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Federal Register / Vol. 86, No. 145 / Monday, August 2, 2021 / Rules and Regulations
quality to support growth and development; 2 prey species of sufficient quantity, quality and availability to support individual growth, reproduction and development, as well as overall population growth;
and 3 passage conditions to allow for migration, resting, and foraging. We identified the same three biological and physical features as essential for the conservation of Southern Resident killer whales within their coastal range, as described below.
1 Water quality to support growth and development. Water quality supports Southern Resident killer whales ability to forage, grow, and reproduce free from disease and impairment. Southern Resident killer whales are highly susceptible to biomagnification of pollutants, such that chemical pollution is considered one of the prime impediments to their recovery NMFS 2008. Water quality is essential to the whales conservation, given the whales present contamination levels, small population numbers, increased extinction risk caused by any additional mortalities, and geographic range and range of their primary prey that includes highly populated and industrialized areas. Water quality is especially important in high-use areas where foraging behaviors occur and contaminants can enter the food chain.
The absence of contaminants or other agents of a type and/or amount that would inhibit reproduction, impair immune function, result in mortalities, or otherwise impede the growth and recovery of the Southern Resident population is a habitat feature essential for the species recovery. Exposure to oil spills also poses additional direct threats as well as longer-term population level impacts. Therefore, the absence of these chemicals is essential to Southern Resident conservation and survival.
2 Prey species of sufficient quantity, quality and availability to support individual growth, reproduction and development, as well as overall population growth. Southern Resident killer whales need to maintain their energy balance all year long to support daily activities foraging, traveling, resting, socializing as well as gestation, lactation, and growth. Maintaining their energy balance and body condition is also important because when stored fat is metabolized, lipophilic contaminants may become more mobilized in the bloodstream, with potentially harmful health effects Mongillo et al. 2016.
Southern Resident killer whales are top predators that show a strong preference for salmonids in inland waters, particularly larger, older age class
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Chinook age class of 3 years or older Ford & Ellis 2006, Hanson et al. 2010.
Samples collected during observed feeding activities, as well as the timing and locations of killer whales high-use areas that coincide with Chinook salmon runs, suggest the whales preference for Chinook salmon extends to outer coastal habitat use as well Hanson et al. 2017, Shelton et al. 2018, Hanson et al. 2021. At some low Chinook abundance level, the prey available to the whales will not be sufficient to forage successfully leading to adverse effects on body condition or fecundity NMFS 2020. Habitat conditions should support the successful growth, recruitment, and sustainability of abundant prey to support the individual growth, reproduction, and development of Southern Resident killer whales.
Age, size, and caloric content all affect the quality of prey, as do contaminants and pollution. The availability of key prey is also essential to the whales conservation. Availability of prey along the coast is likely limited at particular times of year due to the small run sizes of some important Chinook salmon stocks, as well as the distribution of preferred adult Chinook salmon that may be relatively spread out prior to their aggregation when returning to their natal rivers.
Availability of Chinook salmon to the whales may also be impacted by sound from vessels or other sound sources if they raise average background noise within the animals critical bandwidth to a level that is expected to chronically or regularly reduce echolocation space Joy et al., 2019, Veirs et al. 2016, and by competition from other predators including other resident killer whales, pinnipeds, and fisheries Chasco et al.
2017.
3 Passage conditions to allow for migration, resting, and foraging.
Southern Resident killer whales are highly mobile, can cover large distances, and range over a variety of habitats, including inland waters and open ocean coastal areas from the Monterey Bay area in California north to Southeast Alaska. The whales habitat utilization is dynamic. Analyses of Southern Resident killer whales movement patterns on the outer coast from satellite tag data have revealed preferred depth bands and distances from shore that suggest potential travel corridors, and variations in travel speed or duration of occurrence that may indicate different behavioral states Hanson et al. 2017.
Southern Resident killer whales require open waterways that are free from obstruction e.g., physical, acoustic to move within and migrate
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between important habitat areas throughout their range, find prey, communicate, and fulfill other life history requirements. As an example of an acoustic obstruction, killer whale occurrence in the Broughton Archipelago, Canada declined significantly when acoustic harassment devices were in use at a salmon farm, and returned to baseline levels once the devices were no longer used Morton &
Symonds 2002, indicating the introduction of this chronic noise source into the environment acted as an acoustic barrier and/or deterrent to the whales use of the area. The passage feature may be less likely to be impacted in coastal ocean waters compared to the more geographically constricted inland waters because the whales may be able to more easily navigate around potential obstructions in the open ocean, but these passage conditions are still a feature essential to the whales conservation and which may require special management considerations or protection.
We also considered whether to identify sound as a fourth essential feature. Southern Resident killer whales produce and detect sounds for communication, navigation, and foraging. An acoustic environment, or soundscape, in which the whales can detect and interpret sounds is critical for carrying out these basic life functions. In recognition of this, we previously considered identifying sound as a potential essential feature 69 FR
76673; December 22, 2004, but ultimately concluded that we lacked sufficient information to do so. CBD
petitioned us to again consider identifying in-water sound as an essential feature of the currently designated critical habitat and any new designation.
We considered the request and examined new information that has become available since publication of the 2006 critical habitat designation final rule, but similar to limitations in our knowledge in 2006, at this time we are not able to identify specific in-water sound levels or thresholds for communication, behavioral or displacement impacts as specifically requested in the petition by CBD. More importantly, we are able to assess adverse habitat-related effects of anthropogenic sound by evaluating impacts to the prey and passage essential features of current critical habitat for Southern Resident killer whales, as well as to the whales themselves, and thus we do not consider it necessary to identify sound as a separate essential feature. The final rule is consistent with the proposed rule
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