The Potential for the Restoration of Marine Ornamental Fish Populations Through Hatchery Releases

Populations of tropical and subtropical marine fish are being depleted worldwide to supply increasing demands of the aquarium industry and fresh seafood market. Overfishing and destructive harvest techniques have left some marine fish populations virtually extirpated in a number of primarily underdeveloped countries. In situations where only small remnant populations and significantly degraded habitat remain, population recovery even under the complete absence of collection will be slow, with the high potential for population loss due to natural environmental and recruitment variability. Stock enhancement, supplementing natural recruitment with hatchery produced fry, has the potential to significantly increase the rate of population recovery while maintaining population vigor.Stock enhancement research on Pacific threadfin has demonstrated measurable positive impacts on recreational and commercial fisheries for this species in experimental scale releases; similar successes can be expected for enhancement efforts directed toward species of ornamental value. The major technological barrier to ornamental fish enhancement, the development of appropriate culture capabilities, is being addressed in research directed to the commercial production of fish for the aquarium trade.     

渤海鱼类群落结构及其主要增殖放流鱼类的资源量变化

基于2010年5月和8月渤海渔业调查数据,结合1959年以来渤海鱼类相关文献资料,对渤海鱼类群落结构的演替、主要增殖放流鱼类的资源动态作了初步分析.结果表明,渤海鱼类群落优势种由个体大、营养层次高的带鱼Trichiurus haumela、半滑舌鳎Cynoglossus semilaevis等优质底层鱼类逐渐被黄鲫Setipinna taty、鳀Engra ulis ja ponicus等个体小、营养层次低的小型中上层鱼类所替代,并且除黄鲫外,其他小型鱼类优势种也在不断更替中.另外,生物健康度指数(BHI)分析显示,渤海鱼类群落处于相对不稳定状态.鱼类资源量急剧降低,尤其在5月,CPUE由1959年的186 kg/h下降至目前不足1 kg/h,鱼类资源密集区主要分布在莱州湾、渤海湾和渤海中部,而辽东湾分布相对较少,并且鱼类资源与海蜇呈交错分布.近年来,渤海增殖放流的鱼类仅有花鲈Lateolabrax japonicus和许氏平鲉Sebastes schlegeli的资源量有小幅度回升,其他种类从20世纪80年代开始资源量一直处于下降趋势.从渤海鱼类群落结构的演替和增殖放流鱼类的资源量变化来看,渤海鱼类群落依旧是小型经济价值较低的种类控制其能流结构.除花鲈外,其他增殖放流鱼类的资源量均不足历史最高资源量的1％,其资源量的恢复尚有很大的空间,增殖潜力很大.     

北盘江2种典型增殖放流鱼类突进游速研究

长臀（Cranoglanis bouderius）和白甲鱼（Onychostoma sima）是目前北盘江主要放流鱼类,但这2种鱼的放流效果差异较大。由于鱼类的突进游速在一定程度上影响增殖放流的效果,故试验采用自制测试装置,用递增流速法测试了2种鱼的突进游速。结果显示,白甲鱼的突进游速大于长臀,且2种鱼的突进游速均随体长增加而近似线性增大;而相对突进游速则随着体长的增加而近似线性减小。研究结果可为北盘江鱼类增殖放流和放流效果评估,以及日后北盘江的拦鱼、诱鱼、集鱼船等鱼类资源保护措施的实施提供参考。     

我国海洋牧场建设回顾与展望

海洋牧场是基于海洋生态学原理和现代海洋工程技术,充分利用自然生产力,在特定海域科学培育和管理渔业资源而形成的人工渔场。海洋牧场的特点包括以增加渔业资源量为目的、具有明确的边界和权属、苗种主要来源于人工育苗或驯化、通过放流或移植进入自然海域、主要以天然饵料为食和对资源实施科学管理等。早在1965年,我国学者曾呈奎先生就原创性地提出在海洋中通过人工控制种植或养殖海洋生物,建设"牧场"的理念。上世纪八十年代以来,我国海洋牧场经历了从增殖放流、人工鱼礁建设到系统化的海洋牧场发展过程,在取得巨大成就的同时,也面临着海洋牧场的涵义应用过于宽泛、缺乏统筹规划和科学论证、忽视海洋牧场生态作用以及忽视项目评估和系统管理等问题。展望未来,我国的海洋牧场建设应在"生态优先、陆海统筹、三产贯通、四化同步、创新跨越"的发展理念指导下,加强海洋牧场建设的宏观引导、推动海洋牧场体系化建设、实施海洋牧场企业化运营,在获得经济效益的同时,实现产业繁荣和保持健康生态系统的和谐统一。     

