Potsdam Institute of Inland Fisheries, Potsdam, Germany.
J Fish Biol. 2024 Apr;104(4):1079-1090. doi: 10.1111/jfb.15643. Epub 2024 Jan 4.
Fish marking is an essential tool for fisheries management, especially for evaluating the stocking of endangered fish species to support conservation and sustainable use of fish stocks. Batch marking of young European eels Anguilla anguilla (L.) prior to stocking is recommended as the benefits of stocking for the spawning stock can be evaluated by recapturing marked fish over time, therefore mass marking of young eels with substances such as alizarin red S (ARS) is becoming increasingly important. To improve the marking method and reduce marking costs when immersing glass eels in an ARS solution, eight laboratory experiments under varying conditions (e.g., temperature, ARS concentration, immersion time, osmotic induction, fish density) and with ARS from different suppliers were carried out. The results show that optimal marking of glass eels can be carried out in the field or during transport by putting approximately 50 g of glass eels per liter in 150 mg L ARS solution for 3 h at 10-15°C. Lower concentrations did not result in reliable marking. Water temperatures of 5°C and below can have a stunning effect on the eels and increase mortality significantly, regardless of the concentration of ARS. Glass eel densities below 50 g L in the marking bath increase marking costs unnecessarily, while a higher density of 100 g L resulted in significantly higher mortality and lower marking success. A somewhat more difficult but less expensive alternative is to bathe the fish in a saline solution of 1% (10 PSU) of 80 mg L ARS for 3 h at 10°C. Costs can also be significantly reduced by choice of supplier for ARS, but care should be taken as the quality of the powder appears to vary (mean percentage of sufficiently marked eels ranged from 59% to 91% among suppliers in the present study) and can lead to marking failure. The optimal marking conditions can help ensure that stocked glass eels can be reliably identified in future studies to assess stocking benefits while reducing costs.
鱼类标记是渔业管理的重要工具，特别是用于评估濒危鱼类物种的放养，以支持鱼类资源的保护和可持续利用。建议在放养前对年轻的欧洲鳗鲡（Anguilla anguilla（L.））进行批量标记，因为随着时间的推移，可以通过重新捕获标记的鱼类来评估放养对产卵群体的益处，因此，用茜素红 S（ARS）等物质对年轻的鳗鱼进行大规模标记变得越来越重要。为了改进标记方法并降低在 ARS 溶液中浸泡玻璃鳗的标记成本，在不同条件（例如温度、ARS 浓度、浸泡时间、渗透诱导、鱼类密度）下进行了八项实验室实验，并使用了来自不同供应商的 ARS。结果表明，通过在 10-15°C 下将约 50 克玻璃鳗放入每升 150 毫克 ARS 溶液中浸泡 3 小时，可以在现场或运输过程中对玻璃鳗进行最佳标记。较低的浓度不会导致可靠的标记。5°C 及以下的水温会对鳗鱼产生惊人的影响，并显著增加死亡率，而与 ARS 的浓度无关。在标记浴中，玻璃鳗的密度低于 50 克/升会不必要地增加标记成本，而密度为 100 克/升会导致死亡率显著增加和标记成功率降低。一个稍微困难但成本较低的替代方案是将鱼在 10°C 下用 1%（10 PSU）的 80 毫克/升 ARS 盐水浴中浸泡 3 小时。通过选择 ARS 的供应商，也可以显著降低成本，但需要注意的是，粉末的质量似乎有所不同（在本研究中，不同供应商的标记效果足够的鳗鱼的平均百分比范围为 59%至 91%），可能导致标记失败。最佳标记条件有助于确保在未来的研究中，可以可靠地识别放养的玻璃鳗，以评估放养的益处，同时降低成本。
