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Juvenile White Sturgeon, Acipenser transmontanus, in Laboratory Aquaria

Authors:
American Currents
Publication of the North American Native Fishes Association
Volume 33 Number 2 Spring (May) 2007
IInn tthhiiss iissssuuee::
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Spring (May) 2007 American Currents 14
hite Sturgeon (Acipenser transmontanus),
native to Pacific coastal drainages, are infre-
quently maintained in public aquaria or labo-
ratories of the southeastern United States.
We were given the special opportunity to obtain juvenile
White Sturgeon for a swimming performance study and to
keep them indefinitely for future research. Our observations
have provided a great deal of information about care, growth,
behavior, and physical variation of captive White Sturgeon.
We believe that this information will be of interest to profes-
sional aquarists and biologists who are considering work with
this remarkable species, and possibly to native fish aquarists
since young White Sturgeon are sometimes sold in the pet
trade (Goldstein et al., 2000).
Biggest Fish in the River
White Sturgeon are the largest freshwater fish in North
America and can reach lengths of 6 m (20 ft) and nearly 900
kg (2,000 lb) (front cover photo). They are long-lived, possibly
exceeding 100 years, and slow to mature, taking as long as 25
years (Sullivan et al., 2003). As young-of-year, White Sturgeon
are, paradoxically, gray to jet black (Fig. 1). They have light,
often snow-white bellies and their rostra are long and sharply
pointed. With age, the dorsal pigmentation becomes lighter
and the rostrum recedes, leaving a bullet-shaped or snub-
nosed head.
The geographic range of the White Surgeon includes the
Aleutian Islands of Alaska, British Columbia, and big rivers
of the West Coast of the United States south to Monterrey,
California (Lee, 1980). White Sturgeon are anadromous or
semi-anadramous, with adults moving upriver from the ocean
to spawn, and juveniles moving from large river systems to
coastal waters. Land-locked populations occur in the
Kootenai and upper Columbia Rivers. A 3 m (9 ft) female
White Sturgeon can contain close to 5 million eggs, making
this species an important resource in the caviar market
(Perrin et al., 2003).
The European caviar embargo, which began on 3 Jan.
2006 (Vidal, 2006), has re-focused concern for our own
native sturgeon (Raloff, 2006). Overharvest, which devastated
North American populations at the turn of the century
(Tower, 1908) and now threatens Eurasian populations
(Saffron, 2003), is not a widespread threat to White Sturgeon,
which are cultivated in large numbers at aquaculture facilities.
These hatchery-reared fish are used to produce caviar and
meat for gourmet markets. They also provide a valuable
opportunity for biologists to study these fish with no impact
to natural (and in some cases fragile) populations.
We received our fish from Sterling Caviar, LLC. Sterling
produces White Sturgeon on farms in California. Sturgeon
are artificially spawned and then raised in warm-water tanks
for eventual processing into caviar and meat products. Our
sturgeon were spawned from Sacramento-San Joaquin River
broodstock in August 2005. Over 100 fish were sent to us,
double-bagged in two Styrofoam shipping containers, by
overnight delivery, and arrived 11 October 2005. Within 24
hours, all fish were actively swimming and feeding in fiber-
glass, re-circulating tanks made by Living Streams, which we
have used successfully in the past to maintain small Pallid
W
Juvenile White Sturgeon,
Acipenser transmontanus,
in Laboratory Aquaria
Krista A. Varble and Jan Jeffrey Hoover
U.S. Army Engineer Research and Development Center, Waterways Experiment Station, EE-A, 3909 Halls Ferry Rd., Vicksburg,
MS 39180; Krista.A.Varble@erdc.usace.army.mil, Jan.J.Hoover@erdc.usace.army.mil; Photographs by Jan Jeffrey Hoover.
American Currents Vol. 33, No. 215
Sturgeon (Hoover et al., 1999). Because of their small size
(60 mm), we initially confined them in plastic tubs with mesh
side panels (Fig. 2). This prevented the fish from getting caught
in crevices around the filter inserts and around the screen
near the agitator, but allowed effective circulation of water.
