Document 7Nvp02OB4dqzD4z2ExNRmNd6

the significance level when considering all species across 10 years. 6 2-35 Impact to MPAs... from active Why would impacts reach the level of moderate for acoustic sound sources range Marine Mammals inside MPAs when MPAs from nominal to moderate for all represent a pretty small area inside the AOI? Some alternatives except Alternative G might argue that MPAs contain unusual densities of species of concern or contain critical habitat, but neither of these assertions are supported by the best available data (e.g. Duke density maps or what data we have from tags and surveys concerning breeding, foraging and other vital activities). 6a 3-18 8000 cubic inch array with 72 Actual distribution of array sizes ranges from 8400- and elements used as standard less than 2000 with a mean value of 5600 cubic D-25 inches. Assuming the use of an 8000 cubic inch array overestimates reasonably expected source energy for a typical year or decade of effort. Additionally, using an excessively high number of elements in the array (the PEIS assumes the 8,000 cubic inch array is composed of 72 elements, when it would more likely be composed of 48 to 60 elements) further overestimates the expected source amplitude. 9 4-54 Fitness level Consequences of The analysis of fitness level consequences in this level A and Leve B Exposures section involves comparing the number of total animals in a hypothetical 7,000 km2 survey area to the number animals that would be within the acoustic threshold distance at any one time. This seems to have been done to compensate for the fact that exposure modeling was conducted for a 24hr period and discusses the probability of an animal experiencing multiple exposures to Level A acoustic energy, but the logic behind this approach is not at all clear. This should be more fully explained. 10 4-56 There is still a very small The argument made here that seems to be predicated potential for an animal to be in on fitness level consequences coming from multiple the acoustic footprint, thus an exposures of the same individual above Level A even smaller probability of criteria is not clear. There is not support for the experiencing multiple exposure final sentence and there is not an initial logical to Level A acoustic energy. It is argument made for how multiple exposures and not not anticipated that any animal a single exposure would lead to fitness level would experience fitness-level consequences or why the traditional density x area impact from level A exposures. calculation was used for this assessment rather than the results of exposure modeling. 11 4-57 Minimum survey spacing will No support for this is provided in the document and, ensure that marine mammals will to our knowledge, none exists in the scientific have areas where sound levels literature. will not meet the threshold of harassment. 12 4-124 "In March 2015, NMFS The final rule was published April 6, 2016 (81 FR published a proposed rule to 20058). The North Atlantic DPS is listed as 2 ATTACHMENT C remove the current range-wide threatened. Critical habitat is not determinable at listing for green sea turtles and this time but will be proposed in a future to replace it with eight DPSs as rulemaking. threatened and three as endangered. Green sea turtles found in the GOM are part of the threatened North Atlantic DPS (80 FR 15272). The NMFS is currently compiling comments on the proposed rule, with a final rule expected to be published in late 2016." 13 D-25 For geotechnical source Although a 10 dB adjustment is common, there is propagation modeling, a fixed insufficient detail provided here to support that it is +10 dB factor was used to appropriate for the HRG sources. This is especially convert SEL to rms SPL. true at greater ranges where the impulse shape of the signal is changed to an amplitude modulated signal over a variable time window. 14 D-35 Exposure estimates for cSEL Using only the range value would appear to neglect metric were based on the the depth of the animat at the time it was within the exposure history of the animats (assumed maximum-over-depth) range. If slant (this is appropriate). Exposure range and 3D peak SPL sound field were used, this estimates for peak SPL were should be specified. based simply on the how many animats came within the range of the threshold 14a D-42 Max value in the downward AASM generates a vector-specific level at any angle direction is used to estimate and in fact downward energy does not make a exposure substantial reflective or refractive contribution to the longer range propagated signal, so this use of the downward maximum overestimates exposure. 15 D-44 red boxes in Figures 13 and 14 These boxes do not appear to show the same D-45 within which densities are geospatial shift as shown for the two survey areas in calculated from the NODES Figure 10. database 17 D-49 Animats coming within the 230 Not enough detail is provided, but if the ranges to dB (18.7 m) and 200 dB (575.4 animats used were simply horizontal distance rather m) isopleths were counted as than slant-ranges, then this calculation assumes exposed maximum over-depth, which would result in more exposures of deep-diving marine mammals than is realistic. 18 D-84 Sound Speed Profile Analysis There is insufficient description of how the Median Results. and standard deviation values shown in Table 30 were calculated to interpret the results. Presenting differences between worst-case and median models in terms of dB at a maximum distance to a threshold is not as useful as showing actual variation in distances to that threshold or areas exposed above the threshold. Table 30 shows that the median difference between 3 ATTACHMENT C