Download Coastal Ocean Variability and Ocean Survival of Coho Salmon

The Effect of Ocean Conditions on
Salmon Survival and Return
Joseph C. Greene, Research Biologist
Claudia J. Wise, Physical Scientist
Greene Environmental Services
Hypothetical escapements to the Russian River for all species of salmon
[Estimates based on conservative expansion of U. S. Bureau of Fish and Fisheries (1885),
Warm Springs Hatchery return numbers, and anecdotal CDFG reports.] (Steiner, 1996).
Numerous human and natural factors have been
implicated in the crash of West Coast salmon runs.
It seems no one factor alone has caused
the decline, but each has contributed to the
problem in its own negative fashion.
Habitat has been altered or destroyed by:
 sedimentation;
 water diversions;
 riparian vegetation removal; and,
 elevated water temperatures.
The natural equilibria of predation and competition
have been shifted by human activities.
Infection and disease have become increasingly
prominent as water temperatures rose, dams were
built, and hatcheries were operated.
Chinook harvest over the years (both legal and
illegal) has caused further detriment to the species.
Finally, natural events combined with human activity
have culminated in a distinct crisis for the Klamath
species.
The number of returning spawners, wild and
hatchery-reared, fluctuates considerably
between years but in most areas the long-term
trend is that the runs have diminished and in
many cases gone extinct.
The dynamics behind those changes are often
far from understood and due to the complex
salmon life cycle their survival can be impacted
by a multitude of physical and biological
factors in local watersheds and the ocean.
NRC (National Research Council). 1996. Upstream: Salmon and society in the Pacific Northwest. Washington, DC: National Academy Press.
Habitat Salmon Needs at Each Stage of the Life Cycle
When adults spawn, they need the right stream gravel, or substrate, for their nests.
Each species has unique spawning area requirements, including substrate size, area,
depth, and water velocity. Spawning adults also need clear, clean, and cold water.
When fertilized eggs mature into embryos, they need a constant
supply of clean, cold, and clear water. This water flows through
the gravel in the redds (or nests) providing oxygen to the growing
embryos and removing waste products.
When freshly hatched alevins, mature into fry, they need plenty of
food in the form of microscopic plants and animals, called
phytoplankton and zooplankton. Fry also need slower-moving water
when they emerge from the redd, because they are not strong enough
to swim in swift currents.
When fry mature into smolts, they undergo physiological changes so
that they can live in salt water. Shallow estuary areas with brackish
water help smolts adjust gradually to the ocean’s salt water. These
areas also supply smolts with abundant food, helping them grow and
improving their chance of survival after they migrate into the ocean.
When smolts grow into adults, they need ample ocean food.
Unfortunately, little is known about this part of the life cycle, and it
is different among different salmon species and regions.
The U. S. Fish and Wildlife Service Lists 8 Peer-Reviewed
Reasons for Salmon Decline in the Klamath River Basin
 Over fishing;
 Logging;
 The Trinity River Diversion;
 Irrigation Diversions in the lower Klamath Basin tributaries;
 The 1964 Flood;
 The 1976 - 77 drought which was a 50 year/100 year drought,
back-to-back;
 Sea Lion predation;
 Brown Trout predation.
Species differences
Coho salmon appear to be more affected by the Pacific Decadal
Oscillations and El Nino/Southern Oscillation shifts. WHY?
 Coho are shallow water fish. They are tied to:
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Sea Surface Temperatures;
Upwelling;
Spring transition;
1st winter ocean conditions; and,
They have a 3 year life cycle.
 Chinook are deeper water fish, and due to 3,4,5 variable
return age can handle fluctuating ocean conditions
 Steelhead head off the shelf and north to more productive
waters off the artic circle which are less affected by regime
shifts. Their life cycle and variable age of return is more adapted
to variable conditions
 Young salmon in freshwater mainly eat
zooplankton, benthic amphipods and insects.
 Once in the ocean, they continue to eat
zooplankton, but add crustacean larvae to
their diet.
 As they become larger, they will prey on
small fishes and sometimes squid.
 Upon entering fresh water to spawn,
salmon stop feeding entirely.
Plankton
 Phytoplankton are the energy for all of
life in the underworld.
 Most phytoplankton photosynthesize,
changing light energy from the sun into
energy that all non-photosynthesizing
organisms can use.
