THE EFFECT OF PREPARED DIET ON THE SOMATIC … Tripneustes gratilla (LINNAEUS, 1758) ... the binding of ingredients with an improvised steamer ... caliper and wet weight with triple

E-International Scientific Research Journal, VOLUME – IV, ISSUE- 3, 2012, ISSN 2094-1749

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THE EFFECT OF PREPARED DIET ON THE SOMATIC AND GONAD GROWTH PERFORMANCE OF THE SEA URCHIN Tripneustes gratilla (LINNAEUS, 1758)

Facundo B. Asia*, Joji Grace C. Villamor and Jogel C. Faylogna

Mariano Marcos State University College of Aquatic Sciences and Applied Technology

Currimao 2903, Ilocos Norte, Philippines

E-mail: [email protected]

ABSTRACT Somatic growth (wet weight and equatorial and polar test diameters), gonad growth

(gonadosomatic index) and gonad quality (color and granularity) of the sea urchin T. gratilla fed prepared diets were studied in vitro using plastic basins for a period of four months. The study consisted of three treatments, replicated thrice and arranged in CRD as follows: I-Fresh Sargassum sp. (control), II-Dried pellets, and III-Fresh Extruded pellets. The dried and fresh extruded pellets were mainly of Sargassum sp. with 6.0% binder (corn starch and gelatin).

No significant variations were observed in the somatic growth of T. gratilla among the different feeding treatments. Highest growth rates were observed during the first culture month decreasing towards the end of the study. The fresh natural food gave better gonadosomatic index and gonad color than the prepared diets but not for granularity. First spawning was observed at about 1.5 culture months. Observed water parameters were within the favorable ranges for growth and survival of T. gratilla.

The successful introduction of prepared diets for T. gratilla opens the possibility of incorporating gonad color enhancers such as carotenoids in the diet that improves the quality of the organism for market and consumption. This necessitates further studies specifically using locally available pigment sources like tomato, squash, yellow corn and the like. The study likewise demonstrated the viability of land-based culture of the organism using both the fresh natural food and prepared diets. This will be important in sustaining a year-round harvest and possible broodstock source for hatchery and seed stock production.

KEYWORDS: Tripneustes gratilla, prepared diet, somatic growth, gonad growth and quality


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INTRODUCTION

Sea urchin is one of the major fishery resources in the world which is rapidly expanding in many countries because of the high demand for its gonad or roe. However, wild stocks are declining in the major sea urchin fishing nations of the world (Keesing and Hall 1998; Andrew et al. 2002 as cited by Pearce et al. 2004). Market demand for sea urchin gonads is unlikely to diminish in the foreseeable future as Japan’s consumption of sea urchin product remains stable and as Japanese cuisine (e.g. sushi, sashimi) is rapidly becoming popular in the North American food industry. It is unlikely that wild harvests alone will be able to supply future roe market demand. This scenario bodes well for the development of a successful sea urchin aquaculture industry. According to Pearce et al. (2004) the two basic forms of sea urchin culture involves, first, spawning adult broodstock and rearing resultant larvae/juveniles to market size and second, enhancing gonads (i.e. increasing yield and/or quality) of wild caught adults held in captivity by feeding them natural or prepared diets (Pearce et al. 2004).

The most commercially in demand species of sea urchin in the Philippines is Tripneustes gratilla, locally known as “Maritangtang” among the Ilocanos. Its fishery is a major source of livelihood in many coastal villages particularly along the northwestern coast of Luzon Island and in the Bicol region. Sea urchin is harvested for local and export markets generating millions of pesos per annum (Talaue-McManus and Kesner 1995). However, there has been an alarming decline in the landed catch due to over-harvesting from the wild stock.

Presently, there is an observed increase in the mariculture of this species along the northwestern coast of Luzon Island particularly in Pangasinan, Ilocos Sur and Ilocos Norte. Stock enhancement is also being done through seeding or planting of juveniles in open coastal areas. Inspite of these developments, there is still a dearth of the culture and management guidelines for this resource. The mariculture of this resource for increased production and for its sustainable management is a promising venture in the area because of the presence of ideal mariculture sites and abundant natural foods for the organism such as Sargassum and other species of seaweeds and seagrasses.

