The Effect of Size and Diet on Gonad Production by the Chilean Sea Urchin Loxechinus albus

Val. 32, No. 2
June, 2001
JOURNALOFTHE
WORLD AQUACULTURE SOCIETY
The Effect of Size and Diet on Gonad Production by the
Chilean Sea Urchin Loxechinus albus
SERGIO OLAVE AND
EDUARDO
BUSTOS
Divisio'n de Acuiculturu, Instituto d e Foment0 Persquero, Cusillu 665. Pto. Montt, Chile
JOHNM. LAWRENCE
Department of Biology, University of South Florida, Tampa, Floridu 33620 USA
PEDRO CARCAMO
Divisidn de Acuiculturu, Instituto d e Foment0 Persquero, Casilla 665, Pro. Montt, Chile
Abstract.-Conadal production was studied in Loxechinus albus (Molina, 1782) maintained in cages suspended from a long-line in the Estero Castro, ChiloC
for 3 mo during the austral summer. The sea urchins
were fed either an artificial diet or a natural diet consisting of the macroalgae Macrocystis pyrifera and
Ulva sp. Both diets were tested for four size ranges:
40-45, 50-55, 60-65 and 70-75 mm diameter. For all
four size ranges, highest gonad production was with
the artificial diet. Gonad production was greatest in the
40-45 mm individuals with an increase of about
1,400% and 750% in the wet weight of gonads in individuals fed the artificial and natural diet, respectively. With the three other size ranges, the increase was
nearly 100% with the artificial diet and nearly 0% with
the natural diet The gonad index showed similar patterns, being highest in the smallest individuals. Small
individuals fed the artificial diet would provide the
most cost effective aquaculture as production is best.
It is not necessary to grow L. ulbus to the minimal
legal size for fisheries (70-mm diameter) for cost effective gonad production.
1995), Strongylocentrotus droebachiensis
(de Jong-Westman et al. 1995; Klinger et
al. 1997; Walker and Lesser 1998), and
Strongylocentrotus franciscanus (McBride
et al. 1997, 1999).
The present work investigates the effect
of body size on gonad production by sea
urchins fed an artificial feed or algal diets.
We hypothesized that use of artificial feeds
in culture would eliminate the necessity of
growing sea urchins for over 4 yr to obtain
the minimum fishery legal size (70 mm) for
cost effective gonad production.
Materials and Methods
Loxechinus albus artificially produced at
the Centro Tecnol6gico para la Acuicultura
at ChiloC, Chile were maintained in culture
cages (90 X 90 X 30 cm, covered with a
5-mm plastic mesh). The cages were susThe decline in sea urchin fisheries in ma- pended 15 m apart at a depth of 3 m from
jor producing countries such as Chile and a long-line in the Estero de Castro approxthe strong demand for sea urchin roe pro- imately 200 m from the shore at ChiloC
vides opportunities for sea urchin aquacul- (42"30'S; 73'45'W). Each cage contained
ture and roe enhancement (Keesing and 60 sea urchins of a specific body size (40Hall 1999). To generate high quality indi- 45; 50-55; 60-65 or 70-75 mm diameter).
viduals of the Chilean sea urchin LoxechinOver 3 mo (22 October 1998 to 22 Janus albus with high gonad production year- uary 1999), the sea urchins were fed ad liround is a great commercial and technical bitum either an artificial diet (prepared by
challenge. The use of artificial diets as feed Wenger Manufacturing, Inc., Kansas City,
for sea urchins has proven to be an alter- Missouri, USA) previously tested with Loxnative to natural foods. High gonadal pro- echinus albus by Lawrence et al. ( 1 997) or
duction by feeding with artificial diets has a macroalgal diet consisting of Macrocystis
been reported for Loxechinus albus pyrift'ra and Ulva sp. The formulation and
(Lawrence et al. 1997), Paracentrotus livi- proximal composition of the diets are
dus (Lawrence et al. 1992; Fernhdez et al. shown in Tables 1 and 2. The temperature
0 Copyright by the World Aquaculture Sociely 2001
210
21 1
GONAD PRODUCTION B Y CHILEAN SEA URCHIN
TABLEI . Formulation of the prepared feed (% dry
weight).
