On 19 January 2000, the U. S. Army Corps of Engineers issued an Environmental Assessment: Caspian Tern Relocation FY 2000 Management Plan & Pile Dike Modification. Comments were due by 18 February 2000. In this Environmental Assessment, it was proposed that the Caspian tern colony on Rice Island in the Columbia River be relocated to East Sand Island (which is downstream of Rice Island) and to Grays Harbor.
Below are comments I made about the Environmental Assessment. I have added the number of breeding terns at Grays Harbor and Rice Island to section B and, because the Assessment may not continue to be available online, an Appendix (section E) about the effects of Grays Harbor Caspian terns on salmonid returns. Additionally, I have added online links to many of the references in the Literature Cited (section D).
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In the first paragraph of p. 3, the Environmental Assessment states that there were 200-250 million smolts produced in the Columbia River Basin in 1997, but only 100 million reached the estuary. This means that 100-150 million smolts died upstream, which is considerably greater than the Assessment's 6-25 million estimate for those taken by terns.
Given the massive losses upstream, the Environmental Assessment needs to make it clear that the proposed tern management plan may not be as useful in salmon recovery as the Assessment suggests. Such clarity is required because when the Environmental Assessment correlates salmonid returns with the presence of Caspian terns at Grays Harbor (where the tern breeding population in 1987 of 7,180 birds [p. 33] was roughly comparable to that of the 14,000-16,200 birds at Rice Island in 1997-1999 [p. 2]), the conclusion on the bottom of p. 33 [also see section E] is that:
"In summary, there is no apparent relationship between Caspian tern
breeding population size in Grays Harbor and returns of adult
salmonids, suggesting that tern predation was not a limiting factor
for adult returns."
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The Environmental Assessment suggests that any effort to increase the number of smolts is useful in salmon recovery; however, past experience has shown that this is not the case. The Environmental Assessment's opinion is stated in the second paragraph of p. 4:
"Junge (1967) provides an argument that ocean survival is not
density dependent and concludes '... that a reduction of smolts by
a fraction m will on the average reduce the production of returning
adults also by a fraction m.' While there is considerable debate
about the effects of ocean conditions, and some more recent reviews
attach some qualifiers to Junges conclusion (Emmett and Schiewe,
1997), it is a central assumption behind most of the multi-million
dollar Columbia Basin fish mitigation activities: If more live
smolts can be delivered to the ocean, more adults will return. "
Though the idea of increasing the number of smolts to increase the number of returns is attractive, this will only happen if survival is relatively constant, but survival for coho and chinook salmon is highly variable (e.g., Nickelson 1986, Hilborn and Coronado 1997:11-15). Thus, an increase in numbers can be nullified by a decrease in survival.
The hypothesis that an increase in the number of smolts increases the number of returns has not withstood the tests of time. One test is that while increasing hatchery releases of coho or chinook in the 1960's did result in increased returns, this has not been true in many years since then (especially the 1980's and 1990's), probably because unfavorable ocean conditions have reduced survival (McGie 1984, Nickelson 1986:528, Pearcy 1992:46-48, Anderson 1997:44, Beamish et al. 1997:1211, Beamish and Neville 1997:214, Bottom 1997:588, Hilborn and Coronado 1997:11-15).
A test of whether increasing smolt numbers delivered to the ocean increases adult returns has been the transportation of smolts directly into the ocean. Although coho smolts transported into the ocean occasionally had increased survival, coho, chinook, and steelhead smolts generally had greater survival when released into an estuary, rather than the ocean (Ward and Slaney 1990, McNeil et al. 1991, Pearcy 1992:32-33, Johnson 1997:37, Levings and Bouillon 1997:162-163).
The premise of the Environmental Assessment that tern management will be useful in salmon recovery is considerably more speculative than is indicated because smolts saved from terns can succumb to unfavorable ocean conditions or nearshore predators. Collis et al. (1999:48-49, 71- 72) found that terns selectively took hatchery smolts (i.e., at least 78.5% of smolts taken by terns were from hatcheries, 13.1% were of unknown origin, and 8.4% were wild) because hatchery smolts appear to be particularly vulnerable to predation. Removing terns does not change the vulnerability of hatchery smolts, which can then be taken by nearshore predators, including birds other than Caspian terns and cormorants (Matthews 1983, Bayer 1986, 1989:36-38; Emmett 1997:152, Fresh 1997) and fish (Angstrom and Reimers 1964, Fresh et al. 1981:17, 27, 35; Stuart and Buckman 1985, Brodeur et al. 1987:9, Beamish et al. 1992, Beamish and Neville 1995, National Research Council 1996:40, Pearcy 1997:341).