This study aimed to assess the viability of using prepared diets for the culture and growth of the organism on land-based conditions. This is important in increasing production and continuous supply in the market and for future gonad enhancement studies to improve its marketability. Specifically, it aims to: (1) determine the somatic growth (wet weight and test diameter) performance of the organism fed with prepared natural diets; (2) determine the gonad growth performance (gonadosomatic index) and gonad quality (color and granularity) of the organism fed with prepared diets; and (3) monitor the water parameters affecting the somatic growth performance and gonad quality of the sea urchin.


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MATERIALS AND METHODS Location of the Study

The experiment was set-up and conducted within the premises of the MMSU College of Aquatic Sciences and Applied Technology campus, Pias Sur, Currimao 2903, Ilocos Norte, Philippines. Experimental Media

Nine polycarbonate plastic basins each measuring 60 cm in diameter by 25 cm depth were used in the experiment. Seawater was pumped from the coast in front of the college building using a diesel water pump into four concrete tanks measuring 4.0 m x 2.5 m x 2.0 m (L x W x D). Unfiltered seawater from the concrete tanks was pumped using a 0.5 HP electric water pump into two circular fiberglass tanks measuring 1.0 m diameter x 1 m depth provided with gravel and sand serving as filtration tanks that supply the nine experimental basins on a flow-through system. The culture basins were aerated with NSB electric air pumps. EXPERIMENTAL DESIGN

The experiment consisted of three feeding treatments, namely: Treatment I - control consisting of fresh unformulated Sargassum sp diet; Treatment II - dried Sargassum sp pellets; and Treatment III - fresh extruded Sargassum sp pellets with three equal replications (Table 1). The dried and fresh extruded pellets were mainly of Sargassum sp. Asia and Tabije (2003) found out that Sargassum is a better natural feed affecting the growth and gonad development of T. gratilla as compared with the seagrass Enhalus acoroides. Arrangement of the culture basins was done in a completely randomized design (CRD) (Fig. 1).

Table 1. Feeding treatments and stocking density used in the study.

Treatments Stocking density Replicates

I. Control ( Fresh Diet) 38 individuals/basin 3

II. Dried Pellets 38 individuals/basin 3

III. Fresh Pellets 38 individuals/basin 3


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Fig. 1. View of the experimental set-up.

EXPERIMENTAL ORGANISMS

Three hundred Forty two (342) post-juvenile T. gratilla with test diameter ranging from 36.00 to 55.00 mm and weighing from 22.00 to 54.00 g (wet weight) were used in the experiment. These were taken from the wild stock in Dadalaquiten, Sinait, Ilocos Sur, Philippines, a nearby municipality of about 15 kilometers from the experimental site. FEED PREPARATION

The prepared dried pellets were composed of finely ground dried Sargassum sp. (sun-

dried for 1-2 days before grinding) with 6% binder consisting of corn starch and gelatin. The steps in feed preparation following that of Alava (1996) were observed. The finely ground seaweed was sieved into uniform particle size. The binder was suspended into half of the required water (the required water for a kilo of prepared feed is 1,200 ml) while the remaining half was boiled then the suspended binder was poured slowly to the boiled water stirring constantly with low flame until jelly-like consistency was obtained. The gelatinized binder was added to the Sargassum and mixed. The feed mixture was pelletized at a size of 5mm diameter using a manually-operated pelletizer (Fig 2), steamed with sea water for 5 minutes to enhance the binding of ingredients with an improvised steamer set-up, fan-cooled and sun dried for one day. The pelletized feeds were placed and sealed in plastic containers and refrigerated. The fresh extruded pellets, on the other hand, were prepared by grinding the fresh Sargassum and mixed with the finely ground Sargassum at 1:1 ratio after which the gelatinized binder (as prepared above) was added and mixed. The feed mixture was pelletized at a size of


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5 mm diameter using a manually-operated pelletizer. The pelletized feeds were given immediately to the organism while remaining pellets were placed and sealed in plastic containers for refrigeration. Refrigerated fresh extruded feeds were given to the organisms in four days.

Fig. 2. Finely ground Sargassum sp. mixed with the binder and pelletized.

