Summer–Fall Distribution of Stocks of Immature Sockeye Salmon in the Bering Sea as Revealed by Single‐Nucleotide Polymorphisms

Abstract

We report stock composition estimates for immature (ocean-age .1 and .2) sockeye salmon Oncorhynchus nerka distributed across the Bering Sea in late summer and fall. We establish a baseline data set composed of single-nucleotide polymorphism markers that can achieve very high accuracies in identifying sockeye salmon stocks from throughout their range in Asia and North America. We demonstrate the capabilities of this data set to address high-seas salmon issues by analyzing samples collected by researchers from Russia, Japan, and the United States during late summer and fall 2002-2004 as part of the Bering-Aleutian Salmon International Survey. According to our findings, (1) Gulf of Alaska (GOA) stocks formed a significant portion of the immature sockeye salmon migrating in the eastern and central Bering Sea in summer and fall, and western GOA stocks had a broader distribution in the Bering Sea than eastern GOA stocks; (2) Asian stocks migrated as far east as the western Aleutian Islands and the Donut Hole area (international waters in the center of the Bering Sea); and (3) Bristol Bay stocks were the most widely distributed, accounting for more than one-half of the mixtures in all areas except the central and southern areas of the Russian Exclusive Economic Zone (REEZ) in the western Bering Sea and north of the western Aleutian Islands. These results provide a significant increase in our knowledge of the distribution of sockeye salmon, firmly establishing that the REEZ is a summer-fall feeding area for immature North American sockeye salmon, particularly stocks of southeastern Bristol Bay origin. Bristol Bay sockeye salmon appear to enter and exit the REEZ primarily along a migration route that extends across the Aleutian Basin.

Understanding Smolt Survival Trends in Sockeye Salmon

“…Sockeye Salmon from Puget Sound to southeastern Alaska spend most of their time within the Gulf of Alaska where they overlap with, and presumably compete with many species, including Asian Chum Salmon during the winter. Recent genetic evidence also demonstrates North American Sockeye Salmon extend farther northward and westward into the Bering Sea than thought previously where they overlap with Asian Sockeye and Pink Salmon (Habicht et al 2010). Body size for many Sockeye Salmon populations increased from the 1960s until the late 1970s, followed by decreases (Eggers and Irvine 2007).…”

“…These estimates may be low; Dronova and Spiridonov (2008) reported that Sockeye Salmon catches in Kamchatka were 1.5-3 times higher than reported. However, Russian salmon fisheries primarily occur close to Russia, and although some Canadian Sockeye Salmon are found in the Bering Sea (Habicht et al 2010;Beacham et al 2011), their numbers in the western North Pacific Ocean are low. We therefore think it is unlikely that declining North American Sockeye Salmon survivals after 1991 are a consequence of these salmon being caught in Russian fisheries and not included in marine harvest estimates.…”

Four decades of foraging history: stock-specific variation in the carbon and nitrogen stable isotope signatures of Alaskan sockeye salmon

“…Salmon may have stock-specific spatial distributions in the ocean (Myers et al 2007, Habicht et al 2010, or use different foraging strategies during the marine phase of their lives that may also produce asynchronous population responses to broad-scale changes in climate. For example, marine biocomplexity among salmon stocks may be expressed as stocks using space or prey resources differently in the ocean.…”

Landscape heterogeneity and local adaptation define the spatial genetic structure of Pacific salmon in a pristine environment

“…A composite phenotype for the two loci was used for both the SAMOVA and BARRIER analyses. The phenotype was generated by combining the two genotypes, ordering them alphabetically, and then assigning a numeric code to the resulting composite phenotype (Habicht et al 2010).…”

“…The data for 45 SNP loci included three mitochondrial and 42 nuclear loci described in Elfstrom et al (2006) and Habicht et al (2010). Chinook salmon data were drawn from Seeb et al (2009); data for 52 SNPs included one mitochondrial and 51 nuclear loci (Smith et al 2005a(Smith et al , b, 2007Narum et al 2008).…”