Survival, Growth, and Feed Utilization of Pre- and Postmetamorphic American Shad Exposed to Increasing Salinity

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  • This article was downloaded by: [Washington State University Libraries ]On: 25 October 2014, At: 00:05Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

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    Survival, Growth, and Feed Utilizationof Pre- and Postmetamorphic AmericanShad Exposed to Increasing SalinityYanju Jia a , Qinghua Liu b , Cheryl A. Goudie c & Bill A. Simco da College of Biological Science and Engineering, Hebei Universityof Economics and Business , Shijiazhuang, 050061, People'sRepublic of Chinab Aegis EcoTechnology Development Company, Inc. , Shanghai,201203, People's Republic of Chinac Aegis EcoTechnology Development Company, Inc. and EcologicalResearch Center , University of Memphis , Memphis, Tennessee,38152, USAd Ecological Research Center, University of Memphis , Memphis,Tennessee, 38152, USAPublished online: 09 Jan 2011.

    To cite this article: Yanju Jia , Qinghua Liu , Cheryl A. Goudie & Bill A. Simco (2009) Survival,Growth, and Feed Utilization of Pre- and Postmetamorphic American Shad Exposed to IncreasingSalinity, North American Journal of Aquaculture, 71:3, 197-205, DOI: 10.1577/A07-095.1

    To link to this article: http://dx.doi.org/10.1577/A07-095.1

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  • Survival, Growth, and Feed Utilization of Pre- andPostmetamorphic American Shad Exposed to Increasing Salinity

    YANJU JIACollege of Biological Science and Engineering, Hebei University of Economics and Business,

    Shijiazhuang 050061, Peoples Republic of China

    QINGHUA LIUAegis EcoTechnology Development Company, Inc.,

    Shanghai 201203, Peoples Republic of China, and Memphis, Tennessee 38152, USA

    CHERYL A. GOUDIE*Aegis EcoTechnology Development Company, Inc., and Ecological Research Center,

    University of Memphis, Memphis, Tennessee 38152, USA

    BILL A. SIMCOEcological Research Center, University of Memphis, Memphis, Tennessee 38152, USA

    Abstract.The American shad Alosa sapidissima is currently an emerging aquaculture species in China,and establishing conditions required for optimal growth will play a key role in future development of

    American shad culture. We evaluated the effects of increasing salinity concentrations on survival, growth, and

    feed utilization of American shad in two separate 30-d experiments. In experiment 1, 25-d-old,

    premetamorphic fish (mean weight 6 SD 0.07 6 0.04 g) were exposed to 0, 10, 20, and 30-ppt salinity(26298C). In experiment 2, 80-d-old, postmetamorphic fish (1.46 6 0.52 g) were exposed to 0, 5, 10, 20, and30-ppt salinity (21268C). Mortality was markedly higher at salinities of 20 ppt (52% and 74%, respectively,for pre- and postmetamorphic fish) and 30 ppt (100% and 90%, respectively) than at 0 and 5 ppt (,1%).Specific growth rate (SGR) and feed conversion efficiency (FCE) were highest at 0-ppt salinity for

    premetamorphic fish (SGR 8.81% per day; FCE 1.12) and at 5-ppt salinity for postmetamorphic fish(SGR 4.59% per day; FCE 0.87). The SGR and FCE were lowest at 30-ppt salinity, and a significantnegative relationship was demonstrated between salinity and SGR and between salinity and FCE. In both

    experiments, SGR and FCE were positively correlated. Our observations demonstrate that culture of young

    American shad may be possible at salinities up to 10 ppt, but 05-ppt salinity produced the best growth.

    Salinity is an important environmental factor

    affecting fish survival, growth, and distribution, and

    its interaction with temperature is complex (Boeuf and

    Payan 2001; Schreiber 2001). It is generally accepted

    that the energetic cost of osmoregulation is lower in an

    isosmotic medium, where the gradients between blood

    and water are minimal, and that these energy savings

    are substantial enough to increase growth (Brett 1979).

    However, optimal salinities for growth and metabolic

    rates are influenced both by species and developmental

    status (Morgan and Iwama 1991). Growth increases

    can be mediated by direct effects of salinity on food

    intake and food conversion efficiency or indirectly by

    physiological consequences of salinity exposure

    (Boeuf and Payan 2001).

    The Reeves shad Tenualosa reevesii is an anadro-

    mous herring native to China (Wang and St. Pierre

    1997). It historically constituted a significant fishery in

    China and has experienced dramatic depletions due to

    common factors, such as overfishing and alteration,

    degradation, and loss of habitat. The Reeves shad is in

    great demand at local markets and commands a high

    price due to its scarcity and particularly esteemed value

    in Chinese culture (Qiu et al. 1998; Liu et al. 2002;

    Wang 2003). The morphologically similar American

    shad Alosa sapidissima is considered an emerging

    aquaculture species in China (Liu et al. 2006) and

    could be a potential alternative to alleviate commercial

    pressure on Reeves shad. Establishing the conditions

    required for optimal growth of American shad will play

    a key role in the development of future aquaculture

    efforts.