EXPERIMENTAL PROCEDURE AND SAMPLING

Thirty-eight sea urchin individuals were placed in each basin. They were fed with the

fresh Sargassum diet daily on an ad libitum basis and with the prepared diets daily at 1.5 % of wet body weight. Pearce et al. (2002) concluded in their research that gonad yield of the green sea urchin Strongylocentrotus droebachiensis is maximized at 0.5 to 1.0% body weight (BW)*day-1 feeding of prepared diets. Since T. gratilla is a tropical species which presumably has a higher metabolic rate than S. droebachiensis which is a temperate species, a feeding rate of 1.5% of BW*day-1 was tried. However, during the first week it was observed that the 1.5 % wet body weight feeding ration was inadequate hence this was increased to 2.0 % during the second week and to 3.0 % on the third week until the end of the study. Daily cleaning and maintenance of basins were also done.

Prior to stocking in the basins, the initial test diameter and weight of each experimental organism were measured and recorded. To monitor the somatic growth of sea urchin, the experimental organisms were measured in terms of their test diameter (mm) both equatorial and polar using a Vernier caliper and wet weight with triple beam balance of 1.0 g sensitivity. Sampling was done once a week for a period of six weeks.

Three test organisms randomly taken from each basin were shucked upon the termination of the study to determine gonad growth in terms of the gonadosomatic index (GSI) and quality (color and granularity) (Fig 3). The GSI of the organisms was determined using the following formula (Lozano 1995):


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Wet - weight of gonads GSI = x 100

Wet - weight of sea urchin Gonad quality in terms of color was determined using the Munsell Color Guide. The

guide has three simple variables that combine to describe colors as hue, value and chroma. This study used the hue Yellow-Red (10YR) which is preceded by numbers from 0 to 10 where the hue becomes more yellow and less red as the numbers increase. The value notation used was 8 (near white) and the chroma notation used ranged from 1 to 8 where the color becomes more yellow with increasing number. The values based on the chroma notation were the ones recorded in this study for gonad color comparison. The combination of a bright yellow color and fine granularity of gonad is most preferred by the market (Blount and Worthington 2002).

Fig. 3. Determination of the GSI and gonad quality of the test organisms. MONITORING OF WATER PARAMETERS

The water parameters which may affect the somatic growth and gonadal growth and quality of the experimental organisms were measured. Dissolved oxygen and temperature were measured by an Oaklon Dissolve Oxygen meter; salinity by an Atago refractometer; and pH by a pH paper. ANALYSIS OF DATA

Means and ranges were used to describe growth parameters of the test organisms and the water parameters. Analysis of covariance (ANCOVA procedure of the SAS System) was used to determine differences of somatic growth parameters among treatments with wet weight and test diameter as covariates. Analysis of variance (ANOVA procedure of the SAS System) was also used to determine the differences of the GSI, gonad color and granularity among treatments. A post test using the Duncan’s Multiple Range Test (DMRT) was used to further test significant findings.


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Further, a correlation analysis using the Proc Corr procedure of the SAS System was used to determine the strength of relationship of the somatic growth parameters, gonad growth and quality parameters, and water parameters.

RESULTS AND DISCUSSION SOMATIC GROWTH

Wet Weight. Growth increments in wet weight of sea urchins cultured in basins for four months culture period (MCP) at different feeding treatments are shown in Table 2. The values are adjusted means with initial weight as covariate. After one month culture period, Treatment I significantly (p = 0.05) had the highest weight increment of 20.62 g compared to Treatments II and III with 13.88 g and 8.35 g, respectively. Although there were no significant differences among treatments means of Treatments II and III, Treatment II relatively had the higher mean growth increment in wet weight. The comparatively lower growth rates of Treatments II and III may be due to the adjustments made by the organisms feeding with the prepared diet. It was observed that the organisms only fed on the prepared diets after three days of introduction.

At the succeeding culture periods (second, third and fourth month), the growth increments in wet weight of the organisms did not significantly differ among the three treatments, however, Treatment I generally had the highest wet weight growth increment followed by Treatment II. Treatment III had the least wet weight growth increment.

Highest wet weight growth increment in all treatments was observed during the first MCP and had a decreasing trend towards the end of the study.

