Coupling Amino Acid Requirements and Strong Sensory Evaluations in the Development of Formulated Feeds Specifically for the Northeastern Green Sea Urchin
The research we are proposing to conduct addresses the Sea Grant Development Fund program priorities of 1) Research that will lead to and improve a full NH Sea Grant proposal and 2) Research that will lead to additional or increased funding of the Principle Investigator from any extramural funding agency. This research is based on research proposed in a recently denied full NH Sea Grant proposal entitled, "Coupling amino acid requirements and strong sensory evaluations in the development of formulated feeds specifically for the Northeastern green sea urchin" and conducting it would give us important data to make our proposals more competitive in the future.
Rational and Brief Description of Proposed Research
Since edible sea urchin fisheries are highly valuable commercial enterprises on all coasts of the United States and all US natural populations have been dramatically over-fished, aquaculture for this animal is becoming vital. The last significant roadblock to successful land-based aquaculture of green sea urchins is the production of large gonads simultaneously characterized by consistently high-quality sensory evaluations for taste, texture, color and firmness. The only large-scale, commercially available formulated sea urchin feed (the Wenger Feed) does yield large urchin gonads in both sexes, but sensory evaluations are unsatisfactory. In the current study, we will develop formulated feeds specific to green sea urchins by combining available information on wild collected green sea urchins with our methods.
We want to determine concentrations of taste essential amino acids (alanine, glycine, glutamine, methionine and valine), sensory scores and cellular composition of wild harvested green sea urchins collected in September (most marketable texture) and January (largest gonad, time of fishery) and compare the results to individuals maintained under invariant photoperiod and fed kelp to identify which parameter combination will lead to the most marketable roe. This experiment will demonstrate the difference in amino acid/cellular composition and sensory scores during different stages of gametogenesis, one stage that is most advantageous because sea urchins have the most marketable texture (August), the other stage because it is the time of the year sea urchins are harvested. It will also show that when maintaining sea urchins at July photoperiod we can achieve the same favorable scores as for animals collected in August while feeding them a natural diet. Since sea urchin gonads mirror protein and amino acid concentrations of the feed, we will therefore design a feed with the taste essential amino acids present in the optimal concentrations.
In order to conduct this research we will collect green sea urchins (n = 50) by SCUBA in September and January, sacrifice ten individuals initially, measure gonad indices and record color and take samples for amino acid analysis and stereology. Twenty animals will be provided each time for sensory analysis to Mr. Tamaki at ISF Trading. Mr. Tamaki (major sea urchin processor and importer in Maine) will rank gonads from 10 individuals on a scale of 1-5 (5 being the highest score) for color, texture, taste and marketability using his knowledge of the Japanese and American sushi markets. Amino acids will be hydrolyzed from gonadal protein samples and identified and quantified by HPLC by their chromatographic peaks. We will also collect 100 individuals in September for maintenance under invariant (July) photoperiod for two months. These animals will be fed a natural diet of Laminaria sp. Upon completion of the study, urchins will again be supplied for sensory and amino acid analysis and stereology. Results will be compared between wild collected and animals maintained under invariant photoperiod, and success of invariant photoperiod treatment regarding NP size and gametogenic progress will be determined using histological and stereological evaluation of the gonads.
We expect to find that concentrations of the taste essential amino acids will be most advantageous during wild collections in August and in animals maintained under invariant photoperiod, due to the fact that at these times animals will be filled with nutritive phagocytes (texture) containing glycoproteins that will provide optimal taste. Though roe is largest in January (the reason for fishing during this time) its texture is relatively poor, since the gonads are filled with gametes and are much more fragile. By combining data of amino acid composition, sensory scores and gametogenic stage of the sea urchin gonads we will work with industry participants to develop and distribute currently unavailable green sea urchin specific formulated feeds for land-based aquaculture that will maximize size and achieve excellent sensory scores.