    Although larval American shad naturally live in

    freshwater, their growth rate may not be optimal in

    freshwater compared with that in a saline environment.

    Several studies have reported the effects of salinity on

    * Corresponding author: cgoudie@memphis.edu

    Received November 16, 2007; accepted July 25, 2008Published online May 7, 2009

    197

    North American Journal of Aquaculture 71:197205, 2009 Copyright by the American Fisheries Society 2009DOI: 10.1577/A07-095.1

    [Article]

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  • American shad (e.g., Chittenden 1973; Howey 1985;

    Shrimpton et al. 2001). However, the contradictory

    results of these experiments do not provide enough

    information for proper salinity management.

    In this study, we evaluated survival, growth, and

    feed utilization of American shad exposed for 30 d to

    salinity concentrations from 0 to 30 ppt. Two

    experiments were conducted: the first began with 25-

    d-old American shad that would be undergoing

    metamorphic transformation from the larval to juvenile

    stage during the experiment (see Zydlewski and

    McCormick 1997), and the second began with 80-d-

    old, postmetamorphic juveniles that presumably would

    have the osmoregulatory capacity for oceanic migra-

    tion. Our objective was to identify the optimal salinity

    for use during early culture of American shad.

    Methods

    Experimental fish.In June 2006, American shadeggs were obtained from Shanghai Aquaculture

    Research Institute, Shanghai, Peoples Republic of

    China, and were cultured at Aegis EcoTechnology

    Company, Ltd. in Shanghai. Hatched larvae were

    stocked in circular concrete tanks containing 9 m3 of

    freshwater (hardness 7.40 mg/L; calcium 90.18mg/L; pH 6.9). About 20% of the rearing water wasexchanged daily. Larvae were fed rotifers beginning at

    3 d posthatch and were gradually converted to a dry

    shrimp diet (Shunde Aquatic Feed Company, Guang-

    dong, China) beginning at 7 d posthatch. All

    experimental fish were randomly selected from this

    hatchery population.

    The effects of salinity on culture of American shad

    were investigated in two separate 30-d periods. In

    experiment 1, 25-d-old, premetamorphic fish (mean

    weight 6 SD 0.07 6 0.04 g; total length [TL] 23.46 2.6 mm) were exposed to 0, 10, 20, and 30-pptsalinity. During the course of experiment 1, the

    metamorphic transition from larvae to juveniles was

    completed. In experiment 2, 80-d-old postmetamorphic

    fish (1.46 6 0.52 g; 56.3 6 5.0 mm TL) were exposedto 0, 5, 10, 20, and 30-ppt salinity.

    Experimental conditions.Fish were exposed toeach salinity treatment in independent recirculating

    water systems. Each salinity treatment was conducted

    in duplicate, so there were eight systems in experiment

    1 and 10 systems in experiment 2. Each independent

    recirculating system contained one circular concrete

    tank (2 m2) with a water depth of 50 cm for rearing fish

    and one silo tank for upwelling filtration. Water flow

    rate in each system was 9 L/min. Salinity concentra-

    tions (measured with a YSI Model 85 salinity meter;

    Yellow Springs Instruments, Yellow Springs, Ohio)

    were gradually obtained over a period of 2 d by

    addition of commercial artificial ocean salts. Water

    temperatures ranged from 268C to 298C in experiment1 and from 218C to 268C in experiment 2. Dissolvedoxygen was measured daily and remained above 5 mg/

    L throughout the two experimental periods. Density in

    each rearing tank was 1,000 fish/m3 in experiment 1

    and 260 fish/m3 in experiment 2.

    Feeding.The same person fed fish throughout bothexperiments for consistency in diet application. Fish

    were fed to apparent satiation four times per day.

    Initially, a small amount of diet was offered during the

    feeding, but as more fish assembled at the feeding

    location more food was offered. As fish that were fed

    to satiation dispersed from the feeding location, the

    amount of diet offered was gradually decreased. Diet

    offering ceased when fish stopped eating. Total weight

    of food offered daily was recorded as feed intake (FI).

    Experiment 1 was terminated after 27 d due to 100%mortality in both replicates of 30-ppt salinity. Thirty

    fingerlings from each tank were individually weighed

    (nearest 0.01 g) and measured for TL (nearest 0.1 mm)

    on days 0, 10, 20, and 27 (for experiment 1) or 30 (for

    experiment 2).