The above results indicate that the test organisms fed with both the dried and fresh pellets have almost similar growth in wet biomass with those fed with the fresh diet of Sargassum sp. The effect of prepared Sargassum sp. diet at 4.0 to 5.0% BW*day-1 on wet weight was even significantly higher (p<0.05) than that of the fresh diet of Sargassum sp. in a follow-up study of Asia (2009) to optimize the feed ration of the organisms. Table 2. Mean growth increment in wet weight* (g,) of the sea urchin T. gratilla at different feeding treatments for four MCP.

Feeding Treatment

Months After Stocking

Total

Mean

Initial 1 2 3 4

I – Fresh Diet (Control) 40.40 20.62a 12.29a 10.85a 4.54a 48.30 12.08a

II – Dried Pellets 40.27 13.88b 9.86a 9.75a 3.93a 37.42 9.36a


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III – Fresh Pellets 37.88 8.35b 7.22a 9.78a 2.08a 27.43 6.86a

Means with different superscripts are significantly different at 5% level.

*Adjusted mean with initial wet weight as covariate.

Growth increments in equatorial test diameter of the sea urchins during the four MCP are shown in Table 3. The values are adjusted means with initial equatorial test diameter as covariate. Although not significantly different, it was observed during the first MCP that Treatment I had the highest mean growth increment in equatorial test diameter of 9.65 mm followed by Treatments II and III with 7.06 mm and 6.63 mm, respectively. However, on the second MCP until the end of the study, Treatment II comparatively had higher equatorial test diameter growth increment than Treatments I and III. Again, there were no significant differences among treatments means. The overall mean also shows no significant differences among treatments which indicate that the prepared diets are comparable with the fresh diet given to the test organisms.

Highest wet equatorial test diameter growth increment in all treatments was observed during the first MCP and had a decreasing trend towards the third MCP with a slight increase in the last month of culture. Bangi (2001) also observed the same trend for the same species grown for six months in cages on sea-based conditions at Bolinao, Pangasinan, Philippines. The organisms had a mean test diameter increment of 6.89 mm fed with low Sargassum and 11.10 mm for those fed with high quantity of Sargassum on the first month of culture. She observed a generally decreasing trend towards the fifth month of culture with 1.84 mm and 2.94 mm for the low and high feeding of Sargassaum, respectively. There was a slight increase in test diameter in both feeding treatments at the sixth month of culture. The values obtained in this study are almost similar with the values she observed in her study. Table 3. Mean growth increment in equatorial test diameter* (mm) of the sea urchin T. gratilla at different feeding treatments for four MCP.

Feeding Treatment


Total

Mean

Initial 1 2 3 4

I – Fresh Diet (Control)

44.98 9.65a 1.84a 0.25a 1.34a 13.08 3.27a

II – Dried Pellets

45.51 7.06a 2.52a 0.27a 2.66a 12.51 3.13a

III – Fresh Pellets

45.47 6.63a 1.04a 0.16a 1.90a 9.73 2.43a

Means with different superscripts are significantly different at 5% level.


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*Adjusted mean with initial equatorial test diameter as covariate. Table 4 shows the data on growth increments in polar test diameter of the test

organisms during the four MCP. The values are adjusted means with initial polar test diameter as covariate. Results show that there were no significant differences among the treatments which indicate that the prepared diets are comparable with the fresh diet. It was also observed that the highest growth increment in polar test diameter was during the first MCP which follows the trend on the growth in wet weight and equatorial test diameter.

Further, although not significantly different, Treatment I also comparatively had the highest growth increment in polar test diameter than Treatments II and III. Samples of harvestable sea urchins representing the different treatments are shown in Appendix Figure 1. Table 4. Mean growth increment in polar test diameter* (mm) of the sea urchin T. gratilla at

different feeding treatments for four MCP.

Feeding Treatment


Total

Mean

Initial 1 2 3 4

I – Fresh Diet (Control) 27.09 4.90a 1.30a 0.34a 1.40a 7.94 1.99a

II – Dried Pellets 27.69 3.60a 1.28a 0.35a 0.35a 5.48 1.40a

III – Fresh Pellets 26.75 2.47a 0.79a 0.05a 0.40a 3.71 0.93a

Means with different superscripts are significantly different at 5% level. *Adjusted mean with initial polar test diameter as covariate. GONAD GROWTH AND QUALITY

Gonad growth and development measured in terms of gonadosomatic index and gonad quality determined in terms of color and granularity were assessed upon the termination of the study (Table 5). It was observed that spawning occurred as early as the second month of culture period. Garvida and Asia (2004) also noted that T. gratilla grown in cages placed on land-based concrete tanks and fed with Sargassum sp reached maturity and spawned at about 45 days of culture.