Phytoplankton = microscopic plant life
Zooplankton = animal like organisms
In most cases
phytoplankton are
eaten by very
small animal-like
organisms called
zooplankton.
Plankton size relative to the eye of an needle
The Pacific Northwest Index (PNI)
characterizes cool/wet and warm/dry climate
patterns in the Pacific Northwest
James J. Anderson, School of Fisheries, University of Washington, Review of the Influence of Climate on Salmon
The catch of the Columbia River spring
chinook is correlated with the PNI
Warm & Dry
Warm & Dry
Cool & Wet
Cool & Wet
James J. Anderson, School of Fisheries, University of Washington, Review of the Influence of Climate on Salmon
Coastal Ocean Variability and
Ocean Survival of Coho Salmon
 Coastal ocean conditions play an important role in
marine survival of young coho salmon, and the
number of adults returning to freshwater each year.
 Upwelling variability during the juvenile coho's first
ocean spring and summer may be particularly
important in determining adult production.
Since 1985 there has been a sharp decline in
the ocean survival of coho salmon.
Frank Schwing, Completion of Manuscript on Remotely Sensed Coastal Ocean Variability and Ocean Survival of Coho Salmon,
(831-648-9034, [email protected])
Returns of Steelhead to Iron Gate Hatchery had been
increasing at about 2% per year since 1963, but
exhibited a strong decline since 1987
Figure B-17. Returns of adult steelhead to Iron Gate Hatchery on the Klamath River
NOAA, 1994, Status Review for Klamath Mountains Province Steelhead, Technical Memorandum NMFS-NWFSC-19
Coastal Ocean Variability and
Ocean Survival of Coho Salmon
The relationship between coho survival
and sea surface temperature anomalies,
calculated weekly in the region 37-51°
N during 1985-1996, was examined
using univariate and bivariate
regression analysis for a number of
different time frames.
Frank Schwing, Completion of Manuscript on Remotely Sensed Coastal Ocean Variability and Ocean Survival of Coho Salmon,
(831-648-9034, [email protected])
Coastal Ocean Variability and
Ocean Survival of Coho Salmon
The sum of negative sea surface temperature
anomalies from April to June, when juvenile
coho first enter the ocean, was highly
correlated against survival.
The sea surface temperature variables
explain over 90% of interannual variability in
the marine survival of hatchery-reared coho
salmon from 1985 to 1996.
Frank Schwing, Completion of Manuscript on Remotely Sensed Coastal Ocean Variability and Ocean Survival of Coho Salmon,
(831-648-9034, [email protected])
Hatchery Raised Fish
 Numerous studies have been published describing
the genetic and ecological risks that artificial
production may pose for naturally spawning fish
populations.
 In assessing the risks to any particular population, it
is usually difficult to demonstrate conclusively that
adverse effects are actually occurring, and, if they
are demonstrated, how serious they are.
 In assessing the status of stocks proposed for
listing under the ESA, NMFS found the effects of
artificial propagation to be among the most difficult
and controversial to incorporate into risk analyses.
CDFG, National Marine Fisheries Service Southwest Region Joint Hatchery Review , 2001, Report on Anadromous Salmonid Fish Hatcheries in California.
Survival rates of coho and chinook salmon
released from hatcheries on the U.S. and
Canadian Pacific coast 1972–1998
 Smolt-to-adult survival rates were
estimated for 18,659 coho and chinook
coded wire tag groups released in 1972–1998
from 206 hatcheries on the U.S. and
Canadian Pacific coast.
Survival rates of 153 wild coded wire tag
groups showed similar trends as those of
hatchery fish.
Magnusson, A., 2002, Survival rates of coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) released from hatcheries on the U.S. and Canadian
Pacific coast 1972–1998, with respect to climate and habitat effects, University of Washington, School of Aquatic and Fishery Sciences, Thesis for Masters Degree.
Survival rates of coho and chinook salmon
 The long-term trend for both coho
and chinook was a decline in all
regions south of Alaska.
 Regional and annual variation
explained 46% of the total variation
for coho, 34% for fall chinook, and
42% for spring chinook.
Magnusson, A., 2002, Survival rates of coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) released from hatcheries on the U.S. and Canadian
Pacific coast 1972–1998, with respect to climate and habitat effects, University of Washington, School of Aquatic and Fishery Sciences, Thesis for Masters Degree.
