Figure - available from: Journal of Paleolimnology
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Stable nitrogen isotope (δ¹⁵N) data from sediment cores taken in clear-water Upper Russian Lake (Kenai River Watershed, Alaska, USA) indicate that sockeye salmon (Oncorhynchus nerka) populations varied significantly over the past 4000 years, with a prominent ~ 650-year period of lower salmon abundance from ~ 100 BCE to 550 CE. Sediment characterist...
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... The primary research goal should be to identify additional marine management actions, with the secondary goal of improving forecasts of short-and long-term prospects for decision makers. Paleontological, as well as recent studies, have shown that major fluctuations in salmon populations track changes in the marine climate [450]. Therefore, an exclusive focus on freshwater options is unlikely to prevent devastating climate impacts on salmon. ...
As we confront novel environmental challenges, a full understanding of the physical and biological processes that govern species responses to climate change will help maintain biodiversity and support conservation measures that are more robust to irreducible uncertainty. However, climate impacts are so complex, and the literature on salmon and trout is so vast that researchers and decision makers scramble to make sense of it all. Therefore, we conducted a systematic literature review of climate impacts on salmon and anadromous trout as a resource for stakeholders, managers, and researchers. We reviewed studies published from 2010 to 2021 that address climate impacts on these fish and organized them in a database of 1169 physical and 1853 biological papers. Papers are labeled with keywords across eight categories related to subject matter and study methods. We compared the literature by biological process and life stage and used these comparisons to assess strengths and weaknesses. We then summarized expected phenotypic and genetic responses and management actions by life stage. Overall, we found the largest research gaps related to species interactions, behavioral responses, and effects that carry over across life stages. With this collection of the literature, we can better apply scarce conservation resources, fill knowledge gaps, and make informed decisions that do not ignore uncertainty.
... In addition, North Goat Glacier, a tributary to Skilak River (Fig. 1), advanced to its 2006 extent after 1470 ± 85 CE and then overtopped the topographic divide of Goat Lake where rock flour deposition began at 1660 ± 165 CE (Daigle and Kaufman, 2009). For reasons currently unclear, a core taken from Upper Russian Lake, which is downstream of Goat Lake and tributary to Skilak Lake, does not seem to contain the overflow rock flour from Goat Lake (McCarthy et al., 2018). Instead, rock flour was deposited in Upper Russian Lake between 100 BCE and 550 CE, possibly representing the evulsion of outwash channels that emanate from cirque glaciers, which presently flow to the east rather than into Upper Russian Lake. ...
Holocene glacier fluctuations in south-central Alaska reflect hydroclimate changes in a region strongly influenced by large-scale features of North Pacific climate. Glacier fluctuations over the past approximately 2300 years were inferred from multiple geophysical and geochemical properties of a new 13-m-long sediment core from proglacial Skilak Lake. The chronology is based on annual-layer (varve) counting, supported by radiocarbon ages and the identification of the 1912 CE Katmai tephra. Sediment density and accumulation rate show two prominent century-scale increases, one near the base of the cored sequence (around 270-370 BCE) and one near the top (around 1600–1900 CE, Little Ice Age). These two peaks, and the absence of such increases between them, coincide with sedimentation-rate changes as previously measured in multiple cores from Eklutna Lake, located 130 km northeast of Skilak Lake. The similarity between the two sedimentary sequences, despite their contrasting geomorphic settings and spatial scales, implies that regional climate change is the overriding control. Sediment with high bulk density and thick varves was deposited concurrently with the expansion of glaciers in the catchment and elsewhere in the region during the Little Ice Age. We likewise attribute the deposits with similar characteristics to expanded glaciers centered around 320 BCE, and the absence of such sediment during the intervening 1800 years to the lack of a major glacier advance. Climatologically, both periods of high sediment accumulation rate correspond with times of intensified Aleutian Low pressure, as recently reconstructed based on regional syntheses of oxygen-isotope records for the earlier period, and on sea-salt concentration in two Alaskan ice cores for the later period. Both periods also coincide with pronounced multi-decadal downturns in combined solar and volcanic global radiative forcing. The massive buildup of glaciers during the Little Ice Age might reflect the increased frequency of these downturns combined with millennial-scale decrease in orbitally driven insolation. Glaciolacustrine records from these two lakes add a new perspective on the multi-century variability of glaciers and hydroclimate in the North Pacific region.
... Results suggest that anthropogenic impacts had the biggest influence on survival and abundance. McCarthy et al. (2018) provided perspective on pre-historic trends of sockeye salmon abundance from populations in Alaska. They utilized stable isotope data (δ 15 N) from sediment cores taken from Russian Lake in the Kenai River watershed and compared them to records from the same periods previously taken from Kodiak Island. ...
A summary of the literature most relevant to the future impacts of climate change on Pacific Salmon from the year 2018