The data showed that Treatment I had a significantly (p = 0.05) higher GSI of 5.77% than Treatments II and III with 3.64 % and 3.40 %, respectively. Treatments II and III did not differ significantly. Bangi (2001), in her study on the cage culture of the same species on sea-based conditions, observed a mean gonad index ranging from 2.70 % to 5.16 % for the low Sargassum diet and from 5.38 % to 8.14 % at the end of the six month culture period. The data obtained in this study, although the organisms were grown in vitro conditions and fed with prepared diets, are comparable with her study. Garvida and Asia (2004) also observed an average GSI of the


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organism reared for 75 days in land-based cages placed in concrete tanks ranging from 5.60 to 7.47 %. Table 5. Mean GSI, gonad color and gonad granularity of the sea urchin T. gratilla at different feeding treatments for four MCP.

Feeding Treatment

Gonad Growth and Quality Parameters

GSI (%) Color Granularity, mm

I – Fresh Diet (Control) 5.77a 7.11a 0.037a

II – Dried Pellets 3.64b 5.22b 0.028a

III – Fresh Pellets 3.40b 4.67b 0.033a

Means with different superscripts are significantly different at 5% level by DMRT. Gonad quality was measured by determining the gonad color and granularity of the test organisms. For gonad color, higher values indicate brighter yellow colors which are considered of better quality for the gonads. In the Munsell Color Chart, the value of 8 has the brightest yellow and becomes paler as the value decreases to 1. Results show that the fresh diet treatment (Treatment I) significantly had brighter yellow color (p = 0.05) than Treatments II and III. However, in a follow-up study (Asia 2009) to optimize the feed ration of the organisms, the effect of natural food and prepared Sargassum sp. diet at 4.0 to 5.0% BW*day-1 on gonadosomatic index and gonad color was comparable (p<0.05). It was concluded in this follow-up study that the best ration for prepared diet (dried pellets) based on Sargassum sp. was at 4.0% BW/day to optimize somatic growth and gonad production and quality. The gonadosomatic index observed was also comparable with the findings of Garvida and Asia (2004) on a land-based culture of T. gratilla fed with Sargassum sp. Samples of gonads representing the different treatments are shown in Appendix Figure 2.

Gonad quality in terms of granularity revealed no significant differences among the three treatments. The combination of yellow color, firm texture and fine granularity of gonad is most preferred by the market (Blount and Worthington 2002).


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WATER PARAMETERS

The water parameters which are believed to have influences on the growth of the test organisms such as dissolved oxygen, water temperature, salinity and pH were monitored during the course of the study (Table 6). The dissolved oxygen ranged from 5.12 to 8.43 mg*L-1 throughout the culture period with an average of 6.47 mg*L-1 while the temperature ranged from 25.00 to 30.30 oC with an average of 27.94 oC. An increasing trend in dissolved oxygen and temperature was observed during the study period. For temperature, the increasing trend may be due to the onset of summer. Salinity ranged from 33.00 to 35.00 ppt with an average of 34.60 ppt while pH ranged from 7.0 to 8.0 with an average of 7.5 throughout the culture period. The measurements of said parameters are within the favorable range for the growth and survival of the test organisms. Table 6. Water parameters monitored in the culture of the sea urchin T. gratilla for four MCP.

