A detached housing subdivision was developed in the 1990s in the city of Otsuki, Japan, located approximately 75 km west of Tokyo. In the environmental impact assessment, Japanese squirrels (Sciurus lis) were found to inhabit the development site, raising the concern that squirrels could be killed when crossing roads in the residential area. As a solution, a squirrel crossing structure was installed in 1997 and monitored periodically. The structure was used by squirrels on 27 of the 32 days monitored. During the inspection in July 2003, the cedar boards of the deck were replaced with wire mesh because of rotting. Based on monitoring from November 2004 to October 2005, Japanese squirrels used the structure on 99 of 176 days monitored, and it appeared to be used consistently, even by successive generations of squirrels. With time, the structure became difficult to maintain and was removed in March 2013.

A German public research institution called BGR and a Belgian private company called GSR respectively submitted an Environmental Impact Statement (“EIS”) to the International Seabed Authority (“ISA”) in March 2018. Each of the EIS focused on environmental impacts arising from testing activities using a pre-prototype polymetallic nodule collector vehicle on the seafloor at the depth of approximately 4,100 m and 4,500 m respectively in the area beyond the limits of national jurisdictions (“the Area”), where each of them has an exploration license under the contract with the ISA. As far as we know, these were the first EIS in the world produced under the context of deep seabed mining in the Area. In this paper, we explore what are described in each of the EIS.