Component
% dry weight
Kelp meal
Corn grain
Wheat middlings
Soybean
Fish meal
Potassium diphosphate
Fish oil
Cholesterol
Ethoxide
Mineralshitamins
Vitamin C
Carotenoids
14.00
32.00
27.53
11.10
12.00
1.33
0.24
0.30
0.20
0.08
0.08
0.01
TABLE2. Proximate composition (% dry weight) and
water content (% wet weight) of the artificial diet,
Macrocystis pyrifera, and Ulva sp. Values for the
macroalgae are annual means from Westermeier
( I 982).
~
~~
Artificial Macrocystis
diet
pyrifera UIva sp.
Component
Soluble protein
Lipid
Soluble carbohydrate
Fiber
Organic matter
Water
24
20.1
4.7
62.2
4.6
91.6
27
11.4
6.2
9.74
, A
Results
The gonad weights at the end of the experiment of individuals of all four size
ranges were significantly higher for those
fed the artificial diet ( P < 0.01 for 40-45
mm individuals, P < 0.05 for the other size
ranges) (Fig. I ) . The gonad weights of in-
-
-
72.7
87
72.7
82
J
dbl
+e*oyded
t m l g s l dbl
20.
ranged from 12 to 15 C in the austral spring
and 15 to 18 C in the austral summer (mean
= 15 +- 1 C over the experimental period).
There were three cages (replicates) for each
size range with the artificial feed and two
with the macroalgae. The animals were fed
ad libitum, with uneaten food removed and
fresh food added every 10 d. The artificial
feed showed no signs of breaking up or
spoilage over this time.
The wet body weight and gonad weight
was measured at the beginning of the experiment for 15 individuals in each size
range to the nearest 0.01 g. Subsequently,
the wet body weight and gonad weight
were measured for six individuals for each
replicate every 2 wk. The gonad index (gonadal wet weight X 100hody wet weight)
was calculated (Gonor 1972).
Gonad production (both weight and index) between size ranges and between diets
were compared statistically with a two way
ANOVA and an a posteriori multicomparative analysis by Scheffk’s test (Sokal and
Rohlf 1981).
17.1
6.6
12.72
36.
12.
T
4.
0.
40.
D
oJ
22 Od 98
21 Nov 98
21 DecW
20 Jan 99
DATE
FIGURE
1. Gonad wet weight ( g ) of Loxechinus albus
of different sizes fed an artificial diet or macroalgae
over a 3-mo period (Mean SE) A: 40-45 mrn diameter, B: 50-55 mm diameter, C: 60-65 mm diameter, D: 7&75 mm diameter.
*
212
OLAVE ET AL.
40
32
4
I
diet did not differ significantly with size (P
> 0.05).
A decrease in the gonad weight and index occurred in the 50-55 mm individuals
in January, but not for the other size ranges.
Discussion
These data confirm that gonad production is greater with an artificial diet than
with macroalgae as reported by Lawrence
et al. (1991, 1997), Fernandez et al. (1995),
de Jong-Westman et al. (1995), Klinger et
al. (1997), McBride et al. (1997, 1999), and
Walker and Lesser (1998). Undoubtedly
much of this difference is the presence of
refractory cell walls in the algal diet
(McClintock 1986) although the quality of
the nutrients could also be a factor.
Individuals in the smallest size range
used here are at the lower limit for sexual
maturity, as Loxechinus albus reaches sexual maturity in the field at a diameter between 35-45 mm (Bustos et al. 1991). The
gonads reach maturity and spawning occurs
in the austral spring from November to December (Bay-Schmith et al. 1981). Thus the
sea urchins were at the beginning of gonadal
development when the experiment began.
oJ
22 O d 88
21Nov98
21 D-98
20 JM 99
The
size of the gonads and the gonad index
DATE
at that date were directly related to body
FIGURE
2. Gonad index of Loxechinus albus of dqsize. Small individuals, 40-45 mm in diferent sizes fed an artijicial diet o r macroalgae over
ameter,
had much smaller gonads than larga 3-mo period (Mean -C SE.). A: 40-45 mm diameter, B: 50-55 mm diameier, C: 60-65 mm diameier, er individuals. After 3 mo feeding on the
D: 70-75 mm diameter.
artificial diet or macroalgae to the date
when gonad maturity could be expected, the
gonads of the small individuals had individuals fed the macroalgae increased dur- creased approximately 1,400% and 750%
ing the experiment only in the smallest (40- respectively. The increase in gonad weight
45 mm) individuals. The gonad weight at of the other three size ranges was nearly
the end of the experiment of sea urchins fed 100% with the artificial diet and almost nil
the artificial diet was significantly related to with the macroalgae.