Parameters Months

February March April May June Dissolved Oxygen Range (mg*L-1) Mean

5.12 – 6.98 6.13

5.76 – 6.50 6.16

5.41 – 6.97 6.20

6.55 – 8.43 7.14

5.81 – 7.49 6.72

Water Temperature Range (oC) Mean

25.40-28.87 26.48

25.00-27.83 25.53

29.80-30.00 29.87

27.60-28.00 27.82

29.60-30.30 30.04

Salinity (ppt) Range Mean

- 33.0

- 35.0

- 35.0

- 35.0

- 35.0

pH Range Mean

- 7.0

- 8.0

- 7.5

- 7.5

- 7.5

CORRELATION ANALYSES

In order to determine the degree of relationships that exist among the somatic and gonad growth and quality and the various water parameters, a correlation analysis was done as shown in Table 7. Observed water parameters such as dissolved oxygen, temperature, salinity and pH were within the favorable ranges for growth and survival of T. gratilla. Significant positive correlation existed between wet weight and equatorial test diameter (r=0.78, p=0.01) and polar test diameter (r=0.97, p=0.0001). Likewise, equatorial test diameter and polar test diameter are significantly positively related (r=0.80, p=0.01). Wet weight and gonadosomatic index were also positively related (r=0.70, p=0.04); polar test diameter and gonadosomatic index (r=.0.70, p=0.03); wet weight and gonad color (r=0.80, p=0.01); polar test diameter and gonad color (r=0.84, p=0.004); dissolved oxygen and wet weight (r=0.81, p=0.01); and dissolved oxygen and polar test diameter (r=0.80, p=0.01). On the other hand, water temperature had a significantly negative correlation with gonad color (r=-0.69, p=0.04).


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Table 7. Correlation analysis of the different somatic and gonad growth and quality with the various water parameters.

Pearson Correlation Coefficients, N = 9 Prob > |r| under H0: Rho=0

Wwt Etd Ptd GSI Color Gran DO Temp Wwt 1.0000 0.7825 0.9662 0.6953 0.7989 0.2664 0.8133 -0.3369 0.0127 <.0001 0.0376 0.0098 0.4883 0.0077 0.3753 Etd 0.7825 1.0000 0.7998 0.3104 0.5793 0.2091 0.6489 -0.2752 0.0127 0.0096 0.4162 0.1021 0.5892 0.0586 0.4734 Ptd 0.9662 0.7998 1.0000 0.7040 0.8414 0.2276 0.8132 -0.4153 <.0001 0.0096 0.0343 0.0045 0.5558 0.0077 0.2663 GSI 0.6953 0.3104 0.7040 1.0000 0.4297 0.0172 0.5340 0.1324 0.0376 0.4162 0.0343 0.2483 0.9648 0.1386 0.7342 Color 0.7989 0.5793 0.8414 0.4297 1.0000 0.2358 0.5602 -0.6905 0.0098 0.1021 0.0045 0.2483 0.5413 0.1166 0.0395 Gran 0.2664 0.2091 0.2276 0.0172 0.2358 1.0000 0.2722 -0.5116 0.4883 0.5892 0.5558 0.9648 0.5413 0.4784 0.1592 DO 0.8133 0.6489 0.8132 0.5340 0.5602 0.2722 1.0000 -0.3157 0.0077 0.0586 0.0077 0.1386 0.1166 0.4784 0.4078 Temp -0.3369 -0.2752 -0.4153 0.1324 -0.6905 -0.5116 -0.3157 1.0000 0.3753 0.4734 0.2663 0.7342 0.0395 0.1592 0.4078 Legend: Wwt = Wet weight, g Color = Gonad color

Etd = Equatorial test diameter, mm Gran = Gonad granularity, mm

Ptd = Polar test diameter, mm DO = Dissolved oxygen, mg/L

GSI = Gonadosomatic Index, % Temp = Water temperature, oC


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CONCLUSIONS AND RECOMMENDATIONS

The prepared diets were comparable with the fresh Sargassum sp. natural food in terms of somatic growth. For gonad growth and color, the fresh natural food gave better results; however in a follow-up study of Asia (2009) on optimizing the prepared feed ration, the prepared dried diet given at 4 to 5% BW/day was comparable with the fresh food in both the somatic and gonad growth and quality performances of the organism. Prepared natural diets can be given to the organisms in lieu of the fresh natural food.

The successful introduction of prepared diets for the sea urchin T. gratilla can be of great help in the development of the land-based aquaculture and stock enhancement of this organism for food production. Feeding prepared diets to the organism opens opportunities for further studies on gonad quality enhancement. Coloring pigments such as carotenoids from natural and artificial sources can already be incorporated in the diet of the organism to improve its quality for market and consumption. This necessitates further studies specifically concentrating on locally available pigment sources like tomato, squash yellow corn and the like. Pearce et al. (2004) found out that the green sea urchin Strongylocentrotus droebachiensis fed with prepared diet mixed with β-carotene had a significantly better gonad quality than those fed with kelp. Higher quality gonads command a higher value in the world market particularly that of Japan.

