遍大于荫蔽的林冠下，这些充分说明银杉是典型的林窗更新方式。 银杉结实有明显的大小年之分，一般在2-3个小年之后为1-2个大年，母树结实量不与树龄成正相关，在植株间差别很大。每个球果出种量平均为4.267粒，无种子的球果占比重达12.2%。饱满种子的平均重量仅为0.0197克，远远低于乔木树种种子的平均水平。林地内自然善状况下播种，种子发芽率仅为21%，松土后播种可使发芽率加倍。种子宜于湿沙贮藏，干藏导致种子发芽率大幅度下降。松鼠是长期危害球果的主要动物，其危害率可达15%。 对银杉生长规律的研究发现，幼龄银杉在全光照下和荫蔽林冠下比在林窗内高生长都要缓慢;成年银杉高生长盛期在130年前出现;银杉种群地上部分生物量在大部分群落类型间介于62000-91000千克/公顷之间。 第四纪冰川时期，强烈的气候变迁，造成银杉种群的大尺度减少，并导致其间断分布于我国亚热带山地;冰后期以来的气候波动及近代剧烈的人类活动使已经片断化的银杉种群数量进一步下降。从而导致银杉遗传多样性低和生殖障碍大，后者反过来又进一步引起种群数量下降和分布区缩小，形成恶性循环，造成银杉濒危。

Break through in 10 million fry production at Khutelabhata fish seed farm, Durg, Madhya Pradesh

This paper presents a resume of the work carried on the production of 10 million major carp fry by stocking at the rate of 10 million spawn per hectare in 38 nursery ponds covering 2.1 ha. water spread area at Khutelabhata fish seed farm, Durg, Madhya Pradesh. Observations made on the effect of various types of feed on survival and growth rate of Indian Major carp fry in nurseries are reported. Physico-chemical parameters and plankton populations in the three sets of nurseries are given. The experiments indicates that optimum survival rate of fry can be obtained by feeding tender spawn with animal protein feed. The economic viability of the experiment discussed shows that for a little increase in the expenditure on improved artificial food the survival and growth of fry can be enhanced.

Strategy of fish seed production in India

In tropical countries like India, climatic conditions vary in different parts, as a result the breeding of fast growing species such as Catla and silver carps poses considerable problems due to erratic or late monsoon or prolonged dry spell. Hence it is not possible to meet the fish seed requirement of the country. Therefore: to meet the future requirement and to over-come the environmental conditions a Modern carp Hatchery CIFE D-81 was designed. The system provides optimum temperature, silt free clean, cool, highly oxygenated water, low current and continuous removal of metabolites. It has been successfully demonstrated at Rawatbhata (Rajasthan), Badkhal (Haryana), Badbhada (M.P), Guntur and East Godavari District (A.P). Recently a Modern Carp Hatchery was installed in a semi-arid zone, Damdama (Haryana), during 1984, where it has produced record 1.88 crores of fish seed and worked successfully.

Prawn seed resources and its farming potentialities in Sunkeri back waters (Kali Estuary - Karwar)

Prawn seed resources of Sunkeri back waters indicated the availability of Penaeus indicus, P. monodon, Metapenaeus dobsoni and M. monoceros. The monthly variation in seed composition, its correlation with environmental parameters and the aquaculture potentialities are reported

Control of crabs and snakes in freshwater fish seed farms

A design has been developed to adopt in freshwater fish seed farms for controlling crabs and snakes. The method is convenient and effective. It prevents the entry of crabs and snakes into the ponds.

Carp seed production during drought year 1987 under controlled hatchery system

The introduction of the controlled hatchery system "Model CIFE D-81" resulted in a production of 60 lakhs Indian major carp seed in the drought area of eastern Uttar Pradesh. The hatchery system provided optimum temperature, dissolved oxygen and pH for breeding and hatching and also removed the metabolites generated. The technology is simple and the success of the program attracts pisciculturists.

Fish seed production under controlled hatchery system: a cottage industry

The fish seed production in recent times has emerged as a cottage industry, with the development of controlled hatchery system. Two units of six buckets of vertical hatchery system i.e. Modern Carp Hatchery CIFE D-81 were installed in a private fish farm. 130.25 lakh spawn of Indian Major Carp (Cyprinidae) was produced during the 1988 season, with an average survival rate of 70%. The results support the viability of technology especially for the economically weaker section.

Recent advances in the hatchery production of seed of some commercial bivalves in India

The Central Marine Fisheries Research Institute has established a shellfish hatchery laboratory at its Tuticorin Research Centre with the objective of developing appropriate technology for the production of seed of commercial bivalves. A viable technology was developed for the mass production of the seed of Pinctada fucata, P. margaretifera, Crassostrea madrasensis, Perna indica, P. viridis, Anadara granosa and Meretrix meretrix. The hatchery facility and the technology, comprising brood stock conditioning, induced spawning, larval rearing and seed production are described. In the light of these developments the future outlook is appraised.