With the global increase of marine protected area (MPA) implementation, the need for monitoring and the evaluation of their effectiveness becomes ever more important. Currently there is a severe lack of information about the protection effects of soft-substrate ecosystems. While many different methods have been established for the monitoring of hard-substrate ecosystems, most of these minimally invasive methods prove ineffective for soft- bottom habitats. Information and quantification of the impact of monitoring methods is needed to provide decision makers with the necessary knowledge to choose appropriate and feasible monitoring methods. In this study we quantify the impact of experimental trammel net fishing as a monitoring method of the soft-substrate demersal fish community using the Arrábida MPA (Portugal) as a case study. Over the 14 biannual sampling campaigns (between 2010 and 2019) 21,873 individuals and 5.61 tonnes of fish were caught. The gear is highly effective with an average catch per unit effort higher than reported for commercial fisheries in adjacent areas. When excluding the pelagic species, mortality rates are 41.2% and 30.4% in numbers and biomass, respectively. Most of the dead individuals belong to small, non-protected species with relatively little commercial value while MPA conservation target groups such as Soleidae and Rajidae have high survival rates. Due to its low size- and species-selectivity and the high survival rate of protected valuable species, the trammel net experimental fishing proved to be an effective monitoring method for soft-substrate demersal fish communities. Given their relatively low impact on the local ecosystem experimental trammel nets are a good alternative for areas where non-extractive methods are not effective. Nevertheless, quantification of the impact of other monitoring methods is necessary to enable the determination of the methods with the lowest mortality and impact for future soft-substrate MPA monitoring.

随着全球海洋保护区（MPA）实施的增加，对其有效性进行监视和评估的需求变得越来越重要。当前，关于软基质生态系统保护作用的信息严重缺乏。尽管已经建立了许多用于监视硬质底物生态系统的方法，但是大多数这些微创方法对软底生境无效。需要信息和监测方法的影响的量化，以便为决策者提供必要的知识，以选择适当和可行的监测方法。在这项研究中，我们以ArrábidaMPA（葡萄牙）为例，对作为试验性软底沉鱼群落的一种监测方法，对实验性践踏网捕鱼的影响进行了量化。在14个半年一次的采样活动中（2010年至2019年之间），捕获了21873个人和5.61吨鱼。该渔具非常有效，平均单位捕捞量比邻区的商业性渔业要高。当排除浮游物种时，死亡率和生物量死亡率分别为41.2％和30.4％。大多数死亡个体属于较小的，未受保护的物种，具有相对较小的商业价值，而MPA保护目标群体（如So科和Raj科）具有较高的成活率。由于其对大小和物种的选择性低以及受保护珍贵物种的高成活率，因此，践踏网实验捕鱼被证明是对软质底栖鱼类种群的有效监测方法。考虑到它们对当地生态系统的影响相对较小，对于非提取方法无效的地区，实验性特拉梅尔网是一个不错的选择。但是，必须量化其他监测方法的影响，才能确定死亡率和影响最小的方法，以用于将来的软基板MPA监测。