Gomez Gaspar, A.

English

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15
INDUCED SPAWNING AND REAR LARVAE OF
SPADEFISH CHAETODIPTERUS FABER IN MARGARITA
ISLAND, VENEZUELA.
         
ALFREDO GOMEZ GASPAR
Instituto de Investigaciones Cientificas
Universidad de Oriente Núcleo Nueva Esparta Boca del Río 
Isla de Margarita, Venezuela
ABSTRACT
 
This paper describes standard procedures developed to induced spawning
of the spadefish  Chaetodipterus faber (Broussonet) (Pisces: Ephippidae) and rear
their larvae under controlled conditions. The spadefish are induced to spawn using
human chorionic gonadotropin and luteinizing-releasing hormone analog. Larval
rearing is done in the same tank in which the eggs hatched. Larvae were fed with
mixed live food and normally after 31 days attained a total length between 24 and
33 mm. In twenty four trials realizated the whirling disease and vibriosis were
common. During 1991-1992 a total of 26,731 juveniles were harvested. 
Key Words: aquaculture, Chaetodipterus faber, finfish, larviculture, Venezuela. 
         
INTRODUCTION
Much attention has been directed towards the artificially induced spawning
of fishes and the intensive rearing of the larvae to increase the available supply of
aquatic protein resources. The atlantic spadefish Chaetodipterus faber has a wide
distribution (USA to BRASIL) in a variety of habitats. Said to reach a length of 3
feet and a weight of 20 pounds, their flesh is good to eat (Randall, 1966). The
spadefish readily take a baited hook and have a fine flavor (Bohlke and
Chaplin,1968). 
         In Venezuela it has some commercial importance (Cervigon and Fischer,
1979). The embryonic development of the eggs and larvae stages were described
(Gomez,1984), and carried out experimental cage culture (Gomez and Larez,1984)
and mature in captivity. The spadefish may have ornamental importance, the young
are melanistic, the small juveniles solid black and the may resemble dark-colored
bits of plant debris and molluscs (Breder and Rasquin,1955). This fish is a
candidate for aquaculture in the Caribbean region (Tucker and Jory, 1991). 
         This paper describes standard procedures developed to induce spawning of
the spadefish and rear their larvae under controlled conditions and operational
procedures for successful mass propagation at the Instituto de Investigaciones
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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Cientificas (Universidad de Oriente) in Margarita Island, Venezuela. 
         