The net result of tern removal at the Columbia can be expected to be similar to the reduction of terns at Grays Harbor, which has not resulted in increased salmon returns (Environmental Assessment, p. 33 [also see section E]).
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Anderson, J. J. 1997. Decadal scale climate pattern and salmon survival
indicators, interactions, and implications. P. 43-53 in R. L. Emmett
and M. H. Schiewe (eds.), Estuarine and ocean survival of Northeastern
Pacific salmon: proceedings of the workshop. U. S. Dept. Commerce,
National Oceanic and Atmospheric Administration, National Marine
Fisheries Service, NOAA Tech. Memo. NMFS-NWFSC-29. (This is at
http://www.nwfsc.noaa.gov/pubs/tm/tm29/Papers/Anderson.htm)
Angstrom, R. L. and P. E. Reimers. 1964. Occurrence of juvenile salmon in
stomachs of adult coho salmon. Oregon Fish Commission, Research
Briefs 10(1):69.
Bayer, R. D. 1986. Seabirds near an Oregon estuarine salmon hatchery in
1982 and during the 1983 El Nino. Fishery Bulletin 84:279-286.
Bayer, R. D. 1989. The cormorant/fisherman conflict in Tillamook County,
Oregon. Studies in Oregon Ornithology No. 6. (This is at s6_cnt.htm).
Beamish, R. J. and C. M. Neville. 1995. Pacific salmon and Pacific
herring mortalities in the Fraser River plume caused by river lamprey
(Lampetra ayresi). Can. J. Fish. Aquat. Sci. 52:644-650.
Beamish, R. J. and C. Neville. 1997. Climate-ocean changes and the
impacts on young salmon in the Strait of Georgia. P. 213-220 in R. L.
Emmett and M. H. Schiewe (eds.), Estuarine and ocean survival of
Northeastern Pacific salmon: proceedings of the workshop. U. S. Dept.
Commerce, National Oceanic and Atmospheric Administration, National
Marine Fisheries Service, NOAA Tech. Memo. NMFS-NWFSC-29. (This is at
http://www.nwfsc.noaa.gov/pubs/tm/tm29/Papers/Beamish.htm)
Beamish, R. J., B. L. Thomson, and G. A. McFarlane. 1992. Spiny dogfish
predation on chinook and coho salmon and the potential effects on
hatchery-produced salmon. Trans. Am. Fish. Soc. 121:444-455.
Beamish, R. J., C. Mahnken, and C. M. Neville. 1997. Hatchery and wild
production of Pacific salmon in relation to large-scale, natural
shifts in the productivity of the marine environment. ICES Journal of
Marine Science 54:1200-1215.
Bottom, D. L. 1997. To till the water--a history of ideas in fisheries
conservation. P. 569-597 in D. J. Stouder, P. A. Bisson, and
R. J. Naiman (eds.), Pacific salmon & their ecosystems. Chapman &
Hall, New York.
Brodeur, R. D., H. V. Lorz, and W. G. Pearcy. 1987. Food habits and
dietary variability of pelagic nekton off Oregon and Washington,
1979-1984. U.S. Dept. of Commerce, National Oceanic and Atmospheric
Administration, National Marine Fisheries Service, NOAA Tech. Report
NMFS 57.
Collis, K., S. Adamany, D. D. Roby, D. P. Craig, and D. E. Lyons. 1999.
Avian predation on juvenile salmonids in the lower Columbia River.
1998 draft annual report to the Bonneville Power Administration and
U.S. Army Corps of Engineers. (This was available on 3/6/2000 at
http://www.efw.bpa.gov/EW/EWP/DOCS/DRAFTS/cgi-lib.4812.pdf, 649K).
Emmett, R. L. 1997. Estuarine survival of salmonids: the importance of
interspecific and intraspecific predation and competition. P. 147-158
in R. L. Emmett and M. H. Schiewe (eds.), Estuarine and ocean survival
of Northeastern Pacific salmon: proceedings of the workshop. U. S.
Dept. Commerce, National Oceanic and Atmospheric Administration,
National Marine Fisheries Service, NOAA Tech. Memo. NMFS-NWFSC-29.
(This is at http://www.nwfsc.noaa.gov/pubs/tm/tm29/Papers/Emmett.htm).
Emmett, R. L and M. H. Schiewe (eds.). 1997. Estuarine and ocean survival
of Northeastern Pacific salmon: proceedings of the workshop. U. S.
Dept. Commerce, National Oceanic and Atmospheric Administration,
National Marine Fisheries Service, NOAA Tech. Memo. NMFS-NWFSC-29.
(This is at http://www.nwfsc.noaa.gov/pubs/tm/tm29/index.html).