We tested White Sturgeon to quantify swimming
performance: orientation into flowing water, endurance, and
station-holding behaviors. Testing took place in a Blazka
swim tunnel and followed previous protocols used for
Paddlefish and other species of sturgeon (Hoover et al.,
2005). Tests consisted of timed trials at specific water veloci-
ties. After the trial, the fish was placed back in a Living
Stream or in a flowing fiberglass racetrack with water velocity
of 11 cm/s (Fig. 3). Retesting fish from the racetrack allowed us
to evaluate the effects of “training” on swimming performance.
We studied White Sturgeon swimming performance to estimate
risk of entrainment from dredges and to evaluate certain
rearing practices prior to stocking.
Living Conditions and Daily Care
Nearly all fish were kept in one of three 530-liter Living
Streams or in the 1500-liter racetrack. Water temperature was
19°C. A few fish were kept in a rectangular 80-liter all glass
aquarium at room temperature (~22°C). Fish experienced
almost no “natural” mortality. Some accidental deaths
occurred when the slender caudal fins of individuals slipped
between the narrow space of the false bottom and the wall of
the Living Streams. Weekly water changes of 15% were
sufficient to maintain water quality. Mean specific conductance
was 0.275 mmhos; pH ranged from 7.6 to 8.3, dissolved
oxygen 7.4 to 8.1 mg/L, and turbidity 0.2 to 0.6 NTUs. Fish
were fed four times daily during the first few months of
captivity (when swimming performance tests were underway)
and then twice daily afterwards. Principal foods were frozen
brine shrimp and bloodworms. Other foods included krill,
mosquito larvae and chopped shrimp. Swimming tests were
completed after four months. At that time, most fish were
transferred to Living Streams or Ferguson flumes for long-
term accommodation. We observed no mortality as a result of
experimental tests.
Behavior
As soon as the White Sturgeon entered the tanks, they
swam throughout the tank at a rapid pace that continues even
now. Most sturgeon species swim actively but periodically rest
at the bottom. We rarely saw our White Sturgeon stop for breaks.
They were constantly swimming and exploring their tank.
They are extremely active but not “frantic” in their behavior.
Fig. 1.
Lateral view of juvenile White Sturgeon, showing that it is actually black (or gray) instead of white.
Spring (May) 2007 American Currents 16
They rarely dash about the tank and we have observed no
injuries, including fish maintained in the traditional all-glass
aquarium with sharp corners. Our fish also seem to lack the
“jumping” behavior seen by other captive sturgeon species.
Therefore, the water levels in the tanks can be relatively high
and a cover is not necessary. A previous account of a captive
White Sturgeon (76 mm TL), indicated more extreme
behavior (caught in plants and cutting rostrum on tank) in
captivity and required special modification of its tank to
prevent the fish from injuring itself (Fulton, 1985).
Fish were strongly rheotactic with very few fish failing to
orient into flowing water. During swimming tests sturgeon
exhibited four swimming behaviors: energetic free-swimming
up in the water column, slower skimming along or just above
the tank bottom, stationary hunkering when appressed to the
tank bottom, and tail-bracing against the back cap of the
swim tunnel. These behaviors have all been reported for
Pallid Sturgeon and Lake Sturgeon (Hoover et al., 2005).
When not being tested, and when allowed to move at will in
a gradient of water velocities, sturgeon exhibit all of these
behaviors with skimming predominating and tail-bracing
rarely observed. Swimming endurance of trained fish was
significantly higher than untrained or naïve fish.
Growth and Facial Variation
Fish grew rapidly at first (Table 1). On arrival, one group
of fish appeared to be >60 mm TL, the other group some-
what smaller and slimmer. During the first month of testing,
fish averaged 85 mm TL and 2.9 g. During the second month
of testing, fish averaged 108 mm TL and 5.3 g, an increase
of 26% in length and 83% in weight. After three months, fish
averaged only 112 mm TL and 6.0 g, an increase of <5% in
length and only 13% in weight. Condition factor, an index
expressing robustness of a fish, did not vary greatly over time,
but was slightly higher during the first month. (Note: Ranges
of length and weight overlap among periods and maximum
values do not consistently increase because not all fish were
tested and measured during every period.)
Now, 15 months later, a typical fish is only 150 mm TL.
This is small, no matter what the basis for comparison. Fish
at the aquaculture facility where we obtained the fish report
that 25% of Age I fish weigh 1 kg (P. Struffenegger, pers.
comm.), which corresponds to a length of >600 mm FL
(Carlander, 1969). Wild fish from California are 406-508 mm
FL at Age I, and 457-584 mm FL at Age II (Carlander, 1969).
