Harbour seal movements and haul‐out patterns: implications for monitoring and management

• 1. Compliance with conservation legislation requires knowledge on the behaviour, abundance and distribution of protected species. Seal life history is characterized by a combination of marine foraging and a requirement to haul out on a solid substrate for reproduction and moulting. Thus understanding the use of haul out sites, where seals are counted, as well as their at‐sea movements is crucial for designing effective monitoring and management plans.
• 2. This study used satellite transmitters deployed on 24 harbour seals in western Scotland to examine movements and haul‐out patterns.
• 3. The proportion of time harbour seals spent hauled out (daily means of between 11 and 27%) varied spatially, temporally and according to sex. The mean haul‐out duration was 5 h, with a maximum of over 24 h.
• 4. Patterns of movement were observed at two geographical scales; while some seals travelled over 100 km, 50% of trips were within 25 km of a haul‐out site. These patterns are important for the identification of a marine component to designated protected areas for the species.
• 5. On average seals returned to the haul‐out sites they last used during 40% of trips, indicating a degree of site fidelity, though there was wide variation between different haul‐out sites (range 0% to >75%).
• 6. Low fidelity haul‐out sites could form a network of land‐based protected areas, while high fidelity sites might form appropriate management units.

Copyright © 2008 John Wiley & Sons, Ltd.     

The Moray Firth Seal Management Plan: an adaptive framework for balancing the conservation of seals,salmon, fisheries and wildlife tourism in the UK

• 1. Within the Moray Firth, north‐east Scotland, there is a history of conflict between seals and salmon fisheries. Under the UK's Conservation of Seals Act 1970 (CoSA) seals are shot to protect fisheries. In 1999 six rivers in the Moray Firth were designated as Special Areas of Conservation (SACs) for Atlantic salmon under the EU Habitats Directive, and in 2000 an SAC for harbour seals was designated in the Dornoch Firth.
• 2. In the 1990s salmon stocks declined. Fisheries managers believed the decline was partly caused by seal predation and consequently increased shooting effort. In years 1993–2003 Moray Firth harbour seal numbers declined possibly due to shooting, posing a potential threat to the status of the Dornoch Firth SAC. Meanwhile wildlife tourism based on marine mammals has increased. The declines in salmon and harbour seals, and the implementation of the Habitats Directive forced a watershed in the approach of statutory authorities to managing seals, salmon and tourism.
• 3. In years 2002–2005 local District Salmon Fishery Boards, the Scottish Executive, Scottish Natural Heritage and stakeholders negotiated a pilot Moray Firth Seal Management Plan to restore the favourable conservation status of seal and salmon SACs, and to reduce shooting of harbour seals and seal predation on salmon.
• 4. Key facets of the plan are the management of the Moray Firth region under a CoSA Conservation Order; application of the Potential Biological Removal concept to identify a limit of seals to be killed; management areas where removal of seals is targeted to protect salmon, while avoiding seal pupping and tourism sites; a training and reporting system for marksmen; a research programme, and a framework allowing an annual review of the plan.
• 5. The plan was introduced in April 2005. A maximum limit of 60 harbour and 70 grey seals was set. Forty‐six harbour and 33 grey seals were killed in 2005 while in 2006 these figures were 16 and 42 respectively. Although the numbers killed were below the maximum limits in both years the returns raised questions about the plan's ability to manage seal shooting at netting stations. The plan provides a useful adaptive co‐management framework for balancing seal and salmon conservation with the protection of fisheries and/or fish farms and tourism for application in the UK and internationally.

Copyright © 2008 John Wiley & Sons, Ltd.     