         
MATERIAL AND METHODS 
            Mature broodstock available in the Instituto and some loaned by
FundaCiencia marine laboratory (Mochima Bay) were used for the trials carried out.
Males and females were staged for maturity by applying slight pressure to the
abdomen. The spadefish are induced to spawn in captivity using human chorionic
gonadotropin (HCG) and luteinizing-releasing hormone analog (LHRH)
(des-Gly10[D-Ala6]) both from Sigma Co. Protocols, weight of female fish used
and hormonal dosis are summarized in Table 1. Selected fishes were anaesthetized
in 200-300 ppm tricaine methasulfonate weighted and marked, intramuscular
injections were applied in the epaxial musculature adjacent to the anterior part of
the dorsal fin, normally the males do not require hormones. Sometimes the females
were catheterized with a polyethylene cannula inserted into the oviduct and oocyte
samples obtained by mouth aspiration. A sex ratio of two females to three males
was used and they were maintained in 1500 l tanks supplied with aeration and
containing filtered and irradiated seawater (salinity 38-40 °/oo and temperature
25-30°C). The criterion for a successful spawn was the release of eggs into the
water. The number of eggs was estimated by determining the number in 10 l aliquot
and extrapolating for the tank volumen. Fertilized eggs were found floating in the
holding tank and skimmed from the surface water. The eggs were transferred to
tanks (90 cm diameter and 80 cm depth) where the water was gently aerated. After
hatching, the larvae were reared for 31 days and fed with live food. Cultured
Tetraselmis chuii (50,000 cel/ml), rotifers and nauplii of Artemia were introduced
into the larval rearing tanks in the morning. Live mysids collected in a near coastal
lagoon were administered in the last week of each rearing period. 
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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Figure 1 illustrates the schedule of feeding and larval growth of paguara. 
RESULTS AND DISCUSSION
Table 1 shows the performance of paguaras broodstock (females)
subjected to induced spawning during various periods of the year. During two years
(November 1990 to November 1992) were injected 68 females and 29 responded
successfully to HCG and LHRH (range doses 60 to 2200 UI/k and 12 to 42 ug/k
respectively) (Table 2). Generally fishes injected in July through November
spawned 36-45 h after the injection, in the other months the paguara responded
poorly to injections. Successful spawns occurred when therapy was iniciated on
females with oocyte diameter of more than 400 um and the released eggs have
between 0.9 and 1.0 mm (Gomez,1984) and total fecundity ranged between 16,500
and 502,000 eggs (Table 3). The range of dosages used in this study had no effect
on fertilization rates or spawned egg diameters.
Table 1. Chaetodipterus faber females treated with hormones during two years of
experiments in Margarita Island, Venezuela
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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DATE WEIGTH(G HORMMONE DOSE SPAWN HOURS
26-11-90 304 GCH 500 Y 36
360 GCH 500 N
402 GCH 1000 N
298 GCH 1000 N
450 GCH 1500 N
415 GCH 1500
405 GCH 1000 Y 38
375 GCH 1000 Y 38
04/12/90 332 GCH 250 Y 40
418 GCH 250 Y 40
21/03/91 655 LHRH 15 N
523 LHRH 10 N
404 LHRH 10 N
360 LHRH 13 N
18/04/91 525 LHRH 13 N
618 LHRH 11 N
04/05/91 460 GCH 217 Y 36
375 GCH 266 Y 36
10/05/91 305 GCH 245 N
483 GCH 155 N
394 LHRH 35 N
411 LHRH 35 N
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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441 LHRH 35 N
01/06/91 560 GCH 450 N
390 GCH 640 N
550 GCH 330 N
465 GCH 400 N
08/06/91 383 GCH 156 N
374 GCH 160 N
12/06/91 383 GCH 456 N
443 GCH 451 N
19/06/91 457 GCH 800 N
354 GCH 500 N
01/07/91 575 GCH 2100 Y
465 GCH 2200 Y
06/07/91 787 GCH 600 N
710 GCH 700 N
615 LHRH 20 Y 40
18/09/91 338 GCH 600 Y 36
352 GCH 620 Y 36
437 GCH 350 Y 36
406 GCH 350 Y 36
425 LHRH 12 Y 36
428 LHRH 12 Y 36
16/10/91 441 GCH 450 Y 36
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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471 GCH 480 Y 36
14/02/92 395 LHRH 25 N
443 LHRH 22 N
512 LHRH 25 N
26/03/92 575 LHRH 17 N
590 LHRH 42 N
04/04/92 555 LHRH 22 N
570 LHRH 24 N
21/04/92 452 LHRH 20 N
420 LHRH 27 N
07/05/92 1010 LHRH 20 N
746 LHRH 27 N
10/06/92 359 GCH 500 Y 40
05/07/92 460 GCH 435 Y 40
635 GCH 275 Y 40
910 GCH 357 Y 40
02/10/92 502 GCH 99 Y 45
640 GCH 78 Y 45
837 GCH 60 Y 45
06/11/92 663 GCH 75 Y 38
643 GCH 77 Y 38
767 GCH 66 Y 38
831 GCH 120 0 38
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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         Newly hatched larvae vary in length from 1.9 to 2.1 mm and have a yolk sac
which is depleted after two or three days (Gomez,1984). Larval rearing is usually
done in the same tank in which the eggs hatched. Feeding start 48 - 72 hours after
hatching and was a common practice to add Tetraselmys to naturalize the tank
water and to provide natural food. The larvae were reared for 31 days and fed with
mixed live food. Cultured rotifer Brachionus was given on day 3 at density of 5-12
pieces/ml and increased until 20/ml. Newly hatched Artemia were administered
beginning on day 5 at density of 2/ml and increased until 10/ml (day 25). On the
last week of the rearing period were supplied with live mysids. Figure 1 illustrates
the schedule of feeding and larval growth of paguara. After 31 day larvae normally
attained a total length between 24.1 and 33.1 mm (Table 4) but larval growth is
dependent on larval density and diseases problems which cause slow growth ( 13
to 16 mm in 31 days) (Table 4). Larvae are vulnerable to problems resulting from
ingestion of the empty cyst or shells of Artemia. Poor tanks management can also
result in high mortality rate, an important task is the cleaning of the tank bottom
where debris, fecal heces, dead fish and unconsumed food are deposited. Some
diseases were observed in trials, during 1991 a heavy mortality (whirling disease)
was caused by a myxosporidian which invaded the brain of larvae and during 1992
vibriosis diseases were common.
Table 2. Summary of induced spawning trials of Chaetodipterus faber in Margarita
Island, Venezuela.
_______________________________________________________________
Females injected; 68 Spawned: 29
eggs/spawn: 16,000 to 502,000
Range females weights (g) Hormone Doses range
298 to 910 GCH 60 to 2,200 UI/K
360 to 1010 LHRH 12 to 42      Ug/k
______________________________________________________________________
Table 3. Data from the experiments on the rearing of Chaetodipterus faber in
Margarita Island, Venezuela. (TL = total length)
DATE TRIAL TEMPERATURE TL AFTER 31 DAYS
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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07/5-6/91 1 26.0-29.5 33.1
2 25.6-29.3 29.2
9/7-8/8/91 3 26.1-28.9 28.0
20/9-21/10/91 4 26.5-28.7 24.4
5 26.5-28.6 26.1
6 26.5-28.7 29.3
7 27.0-28.5 29.3
8 26.5-28.6 27.7
9 27.1-29.0 29.1
20/10-19/11/91 10 26.0-28.8 28.2
11 26.2-28.7 29.5
12 26.2-28.9 30.8
13 26.4-29.1 30.9
07/07-08/08/92 14 26.4-29.1 16.5
15 25.4-27.1 13.2
16 25.3-27.4 15.4
17 25.4-27.2 15.3
18 26.0-27.6 16.9
19 26.4-27.3 13.9
04/10-05/11/92 20 26.3-29.1 26.3
21 26.4-28.5 26.5
22 26.5-28.2 27.7
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
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23 26.5-28.3 27.0
24 26.5-28.4 28.5
Table 4. Production data on the rearing of Chaetodipterus faber in Margarita Island,
Venezuela.
TRIAL EGGS %
FERTILIZATION
# JUVENILES
1 39,000 84.61 1,497
2-3 190,250 72.40 989
4-5 303,000 82.17 5,161
6-7 219,000 69.86 4,039
8-9 409,500 71.79 2,542
10-11 81,000 37.04 2,385
12-13 16,500 1.00 --
14-19 502,000 19.17 6,600
20-24 348,000 58.60 3,518
JUVENILES OF SPADEFISH REARED/1991 : 16,613
 /1992 : 10,118
              TOTAL :26,731
         In the 1991 trials the harvested fish totaled 16,613 and 10,118 during 1992 (Table 4).
The fishes that are grown to a size of 30 mm or so are used as seedlings for further
cultivation in captivity and others restocked to the sea.
         