Fresh, K. L. 1997. The role of competition and predation in the decline
of Pacific salmon and steelhead. P. 245-275 in D. J. Stouder,
P. A. Bisson, and R. J. Naiman (eds.), Pacific salmon & their
ecosystems. Chapman & Hall, New York.
Fresh, K. L., R. D. Cardwell, and R. R. Koons. 1981. Food habits of
Pacific salmon baitfish, and their potential competitors and predators
in the marine waters of Washington, August 1978 to September 1979.
Wash. Dept. of Fisheries Progress Report No. 145.
Hilborn, R. and C. Coronado. 1997. Changes in ocean survival of coho and
chinook salmon in the Pacific Northwest. P. 9-18 in R. L. Emmett and
M. H. Schiewe (eds.), Estuarine and ocean survival of Northeastern
Pacific salmon: proceedings of the workshop. U. S. Dept. Commerce,
National Oceanic and Atmospheric Administration, National Marine
Fisheries Service, NOAA Tech. Memo. NMFS-NWFSC-29. (This is at
http://www.nwfsc.noaa.gov/pubs/tm/tm29/Papers/Hilborn.htm).
Johnson, S. L. 1997. Factors influencing freshwater and marine survival
of Oregon's coastal coho salmon--what we know and what we don't.
P. 35-42 in R. L. Emmett and M. H. Schiewe (eds.), Estuarine and ocean
survival of Northeastern Pacific salmon: proceedings of the workshop.
U. S. Dept. Commerce, National Oceanic and Atmospheric Administration,
National Marine Fisheries Service, NOAA Tech. Memo. NMFS-NWFSC-29. (This is at
http://www.nwfsc.noaa.gov/pubs/tm/tm29/Papers/Johnson.htm).
Junge, C. O. 1967. The effect of superimposed mortalities on reproduction
curves. Fish Commission of Oregon, Research Division, Clackamas,
Oregon. 8 pages. (Not seen--cited in Environmental Assessment.)
Levings, C. D. and D. Bouillon. 1997. Criteria for evaluating the
survival value of estuaries for salmonids. P. 159-168 in R. L. Emmett
and M. H. Schiewe (eds.), Estuarine and ocean survival of Northeastern
Pacific salmon: proceedings of the workshop. U. S. Dept. Commerce,
National Oceanic and Atmospheric Administration, National Marine
Fisheries Service, NOAA Tech. Memo. NMFS-NWFSC-29. (This is at
http://www.nwfsc.noaa.gov/pubs/tm/tm29/Papers/Levings.htm).
Matthews, D. R. 1983. Feeding ecology of the Common Murre, Uria aalge,
off the Oregon Coast. M. S. Thesis, Univ. Oregon, Eugene.
McGie, A. M. 1984. Commentary: evidence for density dependence among coho
salmon stocks in the Oregon Production Index Area. P. 37-49 in
W. G. Pearcy (ed.), The influence of ocean conditions on the
production of salmonids in the North Pacific. Oregon State Univ., Sea
Grant College Program ORESU-W-83-001.
McNeil, W. J., R. Gowan, and R. Severson. 1991. Offshore release of
salmon smolts. Am. Fish. Soc. Symp. 10:548-553.
National Research Council. 1996. Upstream: salmon and society in the
Pacific Northwest. National Academy of Sciences Committee on
Protection and Management of Pacific Northwest Anadromous Salmonids.
National Academy Press, Washington, D.C.
Nickelson, T. E. 1986. Influences of upwelling, ocean temperature, and
smolt abundance on marine survival of coho salmon (Oncorhynchus
kisutch) in the Oregon Production Area. Can. J. Fish. Aquat. Sci.
43:527-535.
Pearcy, W. G. 1992. Ocean ecology of North Pacific salmonids. Washington
Sea Grant Program, Univ. of Washington Press, Seattle.
Pearcy, W. G. 1997. Salmon production in changing ocean domains.
P. 331-352 in D. J. Stouder, P. A. Bisson, and R. J. Naiman (eds.),
Pacific salmon & their ecosystems. Chapman & Hall, New York.
Stuart, A. and B. Buckman. 1985. Adult coho predation on coho smolts.
Oregon Dept. of Fish and Wildlife, Ocean Salmon Mgmt. Memorandum.
South Beach, Oregon.
Ward, B. R. and P. A. Slaney. 1990. Returns of pen-reared steelhead from
riverine, estuarine, and marine releases. Trans. Am. Fish. Soc.
119:492-499.
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This Environmental Assessment may not be available online in the future, so the following material from p. 32-34 is given because it discusses Caspian tern impact on salmonids at Grays Harbor. This is part of the Assessment's section, "Impacts to Grays Harbor," that project the effects on Grays Harbor if terns are relocated from Rice Island (Columbia River) to Grays Harbor and other sites as proposed in the Assessment. Tern breeding at Grays Harbor is also discussed on p. 25-27 of the Assessment.