Our fish are also quite small when compared with the pub-
lished account of a captive 76 mm TL fish that grew to 510 mm
in 18 months (Fulton, 1985). Clearly, our sturgeon are stunted.
We also observed different facial colors (and anterior
portions of the body and pectoral fins) which may be due to
Fig. 2.
Juvenile White Sturgeon in plastic mesh-sided tubs
submerged in a Living Streams recirculating tank.
Table 1. Growth of juvenile White Sturgeon in laboratory aquaria. N is the number of fish measured. Values for length, weight, and condition
(an index of robustness) represent arithmetic mean (and ranges).
Period in Captivity Total Length, mm Weight, g Condition, K
First Month, N=67 85 (65-108) 2.9 (1.3-5.1) 0.46 (0.34-0.60)
Second Month, N=53 107 (90-131) 5.3 (3.0-8.7) 0.42 (0.34-0.53)
Fourth Month, N=28 112 (104-123) 6.0 (4.5-8.2) 0.42 (0.35-0.50)
American Currents Vol. 33, No. 217
our variable accommodations. Colors ranged from black,
gray, white with gold highlights, and pure white (Table 2).
White Sturgeon from tanks with lighter bottoms were more
likely to exhibit darker pigmentation than those from tanks
with darker bottoms. When ventral surfaces were dark,
however, lips and the oral cavity were still lightly pigmented
(Fig. 4). Frequency of the different pigmentation patterns were
not correlated with size of fish but may have been influenced
by size of the tank, with darker fish being more common in
smaller tanks. Relative roles of bottom color and tank size on
fish pigmentation cannot be determined, however, without
additional experiments. In addition to variation in ventral face
color, we also observed rostra receding prematurely, or preco-
ciously (Fig. 5). This was seen in only in a few fish.
Lesser Leviathan in the Lab
We found that White Sturgeon are ideal laboratory animals
—easy to maintain in captivity and resilient to recovery from
experimental studies. Our fish exhibited very low mortality,
high levels of activity, and excellent condition, but relatively
“restrained” growth. Small size may be a physiological
Fig. 3.
Racetrack used to train juvenile White Sturgeon.
Table 2. Characteristics of juvenile White Sturgeon maintained in aquaria of different sizes and bottom types after 11 months in captivity.
80-liter tank; 347-liter flume; 530-liter Living Stream;
white gravel Plexiglas over wood blue fiberglass
Number 8 41 28
Mean Total Length (mm) 153 137 137
Black Ventral Surface 37.5% 4.9% 0%
Gray Ventral Surface 37.5% 17.1% 3.6%
White/Gold Ventral Surface 0% 29.3% 25.0%
White Ventral Surface 25.0% 48.8% 71.4%
Spring (May) 2007 American Currents 18
response to our low, near-constant rearing temperatures, to
effects of fish density or container size, or possibly to some
nutritional deficiency. Pallid, Lake and Atlantic Sturgeon
raised in our laboratory under similar conditions, however,
have attained larger sizes than the White Sturgeon, so we
cannot say for certain why our fish are growing so slowly. Our
observations do suggest, though, that the largest freshwater
fish in North America does not have to be a “tankbuster,” and
can, in fact, be successfully maintained for more than a year
at relatively small (and convenient) sizes.
Acknowledgments
Peter Struffenegger, Sterling Caviar, LLC, provided our
fish and Joseph Beard assisted with care. Wendy Turnbull
from the New Westminster Public Library (New Westminster,
B.C.) for permission to use White Sturgeon archive pho-
tographs. Funding was provided by the U.S. Army Corps of
Engineers Dredging Operations and Environmental
Research Program. Permission to publish was provided by
Chief of Engineers.
Literature Cited
Carlander, K. D. 1969. Handbook of freshwater fishery biology.
Volume one. Ames, Ia.: Iowa State University Press.
Fulton, T. 1985. Living fossils. Freshwater and Marine Aquarium
8 (12) [Dec.]: 37-40.
Goldstein, R. J., R. W. Harper, and R. Edwards. 2000.
American aquarium fishes. College Station, Tx.: Texas A&M
University Press.
Hoover, J. J., K. J. Killgore, and S. R. Adams. 1999. Juvenile
pallid sturgeon in laboratory aquaria. American Currents 25
(4) [Fall]: 1-6.