The gonad indices found here at the end
body size (P < 0.05).
The gonad indices of sea urchins fed the of the experiment are similar to those reartificial diet was significantly larger than ported for Loxechinus albus by Lawrence
those of individuals fed the macroalgal diet et al. (1997). Although the gonadal weights
(P < 0.01 for 40-45 mm individuals, P < at the end of the experiment with the arti0.05 for the other sizes) (Tables 5 , 6, Fig. ficial diet were directly related to body size,
2). In contrast to the gonad weights, the go- the gonad index was similar at all sizes and
nad indices of individuals fed the artificial the efficiency of gonadal production was in-
GONAD PRODUCTION BY CHILEAN SEA URCHIN
versely related to body size. The decrease
in gonad size and index in the last month
of the experiment in the 50-55 mm individuals probably indicates spawning.
The commercial development of culture
of the sea urchin Loxechinus albus has been
held back by the long period of culture and
the high costs required to obtain individuals
of commercial size, i.e., 70 mm (3-5 yr:
Zegers et al. 1983; Bustos et al. 1992; Olave et al. 1993). This present work indicates
that, in culture, it would not be necessary
to grow L. albus in aquaculture to a very
large size since 40-45 mm individuals, fed
with artificial diet, offer better economic
prospects. These small individuals fed an
artificial diet have a higher gonad production efficiency and similar gonad indices
compared to larger individuals. Small L. albus always have higher indices than individuals of all size ranges fed macroalgae.
These results also have implications for
“bulking” (gonad conditioning, wild stock
enhancement) of sea urchins obtained from
areas where food is limited and gonads are
not produced (Moylan 1997; Robinson and
Colborne 1997; Hagen 1998). Current fisheries regulations prohibit taking individuals
< 70 mm as the gonads are too small for
marketing. It is possible that individuals
40-45 mm individuals could be fished for
bulking.
Acknowledgments
The present work was funded by Project
FONDEF D/96/1101 “Diversificaci6n de la
Acuacultura en la X Regidn, Chile”. (Diversification of Aquaculture in the X Region, Chile). We thank Dr. A. L. Lawrence
for formulating the diet and Wenger Manufacturing, Inc., Kansas City, Missouri,
USA for supplying the extruded feed. We
are grateful for the collaboration of Miss
Claudia Puebla and Mr. RenC Silva in the
field work.
Literature Cited
Bay-Schmith, E., C. Werlinger, and J. Silva. 1981.
Ciclo anual de reproduccibn del recurso Loxechin-
213
us albus entre la X y XI1 Regibn. Informe final
Proyecto de Investigacibn Subsecretaria de Pesca.
Universidad de Concepcibn. Concepcibn, Chile.
Bustos, E., C. Godoy and R. Troncoso. 1991. Investigacibn repoblamiento de recursos bentbnicos
Area Piloto IV Regibn. Etapa 111. 4. Investigaciones en erizo Loxechinus albus (Molina. 1782).
CORFO-IFOP (SGI-IFOP 91/5).
Bustos, E., S. Olave, R. Troncoso, and C. Godoy.
1992. Investigacibn repoblamiento de recursos
bentdnicos Area Piloto IV Regibn. Etapa IV. 5.
Investigaciones en erizo Loxechinus albus (Molina, 1782). CORFO-IFOP (SGI-IFOP 92/8).
de Jong-Westman, M., B. E. March, and T. H. Carefoot. 1995. The effect of different nutrient formulations in artificial diets on gonad growth in the
sea urchin Srrongylocentrotus droebachiensis. Canadian Journal of Zoology 73: 1495-1502.
Fernhdez, C., E. Dombrowski, and A. Caltagirone.
1995. Gonadal growth of adult sea urchin Paracentrotus lividus (Echinodermata: Echinoidea) in
rearing: the effect of different diet type. Pages
269-275 in R. Emson, A. B. Smith, and A. Campbell, editors. Echinoderm research 1995. A.A.
