Hediste diversicolor, commonly known as the ragworm, is a polychaete species widely distributed in estuarine and brackish waters across the Atlantic coasts of Europe and North America. This burrowing worm is highly adaptable, capable of feeding as a carnivore, herbivore, detritivore or suspension feeder depending on resource availability.
Its importance for aquaculture has grown steadily in recent years. On the one hand, ragworms are a valuable natural bait in recreational and commercial fisheries. On the other, they are increasingly used as a nutritional supplement in broodstocks diet of fish and crustaceans, improving reproductive performance. The species also plays a role in integrated multi-trophic aquaculture systems thanks to its ability to recycle organic matter, contributing to environmental management.
Moreover, Hediste diversicolor is one of the few marine invertebrates capable of de novo synthesizing long-chain polyunsaturated fatty acids, compounds essential for the health and growth of many cultured fish and shellfish. These characteristic positions the species as a potential ingredient in aquafeed formulations, adding value beyond its traditional use as a bait.
Although Hediste diversicolor has clear potential for aquaculture, its large-scale still faces technical challenges. Until now, feeding practices have often been based on trial and error, with little knowledge of the true intake need of the species. Likewise, the effect of stocking density on growth and survival has not been fully understood, despite being a critical variable in intensive farming systems.
A study, published in the Journal of the World Aquaculture Society, was carried out by scientific from Spanish Institute of Oceanography (IEO-CSIC) at the “El Bocal” marine plant in Cantabria to elucidate what is the better density and feeding rates to raise this invertebrate.
The experiments tested the effects on growth, feed intake and efficiency across a range of worm sizes and temperatures. Results confirmed that “density and body weight were inversely related to feed intake but inversely to feed efficiency.”
In addition, the team observed that worms tended to cluster by size within tanks. “Mean individual weight and biomass tend to be higher in the central area of the tanks, with a higher density of small individuals toward the periphery”.
Using regression analysis, the researchers developed predictive equations to estimate growth, feed intake and efficiency under different production scenarios. According to the authors, these tools “show that managing density allows significant performance enhancement”.
The research was funded by the Spanish Ministry of Science, Innovation and Universities through the State Research Agency, with support from NextGenerationEU funds and the Government of Cantabria.
Reference:
Aguado-Giménez, F., Gago, S., & Martín, I. (2025). Enhancing Hediste diversicolor aquaculture production: Density and feeding rate as key variables for intensive production management. Journal of the World Aquaculture Society, 56, e70053. https://doi.org/10.1111/jwas.70053
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