三横山人工鱼礁区鱼类和大型无脊椎动物诱集效果初探

为了解人工鱼礁投放对鱼类和大型无脊椎动物(简称FM,以下同)的诱集效果,分别于2007年5、9月和2009年3、5、7月对上三横山人工鱼礁B区与泥底区进行了拖网本底和跟踪调查,并于2009年1-8月对下三横山人工鱼礁A区与鳗头山岩礁和泥底区进行了刺网调查。采用CPUE、Margalef种类丰富度d、经济种类数变化、Whilm多样性指数H′′等反映FM的资源状况。结果显示,(1)鱼礁A区和岩礁区在CPUE、种类丰富度、经济种和多样性上均无明显差异(P>0.05),而两者各指标与泥底区皆存在显著差异(P<0.05);(2)鱼礁B区,投礁后CPUE和经济种类数都明显高于投礁前也大于同期对照区,差异显著(P<0.05);礁区平均丰富度水平高出同期对照区31.1%(P<0.05);多样性水平相对投礁前和对照区都有一定提高,但尚无显著差异(0.05相似文献   

Potential for reintroduction of lake sturgeon in five northern Lake Michigan tributaries: a habitat suitability perspective

• 1. Conservation and rehabilitation efforts for lake sturgeon Acipenser fulvescens throughout the Great Lakes include the re‐establishment of self‐sustaining stocks in systems where they have been extirpated.
• 2. Information on the suitability of potential lake sturgeon habitat in tributaries is important for determining their capacity to support lake sturgeon stocking and to develop system‐specific rehabilitation strategies.
• 3. Geo‐referenced habitat information characterizing substrate composition, water depth, and stream gradient were applied to a life‐stage specific lake sturgeon habitat suitability index in a geographic information system to produce spatially explicit models of life‐stage specific habitat characteristics in five northern Lake Michigan tributaries from which lake sturgeon have been extirpated.
• 4. Habitat models indicated that high quality lake sturgeon spawning and staging habitat comprised 0 to 23% and 0 to 9% of the available habitat, respectively, whereas high quality juvenile lake sturgeon habitat was relatively ubiquitous throughout each river and comprised 39 to 99%.
• 5. Comparison of these data to lake sturgeon habitat availability in Lake Michigan tributaries currently supporting populations indicated that spawning and staging habitats may limit the ability of these systems to support spawning. Efforts to re‐establish lake sturgeon populations in these systems should consider the creation of spawning and staging habitat to increase reproductive and recruitment potential prior to the initiation of stocking efforts.

Copyright © 2007 John Wiley & Sons, Ltd.     

数字图像处理在SEM空蚀图像定量分析中的应用

针对收缩-扩散型水洞中进行铝制翼型空蚀破坏试验时,传统度量不能准确量化翼型表面不同位置的空蚀程度,提出了数字图像检测的方法.获取试验翼型表面SEM空蚀图像,然后对图像进行模糊增强,并进行类间方差最大阈值分割,用二值形态学方法处理边缘,最后由统计特性计算出空蚀破坏表面积、蚀坑数量等.图像测量可得到空蚀对翼型表面破坏数值的定量结果.     

Effects of instream structures on Kirikuchi charr, southernmost population of genus Salvelinus, in a small mountain stream of Japan

ABSTRACT:   The changes in physical habitats and responses of fish, e.g. the Kirikuchi charr Salvelinus leucomaenis japonicus , were examined by placing instream structures in a stream on the upper drainage of the Totsu River system of the Kii Peninsula, Japan, over a two-year period. Instream structures created pools below the structures, and these pools have maintained their functions as fish habitats over two years. In two treatment sections, sections A and B (some red-spotted masu salmon were removed in advance in section B), mean water depth increased soon after placing the structures, but decreased over two years. Mean water velocity slowed after placing the structures in both sections. Total fish abundance has been relatively high at the two treatment sections compared with a control section after placing the structures. Age 1 Kirikuchi charr, however, increased only in section B. These results indicate that instream structures can serve as habitat enhancement for fish, including Kirikuchi charr, in the study area if other appropriate habitat factors for respective species are taken into consideration.     

Scale stocking checks to differentiate between hatchery-reared and wild mulloway Argyrosomus japonicus

Abstract  Scales from hatchery-reared, stocked and wild mulloway Argyrosomus japonicus (Temminck and Schlegel) captured in the Georges River, and a library of mulloway scales from coastal New South Wales, were examined for the presence of scale checks. Checks specific for hatchery-reared fish were present in 100% of recaptured hatchery-reared mulloway; the origin of which was confirmed by the presence of a chemical mark in the otolith or fin spine. Up to 7% of wild mulloway were incorrectly classified as hatchery-reared on the basis of these checks. An abrupt reduction in salinity from 35 to 5 and 6 days starvation successfully induced checks in the scales of hatchery-reared mulloway. The marking efficiency for stocking checks was comparable to that obtained using oxytetracycline hydrochloride, and supports the short-term use of scale stocking checks to evaluate mulloway stock enhancement programmes in Australia.