Survival rates of coho and chinook salmon
 Regression analysis was used to explore the
relationship between survival rate and climate
during the year of release, and the variable that
showed the strongest relationship was summer
sea surface temperature at the place where the fish
reach the ocean.
 The sea surface temperature variable alone
explained 41% of the regional and annual variation
of coho survival rates.
Magnusson, A., 2002, Survival rates of coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) released from hatcheries on the U.S. and Canadian
Pacific coast 1972–1998, with respect to climate and habitat effects, University of Washington, School of Aquatic and Fishery Sciences, Thesis for Masters Degree.
Survival rates of coho and chinook salmon
 Little is known about the ecological dynamics
that link sea surface temperature and survival rate,
but sea surface temperature is highly correlated
with a suite of physical and biological factors in
the ocean.
 There has been a long-term increase in sea
surface temperature from the early 1970s to the
late 1990s, corresponding to the declining survival
rates south of Alaska and increasing survival rates
in Alaska.
Magnusson, A., 2002, Survival rates of coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) released from hatcheries on the U.S. and Canadian
Pacific coast 1972–1998, with respect to climate and habitat effects, University of Washington, School of Aquatic and Fishery Sciences, Thesis for Masters Degree.
Survival rates of coho and
chinook salmon
The decline in wild salmon abundance
in the 1990s was due in considerable
part to changes in ocean conditions
and increases in wild stock
abundance may be expected if ocean
conditions change.
Magnusson, A., 2002, Survival rates of coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) released from hatcheries on the U.S. and Canadian
Pacific coast 1972–1998, with respect to climate and habitat effects, University of Washington, School of Aquatic and Fishery Sciences, Thesis for Masters Degree.
Effects on Fish
 The 1998 El Nino and the following 1999 La Nina
were the largest amplitude El Nino/Southern
Oscillation cycle in recent (measured) history;
 Many Pacific Northwest stocks will be depleted
for several decades;
 Several year classes already severely depleted
were subject to this event; and,
 The effects were particularly severe on coho
salmon.
What does this mean for fish?
 Winter sea surface temperature in the
smolt year;
 Date of spring transition to saltwater;
 Spring upwelling; and,
 winter sea surface temperature …
correlate with annual mean temperature
and are indicators of coho production.
What does this mean for fish?
Lowering of sea surface temperature,
increased upwelling,
increases ocean productivity,
Increase in prey species,
decrease in predator species, and
shift from salmon to baitfish (herring, anchovy,
sardine and smelt) as prey item for predators
… favors ocean survival
Recent Research
 Pacific Decadal Oscillation signal has turned and
remained negative since July 1998, longest period of
negativity since 1976 (Peterson, 2002 NOAA).
 Oregon Plankton tows show a doubling of the
copepod species has been observed, and a shift in
biomass to increased boreal neritic species”,
concurrently with decreased “transitional/subtropical
neritic species”- CA copepods have disappeared from
BC tows (Zamon 2002).
 Zooplankton resemble the assemblage seen in the
1970’s during the last negative Pacific Decadal
Oscillation.
Causes of Decline for Coho Salmon
The petitioners for ESA status for Coho salmon identified:
 habitat destruction;
 over fishing;
 artificial propagation; and,
 poor ocean conditions
as the causes of decline for coho salmon. Both petitioners argued
that the primary cause for decline has been habitat destruction
(Oregon Trout et al. 1993, Pacific Rivers Council et al. 1993). Oregon
Trout et al. (1993) also identified over utilization of the species for
commercial and recreational purposes as an equally important factor
for Oregon coho salmon, while the Pacific Rivers Council et al. (1993)
identified deteriorating ocean conditions as a major cause for the
general decline of west coast coho salmon. Both petitioners cited
adverse effects of artificial propagation as an aggravating factor.
Pacific Rivers Council et al. (1993) also identified intraspecific
hybridization and interspecific hybridization with chinook salmon as
an additional concern.
NOAA, 1995, Status Review of Coho Salmon from Washington, Oregon, and California, NOAA Technical Memorandum NMFS-NWFSC-24
 A principal component analysis reveals that Pacific salmon
catches in Alaska have varied inversely with catches from the
U.S. West Coast during the past 70 years.
