Supplementary Information for Transhemispheric ecosystem disservices of pink salmon in a Pacific Ocean macrosystem Alan M. Springer (University of Alaska Fairbanks) Gus B. van Vliet (PO Box 210442, Auke Bay AK) Natalie Bool (University of Tasmania) Mike Crowley (Formerly: State Forests of NSW, Australia) Peter Fullagar (Formerly: CSIRO Division of Wildlife Research, Australia) Mary-Anne Lea (University of Tasmania) Ross Monash (Marine Conservation Program, Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania) Cassandra Price (University of Tasmania) Caitlin Vertigan (University of Tasmania) Eric J. Woehler (University of Tasmania) Alan M. Springer
[email protected] This PDF file includes: Supplementary text Figs. S1 to S2 References for SI reference citations
www.pnas.org/cgi/doi/10.1073/pnas.1720577115
Supplementary Information Long-term change in shearwater abundance Short-tailed shearwater abundance has not been monitored systematically at most colonies, thus estimates of the total population size and trends in abundance are imprecise. Overall abundance is thought to have increased considerably after the 1940s and 1950s and then stabilized through the 1970s (1, 2). However, in a region of north central Bass Strait, where about 1.3 x 106 pairs were recorded in 1978-1980 (3), abundance had declined by some 35% to about 0.75 x 106 pairs by 2011 (4). That pattern appears to be similar in timing to the decline in the 1980s at Montagu Island. As many as one million short-tailed shearwater chicks were harvested annually in Australia and Tasmania during the 19th and early 20th Centuries, and harvests remained at high levels through the 1980s (5 – in 6, and 6). Millions of shearwaters also were killed on their wintering grounds as bycatch in salmon and squid driftnet fisheries that operated between 1952-1991 in the northern North Pacific Ocean, most of which were immature birds as they are in the occasional wrecks off Japan (7-10). Uhlmann et al. (11) subsequently estimated that 2.9–16.6 (95% CI) million short-tailed shearwaters were killed in total in the driftnet fisheries between 1952 and 1977, and between 4.6 and 21.2 (95% CI) million overall between 1952 and 2001. The effect those losses had on the abundance of shearwaters is not known, but such extensive and sustained mortality might have caused, or contributed to, the population declines observed in Bass Strait and at Montagu Island. However, in the case of the sooty shearwater (Ardenna grisea), a closely related species in New Zealand that also migrates to the North Pacific Ocean in the austral winter, also was caught in great numbers in the drift net fisheries, and also is in decline, (11) stressed that for various reasons it is not possible to infer the cause or causes of the recent decreases. That reasoning also can be applied to short-tailed shearwaters. Yet, the declines of short-tailed shearwaters in Bass Strait sometime after the early 1980s, at Montagu Island in the 1980s, and to some extent at Montagu Island and the Furneaux Islands in this century, and declines of sooty shearwaters in New Zealand all coincided with the growth in abundance of North Pacific salmon since the 1970s, and thus it could be hypothesized that competition with salmon in the North Pacific Ocean and Bering Sea was a contributing factor. References 1. Naarding JA (1981) Population estimates of the short-tailed shearwater (Puffinus tenuirostris) in Tasmania. Tasmanian Naturalist July 1981:3-4. 2. Skira IJ, Brothers NP, Pemberton D (1996) Distribution, abundance and conservation status of Short-tailed Shearwaters Puffinus tenuirostris in Tasmania, Australia. Mar Ornith 24(1-2):1-14. 3. Harris MP, Norman FI. (1981) Distribution and status of coastal colonies of seabirds in Victoria. Mem Nat Mus Victoria 42:89–106.
4. Schumann N, Dann P, Arnould JPY (2014) The significance of northern-central Bass Strait in south-eastern Australia as habitat for burrowing seabirds. Emu 114(3):234-240. 5. Skira IJ (1987) Socio-economic aspects of muttonbirding in Tasmania, Australia. ICBP Tech Pub 6:63-75, (International Council for Bird Preservation, Cambridge). 6. Bradley JS, Skira IJ, Wooler RD (1991) A long-term study of Short-tailed Shearwaters Puffinus tenuirostris on Fisher Island, Australia. Ibis 133(s1):55-61. 7. Ainley DG, DeGange AR, Jones LL, Beach RJ (1991) Mortality of seabirds in highseas salmon gill nets. Fish Bull 79(4):800-806. 8. Oka N, Maruyama N (1986) Mass mortality of short-tailed shearwaters along the Japanese coast. Jap J Ornith 34(4):97-104. 9. DeGange AR, Day RH (1991) Mortality of seabirds in the Japanese land-based gillnet fishery for salmon. Condor 93(2):251-258. 10. DeGange AR, Day RH, Takekawa JE, Mendenhall VM (1993) Losses of seabirds in gill nets in the North Pacific. The Status, Ecology, and Conservation of Marine Birds of the North Pacific, ed Vermeer K, Briggs KT, Morgan KH, Siegel-Causey D (Canadian Wildlife Service, Ottawa), pp 204-211. 11. Uhlmann S, Fletcher D, Moller H (2005) Estimating incidental takes of shearwaters in driftnet fisheries: lessons for the conservation of seabirds. Biol Cons 123(2):151–163.
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Fig. S1. Locations of Montagu Island, the Furneaux Islands, Wedge Island, Bruny Island, and other locations mentioned in the text.
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Fig. S2. Trends in the abundance of pink salmon (millions of fish) from four geographic regions of the North Pacific Ocean. 1Excludes the Western Kamchatka Peninsula.
