Acoustic monitoring report, Noatak National Preserve – 2013 and 2014

Betchkal, Davyd

In 2009, natural soundscapes were recognized as a fundamental resource of Noatak National Preserve in their foundation statement (NPS 2009). In 2013 and 2014, NPS staff deployed acoustic monitoring systems to a total of four locations across Noatak National Preserve. The goal of this effort was to measure baseline natural sound conditions and to collect data on overflight and river boat activity during the hunting season. This effort is one component of a larger, integrated, multi-phase research effort by Western Arctic Parklands (WEAR) staff. The effort seeks to further understand fall caribou hunting conflict between local subsistence and non-local hunters in Noatak. These acoustic data add to research conducted from 1988 through present by the National Park Service (NPS), State of Alaska (SOA), and the academic community. Data collected included sound pressure levels every second and continuous MP3 audio recordings throughout the sampling period. These data serve as a permanent record of existing acoustical conditions at select locations during the hunting seasons of 2013 and 2014. During hunting season the average aircraft noise events per day ranged from 3.7 events per day at Kugururok River (2014) to 7.8 events per day at Sapun Creek (2014). Note that these two sites were deployed over the same time period and on the same river (Noatak), but the site 57 miles farther east had over twice the number of aircraft noise events. Whether this is the result of the NPS delayed-entry area and Alaska Department of Fish & Game (ADFG) Controlled-use Area (CUA) covering areas to the west of Sapun or due to the recent easterly trend of the primary migration routes of the Western Arctic caribou herd (Joly, 2014) cannot be determined from the data that were collected during this study. However, it is clear that propeller aircraft noise differs between the two sites at this time of the year. Conversely, and as expected, watercraft were less commonly detected on the eastern portions of the Noatak. At the Kugururok River site, 40 miles from the Village of Noatak, motorboats were detected at an average of 5.1 events per day. Another 57 river miles upstream at Sapun Creek (2014), there was less than one third the observed boat traffic - 1.4 events per day. Again, it cannot be determined from this study whether this is an effect of management action or simply due to the physical and economic constraints of water travel. Typical maximum sound pressure levels differed between aircraft and watercraft. At sites where boats passed nearby (Kugururuok 2014, Sapun Creek 2014,) median levels were comparable to aircraft. Median sound pressure levels for aircraft were always in the 40 – 50 dBA range, with a louder subset was always observed between 60 and 80 dBA. By comparison, the loudest level observed for boats at any site was less than 60 dBA. Furthermore, takeoffs at Agashashok River (2013) and Sapun Creek (2014), with maximum sound pressure levels at or above 100 dBA. (Figure 8, Figure 26.) On the other hand, Noatak is among the rare park units that have minimal noise intrusions from jet aircraft. For example, a single jet noise event was detected at Kugururok River (2013) over the course of the 12 day sampling period. This is in direct contrast with parks in the contiguous United States, where jet traffic is the most widespread source of noise. (Lynch 2011) Thus, during times when fixed-wing aircraft use is low, the preserve is likely to have natural quiet of a condition unmatched by any parks but its Alaskan relatives.

Acoustic monitoring report, Noatak National Preserve – 2013 and 2014

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