 If variations in catch reflect variations in salmon production,
then results of our analysis suggest that the spatial and temporal
characteristics of this “inverse” catch/production pattern are
related to climate forcing associated with the Pacific Decadal
Oscillation, a recurring pattern of pan-Pacific atmosphere-ocean
variability.
 Temporally, both the physical and biological variability are
best characterized as alternating 20-to 30-year-long regimes
punctuated by abrupt reversals.
 From 1977 to the early 1990s, ocean conditions have
generally favored Alaska stocks and disfavored West Coast
stocks.
 Unfavorable ocean conditions are likely confounding recent
management efforts focused on increasing West Coast Pacific
salmon production.
Hare, S. R., N. J. Mantua and R. C. Francis, 1999, Fisheries, 24:6–14
What scientists at the University of Alaska
Fairbanks say about salmon declines in Alaska
Ted Cooney, professor of fisheries oceanography
Institute of Marine Science
School of Fisheries and Ocean Sciences
University of Alaska Fairbanks
Do salmon runs in the North Pacific Ocean fluctuate
according to cycles?
Cooney: "Scientific data on these natural cycles in
salmon populations go back to the 1920s. These
analyses show that for Alaska salmon stocks, there
have been cycles in the past. The cycles seem to run
on the order of 20 years. In some years more fish are
produced and in other years fewer fish are produced.
So, the recent declines aren't terribly surprising."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Milo Adkison, professor of fisheries
Fisheries Division
School of Fisheries and Ocean Sciences
University of Alaska Fairbanks
Explain what you mean by the history of
salmon fisheries.
Adkison: "The record of salmon returns is that they
are highly variable. The salmon survival rates are
highly variable. You get large year-to-year variations
and you also get shifts in the productivity that run for
a couple of decades or so and then shift to a different
level of productivity. And it's all connected to changes
operating on similar time scales on the ocean."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Milo Adkison, professor of fisheries
Fisheries Division
School of Fisheries and Ocean Sciences
University of Alaska Fairbanks
So what went wrong this year?
Adkison: "The conditions out in the ocean have been really unusual
the last couple of years. It's not surprising that the models we use
to make predictions fall apart when we encounter a whole new set
of conditions. Generally, warmer sea surface temperatures are
better for salmon [in Alaska]. But the temperatures these past
couple of years have been much warmer than what we've seen
before. We may be going past the optimum to where warmer
temperatures may actually be counterproductive for salmon.
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Milo Adkison, professor of fisheries
Fisheries Division
School of Fisheries and Ocean Sciences
University of Alaska Fairbanks
Is that what you think is happening now, that
salmon are responding to long-term ocean cycles?
Adkison: "I'm not saying that we've entered a new regime, but the
problem is that you have shifts that occur every 15 years or so. On
top of that you have this huge year-to-year variation. So it's really
hard to look at a year like last year and say 'Okay, things were lousy
this year and so they're going to be lousy next year.' It's very
common to have things be lousy one year and good the next year.
Because there's this large interannual variability, you have a hard
time deciding that you're in a new regime until you've seen five years
of bad returns in a row or five years of exceptional returns in a row."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Should the environmental changes seen in the North
Pacific Ocean last year, such as warmer water
temperatures, seabird die-offs, and scarce plankton
have tipped off managers that the salmon returns
would be low this year?
Adkison: "I wouldn't have thought so, but we have to take a look at
that. The thinking among most fisheries biologists is that it's the
youngest salmon that are the most vulnerable. So what you would
have expected to see is a bad year out in the ocean and then a couple
of years later a fall-off in salmon production, because the fish that
had just gone to the ocean that year would be the ones most strongly
affected. The adults due to come in that year could probably weather
it better. So it's puzzling that the year the ocean conditions were a bit
strange, the run failed the same year and not a couple years later."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Fishery managers have come under fire for not
considering the ocean's effects in their forecasts. Do
you sense that fisheries managers are willing to take
ecosystem influences into account in their forecasts?
Adkison: "There's an increasing verbal focus on ecosystem
considerations. But where the rubber hits the road there is
a growing awareness that from a practical point of view it's
very difficult to take an ecosystem approach to managing
fish stocks. The data requirements are beyond what is
available for most fisheries."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Are there some key environmental variables that
could be used to improve salmon return
predictions without having to fully understand the
entire ecosystem?
