EFFECTS OF THE PROTEIN AND CARBOHYDRATE LEVELS ON GONAD INDEX AND GONAD QUALITY OF ADULT PURPLE SEA URCHIN Strongylocentrotus purpuratus FROM BAJA CALIFORNIA, MEXICO  

An increased understanding of dietary protein and carbohydrate levels for gonad production in Strongylocentrotus purpuratus is needed for nutritional knowledge of this sea urchin and will contribute to the development of formulated diets of this aquaculture target species. Therefore, the main goal of this study was to find a diet formulation that helps us promote gonad increase combined with gonad quality improvement. Diets were defined as Protein/Carbohydrate level (Table 1) and were offered ad libitum in a 9 week feed trial at 18.5 ± 0.5 °C and 34.9 ± 0.4  

In the experimental feed trial, gonad index, color, texture, taste and firmness of the gonads were evaluated. Urchins fed with diets containing high carbohydrate levels utilized protein more efficiently and showed a better digestibility of the diet and protein. The highest gonad index (GI) gain was observed in urchin fed HP-LC (5.28 ± 2), but no significant differences were found in GI between diets offered in each sample period (Figure 1).  

In general, gonad texture was improved when urchins were fed HP-LC or LP-HC diets and gonad taste was improved when diets containing more than 50% of carbohydrate and less than 23% of protein were offered. On the other hand, firmness and color were not affected by diet but gonads tend to be closer to the orange-yellow standard color card.

Data suggest that all diets offered supports gonad growth. Although, inclusion of proteins and carbohydrates from the MP-MC diet supports growth and also helped to obtain a better gonad quality in adult S. purpuratus from Baja California, Mexico.