Spatial and temporal variability in the occurrence and abundance of European hake larvae, Merluccius merluccius, on the Galician Shelf (NE Atlantic)

The European hake (Merluccius merluccius) is represented as one of the most valuable fisheries in the Galician shelf. We analyzed the distribution, abundance, and environmental conditions of the southern-stock European hake larvae from the Galician shelf during the two main spawning peaks, winter-spring and summer, based on the data from three ichthyoplankton surveys (March 2012, March 2017, and June 2017). A total of 395 larvae in March 2012, 121 in March 2017, and 69 in June 2017 were captured. The northeast section of the study area, close to Estaca de Bares, primarily between 100 and 200 m isobaths, had the highest presence of the European hake larvae in all surveys. Generalized additive models (GAMs) indicated that the occurrence of larvae was significantly different between the surveys and was associated negatively with the temperature, while the abundance of larvae was significantly different between sampling years and was the highest at a temperature around 13.36°C and at sea surface heights of about −0.48 m. Studies of the distribution of early life stages and their relation to external conditions are essential to the understanding of the complex process of recruitment, especially in the exploited species and in highly dynamic environments like the Galician shelf