Adkison: "People are doing the obvious things. They look at
the abundance of principal predators; they'll look at the
abundance of food; they'll look at indicators of the state of the
overall ecosystem such as sea surface temperatures, weather
patterns, and use them as empirical predictors of salmon
survival. But it's still baby steps.
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Tom Weingartner, assistant professor of oceanography
Institute of Marine Science
School of Fisheries and Ocean Sciences
University of Alaska Fairbanks
Are you seeing environmental changes in the
North Pacific Ocean?
Weingartner: "It's a little hard to say what the time scales are,
because there is a variety of time scales, but we have seen
some rather striking changes in the last year or so. Last
summer, we noticed an unusual warming that was confined to
the surface layers of the Gulf of Alaska and the Bering Sea.
Those temperature changes were two to three degrees above
normal beginning about the middle of the summer and
continuing through the fall.
http://www.uaf.edu/seagrant/issues/salmon_gone.html
Are you seeing environmental changes in the
North Pacific Ocean? continued …
Weingartner: Beyond the fall, the temperature changes were
even more dramatic. They weren't confined to just the surface
but, at least in the Gulf of Alaska, they extended down at least
250 meters or so on the continental shelf. They were about
two to three degrees above normal, and they continued
through the spring. A lot of heat is required to elevate ocean
temperatures by those few degrees.
http://www.uaf.edu/seagrant/issues/salmon_gone.html
Are you seeing environmental changes in the
North Pacific Ocean? continued …
Weingartner: "Through the winter we noticed that there was a
decrease in the amount of cooling that usually takes place in the
Gulf of Alaska. That was very dramatic. Our Canadian colleagues
have noticed in the Gulf of Alaska that nutrients necessary for
phytoplankton production were depleted from the surface layers
of the ocean. That has not been observed before in the Gulf of
Alaska. Other things that have been noticed are a change in the
phytoplankton species composition in the Bering Sea. That is
usually dominated by a community called diatoms, but the last
couple of summers it has been dominated by cocolithophores, a
very different phytoplankton species."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
Is our understanding of the marine
ecosystem a field that is still in its infancy?
Weingartner: "Yes, very definitely so--I think in large measure
because many of the mechanisms, say temperature change
effects on phytoplankton and how such changes are transmitted
on up the food chain, are not well understood at all. Until those
connections are understood, ecosystem management of, say, a
salmon population would be difficult to make. Although I believe
this is the direction we need to go, it won't occur overnight."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
What scientists at the University of Alaska Fairbanks
say about salmon declines in Alaska
Donald Schell, director
Institute of Marine Science
School of Fisheries and Ocean Sciences
University of Alaska Fairbanks
Your research has focused on understanding
the Bering Sea ecosystem and the role it
played in the declines of Steller sea lions,
seabirds and other species. Specifically, your
work seeks to understand how the sea's
production of plankton, the basis of the marine
food chain, has changed over time. But to
understand ocean productivity, you're studying
bowhead whales. Please explain.
http://www.uaf.edu/seagrant/issues/salmon_gone.html
Schell: "We've actually looked at bowhead whales to learn
how ocean productivity has changed over the past 50 years.
… Bowhead feed on zooplankton. Zooplankton are the first
consumers of phytoplankton, the small plants that are the
first rung of the ocean food chain and an important indicator
of productivity in the ocean. … This productivity can be
measured by using isotope ratios in the baleen of whales.
Since you are what you eat, the carbon in this case is from
the consumption of plankton. The changes in carbon type in
whale baleen reflects the abundance of plankton in any
given year and can be used as an index to changes in ocean
primary productivity."
http://www.uaf.edu/seagrant/issues/salmon_gone.html
Schell: We have developed a record of phytoplankon
productivity in the Bering Sea all the way back to
1946. The story it tells is amazing because the whale
baleen reflects phytoplankton productivity quite well.
 The record shows that from 1946 to 1963 everything went
along fairly smoothly at a relatively high rate of productivity.
 And then in the mid-1960s it increased and peaked at around
1965.
 Then ocean plankton productivity began to decline, and since
the mid-1970s it has gone down and down and down.
 The last samples we have from 1994, 1995 and 1996 show the
lowest primary productivity in the Bering Sea over this 50-year
period."
http://www.uaf.edu/seagrant/issues/salmon_gone.html