Balkema, Rotterdam, The Netherlands.
Gonor, J. J. 1972. Gonad growth in the sea urchin
Strongylocentrotus purpurarus (Stimpson) (Echinodermata: Echinoidea) and the assumptions of
gonad index methods. Journal of Experimental
Marine Biology and Ecology 19:89-103.
Hagen, N. T. 1998. Effect of food availability and
body size on out-of-season gonad yield in the
green sea urchin, Srrongylocenrrotus droebachiensis. Journal of Shellfish Research 17: 1,533-1.539.
Keesing, J. K. and K. C. Hall. 1999. Review of harvests and status of world sea urchin fisheries
points to opportunities for aquaculture. Journal of
Shellfish Research 17597-1,604.
Klinger, T. S., J. M. Lawrence, and A. L. Lawrence.
1997. Gonad and somatic production of Srrongylocenrrotus droebachiensis fed manufactured
feeds. Bulletin of the Aquaculture Association of
Canada 1997:35-37.
Lawrence, J. M.; L. Fenaux, M. C. Corre, and A.
Lawrence. 1992. The effect of quantity and quality of prepared diets on production in Paracenrrotus lividus (Echinodermata: Echinoidea). Pages107-110 in L. Scaiera-Liaci and C. Canicatti,
editors. Echinoderm research 1991. A.A. Balkema, Rotterdam, Netherlands.
Lawrence, J. M., S. Olave, R. Otaiza, A. Lawrence,
and E. Bustos. 1997. Enhancement of gonad production in the sea urchin Loxechinus albus in
Chile fed extruded feeds. Journal of the World
Aquaculture Society 28:9 1-96.
McBride, S. C., W. D. Pinnix, J. M. Lawrence, A.
Lawrence, and T. M. Mulligan. 1997. The effect
of temperature on production of gonads by the sea
214
OLAVE ET AL.
urchin Strongylocentrotus franciscanus fed natural and prepared diets. Journal of the World Aquaculture Society 28:357-365.
McBride, S. C., J. M. Lawrence, A. L. Lawrence,
and T. J. Mulligan. 1999. Ingestion, absorption,
and gonad production of adult Strongylocentrotus
franciscanus fed different rations of a prepared
diet. Journal of the World Aquaculture Society 30:
364-370.
McClintock, J. B. 1986. On estimating energetic values of prey: implications in optimal diet models.
Oecologia 70:161-162.
Moylan, E. 1997. Gonad conditioning and wild stock
enhancement of the purple sea urchin Paracentrotus lividus on the west coast of Ireland. Bulletin
of the Aquaculture Association of Canada 97-1:
38-41.
Olave, S., C. Godoy, and R. Troncoso. 1993. Investigaci6n repoblamiento de recursos bent6nicos
Area Piloto 1V Regi6n. Etapa V. 4. Erizo ( b x e chinus albus). CORFO-IFOP (SGI-IFOP 93/8).
Robinson, S. M. C. and L. Colborne. 1997. Enhanc-
ing roe of the green sea urchin using an artificial
food source. Bulletin of the Aquacultural Association of Canada. 97-1:14-20.
Sokal, R. R. and F. J. Rohlf. 1981. Biometry. The
principles and practice of statistics in biological
research, second edition. W. H. Freeman and Co.
New York, USA.
Walker, C. M. and M. P. Lesser. 1998. Manipulation
of food and photoperiod promotes out-of-season
gametogenesis in the green sea urchin, Strongylocentrotus droebachiensis: implications for aquaculture. Marine Biology 132:663-676.
Westermeier, R. 1982. Zonierung, hiomasse, energiegehalt und schwermetallakkumulation mariner algen aus Chile, Helgoland und Spanien. Inaugural
Dissertation Justus-Liebig Universitat, Gieben.
Zegers, J., M. Oliva, C. Hidalgo, and L. Rodriguez.
1983. Crecimiento de Lonechinus albus (Molina,
1782) (Echinodermata: Echinoidea) en sistemas
de jaulas suspendidas a media agua. Memoires de
la Asociaci6n Latinoamericano de Acuicultura 5:
369-378.