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Fisheries | www.sheries.org 465
© 2019 American Fisheries Society
DOI: 10.1002/fsh.10273
FEATURE
Recent Ecosystem
Disturbance in the
Northern California
Current
Cheryl A.Morgan  | Cooperative Institute for Marine Resources Studies,Oregon State University, Hateld Marine Science Center,
2030 Southeast Marine Science Drive, Newport, OR 97365. Email: cheryl.morgan@oregonstate.edu
Brian R.Beckman  | National Marine Fisheries Service,Northwest Fisheries Science Center,Environmental and Fisheries Sciences
Division, Seattle, WA
Laurie A.Weitkamp  | National Marine Fisheries Service,Northwest Fisheries Science Center,Conservation Biology Division,
Newport, OR
Kurt L.Fresh  | National Marine Fisheries Service,Northwest Fisheries Science Center,Fish Ecology Division (retired), Seattle, WA
Fisheries | www.sheries.org 465
© 2019 American Fisheries Society
DOI: 10.1002/fsh.10273
Photo credit: NOAA Fisheries/
Oregon State University
466 Fisheries | Vol. 44 • No. 10 • October 2019
An extended marine heat wave occurred across the North Pacic during 2014–2016, including the formation of the warm “Blob”
followed by a strong El Niño in 2016. Coincident with this marine heat wave, we documented unprecedented biological changes
in plankton and nekton in the Northern California Current (NCC) within pelagic surveys conducted over 20years (1998–2017).
The recent warm period was dominated by warmwater gelatinous invertebrates and shes, some of which were previously either
extremely rare or absent. Mixing of organisms originating from more southern or western regions with those previously present
in the NCC may have resulted in novel and unpredictable trophic interactions that produced some of the observed changes in
relative abundance. Continued long- term monitoring is needed to determine whether this is a temporary ecosystem disturbance
or a fundamental change in the very productive NCC upwelling region.
The Northern California Current (NCC) ecosystem (from
the Canadian border to Cape Blanco, Oregon) has undergone
a great deal of oceanic variability over the past 20years, in-
cluding a strong El Niño in 1998, a strong La Niña in 1999, a
Pacic Decadal Oscillation (PDO) regime shift during 1998–
2002 (Peterson and Schwing 2003), and a much- delayed spring/
summer upwelling period in 2005 (Lindley etal. 2009). These
oscillations between warm and cool periods have resulted in
shifts in abundance of many commercially important species,
including squid, hake, rocksh, and juvenile salmonids.
In fall 2014, an extreme warming of coastal waters oc-
curred as a large parcel of anomalously warm water—the so-
called “blob”—moved eastward and caused a sudden increase
in coastal temperatures (Bond etal. 2015). The warm Blob
formed in the Gulf of Alaska during the winter of 2013–2014
and generally persisted in the Northeast Pacic through 2016,
although brief periods of cooling occurred during May–June
2015 following strong equatorward winds and upwelling
(Peterson et al. 2015, 2017). The blob was immediately fol-
lowed by a strong El Niño event in 2015–2016 (Jacox etal.
2016). These oceanographic phenomena resulted in a pro-
longed marine heat wave throughout the NCC during 2014–
2016 (Di Lorenzo and Mantua 2016; Gentemann etal. 2017).
This heat wave resulted in shifts in the occurrence and abun-
dance of a broad range of taxa, including copepods (Peterson
et al. 2017), ichthyoplankton (Auth etal. 2017; Daly et al.
2017), squid (Sakuma et al. 2016), gelatinous invertebrates,
krill and shrimp (Sakuma et al. 2016; Peterson et al. 2017;
Brodeur etal., 2019), and shes (Leising etal. 2015; Sakuma
etal. 2016). Trophic shifts were also evident in juvenile salmon
diets (Daly etal. 2017).
We collected physical and biological data, including plank-
ton and pelagic nekton, on the same coastal grid from central
Oregon to the Washington–British Columbia border over a
20- year period from 1998 to 2017. This allowed us to devel-
op an oceanographic and biological baseline for the pelagic
ecosystem of the NCC. We documented unique abundance
variations within our 20- year time series, with effects at all tro-
phic levels. Unlike other recent publications, our data indicate
that biological disturbances continued through 2017, after
cessation of surface manifestations of the blob. This report
describes effects of the recent marine heat wave on the NCC
pelagic ecosystem and the status of the post- Blob NCC eco-
system. Because of impacts on larval and juvenile shes, we
expect marine heat wave effects to continue for several more
years.
METHODS
We obtained information from surveys conducted over
the continental shelf, 1.9–56.0km (1–30 nautical mi) offshore
of Washington and Oregon, USA, in late June 1998–2017.
During each survey, we sampled ve to seven xed stations
along each of ve to eight transect lines perpendicular to the
shore between the northern tip of Washington (48°13.7’N)
and Newport, Oregon (44°40.0’N; Figure 1). In this paper,
we summarize sampling and analysis methods used for these
surveys, but more detailed descriptions of these methods are
provided by Brodeur etal. (2005), Morgan etal. (2005), and
Peterson etal. (2010).
At each station, we sampled temperature, chlorophyll- a
concentration, zooplankton, and nekton. Temperature was
measured with a conductivity–temperature–depth instru-
ment to within 5m of the bottom or a depth of 200 m, and
chlorophyll- a samples were collected at a depth of 3 m using
a Niskin bottle. Temperatures for each station were aver-
aged over the top 20m of the water column that the trawl
sampled. Zooplankton collections were made with either a
1.0- m- diameter ring net (1999–2000) or a 0.6- m- diameter
bongo net (2001–2016), both of which were tted with 335-
μm mesh and a General Oceanics owmeter to estimate the
water volume ltered. Plankton nets were shed by letting out
60 m of cable and immediately retrieved at 30m/min while
being towed at 3.704km/h (2 knots). The maximum depth
Figure 1. Locations of Oregon–Washington coastal stations
included in the analysis for plankton (white) and pelagic nek-
ton (white and yellow).
Fisheries | www.sheries.org 467
shed was 20–30 m. We did not include plankton samples
from 1998 and 2017 in our results, as samples were taken at
only a few stations in 1998 and those from 2017 have not yet
been analyzed.
Fish and invertebrate nekton were sampled using a Nordic
264 rope trawl (Nor’Eastern Trawl Systems, Bainbridge
Island, Washington) towed to sample the upper 20m of the
water column for 15–30min at approximately 6.5km/h. Only
stations that were sampled during the day, over the continen-
tal shelf (≤200- m water depth), and in at least 10 of the study
years were included in our analyses. We did not include jelly-
sh data from 1998, since jellysh occurrence was not reliably
recorded. We report only on species that exhibited signicant
changes during the blob period compared to previous years.
Our report consists of simple estimates of abundance
for the biological organisms of interest. Our evaluation of
interannual variation in abundance is also simple. We start-
ed by generating an overall mean abundance (grand mean
[GM]) and variance (SD [grand]) based on the average of 20
individual annual means (AMs; 1998–2017; see below). For
each year of sampling, we then determined the number of
SDs (grand)between the AM and the GM. All calculations
were performed using Statgraphics Centurion version 17.1
(StatPoint Technologies, Inc., Warrenton, Virginia). We evalu-
ated the abundance of organisms found in each year in refer-
ence to the number of SDs between the GM and the AM, and
we designated these yearly abundance estimates as follows:
typical (AM<1 SD from the GM), notable (AM>1 SD to 2
SDs from the GM), exceptional (AM>2 SDs to 3 SDs from
the GM), or extreme (AM>3 SDs from the GM).
Abundance was calculated differently for zooplankton
and nekton. Total abundance of each zooplankton species
caught in each haul was calculated using counts and water
volume ltered, converting to biomass by using length- to-
mass regressions and literature values (Morgan etal. 2005),
and then standardizing to units of milligrams of carbon per
cubic meter (mg C/m3). Total abundance of each nekton
species caught in each haul was either (1) determined direct-
ly from a total count of individuals or (2) estimated from
the total weight caught, based on the number of individuals
in a weighed subsample of that haul. Trawl catches of each
species at each station were standardized to linear densi-
ty by dividing station catch by the distance of the tow, as
determined by a Global Positioning System receiver. After
standardizing for distance, densities were log10(x+1) trans-
formed (log10[number/km+ 1]) to make the data easier to
visualize, interpret, and compare.