Movements of fur seals following relocation from fish farms

• 1. The movement patterns of Australian and New Zealand fur seals trapped on salmon farms in south‐east Tasmania and relocated hundreds of kilometres away, were monitored using satellite telemetry. Australian fur seals released 470 km away by sea returned to farms after an average of 8.5±4.4 days (n=9 trips) and those released at 140 km returned after 3.2±0.8 days (n=4 trips). New Zealand fur seals (n=5 trips) averaged a return time of 6.8±1.2 days from 300 km.
• 2. When in south‐east Tasmania, both seal species undertook short trips to sea (mean 2.6 days) from haul‐out sites (minimum distance from farms 21 km) with 33% (1.8 days) of this time spent within 5 km of farms. Mean haul‐out duration was 1.1 days.
• 3. In summer, Australian fur seals repeatedly travelled between northern Bass Strait islands and southern Tasmanian waters following the Tasmanian east coast. Seals did not visit farms during this time.
• 4. Southern Tasmanian waters are important foraging grounds for fur seals and potential exists for a substantial number of seals to visit nearby fish farms. Farms provide predictable food resources from penned and escaped salmon, and wild fish attracted to the area.
• 5. Australian fur seals trapped at Tasmanian salmon farms regularly visited breeding colonies on islands in Victoria.

Copyright © 2008 John Wiley & Sons, Ltd.     

微波消解-原子荧光光谱法测定人参海狗丸中的砷·汞含量

[目的]建立微波消解样品、氢化物发生原子荧光光谱法测定人参海狗丸中砷(As)、汞(Hg)含量的方法。[方法]将人参海狗丸样品经硝酸微波消解后,用原子荧光光谱法同时测定As、Hg 2种元素。[结果]试验测得,供试人参海狗丸样品中As、Hg回收率分别为96.2%～109.5%,95.6%～109.1%,RSD<5%。[结论]所建立的方法操作简便、快速、准确、灵敏、重复性好,适用于人参海狗丸中As、Hg的测定。     

基于动网格的上游泵送机械密封性能参数分析

为了准确获得上游泵送机械密封的液膜厚度,采用Pro/E软件建立螺旋槽上游泵送机械密封的三维参数化模型,应用Fluent软件的动网格技术,同时考虑空化的影响,对机械密封微间隙内流场进行了数值模拟.将得到的液膜厚度与有关文献的测试结果进行对比分析.在同时考虑空化模型和动网格技术的基础上,计算分析了工况参数对液膜刚度和泄漏量的影响.结果表明,应用动网格计算的液膜厚度与测试结果所获得的结果基本一致,最大相对误差为19.6%,最小相对误差为0,平均相对误差为8%,从而验证了动网格技术在机械密封内流场模拟中的可行性;机械密封内流场计算应当考虑空化问题,才能得到比较真实的内流场特性;液膜厚度、泄漏量和液膜刚度随着转速、介质压力的增大而增大,端面螺旋槽在产生泵送效应的同时也产生动压效应.     

中国核桃主要品种坚果缝合线特性研究

以我国的农家核桃品种以和目前主栽的早实品种为试材,以美国主栽品种强特勒为标准品种,对坚果的缝合线特性开展了研究.结果表明:缝合线紧密度与其高度、内褶壁厚度呈显著正相关关系,而与栽植地变化无关.我国传统优良品种的缝合线紧密度与强特勒无明显差异,而早实品种缝合线紧密度差与强特勒有明显差异.     

浮顶储罐二次密封装置的雷击危险性

大型浮顶油罐通常安装二次密封装置,其所处位置存在燃爆油气空间,极易导致雷击火灾事故。雷击危险性理论指出:二次密封装置的导电片依靠外界弹力贴合,并非连续可靠的电气连接,在雷电流流过时存在产生火花放电的可能性。采用8/20s冲击电流波进行雷击危险性实验验证,结果表明:导电片与罐壁接触越可靠,越不易产生雷击打火;油污能够在一定程度上抑制火花的出现,但无法起到绝缘作用,雷电流仍然会通过导电片并产生火花放电现象;雷电流通过导电片时,电流只需达到几百安培即可引起火花放电。基于上述结论,提出了建议措施,对于确保大型浮顶储罐防雷击安全运行具有指导作用。