_____, _____, D. G. Clarke, H. Smith, A. Turnage, and J.
Beard. 2005. Paddlefish and sturgeon entrainment by
dredges: swimming performance as an indicator of risk.
DOER Technical Notes Collection. ERDC TN-DOER-
Fig. 4.
Black and white ventral surfaces of White Sturgeon.
American Currents Vol. 33, No. 219
E22. U.S. Army Engineer Research and Development
Center. Vicksburg, Miss. Available at http://el.erdc.usace.
army.mil/elpubs/pdf/doere22.pdf.
Lee, D. S. 1980. Acipenser transmontanus Richardson. White
sturgeon. In: D. S. Lee, C. R. Gilbert, C. H. Hocutt, R.
E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. Atlas
of North American freshwater fishes. Raleigh: North Carolina
State Museum of Natural History.
Perrin, C. J., L. L. Rempel, and M. L. Rosenau. 2003. White
sturgeon spawning habitat in an unregulated river: Fraser
River, Canada. Transactions of the American Fisheries Society
132: 154-163.
Raloff, J. 2006. Caviar caveats. Science News. 169 [9]. Available
at http://www.sciencenews.org/articles/20060304/food.asp.
Saffron, I. 2002. Caviar: the strange history and uncertain future of
the world’s most coveted delicacy. New York: Broadway Books.
Sullivan, A. B., H. I. Jager, and R. Myers. 2003. Modeling
white sturgeon movement in a reservoir: the effect of
water quality and sturgeon density. Ecological Modeling
167: 97-114.
Tower, W. S. 1908. The passing of the sturgeon: a case of the
unparalleled extermination of a species. Popular Science
Monthly 73: 361-371.
Vidal, J. 2006. Ban on trade in world caviar as sturgeon stocks
plunge. The Guardian. 4 Jan 2006. Available at http://
www.guardian.co.uk/fish/story/0,,1677468,00.html.
Fig. 5.
White Sturgeon with atypically rounded rostrum (left) and typically pointed rostrum (right).
34 years of
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... Juvenile sturgeon, in contrast, are relatively ÔmotivatedÕ and ÔdocileÕ. They require only rare and mild stimulation to swim Boysen and Hoover, 2009), and they are easily maintained and calm in laboratory aquaria Varble and Hoover, 2007). ...
Article
Summary Sturgeon are threatened by dredging, but there is no established protocol for determining risk of entrainment to different populations of wide-ranging species. We demonstrate that laboratory evaluations of swimming performance for individual populations are an effective way to describe susceptibility of entrainment. Using a Blazka-type swim tunnel, we quantified positive rheotaxis (head-first orientation into flowing water), endurance (time to fatigue), and behaviour (method of movement) of juvenile sturgeon in water velocities ranging from 10 to 90 cm s−1. Sturgeon representing four different populations of the United States were tested: two populations of lake sturgeon (Acipenser fulvescens) and two populations of pallid sturgeon (Scaphirhynchus albus). Lake sturgeon from Lake Winnebago were weaker swimmers than those from the Wisconsin River, and pallid sturgeon from the Yellowstone River were weaker swimmers than those from the Atchafalaya River. Rheotaxis, endurance, and behavioural data were used to calculate an index of entrainment risk, ranging from 0 (unlikely) to 1.00 (inevitable), which was applied to hydraulic models of dredge flow fields. Risk of entrainment varied among populations but for all groups tested, substantial entrainment risk occurred only within a 1.25 m radius of the draghead and this risk could be significantly reduced or eliminated by reducing the diameter of the dredge pipe.