We used large- scale indices of ocean conditions, including
the PDO and the Oceanic Niño Index (ONI), to place local-
scale phenomena within a larger- scale mechanistic picture
and to provide a framework in which to examine physical phe-
nomena and lagged biological responses (Mantua etal. 1997;
Fisher etal. 2015; Peterson etal. 2017). Positive PDO values
were associated with relatively warm ocean conditions in our
region. Similarly, positive ONI values—indicative of El Niño
events on the equator—were also often associated with warm-
ing of the NCC. For our study, the PDO was reported as an
average of May and June values for each year (data available
from the Joint Institute for the Study of the Atmosphere and
Ocean, University of Washington: http://jisao.washington.
edu/pdo/PDO.latest.txt), and the ONI was reported as an
average of November–January and December–February val-
ues for each year (data available from the National Weather
Service’s Climate Prediction Center: origin.cpc.ncep.noaa.
gov/products/analysis_monitoring/ensostuff/ONI_v5.php).
RESULTS AND DISCUSSION
Physical Conditions in the Northern California Current
Temperatures in the NCC have been unusually warm since
2014 (Bond etal. 2015; Peterson etal. 2015). This was reect-
ed by the strongly positive PDO during 2014–2016, which
was the longest period of positive PDO in our time series
(48 months; January 2014–December 2017; Figure 2), and
by the highly positive 2016 ONI value, which reected the ex-
tremely strong El Niño at the equator (data from the National
Weather Service’s Climate Prediction Center: http://origin.cpc.
ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_
v5.php). Despite overall warmer temperatures documented in
the NCC due to the warm Blob (Bond etal. 2015; Peterson
etal. 2015), the upper 20- m temperatures in June during our
2014–2016 surveys were not unusually high; this was due to
short periods of upwelling prior to the surveys (data available
from the National Marine Fisheries Service’s Pacic Fisheries
Environmental Laboratory: https://www.pfeg.noaa.gov/prod-
ucts/PFEL/modeled/indices/upwelling/NA/upwell_menu_
NA.html; Figure 2). However, the complete monthly time
series in this region from 2014 to 2016 did show that tempera-
tures in the upper water column were elevated (Leising etal.
2015; McClatchie et al. 2016; Peterson et al. 2017). Finally,
while physical oceanographic indicators suggested a return
to neutral ocean conditions in summer 2017 (PDO; Peterson
etal. 2017), temperatures in our survey area were still high.
Biological Patterns of Change
In 2014, we observed biological changes coinciding with de-
velopment of the offshore blob and a positive PDO (Figure2).
For example, in June 2014, the chlorophyll- a concentration was
rated as exceptional and was one of the three highest values in
the time series. Similarly, Peterson etal. (2017) also observed
high chlorophyll- a concentrations in June 2014 during more
frequent sampling off Newport, Oregon. Among the animals
sampled, both California market squid Doryteuthis opalescens
and furcilia- stage larval North Pacic krill Euphausia pacica
had notable deviations in abundance and were more numerous
than in the previous 15years (Figure2).
In 2015, the abundances of more species deviated mark-
edly from their 20- year mean values (Figure2; Table1). The
deviation in biomass abundance of North Pacic krill furcilia-
stage larvae was exceptional, and for Pacic sand crab Emerita
analoga zoeal- stage larvae, the deviation was notable. Both
species were much more abundant than they had previously
been in the time series. Abundances of all three common jel-
lysh species changed markedly but differed in their direction
of change. The deviation in abundance of the normally scarce
water jellysh Aequorea spp. was exceptional, and it became
the most abundant jellysh in our catches. In contrast, the gen-
erally most common jellysh, the Pacic sea nettle Chrysaora
fuscescens, had notably lower abundances and was nearly ab-
sent from our samples. The deviation in abundance of egg- yolk
jellysh Phacellophora camtschatica was notably high, and this
species became more abundant than in previous years. Finally,
the abundances of three nektonic species increased. Although
only the California market squid was characterized by a no-
table deviation in abundance, Pacic Pompano Peprilus simil-
limus and Jack Mackerel Trachurus symmetricus abundances
were higher than in any of the 8 previous years.
468 Fisheries | Vol. 44 • No. 10 • October 2019
In 2016, 13 species had notable to extreme deviations in
abundance (Figure2; Table1), which occurred during the pe-
riod spanning the blob and following a winter with strongly
positive sea surface height anomalies and strong poleward ow
(Peterson etal. 2017). Two zooplankton species—Pacic sand
crab (zoeae) and North Pacic krill (furciliae)—had exception-
al deviations in abundance. Pacic sand crab zoeal biomass
was higher than in any previous year, while North Pacic krill
furcilia biomass was higher than in all previous years except
2015. Two jellysh species—the water jellysh and Pacic sea
nettle—had exceptional deviations in abundance, whereas the
egg- yolk jellysh had an extreme deviation. Egg- yolk jelly-
sh numbers were higher in 2016 than in any previous year;
water jellysh numbers were higher than in all previous years
except 2015; and Pacic sea nettle numbers were lower than
in all but two previous years (2000 and 2014). Three nektonic
species had notable deviations in abundance: California mar-
ket squid, Pacic Chub Mackerel, and yearling Coho Salmon
Oncorhynchus kisutch. Four nektonic species had extreme de-
viations: juvenile rocksh Sebastes spp., Pacic Pompano,
young- of- the- year (age- 0) Pacic Hake Merluccius productus,
and yearling Chinook Salmon O. tshawytscha. One nektonic
species—the Jack Mackerel—had an exceptional deviation.
California market squid, yearling Coho Salmon, and yearling
Chinook Salmon declined in abundance, whereas the other ve
nektonic species were more abundant than in any previous year.
In 2017, the chlorophyll- a concentration had a notable de-
viation, representing the lowest chlorophyll- a value obtained
during the 20- year time series. Five species had notable to ex-
treme deviations in abundance. The most surprising extreme
Figure2. Variables included in the analysis: large- scale physical indices (teal), average temperature (°C) in the top 20m (red),
chlorophyll- a concentration (μg/L; green), biomass of two plankton species (mg carbon/m3; purple), and surface trawl catches
(log10[number/km+1]) of jellysh (cyan), pyrosomes (pink), squid (orange), and sh (blue). Circles indicate the June average for
each year; bars represent±1 SE. The right y- axis and the corresponding horizontal lines indicate the number of SDs from the
grand mean (dark- red short dash=±1 SD; dark- red long dash=±2 SDs; light- gray long dash=3–6 SDs). The three warm periods
(1998, 2005, and 2014–2016; described in this paper) are shaded in light gray. The plots of Pacic Chub Mackerel and Pacic Hake
are total catch, with the smaller insets showing only young- of- the- year (YOY; i.e., age 0) catches for those species. The age- 0
(YOY) insets follow the same format as other plots, but year shading and SD labels are not shown.
Fisheries | www.sheries.org 469
deviation was the rst- ever occurrence of the colonial gelat-
inous tunicate Pyrosoma atlanticum, which was extremely
abundant throughout our entire survey area. Two other nek-
tonic species, yearling Coho Salmon and yearling Chinook
Salmon, had notable deviations in abundance and declined
to the lowest numbers obtained during the 20- year time se-
ries. Two additional nektonic species—the Pacic Pompano
and Jack Mackerel—had exceptional deviations in abundance,
with Pacic Pompano numbers being the second- highest ob-
served and Jack Mackerel numbers being the highest observed
during the 20- year time series.
Potential Mechanisms Leading to Changed Abundance
Multiple physical and ecological mechanisms are likely re-
sponsible for the variations in abundance documented among
many species (Table2). Although the survey was not designed
to determine the mechanisms that caused these variations, we
can make inferences based on three ecological and organis-
mal traits. First, plankton drift passively; as such, when water
masses are transported from south to north or from west
to east, the distribution of planktonic organisms changes.
Second, nekton can actively swim against currents and can
thus change their distribution in response to local tempera-
tures and seek out thermally preferred water masses. Third,
changes in abundance may be in response to changes in local
processes that regulate population abundances (e.g., repro-
duction and predation). These mechanisms are not mutual-
ly exclusive and probably do not represent a complete list of
possible processes. Moreover, in most cases, more than one
mechanism likely led to the patterns of change we observed
(see below).
Planktonic water jellysh, egg- yolk jellysh, and Pacic
sand crab larvae are normally associated with warmer waters
to the south of our study area and/or offshore (Shenker 1984;
Suchman and Brodeur 2005). High abundances of these spe-
cies in our catches from 2014 to 2016 suggest northward and/
or eastward transport, corresponding with warmer southern
or offshore waters moving onshore (Gentemann etal. 2017).