The study likewise demonstrated the viability of land-based culture of the organism using both the fresh natural food and prepared diets. This will be important in sustaining a year round harvest and possible broodstock source for hatchery and seed stock production. A viable and ready source of seed stock such as a hatchery in the northwestern part of Ilocos region is necessary to carry out further studies and cater to the needs of the increasing adaptors of the grow-out culture technology of the resource.

ACKNOWLEDGMENTS

The authors acknowledge the support provided by the Mariano Marcos State University and its President, Dr. Miriam E. Pascua; Dr. Epifania O. Agustin and Dr. Sixto R. Pascua, Jr., former Directors for Research and Development; Ms. Mary Ann B. Gorospe and to the other staffs of the MMSU Research Directorate for their numerous assistance in the preparation and finalization of the manuscript; and the Commission on Higher Education for a travel grant to present a poster of this paper at the 8th Asian Fisheries Forum, Kochi, India on November 20-23, 2007.


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REFERENCES

Alava, V. R. 1996. Practical notes in feed formulation. Lecture presented during the Training Course on Fish Nutrition, Oct. 23 – Dec. 03, 1996, SEAFDEC, Tigbauan, Iloilo, Philippines.

Asia, F. B. 2009. Optimizing prepared feed ration for somatic growth and gonad production of the sea urchin Tripneustes gratilla (Linnaeus, 1758). Asian Fisheries Science Journal 22(1):71-84.

Asia, F. B. and T. Tabije, Jr. 2003. Culture of the economically important sea urchin Tripneustes gratilla in Ilocos Norte. Research paper presented during the Agency In-house review of R&D highlights. April 23-25, 2003, MMSU College of Agriculture and Forestry, MMSU, Batac, Ilocos Norte.

Bangi, H.G.P. 2001. The effect of adult nutrition on somatic and gonad growth, egg quality and larval development of the sea urchin Tripneustes gratilla Linnaeus 1758 (Echinodermata: Echinoidea). Thesis, Master of Science (Marine Biology), Marine Science Institute, College of Science, University of the Philippines. p 18.

Blount, C. and D. Worthington. 2002. Identifying individuals of the sea urchin Centrostephanus rodgersii with high-quality roe in New South Wales, Australia. Fisheries Research 58:341-348.

Garvida, J. J. and F. B. Asia. 2004. Somatic growth and gonadal maturity of sea urchin (Tripneustes gratilla) fed with selected species of algae and seagrass in vivo condition. Research paper presented during the MMSU Agency In-House Review of R & D Highlights on May 4-7, 2004, Crops Research Laboratory, MMSU, Batac, Ilocos Norte

Keesing, J. K. and K. C. Hall. 1998. Review of harvests and status of world sea urchin fisheries points to opportunities for aquaculture. J. Shellfish Res, 17:5 pp. 1597-1604.

Lozano, J. 1995. Biological cycle and recruitment of Paracentrotus lividus (Echinodermata:Echinoidea) in two contrasting habitats. Mar. Ecol. Prog. Series 122:179-191.

Pearce, C. M., T. L. Daggett and S. M. C. Robinson. 2002. Effect of binder type and concentration on prepared feed stability and gonad yield and quality of the green sea urchin, Strongylocentrotus droebachiensis. Aquaculture 205(3-4):301-323.

Pearce, C.M., T.L. Daggett and S.M.C. Robinson. 2004. Effect or urchin size and diet on gonad yield and quality in the green sea urchin (Strongylocentrotus droebachiensis). Aquaculture 233:337-367.

Talaue-McManus, L. and K.P. Kesner. 1995. Valuation of municipal sea urchin fishery and implications of its collapse. In: Philippine Coastal Resource under Stress. 4th Annual Common Property Conference, Manila.


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Appendix Figure 1. Samples of T. gratilla from the three treatments after four months of culture. Appendix Figure 2. Samples of gonads of T. gratilla from the three treatments after four months of culture.

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THE EFFECT OF PREPARED DIET ON THE SOMATIC … Tripneustes gratilla (LINNAEUS, 1758) ... the binding of ingredients with an improvised steamer ... caliper and wet weight with triple