The marine polychaete Scoletoma laurentiana, known in Galicia, Spain, as gavilán and widely used as fishing bait, has become one of the most commercially important invertebrates harvested along the region’s coast. It now accounts for 63 per cent of all worm landings and generates 83 per cent of the income associated with this fishery.
Its value is further enhanced by its potential as a nutritional raw material for aquaculture, making it a promising candidate for controlled production.
With this aim, a research project led by Lucía Couceiro and Nuria Fernández from the Univesity of A Coruña, in Spain, has taken a decisive step forward by providing the first detailed description of the reproductive cycle of this marine polychaete in temperate Atlantic waters – a key advance for improving the management and sustainability of this resource.
The BIOCOST (CICA-UDC) researchers analysed 849 specimens collected from three coastal sites between 2021 and 2023 and found that oocyte maturation in Scoletoma laurentiana follows a seasonal cycle: it begins in late autumn, progress through winter, and spawning is concentrated in spring, coming to a complete halt in summer.
The study, published in Estuarine, Coastal and Shelf Science, confirms that water temperature is the main regulator of this pattern, having identified a “significant inverse correlation between the percentage of ovigerous females and the water temperature”. By contrast, photoperiod showed no meaningful influence on reproductive timing.
The research also reveals that the species exhibits internal synchrony – each female develops a single cohort of oocytes – yet population asynchrony, as the spawning period extends over several months.
Differences in oocyte size were detected between years and locations, suggesting reproductive plasticity or even genetic differentiation coastal populations, factors that may influence the species’ productivity and resilience.
The marked sensitivity to temperature raises concerns about the potential impact of climate change, since alterations in oceanographic conditions could modify its reproductive dynamics. In this regard, the study warns that the productivity of the gavilán “may be subject to alteration in response to climate change”, a scenario with direct implications for the fishing and aquaculture sectors that rely on a stable supply of this resource.
Understanding reproductive cycles is essential for designing technical management measures such as seasonal closures, minimum size or catch limits.
The authors note that the spring months – particularly between April and June – coincide with the spawning period and therefore constitute the most appropriate window for protection should a temporary closure be considered. However, they stress that continuous monitoring would be necessary to adapt management to year-to-year temperature variations.
This work marks a significant step towards developing sustainable exploitation strategies for a resource of growing economic and ecological relevance in Galicia. It also strengthens CICA’s role as a centre of scientific excellence.
Reference:
Escobar-Ortega, L. Couceiro, A. Fernández-Piñeiro, P. Seoane, D. Fernández-Márquez, R. Muíño, N. Fernández. Reproductive dynamics of Scoletoma laurentiana (Polychaeta: Lumbrineridae) in NW Spain: Temperature-driven seasonal trends, Estuarine, Coastal and Shelf Science, Volume 328, 2026, 109612, ISSN 0272-7714,
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