Other planktonic species, such as copepods, have demonstrat-
ed similar patterns of unusual advection from southern and
offshore waters into the waters off central Oregon during this
same time period (Peterson etal. 2017). Northward shifts in
the distribution of these species have been also reported during
other El Niño events (Pearcy and Schoener 1987; Pearcy 2002;
Brodeur etal. 2005).
Thermal preferences, paired with spatial changes in water
temperature, may result in active migration by some species
from south to north or from west to east. For instance, the
California market squid, Pacic Pompano, Jack Mackerel,
and Pacic Chub Mackerel Scomber japonicus are normally
found in warmer southern waters and were observed in high
abundances during the warm water years since 2014. Other
studies have documented similar changes in the distribution
of these species during previous strong El Niño years (Pearcy
and Schoener 1987; Pearcy 2002; Brodeur etal. 2005).
We sampled only the top 20m of the water column with
the trawl and plankton nets during this survey. Therefore, we
cannot exclude the possibility that changes in abundance of
some organisms captured by our gear were due to changes in
their vertical distribution within our study area rather than
horizontal transport or active migration into the study area
from other locations. For example, some sea nettle species are
known to undergo diel vertical migration, although this be-
havior has not been documented for the species in our region
(Suchman and Brodeur 2005; Suchman etal. 2012), and juve-
nile Chinook Salmon may move deeper in the water column
Table1. Number of standard deviations (SDs) by which the annual mean (AM) was above or below the grand mean (GM) for each variable or spe-
cies examined, 2014–2017 (notable: AM>1 SD to 2 SDs from the GM; exceptional: AM>2 SDs to 3 SDs from the GM; extreme: AM>3 SDs from
the GM). Red indicates positive SDs; blue indicates negative SDs. “NA” indicates that data for the variable were not available in the specied
year.
Variable or species 2014 2015 2016 2017
Oceanic Niño Index +2
Pacic Decadal Oscillation +1 +1 +2
Temperature, top 20m
Chlorophyll a+2 −1
North Pacic krill Euphausia pacica +2 +2 NA
Pacic sand crab Emerita analoga +1 +2 NA
Water jellysh Aequorea sp. +2 +2
Pacic sea nettle Chrysaora fuscescens −1 −1
Egg- yolk jellysh Phacellophora camtschatica +1 +3
Colonial gelatinous tunicate Pyrosoma atlanticum +4
California market squid Doryteuthis opalescens +1 +1
Juvenile rocksh Sebastes spp. +4
Pacic Pompano Peprilus simillimus +3 +2
Yearling Coho Salmon Oncorhynchus kisutch −1
Yearling Chinook Salmon O. tshawytscha −1
Jack Mackerel Trachurus symmetricus +2 +3
Pacic Chub Mackerel Scomber japonicus (age 0) +4
Pacic Chub Mackerel +1
Pacic Hake Merluccius productus (age 0) +4
470 Fisheries | Vol. 44 • No. 10 • October 2019
in response to warmer surface water (Orsi and Wertheimer
1995). However, we currently lack the data to directly test for
changes in depth distribution.
Information from other studies suggests that local pro-
cesses rather than different migration patterns may have been
responsible for the low abundance of juvenile Coho Salmon
and Chinook Salmon in our catches during 2017. Juvenile
Coho Salmon are not known to change depth preference in
response to warm water (Orsi and Wertheimer 1995; Beamish
etal. 2007, 2018), yet abundance trends for this species were
similar to those for juvenile Chinook Salmon in our study.
In contrast to the low catches in our coastal samples, which
mostly consist of Columbia River sh (Van Doornik etal.
2007; Teel etal. 2015), abundances of both juvenile Coho
Salmon and Chinook Salmon in the Columbia River during
2017 were at least average based on Bonneville Dam smolt
counts (the source of most of the juvenile salmon in our
survey; Fish Passage Center 2017) as well as estuary purse
seine smolt catches (L.A.W., unpublished). We also conduct
a separate survey in May, as smolts are entering the ocean
and before any potential changes in northward migratory ten-
dency could change their abundance. Our catches of juvenile
salmon of both species in May 2017 were quite low relative
to previous May survey catches (Morgan etal. 2017), which
have been conducted since 1999 (Jacobson etal. 2012; Teel
etal. 2015).
In contrast to Coho Salmon and Chinook Salmon, the
notable and extreme abundance increases in Pacic sand crab
larvae that were observed in 2015 and 2016, respectively, were
likely due to both local processes and northward transport.
Adult Pacic sand crabs live in the wash zone of sandy beach-
es, spawn in summer and fall, and produce larvae that are
planktonic for approximately 4months (Johnson 1939; Efford
1970, 1976). Larval Pacic sand crabs in our catches had a
bimodal age distribution caused by the presence of both early
(zoeal stage I [ZI]) and late- stage (ZV) larvae, with both stages
sometimes present in the same sample. We never found any
intermediate- stage (ZII–ZIV) larvae. We assume that ZI lar-
vae represented local production of eggs, as these larvae were
too young to have undergone long- range transport. The pres-
ence of older, ZV larvae, coupled with the absence of ZII–ZIV
larvae, indicates that the ZV larvae were transported from the
south, as was suggested to have occurred during other warm
periods, such as the El Niño of 1997–1998 and the warm peri-
od of 2004–2005 (Sorte etal. 2001; Figure2).
The rst observation of age- 0 Pacic Hake in our survey
occurred in June 2016. During February 2016, Auth et al.
(2017) found larval Pacic Hake at every station from 64.82
to 194.46 km (from 35 to 105 nautical mi) off the coast of
Newport, Oregon, 4months prior to and well offshore of our
sampling. This indicates that age- 0 Pacic Hake were relatively
abundant off the Oregon and Washington coasts in 2016. Since
this species usually spawns further south (i.e., off California;
Ressler etal. 2007), the presence of age- 0 Pacic Hake sug-
gests that spawning may have shifted northward. Similarly,
increased abundance of age- 0 Pacic Chub Mackerel in our
June 2016 survey may have been due to a northward shift in
adult distribution and spawning (Auth etal. 2017).
Comparisons with Other Studies
Since different ocean sampling studies may have dissimi-
lar objectives and methods, using results from these studies to
create a coherent picture of the NCC during the recent ma-
rine heat wave is much like the classic parable of blind people
studying an elephant: each person touches a different part of
the animal and thus describes a different creature. We suggest
that common trends across studies may reect large- scale pat-
terns, whereas differences among studies may simply be due to
differences in local distribution, sampling design, or method-
ology; alternatively, they may reect real differences.
Table2. Description of the persistence of a given species within our 20- year survey (continuous, sporadic, or novel during the marine heat wave
of 2014–2017) and change in abundance during the marine heat wave (increase or decrease). Also provided are a description of whether the
organism drifts with currents (plankton) or can swim against currents (nekton), inferred changes in spatial distribution during the marine heat
wave, and whether changes in abundance during the marine heat wave might be attributed to local ecological processes. A question mark indi-
cates that changes in abundance might be due to a change in depth distribution, but we had no data with which to test that possibility.
Species Presence
Recent
abundance
(heat wave)
Plankton
or nekton
Inferred distribution change
Local
processes
South to
north
West to
east
Shallow to
deep
Euphausia pacica (larvae) Continuous Increase Plankton
Pacic sand crab (larvae) Sporadic Increase Plankton ✓ ✓
Water jellysh Continuous Increase Plankton ✓ ✓
Pacic sea nettle Continuous Decrease Plankton ?
Egg- yolk jellysh Continuous Increase Plankton ✓ ✓
Pyrosoma atlanticum Novel Increase Plankton ✓ ✓
California market squid Continuous Increase Nekton
Juvenile rocksh Continuous Increase Nekton
Pacic Pompano Sporadic Increase Nekton
Yearling Coho Salmon Continuous Decrease Nekton ?
Yearling Chinook Salmon Continuous Decrease Nekton ?
Jack Mackerel Continuous Increase Nekton ✓ ✓
Pacic Chub Mackerel (age 0) Sporadic Increase Nekton
Pacic Chub Mackerel Sporadic Increase Nekton ✓ ✓
Pacic Hake (age 0) Novel Increase Nekton ✓ ✓
Fisheries | www.sheries.org 471
Increased abundances of species such as the California
market squid, age- 0 Pacic Hake, age- 0 rocksh, and pyro-
somes were observed off the California coast before similar
changes occurred in our more northern survey region (Sakuma
etal. 2016; Brodeur etal., 2019). Warmwater anomalies rst
occurred in southern California coastal waters during spring
2014 and were subsequently detected farther north later in that
year (Gentemann etal. 2017). Similarly, northerly occurrences
of more southern species were observed rst in California and
then later to the north in our survey area.
