Competition between Asian pink salmon (Oncorhynchus gorbuscha ) and Alaskan sockeye salmon (O. nerka ) in the North Pacific Ocean

2003 ◽  
Vol 12 (3) ◽  
pp. 209-219 ◽  
Author(s):  
G. T. Ruggerone ◽  
M. Zimmermann ◽  
K. W. Myers ◽  
J. L. Nielsen ◽  
D. E. Rogers
2018 ◽  
Vol 115 (22) ◽  
pp. E5038-E5045 ◽  
Author(s):  
Alan M. Springer ◽  
Gus B. van Vliet ◽  
Natalie Bool ◽  
Mike Crowley ◽  
Peter Fullagar ◽  
...  

Pink salmon (Oncorhynchus gorbuscha) in the North Pacific Ocean have flourished since the 1970s, with growth in wild populations augmented by rising hatchery production. As their abundance has grown, so too has evidence that they are having important effects on other species and on ocean ecosystems. In alternating years of high abundance, they can initiate pelagic trophic cascades in the northern North Pacific Ocean and Bering Sea and depress the availability of common prey resources of other species of salmon, resident seabirds, and other pelagic species. We now propose that the geographic scale of ecosystem disservices of pink salmon is far greater due to a 15,000-kilometer transhemispheric teleconnection in a Pacific Ocean macrosystem maintained by short-tailed shearwaters (Ardenna tenuirostris), seabirds that migrate annually between their nesting grounds in the South Pacific Ocean and wintering grounds in the North Pacific Ocean. Over this century, the frequency and magnitude of mass mortalities of shearwaters as they arrive in Australia, and their abundance and productivity, have been related to the abundance of pink salmon. This has influenced human social, economic, and cultural traditions there, and has the potential to alter the role shearwaters play in insular terrestrial ecology. We can view the unique biennial pulses of pink salmon as a large, replicated, natural experiment that offers basin-scale opportunities to better learn how these ecosystems function. By exploring trophic interaction chains driven by pink salmon, we may achieve a deeper conservation conscientiousness for these northern open oceans.


2010 ◽  
Vol 2 (1) ◽  
pp. 306-328 ◽  
Author(s):  
Gregory T. Ruggerone ◽  
Randall M. Peterman ◽  
Brigitte Dorner ◽  
Katherine W. Myers

2011 ◽  
Vol 68 (6) ◽  
pp. 1122-1130 ◽  
Author(s):  
James R. Irvine ◽  
Masa-aki Fukuwaka

Abstract Irvine, J. R., and Fukuwaka, M. 2011. Pacific salmon abundance trends and climate change. – ICES Journal of Marine Science, 68: 1122–1130. Understanding reasons for historical patterns in salmon abundance could help anticipate future climate-related changes. Recent salmon abundance in the northern North Pacific Ocean, as indexed by commercial catches, has been among the highest on record, with no indication of decline; the 2009 catch was the highest to date. Although the North Pacific Ocean continues to produce large quantities of Pacific salmon, temporal abundance patterns vary among species and areas. Currently, pink and chum salmon are very abundant overall and Chinook and coho salmon are less abundant than they were previously, whereas sockeye salmon abundance varies among areas. Analyses confirm climate-related shifts in abundance, associated with reported ecosystem regime shifts in approximately 1947, 1977, and 1989. We found little evidence to support a major shift after 1989. From 1990, generally favourable climate-related marine conditions in the western North Pacific Ocean, as well as expanding hatchery operations and improving hatchery technologies, are increasing abundances of chum and pink salmon. In the eastern North Pacific Ocean, climate-related changes are apparently playing a role in increasing chum and pink salmon abundances and declining numbers of coho and Chinook salmon.


