The remote and uninhabited Northwestern Hawaiian Islands (NWHI) contain 70% of the shallow water coral reefs in the United States and are regularly exposed to derelict fishing nets. These nets snag on the shallow reefs, damaging or killing benthic communities. However, no data exist to quantify this impact. Here we use a novel application of photogrammetry, Structure-from-Motion (SfM), to calculate benthic cover from mosaic images at net-impact and control sites. Net-impact sites had significantly higher cover of bare substrate, sand, and crustose coralline algae and significantly lower coral and macroalgae cover compared to control sites. These differences were unrelated to net size and fouling. Our study demonstrates the utility of using SfM to efficiently quantify impacts of derelict fishing nets. Revisiting these sites will be essential to document how the reef recovers to further our understanding of the lasting impacts of derelict fishing nets on coral reef habitats.

偏远且无人居住的西北夏威夷群岛（NWHI）拥有美国70％的浅水珊瑚礁，并经常暴露于废弃的渔网中。这些网钩住浅礁，破坏或杀死底栖生物群落。但是，没有数据可以量化这种影响。在这里，我们使用摄影测量的一种新颖应用程序，即运动结构（SfM），从网络影响和控制位置的马赛克图像计算底栖生物覆盖率。与对照站点相比，净影响站点的裸露底物，沙子和硬壳珊瑚藻的覆盖率明显更高，而珊瑚和大型藻的覆盖率则显着降低。这些差异与净尺寸和结垢无关。我们的研究表明，使用SfM可以有效地量化废弃渔网的影响。