Several studies in the NCC have reported very low abun-
dances of adult euphausiids during the past few years (Sakuma
et al. 2016; Peterson et al. 2017; Brodeur et al., 2019). In
strong contrast, we found an anomalously high biomass of
E.pacica furcilia larvae during our study in 2014–2016. In
addition, we counted but do not report on several other lar-
val stages of crustaceans in the same plankton samples. We
found that abundances of an earlier larval stage (calyptopis)
of E.pacica were also the highest ever observed during this
same time period, and larvae of another common euphausi-
id (Thysanoessa spinifera) as well as shrimp (Caridea) larvae
had similarly high abundance patterns during this time peri-
od (C.A.M., unpublished). Given the short larval duration
of E. pacica (20–35 d from hatching to early furcilia stag-
es; Bi etal. 2011), adult euphausiids must have been present
to release eggs in the NCC. Therefore, the presence of larval
euphausiids and the absence of adult euphausiids might have
been the result of adults moving to cooler waters, either deep-
er or farther offshore.
The extraordinary increase in age- 0 rocksh (4 SDs above
the mean) in our 2016 catches was a coastwide event, docu-
mented from California (McClatchie et al. 2016) to Alaskan
waters (Strasburger et al. 2018). This suggests that whatever
factors caused the increase in age- 0 rocksh operated over an
extremely large area. However, the juveniles of the more than
70 species of northeast Pacic rocksh are extremely difcult
to distinguish (Love etal. 2002); therefore, we could not doc-
ument which species were involved, and we did not attempt
to identify the mechanism(s) responsible for the increase.
Continued assessment of older, easier- to- identify rocksh
may provide more focus to our current observation.
Pyrosomes were extremely abundant in our 2017 catches,
while other gelatinous species returned to more typical abun-
dance levels (Figure2). In 2014, other surveys encountered
low numbers of pyrosomes further south of our study area as
well as offshore (Wells etal. 2017; Brodeur etal. 2018, 2019).
By 2015, the surveys captured pyrosomes at least as far north
as Willapa Bay, Washington, but well off the continental shelf.
Pyrosomes were also caught for the rst time, and in high
numbers, within Alaskan waters during the winter of 2016–
2017 and through summer 2017 (NOAA- AFSC 2017; Brodeur
etal. 2018). This dramatic expansion in range and abundance
clearly represents favorable conditions for pyrosomes and sug-
gests that their exceptionally high and widespread abundance
was not solely due to changes in water transport.
Consequences of Species Abundance Changes
Understanding the consequences of extreme changes in
species abundance in the NCC is challenging. Ruzicka et al.
(2012) explored changes in abundances of different trophic
groups in the NCC and used modeling to predict how these
changes would impact energy ows through the food web.
Many of the taxonomic groups they identied as important
nodes of energy ow (Figure3, boxes) are ones we found to
have undergone large increases (e.g., water jellysh, euphau-
siids, California market squid, Pacic Chub Mackerel, Jack
Figure3. Energy ow pathways between major functional groups in the Northern California Current food web (modied by J.
Ruzicka from Figure6a in Ruzicka etal. 2012). Box size is proportional to group production rates (whl=whales; msc=miscella-
neous; plgc=pelagic; mesoplgc=mesopelagic; bnthc=benthic; epibnthc=epibenthic; juv=juvenile; macro- Z=macrozooplank-
ton; micro- Z=microzooplankton; invrt=invertebrate; carn=carnivorous; susp=suspension- feeding; phyto=phytoplankton).
Red shading indicates species identied in this paper that have greatly increased or decreased during the recent marine heat
wave.
472 Fisheries | Vol. 44 • No. 10 • October 2019
Mackerel, and Pacic Hake) or decreases (e.g., Pacic sea net-
tles, juvenile Chinook Salmon, and juvenile Coho Salmon) in
abundance. However, our survey focused on the upper water
column during the day and did not sample all of the species
included in the food web analysis.
Decreased Pacic sea nettle abundance during 2015–2017
coincided with increased abundance of zooplankton prey spe-
cies. Sea nettles are known to feed on early stage euphausiids
(Suchman etal. 2008), so the decline in Pacic sea nettles may
have resulted in the high abundance of larval euphausiids in
2015 and 2016. The high juvenile rocksh abundance in 2016
may have been partly inuenced by the very low numbers of
Pacic sea nettles in 2015 due to both decreased predation on
larval rocksh in 2015 as well as decreased competition for
food between Pacic sea nettles and larval rocksh.
The sudden presence and extremely high abundance of
pyrosomes may be the best example of an ecosystem con-
sequence. Pyrosomes were not a component of the Ruzicka
etal. (2012) ecosystem analysis, as these organisms had never
been observed in the NCC (Welch 2017; Brodeur etal. 2018).
P. atlanticum was found to be an extremely effective grazer,
with clearance rates among the highest recorded for any
pelagic grazer (Perissinotto etal. 2007). The high abundance
of pyrosomes could explain the extremely low chlorophyll- a
concentrations we observed in 2017 and could have caused a
reduction in energy ow to higher trophic levels. If this organ-
ism remains abundant in subsequent years, it could produce
lasting effects upon the NCC ecosystem by outcompeting oth-
er lter feeders, which in turn might reduce the food supply to
organisms higher in the food web.
Finally, changes in abundance of various juvenile sh
species, including Pacic Hake, rocksh, Coho Salmon, and
Chinook Salmon, will affect top predators, such as sharks,
pinnipeds, toothed whales, and humans. We believe that the
increased abundances of age- 0 Pacic Hake and Pacic Chub
Mackerel in our 2016 samples were probably due to shifts in
adult spawning distribution (Auth etal. 2017) and thus may not
be indicative of increased abundances on a broad, regional scale.
If this is true, we do not expect the adult abundances of these
species to greatly increase in the future. In contrast, we think
that the very high abundance of juvenile rocksh in our 2016
samples and the very low abundances of yearling Coho and
Chinook Salmon in our 2017 samples represent real changes in
abundance that will likely affect adult recruitment. Low catches
of juvenile salmon in our June surveys have already been asso-
ciated with poor adult returns (Burke etal. 2013; Peterson etal.
2014), so we anticipate poor returns of Coho Salmon to the
Columbia River in 2018 and poor returns of Chinook Salmon
in 2019. The high abundance of juvenile rocksh in 2016 was
an extraordinary event, spanning at least 2,500km of coastline
along the west coast of North America. Although Ralston etal.
(2013) suggested that pelagic abundance of juvenile rocksh is
a good indicator of adult recruitment in central California, the
actual consequences of high juvenile rocksh abundance in
2016 remain to be seen in future years.
Conclusion
We have documented recent dramatic changes in abun-
dance of sh and invertebrates in the surface waters of the
NCC since 2014. These changes likely reect changes in phys-
ical processes and ecological mechanisms (Table2). Some of
what we observed was due to a shift of organisms from south
to north and from west to east, whereas other changes may be
the result of alterations in biological processes for organisms
that have not changed their distributions. It is notable that
we have not seen a complete changeover of species within the
NCC ecosystem—rather, we have seen the novel occurrence
of some organisms mixed with other species that are normally
present (Table2). Mixing of organisms from different regions
may result in novel trophic interactions with unpredictable re-
sults (Naiman et al. 2012). We are particularly interested in
potential continued ecological effects of the occurrence and
abundance of pyrosomes in the NCC during 2017 and beyond.
The value of this paper lies not only in the specic results
we described, but also in its role as a reminder of the impor-
tance of obtaining and maintaining long- term baselines to
measure biological change (McClatchie etal. 2014). We have
already described clear ecosystem- scale change in response
to large- scale climatic changes (the Blob and El Niño). The
National Marine Fisheries Service’s current emphasis on eco-
system management will only be successful if robust eld sur-
veys of those ecosystems continue (Levin etal. 2009).
ACKNOWLEDGMENTS
We dedicate this paper in memory of Dr. Robert (Bob) L.
