Quiero saber acerca de...

khammond on DSKJM1Z7X2PROD with PROPOSALS

47464

Federal Register / Vol. 86, No. 162 / Wednesday, August 25, 2021 / Proposed Rules
fish tissues, including those of Amur sturgeon Kondratyeva et al. 2012, pp.
187189; Levshina et al. 2009, table 1, p. 779. Also in the Songhua, heavy metals leach into the river from nearby mines Jen 2003, p. 4, and fish tissues have PCB concentrations up to 10,000
times those in the sediment Li et al.
1989 cited in Meng et al. 2016, p. 5.
Some Amur River fish are even said to smell of chemicals Simonov and Dahmer 2008, p. 225.
The impacts of pollution on wild Amur sturgeon have not been wellstudied, but their life history and some laboratory studies indicate they are likely quite susceptible. Because the Amur sturgeon is a river bottom species, it is exposed to pollutants that accumulate in sediments and in its bottom-dwelling prey Kasymov 1994
cited in He et al. 2017, p. 10;
Kondrateva et al. 2013, p. 129; Kocan et al. 1996, p. 161. Larvae and small juveniles may be especially sensitive to petrochemicals polluting the Amur Kondratyeva and Stukova 2009, p. 46;
Bickham et al. 1998, pp. 514515;
Kocan et al. 1996, p. 163, although extrapolating results from laboratory trials to impacts on wild fish is not straightforward Tabak et al. 2002, table 3; Bickham 1998, pp. 514515.
Comprehensive toxin concentration data from around the basin and knowledge of the concentration thresholds at which Amur sturgeon are affected are unavailable, and field studies definitively linking population declines to pollution also do not exist, to our knowledge. However, sturgeon are, at least at their early life stages, sensitive to polycyclic aromatic hydrocarbons PAHs, one class of petrochemicals polluting the Amur Kondratyeva and Stukova 2009, p. 46;
Tabak et al. 2002, table 3; Bickham et al.
1998, pp. 514515; Kocan et al. 1996, p. 163;. Methyl mercury, another pollutant found in the Amur basin, interferes with sturgeon growth and reproduction and can even cause direct mortality Depew et al. 2012, table 2;
Webb et al. 2006, pp. 447450.
The future trajectory of water quality in the Amur basin is uncertain, but possibly improving as wastewater and industrial waste treatment capacity have been developed since the early 2000s Meng et al. 2016, pp. 45, table 1.
Mercury concentrations in Amur River sediments have declined since the 1990s, likely due to a Russian economic slowdown that limited industrial emissions Kot et al. 2009, p. 133. In addition, human populations of most Chinese industrial cities in the region are shrinking, as cost-efficient raw materials are exhausted and industry
VerDate Sep<11>2014

16:13 Aug 24, 2021

Jkt 253001

declines Duhalde et al. 2019, not paginated.
Climate Change When and how progressing climate change will affect the species is uncertain. Air temperatures in the region are rising see the SSA report for a detailed analysis, and all species have a thermal maximum; for example, the closely related Yangtze sturgeon becomes stressed above 23 degrees Celsius C Chang et al. 2017, p. 1449.
On the other hand, warmer water can speed the maturation of Amur sturgeon Krykhtin and Svirskii 1997, p. 237 and so may have short-term positive impacts on the species, but we cannot currently estimate their magnitude or at what point increasing water temperature stops being beneficial. We also do not have information on the water temperatures Amur sturgeon experience at present or reliable projections of what the water temperatures are likely to be in the future. Indirect effects of warming temperatures may impact the Amur sturgeon as climate change progresses.
For example, between 1955 and 2014, the average annual duration of ice cover in the Amur basin decreased by 7 days per decade, and the maximum ice thickness decreased by 17 cm 6.7
inches; Vuglinsky and Valantin 2018, p. 83; Ohshima et al. 2016, pp. 1011.
This potentially exposes Amur sturgeon to fishing pressure for a greater proportion of the year.
Other Threats and Conservation Measures Hybridization, disease, and predation presently constitute lesser or negligible threats to the viability of the Amur sturgeon and are addressed in more detail in the SSA report Service 2020, pp. 2829. Although very little information is available on the genetic structure of wild Amur sturgeon populations, representation of the species would be diminished if its genome were diluted by hybridization with escaped captive-bred fish or other sturgeon species. From a fitness perspective, hybridization can erase locally adaptive features that evolved over evolutionary time, and from a conservation-management perspective, muddled genomes make DNA-based identification of traded specimens more difficult Ludwig 2006, pp. 6. That said, we are not aware that wild Amur sturgeon have been documented hybridizing with fish escaped from aquaculture facilities yet Osipov 2020, pers. comm.. However, the presence of over 1,200 sturgeon farms across the whole of China Bronzi et al. 2017, pp.
260 and confirmed escapes and releases
PO 00000

Frm 00067

Fmt 4702

Sfmt 4702

of hybrid fish created in aquaculture suggests it is likely to occur soon, if it has not already Boscari et al. 2017, pp.
250. The best scientific and commercial information available shows that disease and predation do not presently pose a threat to the viability of the Amur sturgeon.
The primary conservation effort targeting recovery of the Amur sturgeon is the release of captive-bred fish into wild habitats, but these activities are not sufficient to restore wild populations and must employ sound genetic management to avoid the potential impacts of hybridizing maladapted captive-bred fish with wild ones.
Whereas some experts have suggested 10 to 11 million fish would need to be released annually to successfully replenish the species Krykhtin and Gorbach 1994 cited in Koshelev et al.
2014a, p. 1316, no more than 10
percent of this volume has been released, on average, in years since restocking began in 1988 Simonov and Dahmer 2008, p. 130; Wei et al. 2004, p. 330; Zhuang et al. 2002, p. 361;
Qiuzhi and Dajiang 1994, p. 67. As of the early 2000s, 99 percent of the Amur sturgeon produced by Chinas aquaculture industry approximately 15
million fish per year Wei et al. 2011, figure 2 were sold for meat or caviar Simonov and Dahmer 2008, p. 131; Wei et al. 2004, p. 330.
We are not aware of any studies that have tracked the growth or reproductive success of Amur sturgeon released from captive-breeding operations. However, when releases do occur, they almost always use very young fish, 30 to 45
days old and weighing in the range of 1 to 5 grams 0.1 ounces. In other sturgeon species, no more than 1 in 2,000 fish survive their first year, although survival rates are much higher thereafter Jaric and Gessner 2013, table 1; Jager et al. 2002, table 1. If hatcheries grew fish to a larger size before release, their survival and population recovery may improve Koshelev et al. 2009 and Mikhailova 2004 cited in Koshelev et al.
2014a, p. 1316, scenario 3 in chapter 5
of the SSA, figures 5.2 and 5.3, tables 5.3 and 5.4.
Current Condition We assessed the current status of the Amur sturgeon in light of the species demographic and habitat requirements for maintaining low-risk levels of resilience, redundancy, and representation. Resilience is a population-level metric; therefore, we only scored its present levels for the three analysis units where Amur sturgeon are extant Amur Estuary, Lower Amur, and Middle Amur. The
E:FRFM25AUP1.SGM

25AUP1