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Federal Register / Vol. 86, No. 1 / Monday, January 4, 2021 / Rules and Regulations
expected Frankson et al. 2017, p. 2.
Projected changes in winter precipitation include an increase in the fractions falling as rain, rather than snow, and potentially decreasing snowpack water storage Frankson et al.
2017, p. 2. These changes in timing and amount of flow could affect June sucker spawning, because the spawning cues of increased runoff and water temperature, on which the June sucker relies to determine spawning time, would potentially occur earlier in the year.
As changes to water availability and timing occur in the future, the JSRIP
will need to coordinate reservoir operations to ensure timely releases. If runoff and upstream reservoir volumes are insufficient, peak and base flows desired in spawning tributaries will be reduced. This, in turn, would negatively impact the early season attractant flows needed by spawning adults, and potentially limit flows needed by larval suckers to move into downstream rearing habitats. As previously described, the JSRIP partnership has acquired 13,000 acre-ft 16,035,240 m3
of permanent water for the Provo River and 8,500 acre-ft 10,485,000 m3 for Hobble Creek. Flows in both systems are intensively managed with consideration for the June sucker. Still, additional permanent water acquisitions may become necessary to secure water that can be used to supplement flows during critical spawning and rearing periods as the climate shifts.
Summary of Habitat-Based Threats Water development and habitat modification, common carp, urbanization, and water quality are threats to the June sucker. Additionally, potential increased temperatures and decreased precipitation caused by climate change may impact water quality. However, since the time of listing in 1986, the JSRIP partnership has implemented the following recovery actions: 1 13,000 acre-ft of permanent water for instream flows are secured to benefit the June sucker; 2 a mechanism for annually recommending and providing flows for June sucker spawning was implemented; 3 the common carp population was suppressed, resulting in measurable habitat improvement in Utah Lake; 4
the impacts of urbanization are being considered through active research and planning; 5 a landscape-scale stream channel and delta restoration for the Provo River is being implemented; and 6 future water quality and availability are actively being studied and prioritized by the JSRIP, UDWQ, and the Utah Lake Commission see Recovery, above. We find that the severity of
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these threats has decreased since the time of listing; adaptive management of these threats is ongoing, and increased resiliency and redundancy are evident as indicated by increasing survival rates and overall population numbers.
Commercial Fishing Commercial fishing, including fishing for June suckers, was historically an important use of Utah Lake Heckman et al. 1981, p. 9. Some commercial fishing for June suckers occurred through the 1970s, but on a very limited basis.
Shortly thereafter, commercial harvest for the species largely stopped due to the limited population size. Currently, the June sucker is a prohibited species and cannot be harvested Utah Administrative Code R657148.
Consequently, commercial or recreational fishing is no longer considered a threat to the species.
Regulated collections of June suckers for scientific purposes occur at a very limited level, but do not pose a threat to the species at the population level.
Disease Neither disease nor the presence of parasites were considered threats to the June sucker at the time of listing 51 FR
10851; March 31, 1986. Although parasites likely exist in June sucker habitat, there is no evidence that June suckers at the individual or population levels are compromised by the presence of parasites. Fish health inspections are regularly conducted on June suckers at the FES hatchery and in Red Butte Reservoir, and no known pathogens have been detected JSRIP 2018c, entire. At this time, the best available information does not indicate that the presence of parasites or disease negatively affects the June sucker.
Predation by Nonnative Fishes Predation by nonnative fishes poses a threat to the successful recruitment of young suckers into the spawning adult life stage Radant and Hickman 1984, p.
6 and was a major factor for listing the June sucker as endangered 51 FR
10851; March 31, 1986. The introduction of predatory nonnative fishes significantly altered the native Utah Lake fish assemblage. Historically, Bonneville cutthroat trout Oncorhynchus clarkii was the toplevel piscivore fish-eating predator in Utah Lake; however, 30 fish species have been introduced since the late 1800s. Twelve nonnative fish species have established self-sustaining populations, and seven of these are piscivorous SWCA 2002, p. 14. As a result, June suckers face an array of predator species, including white bass
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Morone chrysops, walleye Sander vitreus, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus, black bullhead Ameiurus melas, northern pike Esox lucius, and channel catfish Ictalurus punctatus.
Predation by nonnative fishes primarily targets the early life stages of June suckers. Adult June suckers are larger than the gape size of the average predatory fish and, therefore, are significantly less vulnerable. At the time of listing, the effects of predation were exacerbated by the lack of vegetated refuge habitat within Utah Lake.
White bass may have the highest potential to limit recruitment of young suckers into the spawning adult population SWCA 2002, p. 132;
Landom et al. 2010, p. 18. White bass become piscivorous at age-0 in Utah Lake Radant and Sakaguchi 1981, p. 12;
Landom et al. 2010, pp. 1112 and are the most abundant piscivore UDWR
2010, p. 9. The white bass population in Utah Lake could consume as many as 550 million fish of various species throughout the course of 1 year Landom et al. 2010, pp. 810.
However, it appears that restored habitat with complex aquatic vegetation provides the June sucker with effective refuge from white bass. Thus, habitat restoration is likely paramount to young-of-year June sucker resiliency and survival see Recovery, above.
The recent illegal introduction of northern pike in Utah Lake raises concerns similar to white bass. Northern pike predominantly feed on juvenile fish; predation on adults is less than 1
percent Reynolds and Gaeta 2017, p.
12. Thus far, the number of northern pike in the lake has not measurably increased, and active removal efforts continue to suppress populations Reynolds and Gaeta 2017, p. 13.
However, a northern pike population model shows potential for a high degree of population increase with potential for a high negative impact on the June sucker population by the year 2040
Gaeta et al. 2018, entire. Despite these modeling results, unique factors impacting northern pike population dynamics in Utah Lake are still not understood. Recent habitat improvements in the lake from common carp removal see Recovery, above may help mitigate northern pike predation by providing refugia for June suckers.
Additionally, high levels of total dissolved solids TDS, such as those found in Utah Lake, may suppress northern pike spawning and development Scannell and Jacobs 2001, entire; Koel 2011, p. 7. The JSRIP is funding research to clarify this
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