Emmett (1955–2015) and Dr. William (Bill) T. Peterson (1942–
2017), who conceived of this work, were amazing mentors and
dear friends, were lled with enthusiasm for life and science,
and inspired us as scientists and as human beings. We greatly
appreciate the many people who contributed to this project
over the years, including the captains and crews who operated
vessels, especially the FV Frosti, and the many scientists who
collected and processed samples. We especially thank Paul
Bentley, Cindy Bucher, Brian Burke, Ed Casillas, Elizabeth
Daly, Joe Fisher, Troy Guy, Susan Hinton, Kym Jacobson, Jesse
Lamb, Jim Ruzicka, and Jen Zamon. Funding for this study
was provided by the Bonneville Power Administration (Project
1998- 014- 00) and the National Oceanic and Atmospheric
Administration Fisheries. Constructive comments from Brian
Burke, Jennifer Fisher, Kym Jacobson, David Teel, and three
anonymous reviewers greatly improved the manuscript. There
is no conict of interest declared in this article.
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... (2023) Marbled Murrelet diets observed in this study may have been shaped by an unprecedented heat wave ("the Blob"), which was followed by a strong El Niño off the North Pacific coast of the USA from 2014 to 2016. These events caused strong shifts in both prey abundance and size (Bond et al. 2015, di Lorenzo & Mantua 2016, Jacox et al. 2016, and water temperatures, as an indicator of ocean climate, were still above normal off the coasts of Oregon and Washington in 2017 (Morgan et al. 2019). An increase in Market Squid (Sakuma et al. 2016) and North Pacific Krill Euphausia pacifica populations (Morgan et al. 2019) relative to long-term averages were in accord with periods marked by aboveaverage oceanic temperatures. ...
... These events caused strong shifts in both prey abundance and size (Bond et al. 2015, di Lorenzo & Mantua 2016, Jacox et al. 2016, and water temperatures, as an indicator of ocean climate, were still above normal off the coasts of Oregon and Washington in 2017 (Morgan et al. 2019). An increase in Market Squid (Sakuma et al. 2016) and North Pacific Krill Euphausia pacifica populations (Morgan et al. 2019) relative to long-term averages were in accord with periods marked by aboveaverage oceanic temperatures. Seemingly, these conditions led to the unexpectedly high occurrence of squid and krill in the diet of murrelets during 2017 and an even higher occurrence in 2018. ...
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diet of a threatened seabird, the Marbled Murrelet Brachyramphus marmoratus, using high-throughput sequencing. Marine Ornithology 51: 145-155. Understanding prey consumption patterns is critical to understanding the ways in which seabirds cope with a changing ocean. However, characterizing the dietary habitats of seabirds can be challenging. In this study, we investigated the diet of the Marbled Murrelet Brachyramphus marmoratus population that lives in waters off California, Oregon, and Washington, USA, using fecal DNA, custom metabarcoding, and high-throughput sequencing. Murrelets were captured at sea by dip-netting at night. Across this region, murrelets consumed highly diverse prey types including 17 fish species and 10 invertebrate species, in accord with previous work indicating the species' forage on a wide range of prey. Pacific Herring Clupea pallasii was the most common prey in Washington and Oregon (frequency of occurrence = 0.84 and 0.69, respectively), replaced by Northern Anchovy Engraulis mordax in California (frequency of occurrence = 0.77). In Oregon, where our sample size was sufficient, diet composition differed between the 2017 and 2018 breeding seasons, with an apparent decline in the proportional consumption of energy-dense prey. Common and energy-dense prey were consumed in equal proportions by males and females, perhaps because of foraging in the same habitat. Diet did not vary between breeders and non-breeders. Our study offers the first detailed report on the diet of adult Marbled Murrelets in waters where they are listed as Threatened by the US federal government. This indicates that managing fisheries and conserving spawning habitat for high-occurrence prey species could benefit murrelet populations.
... Northern anchovy (Engraulis mordax) is not traditionally viewed as one of the most abundant species of forage fish within the Salish Sea. The high ocean temperatures offshore during The Blob event, 2014-2016 [33,34] has led to much greater abundance of anchovies in recent years, especially in South Puget Sound [35,36], which has been sufficient to feed several hundred California sea lions (Zalophus californianus) for several months in Case Inlet (Jefferies, personal communication). Eulachon (Thaleichthys pacificus) is commonly called "candlefish" because of its high fat content, which also makes it an ideal high-calorie food for harbor porpoise. ...
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Harbor porpoise are typically seen in small groups of 1-3 individuals, with aggregations of 20+ individuals treated as rare events. Since the 1990s, the harbor porpoise population in the Salish Sea has seen a significant recovery, which has led to an increased number of observed aggregations that exceed the more usual small group sizes. By combining the observational data of United States and Canadian research organizations, community scientists, and whale watch captains or naturalists, we demonstrate that harbor porpoise aggregations appear to be more common than previously known, with 160 aggregations documented in 2022 alone. Behavioral data also indicated that foraging behaviors were common and social behaviors, like mating, were seen more often during these encounters compared to small groups. Other behaviors that are considered to be rare or unknown, were also observed during these encounters, including cooperative foraging and vessel approach. These aggregations are likely important foraging and social gatherings for harbor porpoises. This holistic approach integrating data from two countries and multiple sources provides an ecosystem level assessment that more effectively reflects the habitat use of harbor porpoise in this region that do not recognize the socio-political boundaries imposed upon the natural world.
... Eulachon (Thaleichthys pacificus), a high-fat-content fish, is found in the northern Salish Sea and could serve as an ideal high-calorie food [46]. Traditionally, Northern anchovy (Engraulis mordax) was not abundant in these waters until the 2014-2016 Blob event that increased offshore ocean temperatures [47,48] and led to greater abundance of anchovies, especially in South Puget Sound [46,49]. Market squid (Doryteuthis opalescens), another staple of harbor porpoises' diet, are also found in South Puget Sound from December through February [46,50]. ...
Article
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Harbor porpoises are typically seen in small groups of 1–3 individuals, with aggregations of 20+ individuals treated as rare events. Since the 1990s, the harbor porpoise population in the Salish Sea has seen a significant recovery, and an increased number of observed aggregations that exceed the more usual small group sizes has been observed in recent years. By combining the observational data of United States and Canadian research organizations, community scientists, and whale watch captains or naturalists, we demonstrate that harbor porpoise aggregations appear to be more common than previously known, with 160 aggregations documented in 2022 alone. Behavioral data also indicate that foraging behaviors are common and social behaviors, like mating, are seen more often during these encounters compared to small groups. Other behaviors that are considered to be rare or unknown were also observed during these encounters, including cooperative foraging and vessel approach. These aggregations are likely important foraging and social gatherings for harbor porpoises. This holistic approach integrating data from two countries and multiple sources provides a population level assessment that more effectively reflects the behavior of harbor porpoises in this region, which do not recognize the socio-political boundaries imposed upon the natural world.
... Here, climate change has increased the intensity and frequency of storms, heatwaves, hypoxia, ocean acidification, and other coastal environmental disturbances (Simpson 1992;Hare and Matua 2000;Lluch-Belda et al. 2005;Feely et al. 2008;Vergés et al. 2016;Santoso et al. 2017). These climatic events can have critical biological consequences for harbor seals, such as mass mortalities, local extinctions, and species range shifts affecting prey availability (Vergés et al. 2016;Morgan et al. 2019). This, in turn, may cause low pup production, longer foraging trips, reduced body condition, and, ultimately, population depletion (Pitcher 1990;Sydeman and Allen 1999;Le Boeuf and Crocker 2005;Mathews and Pendleton 2006;Kovacs et al. 2012). ...
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The Pacific harbor seal (Phoca vitulina richardii) occurs in the Mexican Pacific region at the southernmost edge of the subspecies’ distribution, along 700 km of coastline and on nine islands west of the Baja California peninsula. Its abundance in this area corresponds to 3% of its total abundance in the north Pacific Ocean. The species is considered relatively sedentary and highly philopatric, which makes it vulnerable to stochastic processes; thus, reproductive and genetic isolation of the Mexican Pacific colonies is expected. This study aimed to genetically characterize the harbor seal in the Mexican Pacific to inform conservation efforts. The levels of genetic diversity were estimated for five colonies, using a 572-base pair mitochondrial DNA control region fragment and seven microsatellite loci, as well as the population genetic structure and its phylogeographic patterns. Fifteen variable sites were found that defined 18 mitochondrial DNA haplotypes. Results show one of the lowest levels of diversity reported for the species (overall haplotype diversity h = 0.626 ± SD 0.041; overall nucleotide diversity π = 0.0018 ± SD 0.0013; mean expected heterozygosity HE = 0.558). Population structure was detected within the range of harbor seals in the Mexican Pacific based on both mitochondrial and nuclear markers. The present study identified higher levels of differentiation (ΦST = 0.043–0.471) among colonies of Mexican Pacific harbor seals located in a relatively small area than that identified by other studies carried out in colonies along the eastern Pacific coast. There were only four haplotypes in common with those observed (451) along the rest of the Pacific colonies, while 11 of the remaining 14 haplotypes in the Mexican Pacific are private of a colony. The Pacific harbor seal colonies found in Mexico may have their origins in California, USA, colonies, via a founder event.