I have added boldface to text of particular interest to salmonids.
----------- from p. 32-34 of Environmental Assessment ---------------------
The rationale behind moving Caspian terns from the Columbia River estuary has been to reduce predation on ESA stocks of juvenile salmonids. Artificial habitat conditions (dredged material islands), coupled with an abundant prey base (juvenile salmonids) and loss of previous tern habitat in the western U.S., attracted nesting Caspian terns to the Columbia River estuary. The presence of Caspian terns in Grays Harbor would result in predation on chum, chinook (fall and spring), coho, steelhead, and coastal cutthroat salmonid stocks, principally originating from the Chehalis and Humptulips Rivers. Concern has been raised that Caspian tern predation will adversely impact these stocks. A review of Grays Harbor Caspian tern numbers compared to terminal run size numbers for salmonids (Table 4) provides some interesting comparisons. The high point for chum salmon returns (1988) occurred during the period of highest Caspian tern numbers in Grays Harbor. Conversely, the lowest run return for chum salmon occurred in 1990; juvenile outmigrants for that adult return would have entered the estuary during a peak population period for Caspian terns. Spring chinook numbers in 1988 were well above the average run size for the period 1981-1997. Juvenile spring chinook, which formed the basis for 1988 returns, would have traveled through Grays Harbor during a high population period for Caspian terns. However, spring chinook numbers fell below the 1981-1997 return run size average from 1990 to 1994. Tern numbers were still relatively high, although declining, when juvenile outmigrants that formed the basis for 1990-1994 adult returns would have passed through Grays Harbor. Adult fall chinook runs exceeded the 1981- 1997 average from 1987-1997, and even attained their highest return number in 1989. These high fall chinook runs occurred during a period when juvenile outmigrants would have encountered some of the highest tern populations. Coho returns fluctuated, exhibiting both high and low returns during the period when Caspian tern numbers in Grays Harbor were high (Table 4). In summary, there is no apparent relationship between Caspian tern breeding population size in Grays Harbor and returns of adult salmonids, suggesting that tern predation was not a limiting factor for adult returns.
Other impacts associated with Caspian tern reestablishment in Grays Harbor are relatively minor. Approximately 4 acres of estuarine island habitat would be converted to barren sand which would negligibly impact existing wildlife and wildlife habitat. Bald eagles and gull species would take advantage of increased prey (eggs, chicks, adults terns) reestablished in the estuary. There would be some increase in avian predation on Gray Harbor fisheries; however, based upon the information presented in Table 4, the reestablishment of Caspian terns in Grays Harbor would not devastate salmonid stocks. Healthy salmon runs would be expected to continue to occur. Significant impacts to commercial fisheries or commercial and subsistence fishing by area tribes in reserved Usual and Accustomed fishing areas are not expected. There should be no impacts to oyster farming or crab fisheries, since oysters and crabs are not a part of the terns expected diet.
---------------------------------------------------------------------------Table 4. Caspian tern and salmon terminal run size numbers for Grays Harbor, Washington.
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Caspian Tern Terminal Run Size - Salmon (thousands)
Year Grays Harbor Chum Spring Fall
(number of birds)a Salmon b Chinook c Chinook c Coho c
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1957 24
1958 150
1959-1971
1972 3000
1973 2000
1974 2000-3000
1975 2488
1976 3680
1977 4084
1978 3712
1979 4004
1980 4394
1981 4314 0.9 13.4 64.7
1982 5216 0.7 14.6 81.7
1983 0.9 9.9 54
1984 5550 1.1 23.7 159.1
1985 1.2 16.9 39.2
1986 2 23.3 128
1987 7180 1.1 34.6 89.4
1988 5652 137 3.6 39.7 131.1
1989 5848 2.4 56 113.3
1990 12.6 1.6 39.8 118.3
1991 1.5 33.2 289
1992 2527 1.7 33.2 61.8
1993 214 1.4 33.9 57.6
1994 0 1.5 31 38.8
1995 0 2.2 31.8 142.5
1996 68 4.6 35.2 180.7
1997 4.8 30.9 42.1
1998
1999
1980-1991d 55.5
1981-1997d 1.95 29.5 105.4
a Caspian tern numbers from WDFW unpublished records. Breeding pair
numbers/number of nests converted to number of birds.
b 1992 Washington State Salmon and Steelhead Stock Inventory, Appendix
Two, Coastal Stocks
c Pacific Fishery Management Council. Review of 1998 Ocean Salmon
Fisheries.
d Average terminal run size.
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