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Scallop By-Products Have Potential use in Aquaculture Feeds

16 September 2013

US - Researchers at the University of Rhode Island have found that scallops have beneficial uses in medicines and as an ingredient in aquaculture feeds.

Chong Lee, URI professor emeritus and research in nutrition and food sciences, found that parts of the scallop that are usually wasted have a potential use in fish feeds and as nutraceuticals.

Fishermen generally discard the roe and viscera of scallops at sea but now they may be able to make profit from these byproducts.

“We have been working on studying the viscera of squid and other fish species, so we have all the know-how and technology to look at scallop viscera,” Mr Lee said.

Mr Lee and his team have been investigating the nutraceutical properties of scallop viscera hydrolysate (SVH) as well as that of squid. 

They found that SVH may aid lipid, or fat, digestion, which is significant since there is a sizable human population that has problems digesting fats. Their research also found properties of both squid and scallop viscera that may help lower blood pressure.

Mr Lee’s team also examined the concentrations of omega-3 fatty acids EPA and DHA in the SVH. Levels of both were found to be higher than those in fish, including salmon, and comparable to those in squid hydrolysate.

While the viscera showed promise in reducing hypertension, Mr Lee conceded that it may not be as effective as products already on the market. “I want to look at it further to validate how important it is,” he said, noting that the team’s study of lipase activity — the fat-digesting enzyme— in SVH is likely “the first time people have looked at lipase in terms of marine resources.”

Potential in Fish Feed

Traditionally, fish meal has been used as a primary source of protein for farm-raised fish. However, it is not sustainable, and efforts are being made to find new sources of proteins besides soybean meal.

Mr Lee and his team assessed SVH for its attractiveness to fish as a flavor enhancer as well as its capacity for stimulating growth. They compared the scallop viscera with that of squid, as well as with soybean and fish meal in a variety of combinations.

They conducted feeding trials on summer flounder and European sea bass that revealed that SVH performed the best in terms of weight gain and feed consumption. They believe this is due to its properties as a feeding attractant or flavoring that stimulates feeding behavior.

In other words, scallops taste good, even to fish. But the use of SVH as a specialty ingredient in aquafeeds, while potentially a good option, is not currently feasible because of the high costs of prototype development and the limited production capability due to the regulations that limit the landing of scallop viscera, leaving fishermen to chuck it overboard instead.

This may change as production and demand for these products scale up. Worldwide, the increasing demand for aquaculture feed is projected to outstrip the current supply, which will drive prices ever higher. Over time, these higher prices may expand the development of cheap sources of protein such as soybean meal and ingredients such as SVH that can be combined to create feeds suitable to meet the demand.

If regulatory and harvesting modifications are changed, they will ultimately benefit scallop fishermen and bring economic opportunity to the Rhode Island and Massachusetts fishing and processing industries while facilitating a sustainable seafood supply.

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