... The novel combination of morphological data and eDNA metabarcoding of ethanol preserved larvae from an ichthyoplankton biorepository in a joint modeling framework The observed ichthyoplankton assemblage shifts during the marine heatwave are consistent with recent studies reporting the tropicalization of terrestrial and marine ecosystems in response to climate change (Chaudhary et al., 2021;Vergés et al., 2016). These deviations can induce novel species interactions, catalyzing changes in ecosystem function (Frölicher & Laufkötter, 2018;Morgan et al., 2019). The high abundances of both Northern Anchovy and southern mesopelagic species seen in our dataset during and after the 2014-2016 marine heatwave is unique in the previous >70- ...
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Marine heatwaves can drive large-scale shifts in marine ecosystems, but studying their impacts on whole species assemblages is difficult. Analysis combining microscopic observations with environmental DNA (eDNA) metabarcoding of the ethanol preservative of an ichthyoplankton biorepository spanning a 23 years time series captures major and sometimes unexpected changes to fish assemblages in the California Current Large Marine Ecosystem during and after the 2014-2016 Pacific Marine Heatwave. Joint modeling efforts reveal patterns of tropicalization with increases in southern, mesopelagic species and associated declines in commercially important temperate fish species (e.g., North Pacific Hake [Merluccius productus] and Pacific Sardine [Sardinops sagax]). Data show shifts in fisheries assemblages (e.g., Northern Anchovy, Engraulis mordax) even after the return to average water temperatures, corroborating ecosystem impacts found through multiple traditional surveys of this study area. Our innovative approach of metabarcoding preservative eDNA coupled with quantitative modeling leverages the taxonomic breadth and resolution of DNA sequences combined with microscopy-derived ichthyoplankton identification to yield higher-resolution, species-specific quantitative abundance estimates. This work opens the door to economically reconstruct the historical dynamics of assemblages from modern and archived samples worldwide. K E Y W O R D S amplicon sequencing, CalCOFI, California Current Ecosystem, eDNA, ichthyoplankton, joint model, marine heatwave, quantitative metabarcoding
... The 2015-16 MHW event was correlated with changes in the distribution of numerous pelagic fishes which meant that predation pressure for euphausiids was very different from other years studied. Age-0 hake were found off Washington and Oregon, meaning that spawning centers shifted northwards during the event (Morgan et al., 2019), and age-1 hake were observed in Canadian waters as far as the southwest coast of Vancouver Island (48.8°N), which is unusual (Gauthier et al., 2016). In addition, in the California Current the Northern Anchovy (Engraulis mordax) and Pacific Sardine (Sardinops sagax) biomass cycles are usually highly predictable, with sardine abundant during warm periods such as positive PDO regimes, and anchovy abundant during cool periods. ...
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Euphausiids form a critical component of oceanic food chains and individual species vary in their responses to perturbation events. We aimed to establish if patterns of fine scale oceanographic variability and larger-scale climate events such as marine heatwaves (MHWs) could be linked with spring variability in the biomass of two key forage species in the northeast Pacific Ocean, Euphausia pacifica and Thysanoessa spinifera. To achieve this, we used long-term datasets from the west coast of Vancouver Island Canada, an important commercial fishing area, to first quantify interannual signals of variability in fine-scale oceanographic conditions using multivariate analysis. We then used geostatistical spatiotemporal modelling to quantify the effects on species-specific euphausiid biomass. Oceanographic data showed that the effects of warm events are not always observable, and effects vary across small spatial scales. Warming due to the 2014-2016 MHW was relatively mild on the continental shelf during spring (<1°C above climatology). Spring biomass of euphausiids, particularly E. pacifica , peaked in 2015, and all euphausiid groups analysed ( E. pacifica , T. spinifera and total euphausiids) exhibited significant correlations with positive phases of the Pacific Decadal Oscillation. These results have implications for marine predators as euphausiids may act as system stabilisers in the northeast Pacific, thereby potentially increasing ecosystem resilience during extreme events.
Technical Report
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This Status Review and the accompanying Background Report compile the best available scientific and commercial information on Guadalupe fur seals and describe the threats to the species. They also evaluate whether the population meets the Distinct Population Segment (DPS) Policy criteria. The review does not represent a decision by NMFS on whether the threatened listing for this species warrants a change in status, or whether any subdivision thereof should be proposed for listing as threatened or endangered under the ESA. That decision will be made by NMFS after reviewing this document, the current efforts being made to conserve the species, and relevant laws, regulations, and policies. The determinations in this regard will be posted on the NNMFS Office of Protected Resources web site (https://www.fisheries.noaa.gov/resources/allpublications).
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Anthropogenic-mediated climate change severely affects the oceans. The most common definition of a Marine heatwave (MHW) considers that water temperatures rise above the 90th percentile threshold values, based on the last 30 years' average of temperature records for a particular location, and remains this high for five or more days. The current review addresses the evolution of definitions used, as well as the current understanding of the driving mechanisms of MHWs. The collected information shows that the study of MHW is recent and there is a growing interest among the scientific community on this topic, motivated largely by the impacts that pose to marine ecosystems. Further, a more in-depth analysis was carried out, addressing the impacts of MHW events on marine decapod crustacean species. The investigation of such impacts has been carried out using three main methodological approaches: the analysis of in situ records, observed in 33 studies; simulating MHW events through mesocosm experiments, found in 6 studies; and using computational predictive models, detected in 1 study. From the literature available it has been demonstrated that consequences are serious for these species, from altered expansion ranges to alterations of assemblages' abundances. Still, studies addressing the impacts of these extreme events on the decapod communities are scarce, often only limited to adult life forms of commercially relevant species, neglecting non-commercial ones and meroplanktonic life stages. Despite the severe impacts on the health of ecosystems, repercussions on socioeconomic human activities, like fisheries and aquaculture, are also a reality. Overall, this review aims to raise scientific and public awareness of these marine events, which are projected to increase in intensity and frequency in the coming decades. Therefore, there is a growing need to better understand and predict the mechanisms responsible for these extreme events and the impacts on key species, like decapod crustaceans.
Article
Dungeness crab (Metacarcinus magister) have significant socioeconomic value, but are threatened by ocean acidification (OA) and other environmental stressors that are driven by climate change. Despite evidence that adult harvests are sensitive to the abundance of larval populations, relatively little is known about how Dungeness megalopae will respond to these stressors. Here we evaluate the ability to use micro-computed tomography (μCT) to detect variations in megalope exoskeleton density and how these measurements reflect environmental variables and calcification mechanisms. We use a combination of field data, culture experiments, and model simulations to suggest resolvable differences in density are best explained by minimum pH at the time zoeae molt into megalopae. We suggest that this occurs because more energy must be expended on active ion pumping to reach a given degree of calcite supersaturation at lower pH. Energy availability may also be reduced due to its diversion to other coping mechanisms. Alternate models based on minimum temperature at the time of the zoea-megalope molt are nearly as strong and complicate the ability to conclusively disentangle pH and temperature influences. Despite this, our results suggest that carryover effects between life stages and short-lived extreme events may be particularly important controls on exoskeleton integrity. μCT-based estimates of exoskeleton density are a promising tool for evaluating the health of Dungeness crab populations that will likely provide more nuanced information than presence-absence observations, but future in situ field sampling and culture experiments are needed to refine and validate our results.
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The community structure of pelagic zooplankton and micronekton may be a sensitive indicator of changes in environmental conditions within the California Current ecosystem. Substantial oceanographic changes in 2015 and 2016, due to the anomalously warm ocean conditions associated with a large-scale marine heatwave perturbation, resulted in onshore and northward advection of warmer and more stratified surface waters resulting in reduced upwelling. Here we quantify changes in the macrozooplankton and micronekton community composition and structure based on five highly contrasting ocean conditions. Data from fine-mesh pelagic trawl surveys conducted off Oregon and Washington during early summer of 2011 and 2013–2016 were examined for interannual changes in spatial distribution and abundance of fish and invertebrate taxa. Overall species diversity was highest in 2015 and lowest in 2011, but 2016 was similar to the other years, although the evenness was somewhat lower. The community of taxa in both 2015 and 2016 was significantly different from the previously sampled years. Crustacean plankton densities (especially Euphausiidae) were extremely low in both of these years, and the invertebrate composition became dominated mostly by gelatinous zooplankton. Fishes and cephalopods showed mixed trends overall, but some species such as age-0 Pacific hake were found in relatively high abundances mainly along the shelf break in 2015 and 2016. These results suggest dramatically different pelagic communities were present during the recent warm years with a greater contribution from offshore taxa, especially gelatinous taxa, during 2015 and 2016. The substantial reorganization of the pelagic community has the potential to lead to major alterations in trophic functioning in this normally productive ecosystem.
