Multi‐century reconstructions of Pacific salmon abundance from climate‐sensitive tree rings in west central British Columbia, Canada

Abstract

Short records of naturally fluctuating Pacific salmon (Oncorhynchus spp.) populations elicit challenges for the long‐term management of North American fisheries. A dendrochronologic approach was used to reconstruct long proxy histories of regional Pacific salmon populations returning to streams along west central British Columbia coastlines. Tree rings from five tree species collected at 18 sites were found to be sensitive to interannual fluctuations in large‐scale ocean and atmospheric circulation patterns. Using a regional network of climate‐sensitive ring‐width and ring‐density tree‐ring chronologies in linear regression models, multi‐century long‐term abundance records for populations of sockeye, chinook, chum and pink salmon were generated. Models explained between 27% and 39% of the variability in escapement records and were more proficient at capturing trends than annual magnitudes. The reconstructions vary in length, dating from 1400, 1536 and 1638 ad and extending to 2009 ad. Notable fluctuations in salmon abundance over the past six centuries are described, with significant population collapses shown to occur during the early 1400s, the late 1500s, the mid‐1600s, the early 1700s, the early 1800s and parts of the 1900s. These models are the first to utilize climate‐sensitive tree‐ring records to reconstruct regional abundance histories and thus contribute potentially valuable information for salmon fisheries managers. Copyright © 2012 John Wiley & Sons, Ltd.

Scientific Merits and Analytical Challenges of Tree‐Ring Densitometry

“…Many of these studies combine new or updated measurements with previously published MXD data acquired by other analytical techniques such as the Walesch technique. Further dendrochronological applications of the Itrax multiscanner include studies on tropical wood (Haines et al, ), reconstructions of salmon abundance (Starheim et al, ), glacier mass balances (Wood et al, ; Wood & Smith, ), or studies comparing X‐ray based wood density of the Itrax with data obtained with the Walesch technique (Helama et al, ), wood density surrogates derived with blue intensity (BI) techniques (Björklund et al, ; Campbell et al, ; Rydval et al, ), and wood anatomical parameters (Pritzkow et al, ). A reference list of studies using the Itrax multiscanner can be downloaded from the manufacturer's website (http://www.coxsys.se/).…”

An inventory of rock glaciers in the central British Columbia Coast Mountains, Canada, from high resolution Google Earth imagery

“…Minimum kill dates were assigned by cross-dating the samples to existent master tree-ring chronologies. Subalpine fir samples were cross-dated to a chronology collected by Starheim, Smith, and Prowse (2013) at Jacobsen Glacier in the nearby Monarch Icefield area (AD 1533(AD -2009. Whitebark pine samples were cross-dated to a tree-ring chronology from Siva Glacier (AD 1189-2000) constructed by Larocque and Smith (2005a; Table 1).…”

Fine-scale spatiotemporal influences of salmon on growth and nitrogen signatures of Sitka spruce tree rings

“…Tree ring information has been used as a proxy for constructing historical salmon abundances at multiple watersheds with riparian zone stand chronologies and nearby salmon-free controls [ 18 ] and at the regional level in climate-sensitive series [ 40 ], both with some success. Similar techniques have been employed to examine historical seabird activity extending from the input of guano to forested nesting colonies [ 41 , 42 ].…”