1995 ◽  
Vol 52 (5) ◽  
pp. 1050-1063 ◽  
Author(s):  
Skip McKinnell

Annual mean body lengths of adult sockeye salmon (Oncorhynchus nerka) covary systematically from year to year in major northern and central British Columbia stocks (Nass River, Skeena River, and Rivers Inlet). These positive correlations are greatest between sexes within rivers, followed by age-classes among rivers. A common factor or factors affecting sockeye length in the North Pacific Ocean is suggested. The mean length of age 1.3 sockeye salmon but not age 1.2 sockeye caught annually in these B.C. fisheries was negatively correlated with the magnitude of Bristol Bay (western Alaska) sockeye catches. During the spring of maturation, age 1.3 sockeye from these B.C. stocks were further from their natal streams, and likely subject to more intense competition with Bristol Bay sockeye than age 1.2 sockeye. The pattern of annual marine growth measured from Skeena River sockeye scales collected during the 1960s provides additional evidence that the length of age 1.3 sockeye was related to Bristol Bay sockeye abundance in the year of maturation. No such correlation was evident in scales collected from age 1.2 sockeye. These results suggest that sockeye populations have more systematic distributions in the North Pacific Ocean than has been previously reported.


2015 ◽  
Vol 72 (6) ◽  
pp. 818-833 ◽  
Author(s):  
Gregory T. Ruggerone ◽  
Brendan M. Connors

Sockeye salmon (Oncorhynchus nerka) populations from Southeast Alaska through British Columbia to Washington State have experienced similar declines in productivity over the past two decades, leading to economic and ecosystem concerns. Because the declines have spanned a wide geographic area, the primary mechanisms driving them likely operate at a large, multiregional scale at sea. However, identification of such mechanisms has remained elusive. Using hierarchical models of stock–recruitment dynamics, we tested the hypothesis that competition between pink (Oncorhynchus gorbuscha) and sockeye salmon for prey has led to reduced growth and productivity and delayed maturation of up to 36 sockeye populations spanning the region during the past 55 years. Our findings indicate the abundance of North Pacific pink salmon in the second year of sockeye life at sea is a key factor contributing to the decline of sockeye salmon productivity, including sockeye in the Fraser River where an increase from 200 to 400 million pink salmon is predicted to reduce sockeye recruitment by 39%. Additionally, length-at-age of Fraser River sockeye salmon declined with greater sockeye and pink salmon abundance, and age at maturity increased with greater pink salmon abundance. Our analyses provide evidence that interspecific competition for prey can affect growth, age, and survival of sockeye salmon at sea.


<em>Abstract.</em>—Limits to the capacity of the North Pacific Ocean to support salmon are suggested based on widespread observations of decreasing size and increasing age of salmon at maturation during time periods where the abundance of salmon has increased throughout the North Pacific rim. The increase in abundance of salmon is partially due to successful establishment of large-scale hatchery runs of chum salmon <em>Oncorhynchus keta </em>and pink salmon <em>O. gorbuscha</em>. The largest hatchery runs are chum salmon, and because of their long life span relative to the more abundant pink salmon, the increase in hatchery terminal run biomass under-represents the actual increase in salmon biomass. To put the increase in hatchery runs in perspective, the historical (since 1925) terminal runs and biomass of hatchery and wild pink, chum, and sockeye salmon <em>O. nerka </em>in the North Pacific Ocean were reconstructed. Various data sets of smolt releases from hatcheries, wild salmon estimates of smolt out-migrants, and subsequent adult returns by age and size were assembled. Age-structured models were fit to these data sets to estimate brood-year specific rates of natural mortality, growth, and maturation. The rates were then used to reconstruct total biomass of the “smolt data” stocks. The estimated ratio of terminal runs to total biomass estimated for the “smolt data” stocks were used to expand the historical time series of terminal run biomass on a species and area basis. The present total biomass (~4 million mt) of sockeye, chum, and pink salmon in the North Pacific Ocean is at historically high levels and is ~3.4 times the low levels observed in the early1970s. At least 38% of the recent ten-year average North Pacific salmon biomass is attributed to hatchery stocks of chum and pink salmon. Recent year terminal run biomass has been greater than the peak levels observed during the mid 1930s.


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