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This report examines the ecosystem state of the California Current System (CCS) from spring 2016–spring 2017. Basin-scale indices suggest conditions that would support average to below average coast-wide production across the CCS during this time period. Regional surveys in 2016 sampled anomalously warm surface and subsurface waters across the CCS. Chlorophyll concentrations were low across the CCS in 2016 and, concomitant with that, copepod communities had an anomalously high abundance of subtropical species. Early in 2017 conditions between northern, central, and southern CCS were dissimilar. Specifically, surface conditions north of Cape Mendocino remained anomalously warm, chlorophyll was very low, and subtropical copepods were anomalously abundant. Southern and central CCS surveys indicated that environmental conditions and chlorophyll were within normal ranges for the longer time series, supporting an argument that biophysical conditions/ ecosystem states in the southern and central CCS were close to normal. Epipelagic micronekton assemblages south of Cape Mendocino were generally close to longer-term average values, however the northern assemblages have not returned to a “normal” state following the 2014–15 large marine heatwave and 2016 El Niño. North of Cape Mendocino the epipelagic micronekton was largely composed of offshore and southern derived taxa. We hypothesize that stronger-than-typical winter downwelling in 2017 and a reduced spawning biomass of forage taxa are contributors to the anomalous forage community observed in the north. Also of note, surveys indicate northern anchovy (Engraulis mordax) abundance was greater than average (for recent years) and nearer shore in northern regions. Finally, record-low juvenile coho and Chinook salmon catches in the 2017 northern CCS salmon survey suggest that out-migrating Columbia Basin salmon likely experienced unusually high early mortality at sea, and this is further supported by similarities between the 2017 forage assemblage and that observed during poor outmigration survival years in 2004, 2005, and 2015. Generally, the reproductive success of seabirds in 2016 (the most current year available) was low in the north but near average in central California. At Yaquina Head off Oregon and Castle Rock off northern California some of the lowest reproductive success rates on record were documented. In addition to reduced abundance of prey, there was a northward shift of preferred seabird prey. Seabird diets in northern areas also corroborated observations of a northward shift in fish communities. Nest failure was attributed to a combination of bottom-up and top-down forces. At Castle Rock, most chicks died of starvation whereas, at Yaquina Head, most nests failed (95% of common murre, Uria aagle) due to disturbance by bald eagles (Haliaeetus leucocephalus) seeking alternative prey. Mean bird densities at sea for the 2017 surveys between Cape Flattery Washington and Newport Oregon were the lowest observed and may indicate continued poor reproductive performance of resident breeders in 2017. South of Cape Mendocino, where forage availability was typical, seabird reproductive success was also below average for most species in 2016, but did not approach failure rates observed in the north. Finally, in 2017, abundances of seabirds observed at-sea off southern California were anomalously high suggesting an improved foraging environment in that area. Marine mammal condition and foraging behavior were also impacted by the increased abundance and shifting distribution of the northern anchovy population. Increases in the abundance of northern anchovy in the Southern California Bight coincided with improved condition of sea lion (Zalophus californianus) pups in 2016. Namely, lipid-rich northern anchovy occurred in great frequencies in the nursing female diet. Increases in northern anchovy nearshore in the central and northern CCS may have also contributed to a shoreward shift in distribution of humpback whales (Megaptera novaeangliae) in these regions. These shifts along with recovering humpback whale populations contributed to recent increases in human-whale interactions (e.g., fixed-gear entanglements).
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Understanding changes in the migratory and reproductive phenology of fish stocks in relation to climate change is critical for accurate ecosystem-based fisheries management. Relocation and changes in timing of reproduction can have dramatic effects upon the success of fish populations and throughout the food web. During anomalously warm conditions (1–4°C above normal) in the northeast Pacific Ocean during 2015–2016, we documented shifts in timing and spawning location of several pelagic fish stocks based on larval fish samples. Total larval concentrations in the northern California Current (NCC) during winter (January–March) 2015 and 2016 were the highest observed since annual collections first occurred in 1998, primarily due to increased abundances of Engraulis mordax (northern anchovy) and Sardinops sagax (Pacific sardine) larvae, which are normally summer spawning species in this region. Sardinops sagax and Merluccius productus (Pacific hake) exhibited an unprecedented early and northward spawning expansion during 2015–16. In addition, spawning duration was greatly increased for E. mordax, as the presence of larvae was observed throughout the majority of 2015–16, indicating prolonged and nearly continuous spawning of adults throughout the warm period. Larvae from all three of these species have never before been collected in the NCC as early in the year. In addition, other southern species were collected in the NCC during this period. This suggests that the spawning phenology and distribution of several ecologically and commercially important fish species dramatically and rapidly changed in response to the warming conditions occurring in 2014–2016, and could be an indication of future conditions under projected climate change. Changes in spawning timing and poleward migration of fish populations due to warmer ocean conditions or global climate change will negatively impact areas that were historically dependent on these fish, and change the food web structure of the areas that the fish move into with unforeseen consequences.
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A warm anomaly in the upper ocean, colloquially named “the Blob”, appeared in the Gulf of Alaska during the calm winter of 2013-2014, spread across the northern North Pacific (NP) Ocean and shifted eastward and onto the Oregon shelf. At least 14 species of copepods occurred which had never been observed in shelf/slope waters off Oregon, some of which are known to have NP Gyre affinities, indicating that the source waters of the coastal “Blob” were likely of both offshore (from the west) and subtropical/tropical origin. The anomalously warm conditions were reduced during strong upwelling in spring 2015 but returned when upwelling weakened in July 2015 and transitioned to downwelling in fall 2015. The extended period of warm conditions resulted in prolonged effects on the ecosystem off central Oregon, lasting at least through 2016. Impacts to the lower trophic levels were unprecedented and include a novel plankton community composition resulting from increased copepod, diatom and dinoflagellate species richness and increased abundance of dinoflagellates. Additionally, the multi-year warm anomalies were associated with reduced biomass of copepods and euphausiids, high abundance of larvaceans and doliolids (indictors of oligotrophic ocean conditions), and a toxic diatom bloom (Pseudo-nitzschia) throughout the California Current in 2015, thereby changing the composition of the food web that is relied upon by many commercially and ecologically important species.
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We report on the anomalous distribution, abundance, and community structure patterns of epipelagic micronekton from a midwater trawl survey in May-June 2015 that has a 26-year time series within a core region off central California (36°35′-38°10′N) and a 12-year time series with expanded spatial coverage (extending from 32°42.5′-39°50′N). The 2015 survey took place during an extended period of record-breaking warm surface temperatures in much of the northeast Pacific Ocean. In the neritic waters off central and northern California, this broad-scale extended marine heat wave was combined with more localized, above average coastal upwelling in spring 2015 that led to slightly cooler than normal surface temperatures over the continental shelf and shelf break. The unusual micronekton assemblages in our 2015 trawl survey featured anomalously high catches of warm water species such as pelagic red crabs (Pleuroncodes planipes), coincident with high catches of colder water species such as YOY rockfish (Sebastes spp.), and also large catches of pelagic tunicates such as Pyrosoma atlanticum. Principal component analysis (PCA) on a subset of the most frequently occurring species for both the shorter time series (expanded survey area) and the longer time series (core region) yielded similar results to previous studies off central California, with a suggested alternation between micronekton communities dominated by coastal pelagic species and those dominated by YOY groundfish (rockfish, Pacific hake [Merluccius productus], and sanddabs [Citharichthys spp.]), krill, and cephalopods. In addition, the leading principal components for the different regions of the expanded survey area were highly correlated, suggesting similar micronekton community responses to forcing mechanisms over a broad spatial scale. As the PCA analysis was limited to a relatively small subset of species and the time series for some frequently encountered species are not continuous throughout the history of the survey, we also report on species that reflect additional aspects of the unusual nature of the 2015 survey catches. Together, these results indicate that the micronekton community structure in the late spring of 2015 was highly anomalous in that species characteristic of what might generally be considered three different nominal states (YOY groundfish/market squid and krill, warm-water subtropical species, and pelagic tunicates) were all encountered in high abundance. © 2016, Scripps Institution of Oceanography. All rights reserved.