    Data analyses.Condition factor (K) was calculatedas:

    K 105 3body weight; g=TL; mm:

    Dead fish were removed and counted from each tank

    daily, and cumulative mortality was calculated as:

    Cumulative mortality % 100

    3total number of dead fish

    initial number of fish

    :

    Feeding rate (FR, %), specific growth rate (SGR, % perday), and feed conversion efficiency (FCE) were

    calculated as:

    FR 1003 FI3 2=t3Wt W0f g;SGR 1003logeWt logeW0=t;

    and

    FCE Wt W0=FI;

    where FI is total feed intake (g), t is the duration of theexperiment (d), W

    tis the final wet body weight (g), and

    W0

    is the initial wet body weight.

    Statistical analyses were performed using STATIS-

    TICA version 6.0 (StatSoft, Inc.). One-way analysis of

    variance (ANOVA) was used to evaluate the effect of

    salinity on mortality, and repeated-measures ANOVA

    was used to assess the effect of salinity on body weight

    and K. Differences among treatment means wereidentified using Duncans multiple comparison tests.

    Linear regression was used to analyze the relationships

    198 JIA ET AL.

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  • TABLE 1.Body weight (g) and condition factor of pre- and postmetamorphic American shad exposed to different salinities

    (030ppt) for up to 30 d. Values represent the mean (6SD) of two replicates at each salinity level; 30 fish from each replicatewere sampled on each date. Within a row, means followed by different letters are significantly different (P , 0.05).

    Day of experiment(d posthatch)

    Salinity (ppt)

    0 5 10 20 30

    Experiment 1 (premetamorphic fish): duplicate tanks, 1,000 fish/m3

    Body weight

    0 (25) 0.07 6 0.04 0.07 6 0.04 0.07 6 0.04 0.07 6 0.0410 (35) 0.39 6 0.10 0.29 6 0.05 0.32 6 0.07 0.23 6 0.0720 (45) 0.90 6 0.05 0.66 6 0.07 0.74a 0.35a

    27 (52)b 1.47 6 0.21 1.05 6 0.15 0.90a 0.52a

    Condition factor

    0 (25) 0.52 6 0.15 0.52 6 0.15 0.52 6 0.15 0.52 6 0.1510 (35) 0.77 6 0.03 0.72 6 0.02 0.73 6 0.06 0.67 6 0.0020 (45) 0.90 6 0.00 0.78 6 0.01 0.84a 0.76a

    27 (52)b 0.89 6 0.01 0.86 6 0.02 0.73a 0.70a

    Experiment 2 (postmetamorphic fish): duplicate tanks, 260 fish/m3

    Body weight

    0 (80) 1.46 6 0.52 1.46 6 0.52 1.46 6 0.52 1.46 6 0.52 1.46 6 0.5210 (90) 2.84 6 0.10 2.64 6 0.21 2.32 6 0.15 2.23 6 0.48 2.09 6 0.3120 (100) 3.90 6 0.30 3.99 6 0.11 2.69 6 0.73 2.86a 1.85a

    30 (110) 5.15 6 0.54 z 5.54 6 0.48 z 2.61 6 0.46 y 2.70a y 2.15a y

    Condition factor

    0 (80) 0.79 6 0.17 0.79 6 0.17 0.79 6 0.17 0.79 6 0.17 0.79 6 0.1710 (90) 1.00 6 0.00 0.97 6 0.02 0.92 6 0.02 0.86 6 0.16 0.87 6 0.0420 (100) 0.91 6 0.04 0.97 6 0.02 0.81 6 0.03 0.85a 0.78a

    30 (110) 1.00 6 0.04 z 0.98 6 0.04 z 0.83 6 0.01 y 0.75a y 0.77a y

    a Values represent data from a single replicate due to 100% mortality in the second replicate.b Experiment 1 was terminated early due to 100% mortality of both replicates at 30-ppt salinity.

    FIGURE 1.Cumulative mortalities (%) of pre- and postmetamorphic American shad exposed to different salinities (030%[ppt]) for up to 30 d. Values represent the mean of two replicates for each salinity level. Experiment 1 was terminated after 27 d

    due to 100% mortality in both replicates of 30% salinity.

    SALINITY EFFECTS ON AMERICAN SHAD 199

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  • between salinity and FR, SGR, and FCE, and between

    growth rate and FCE. Significance was accepted at P-values less than 0.05.

    Results

    Mortality

    Heavy mortality began in one replicate of 20- and

    30-ppt salinity on day 10 of both experiments, and all

    fish in these replicates were dead by day 20. No known

    explanation is apparent for the differential mortality

    between replicates, as water quality remained similar

    throughout the experimental periods. Experiment 1 was

    prematurely terminated on day 27 due to 100%mortality of fish in the second replicate of 30-ppt

    salinity. A Saprolegnia fungal infestation (identified by

    a local aquaculture disea...

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