ACKNOWLEDGEMENTS
This work has been primarily supported by CONICIT (FT.135) and the Research
Council of Universidad de Oriente, Venezuela (Project CI 221/90). We would like to thanks
to the sub-station staff of the Institute de Investigaciones Cientificas. 
         
LITERATURE CITED
Proceedings of the 47th Gulf and Caribbean Fisheries Institute
24
Bolhke, J. and C. Chaplin. 1968. Fishes of the Bahamas and adjacent waters. Livingston
Publ.Co., 771 pp.
Breder, C. and P. Rasquin. 1955. Further notes on the pigmentary  behavior of
Chaetodipterus in reference to background and water transparency. Zoologica,
40(20): 85-90.
Cervigon, F. and W. Fischer. 1979. Catálogo de especies marinas  de intéres económico
actual ó potencial para America Latina. Parte 1. Atlántico Centro y SurOriental.
Infopesca, Roma. FAO/UNDP, SIC/19/l, 372 pp. 
Gomez, A. 1984. Inducción del desove, desarrollo embrionario y  larval de Chaetodipterus
faber (Broussonet)(Pisces: Ephippidae) en la Isla de Margarita, Venezuela.
Ann.Inst.Inv.Mar.Punta de Betin, Colombia, 14: 85-104.
Gomez, A. and F. Lares. 1984. Crecimiento de la paguara Chaetodipterus faber
(Pisces:Ephippidae) durante un aûo de  confinamiento en jaula flotante.
Bol.Inst.Oceanogr. Univ. de Oriente, Venezuela, 23(1-2): 157-161.
Randall, J.E. 1966. Caribbean Reef Fishes.THF Publ.Inc., 318 pp.
Tucker, J.Jr. and D. Jory. 1991. Marine fish culture in the Caribbean region. World
Aquaculture, 22(1): 10-27.


Induced spawning and rear larvae of spadefish Chaetodipterus faber in Margarita Island, Venezuela.

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Induced spawning and rear larvae of spadefish Chaetodipterus faber in Margarita Island, Venezuela.

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