Introduction
The increasing market demand for sea urchin roe has been fostering research to produce sea urchins with high-value gonads. The distinct golden-orange to yellow colour of sea urchin gonads results from the accumulation of carotenoid pigments provided by a wide variety of seaweeds they feed on in their natural habitat (Robinson et al., 2002). The European sea urchin Paracentrotus lividus (Lamarck, 1816) is the most important emergent sea urchin to be produced in Southern Europe, including Portugal. Here, the market demand for sea urchin roe is small. However, the harvesting pressure on P. lividus is increasing to meet the growing markets in Spain, Italy, and France (Louren��o et al., 2021). The production of high-quality sea urchin roe using the practical dry feed is a difficult task, mainly due to an imbalance between dietary nutritional requirements, the supplementation with natural carotenoid pigments, and feed production processes. Roe priming using supplementary sea urchin feeding with fresh and dried seaweed appears as a feasible approach to produce high-quality roe. In the present study, we aimed to enhance the roe colour of sea urchin by combining sea urchin feeding with dry feed and a final priming stage of exclusive feeding with seaweeds.
Materials and Methods
An enhancement trial was conducted with two stages: an initial stage to promote the gonad growth, and a final stage to tune the gonad colour. In the gonad growth stage, the sea urchins were fed for 12 weeks with three experimental diets of identical proximate composition formulated with ingredients of algal, animal and vegetable sources. In the priming stage, the sea urchins were fed, for four weeks, with a green macroalgae (Ulva rigida) and a red macroalgae (Porphyra dioica). The efficiency of each phase was analysed in terms of sea urchin growth performance, gonad proximate composition, including fatty acid and carotenoid pigment profiles, colour and texture quantitative determination and sensory characteristics.
Results and Discussion
The results showed that, after an initial stage of gonad growth as a result of bulk feeding with the dry feeds, the period of exclusive algae feeding improved the colour of gonads with a small but significant reduction in sea urchin gonadossomatic index. The higher colour score observed was followed by significant changes in the carotenoid pigments profile, mainly in echinenone and lutein concentration in the gonads. As in previous studies, the changes observed in gonad colour and carotenoid pigment profile were affected by sea urchin sex. In conclusion, exclusive seaweed feeding can be used as a priming strategy to improve the roe quality of sea urchins produced in aquaculture.
Acknowledgment
This study had the financial support of Operational Programme MAR2020, through the project 16-02-01-FMP-0004: Ouriceira AQUA: Aquaculture and Enhancement of Gonad Production in the Sea Urchin (Paracentrotus lividus), and the support of Funda����o para a Ci��ncia e Tecnologia (FCT), through the strategic project LA/P/0069/2020 (https://doi.org/10.54499/LA/P/0069/2020) granted to the Associate Laboratory ARNET and UID/04292/2025 (https://doi.org/10.54499/UIDB/04292/2025) awarded to the MARE-Marine and Environmental Sciences Centre. SL is supported by the strategic project LA/P/0069/2020, AG is supported with a doctoral grant (2021.07188.BD), and AP is supported by the Scientific Employment Stimulus program (CEECINST/00051/2018) granted by FCT.
References
Louren��o, S., Mendes, S., Raposo, A., Santos, P. M., Gomes, A. S., Ganh��o, R., Costa, J., Gil, M.M. & Pombo, A. (2021). Motivation and preferences of Portuguese consumers towards sea urchin roe. International Journal of Gastronomy and Food Science, 24, 100312.
Robinson, S. M. C., Castell, J. D., & Kennedy, E. J. (2002). Developing suitable colour in the gonads of cultured green sea urchins (Strongylocentrotus droebachiensis). Aquaculture, 206(3-4), 289-303.