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Warm conditions in the North Pacific in 2014-15 were a result of the continuation of the North Pacific marine heat wave, a large area of exceptionally high SST anomalies that originated in the Gulf of Alaska in late 2013. The North Pacific heat wave interacted with an El Niño developing in the equatorial Pacific in 2015. Weekly periods of exceptionally high temperature anomalies (>2˚C) occurred until the start of the El Niño (winter of 2015), when SSTs were still high but not as high as those due to the marine heat wave. During the 2015-16 El Niño, the depth of the 26.0 kg m-3 isopycnal (d26.0) was considerably shallower than during the 1982- 83 and 1997-98 events. The area affected by the marine heat wave and the 2015-16 El Niño in the mixed layer was comparable to the 1997-98 El Niño, but lasted longer. Water column stratification in the upper 100 m during 2015-16 was as strong as the most extreme values during the 1997-98 El Niño. This stratification was primarily driven by the warming of the upper 100 m. Despite notable perturbations, the effects of the 2015- 16 El Niño on hydrographic properties in the CalCOFI domain were not as strong as those observed during the 1997-98 El Niño. Warm ocean conditions, stratification, nutrient suppression, and silicic acid stress likely favored initiation of a toxic Pseudo-nitzschia bloom in fall 2014. Very low zooplankton displacement volumes were associated with anomalously warm and saline surface waters off Baja California. In contrast, during the 1997-98 El Niño, zooplankton volume was near average. Off California, pelagic red crab (Pleuroncodes planipes) adults were abundant in the water column and frequently washed up on beaches of southern California from January 2015 into 2016, and central California by September 2015. Glider measurements of integrated transport up to June 2015 did not detect anomalous northward advection. As expected, HF radar indicated northward surface currents along the central California coast in fall and winter 2015-16. Northward advection appeared to be much stronger during the 1997-98 El Niño. Throughout 2015-16, the zooplankton community on the Oregon shelf was dominated by lipid-poor tropical and sub-tropical copepods and gelatinous zooplankton, indicating poor feeding conditions for small fishes that are prey for juvenile salmon. The presence of rarely encountered species increased copepod species richness during 2015-16 to levels higher than the 1998 El Niño. We infer that the unusual copepod vagrants of 2015-16 originated from an offshore and southwesterly source; an important difference from the southerly origin of vagrants during the 1997-98 El Niño. The very warm conditions caused sardine spawning to shift from central California to Oregon. Mesopelagic fish assemblage off southern California exhibited higher abundances of species with southern affinities, and lower abundances of species with northern affinities. Forage fish (Pacific herring, northern anchovy, and Pacific sardine) were much less abundant in 2015-16 compared to previous years. In contrast, catches of salmon were close to average off northern California. Catches of young-ofthe- year rockfishes were high off central California, but low off both northern and southern California. Seabirds at Southeast Farallon Island in 2015 exhibited reduced breeding populations, reduced breeding success, lower chick growth rates, and lower fledging weights. Common murres were negatively affected in central and northern California, but seabird responses were species-specific. It is clear from the results presented here that the warm anomaly effects on the ecosystem were complicated, regionally specific, and that we do not fully understand them yet. © 2016, Scripps Institution of Oceanography. All rights reserved.
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In the northern California Current, Columbia River Chinook salmon Oncorhynchus tshawytscha that return as adults in spring are primarily hatchery-produced, though they include natural-origin fish listed under the US Endangered Species Act. Anomalously warm ocean conditions persisted in the California Current during 2015 (>2.5°C above normal) through the winter period when fish prey resources of juvenile salmon develop and during spring as salmon enter the ocean. The biomass of ichthyoplankton in winter 2015 was the 4th highest of our 18 yr time-series (1998−2015), predicting good food conditions for salmon and high adult salmon returns several years later. The larval composition of 2015 ichthyoplankton included abnormally large amounts of the warm-water taxa northern anchovy Engraulis mordax and rockfish Sebastes spp. When the composition of ichthyoplankton is dominated by warm-water taxa in winter, we would predict poor returns of salmon. May diets of juvenile Chinook salmon collected in coastal waters reflected high proportions of juvenile rockfish, no evidence of northern anchovy, and most closely resembled those of other warm years. June diets also reflected a warm prey community being consumed, predicting poor returns of salmon. Chinook salmon had high percentages of empty stomachs and were small and thin in 2015, with fish weighing 17.6% less than the same-length fish in a cold year (2008). Lower condition of juvenile Chinook salmon related to decreased returns of adult salmon. Overall, all but one biological predictor (biomass of prey) suggests that the prospects for the 2015 ocean-entry smolts were not favorable for survival.
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Warm conditions in the North Pacific in 2014–15 were a result of the continuation of the North Pacific marine heat wave, a large area of exceptionally high SST anomalies that originated in the Gulf of Alaska in late 2013. The North Pacific heat wave interacted with an El Niño developing in the equatorial Pacific in 2015. Weekly periods of exceptionally high temperature anomalies (>2˚C) occurred until the start of the El Niño (winter of 2015), when SSTs were still high but not as high as those due to the marine heat wave. During the 2015–16 El Niño, the depth of the 26.0 kg m –3 isopycnal (d 26.0 ) was considerably shallower than during the 1982–83 and 1997–98 events. The area affected by the marine heat wave and the 2015–16 El Niño in the mixed layer was comparable to the 1997–98 El Niño, but lasted longer. Water column stratification in the upper 100 m during 2015–16 was as strong as the most extreme values during the 1997–98 El Niño. This stratification was primarily driven by the warming of the upper 100 m. Despite notable perturbations, the effects of the 2015–16 El Niño on hydrographic properties in the CalCOFI domain were not as strong as those observed during the 1997–98 El Niño. Warm ocean conditions, stratification, nutrient suppression, and silicic acid stress likely favored initiation of a toxic Pseudo-nitzschia bloom in fall 2014. Very low zooplankton displacement volumes were associated with anomalously warm and saline surface waters off Baja California. In contrast, during the 1997–98 El Niño, zooplankton volume was near average. Off California, pelagic red crab (Pleuroncodes planipes) adults were abundant in the water column and frequently washed up on beaches of southern California from January 2015 into 2016, and central California by September 2015. Glider measurements of integrated transport up to June 2015 did not detect anomalous northward advection. As expected, HF radar indicated northward surface currents along the central California coast in fall and winter 2015–16. Northward advection appeared to be much stronger during the 1997–98 El Niño. Throughout 2015–16, the zooplankton community on the Oregon shelf was dominated by lipid-poor tropical and sub-tropical copepods and gelatinous zooplankton, indicating poor feeding conditions for small fishes that are prey for juvenile salmon. The presence of rarely encountered species increased copepod species richness during 2015–16 to levels higher than the 1998 El Niño. We infer that the unusual copepod vagrants of 2015–16 originated from an offshore and southwesterly source; an important difference from the southerly origin of vagrants during the 1997–98 El Niño. The very warm conditions caused sardine spawning to shift from central California to Oregon. Mesopelagic fish assemblage off southern California exhibited higher abundances of species with southern affinities, and lower abundances of species with northern affinities. Forage fish (Pacific herring, northern anchovy, and Pacific sardine) were much less abundant in 2015–16 compared to previous years. In contrast, catches of salmon were close to average off northern California. Catches of young-of-the-year rockfishes were high off central California, but low off both northern and southern California. Seabirds at Southeast Farallon Island in 2015 exhibited reduced breeding populations, reduced breeding success, lower chick growth rates, and lower fledging weights. Common murres were negatively affected in central and northern California, but seabird respones were species-specific. It is clear from the results presented here that the warm anomaly effects on the ecosystem were complicated, regionally specific, and that we do not fully understand them yet.
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From January 2014 to August 2016, sea-surface temperatures (SSTs) along the Washington, Oregon, and California coasts were significantly warmer than usual, reaching a maximum SST anomaly of 6.2 °C off southern California. This marine heat wave occurred alongside the Gulf of Alaska marine heat wave, and resulted in major disturbances in the California Current ecosystem and massive economic impacts. Here, we use satellite and blended reanalysis products to report the magnitude, extent, duration, and evolution of SSTs and wind stress anomalies along the west coast of the continental United States during this event. Nearshore SST anomalies along the entire coast were persistent during the marine heat wave, and only abated seasonally, during spring upwelling-favorable wind stress. The coastal marine heat wave weakened in July 2016 and disappeared by September 2016.