School of Environment and Technology, University of Brighton, Cockcroft Building, Lewes Road, Brighton BN2 4GJ, UK.
J Fish Biol. 2011 Jan;78(1):23-38. doi: 10.1111/j.1095-8649.2010.02830.x. Epub 2010 Dec 14.
A method was developed to quantify the number and biomass of European eels Anguilla anguilla escaping to the ocean for breeding. The non-intrusive method, involving a fixed-position, high-frequency multi-beam sonar, permitted constant surveillance of A. anguilla movements throughout their 5 month escapement season (July to December). During this period, >1000 individuals were monitored escaping to the Atlantic Ocean from their freshwater habitat in the River Huntspill study site (Somerset, U.K.). The total length of each fish was measured using the sonar software. These measurements were then converted to an estimate of mass using a length:mass regression relationship derived from historical fyke-net data from this site, comprising c. 500 A. anguilla length:mass measurements collected over a 10 year period. The net biomass of escapement from the study site was equivalent to c. 6 kg ha⁻¹ year⁻¹, lower than the present European target which would require at least 7 kg ha⁻¹ year⁻¹ from this habitat. These findings demonstrate the capabilities of this monitoring technique and its usefulness both as a tool to assess the compliance with conservation targets and as a tool to evaluate the success of conservation measures for elusive aquatic species such as A. anguilla.
开发了一种方法来量化逃逸到海洋进行繁殖的欧洲鳗鲡（Anguilla anguilla）的数量和生物量。这种非侵入性方法涉及固定位置的高频多波束声纳，可在其 5 个月的逃逸季节（7 月至 12 月）中持续监测 A. anguilla 的运动。在此期间，超过 1000 条个体从其在萨默塞特亨特斯皮尔河（Somerset）的淡水栖息地逃逸到大西洋。使用声纳软件测量每条鱼的全长。然后，使用从该地点的历史刺网数据得出的长度-质量回归关系，将这些测量值转换为质量估计值，该关系包括在 10 年期间收集的约 500 条 A. anguilla 的长度-质量测量值。从研究地点逃逸的网生物量相当于每年每公顷 6 公斤，低于目前的欧洲目标，该目标要求该栖息地每年至少产生 7 公斤。这些发现证明了这种监测技术的能力及其有用性，既可以作为评估保护目标合规性的工具，也可以作为评估保护措施对难以捉摸的水生物种（如 A. anguilla）成功的工具。