Article
Spawning habitat used by white sturgeon Acipenser transmontanus in the lower Fraser River, British Columbia, is described based on field sampling in 1998 and 1999. Fraser River flow is unregulated and, within our study area, its channel morphology is largely unaltered by land use activities. The study area consisted of (1) the wandering reach (river km 98–143), which had side channels, wooded islands, and gravel bars; and (2) the confined reach (river km 145–181), which was naturally restricted by mountains, producing a single-thread and simple channel. Six spawning sites were identified in the study area, five in side channels of the wandering reach and one in the main channel of the confined reach. Within the wandering reach, eggs and larvae were collected only from side channels despite sampling efforts in main-channel areas. Multiple lines of evidence, including radio-tracking of prespawning adults and visual observations, substantiated the use of side channels by white sturgeon for spawning. A total of 3 unfertilized and 80 fertilized eggs were captured at water velocities averaging 1.8 m/s, whereas 101 larvae were found in velocities averaging 1.0 m/s. Water depths averaged 2.9 m at capture locations for all life stages and were shallow compared with depths of egg and larval captures reported from most regulated rivers. Turbidity, which averaged 42 nephelometric turbidity units during the spawning period, was notably higher than in regulated rivers. We hypothesize that reduced light attenuation due to turbidity may substantially influence habitat suitability for spawning within the range of available water depths and velocities. Our observations of white sturgeon spawning activity outside of main-channel habitats are unique, and we have demonstrated that spawning may occur over a wider range of habitat conditions than previously reported. Our observations of white sturgeon spawning in an unregulated river in which fluvial processes and channel morphology are relatively unaltered, albeit increasingly threatened by river engineering, are also unique.
Article
We developed a movement model to examine the distribution and survival of white sturgeon (Acipenser transmontanus) in a reservoir subject to large spatial and temporal variation in dissolved oxygen and temperature. Temperature and dissolved oxygen were simulated by a CE-QUAL-W2 model of Brownlee Reservoir, Idaho for a typical wet, normal, and dry hydrologic year. We compared current water quality conditions to scenarios with reduced nutrient inputs to the reservoir. White sturgeon habitat quality was modeled as a function of temperature, dissolved oxygen and, in some cases, suitability for foraging and depth. We assigned a quality index to each cell along the bottom of the reservoir. The model simulated two aspects of daily movement. Advective movement simulated the tendency for animals to move toward areas with high habitat quality, and diffusion simulated density dependent movement away from areas with high sturgeon density in areas with non-lethal habitat conditions. Mortality resulted when sturgeon were unable to leave areas with lethal temperature or dissolved oxygen conditions. Water quality was highest in winter and early spring and lowest in mid to late summer. Limiting nutrient inputs reduced the area of Brownlee Reservoir with lethal conditions for sturgeon and raised the average habitat suitability throughout the reservoir. Without movement, simulated white sturgeon survival ranged between 45 and 89%. Allowing movement raised the predicted survival of sturgeon under all conditions to above 90% as sturgeon avoided areas with low habitat quality.
Acipenser transmontanus Richardson White sturgeon Atlas of North American freshwater fishes
  • D S D S Lee
  • C R Lee
  • C H Gilbert
  • R E Hocutt
  • D E Jenkins
  • J R Mcallister
  • Jr Stauffer
Lee, D. S. 1980. Acipenser transmontanus Richardson. White sturgeon. In: D. S. Lee, C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. Atlas of North American freshwater fishes. Raleigh: North Carolina State Museum of Natural History.
Caviar: the strange history and uncertain future of the world's most coveted delicacy
  • I Saffron
Saffron, I. 2002. Caviar: the strange history and uncertain future of the world's most coveted delicacy. New York: Broadway Books.
The passing of the sturgeon: a case of the unparalleled extermination of a species
  • W S Tower
Tower, W. S. 1908. The passing of the sturgeon: a case of the unparalleled extermination of a species. Popular Science Monthly 73: 361-371.
Ban on trade in world caviar as sturgeon stocks plunge. The Guardian
  • J Vidal
Vidal, J. 2006. Ban on trade in world caviar as sturgeon stocks plunge. The Guardian. 4 Jan 2006. Available at http:// www.guardian.co.uk/fish/story/0,,1677468,00.html.
Living fossils. Freshwater and Marine Aquarium
  • T Fulton
Fulton, T. 1985. Living fossils. Freshwater and Marine Aquarium 8 (12) [Dec.]: 37-40.
American aquarium fishes. College Station
  • R J Goldstein
  • R W Harper
  • R Edwards
Goldstein, R. J., R. W. Harper, and R. Edwards. 2000. American aquarium fishes. College Station, Tx.: Texas A&M University Press.
Juvenile pallid sturgeon in laboratory aquaria
  • J J Hoover
  • K J Killgore
  • S R Adams
Hoover, J. J., K. J. Killgore, and S. R. Adams. 1999. Juvenile pallid sturgeon in laboratory aquaria. American Currents 25 (4) [Fall]: 1-6.