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Mesoscale Eddies Drive Jumbo Flying Squid Aggregation off Chile, Study Finds

CHINA
Monday, May 12, 2025, 00:20 (GMT + 9)

New insights could guide sustainable fisheries management in the Humboldt Current System

A groundbreaking study has revealed a strong connection between the activity of mesoscale ocean eddies and the abundance of jumbo flying squid (Dosidicus gigas) off the coast of Chile. The research, led by Xiaoci Wu and colleagues from several oceanographic institutions in China, provides critical insights into how these swirling ocean features shape the dynamics of a species vital to both marine ecosystems and international fisheries.

The study focused on the Humboldt Current System (HCS), one of the world’s most productive marine ecosystems. Stretching along the western coast of South America, the HCS is known for its nutrient-rich upwelling that supports vast fishery resources. Among its most economically important inhabitants is the jumbo flying squid, a fast-growing, short-lived predator that plays a key role in marine food webs.

Researchers analyzed fishing data for D. gigas between March and May from 2016 to 2021, integrating it with high-resolution datasets on oceanographic conditions and mesoscale eddy activity. Mesoscale eddies are swirling water masses spanning tens to hundreds of kilometers, lasting from days to months. They come in two main types: cyclonic eddies (CEs), which bring cooler, nutrient-rich waters to the surface, and anticyclonic eddies (AEs), which generally suppress upwelling.

Key findings from the study showed that mesoscale eddies—particularly CEs—correlate positively with the abundance and distribution of jumbo flying squid. “We found that D. gigas tends to aggregate more in regions influenced by cyclonic eddies, which provide more favorable environmental conditions,” said lead author Wu.

Using satellite data from the AVISO+ project and environmental reanalysis products from Copernicus Marine Service, the team tracked 8,463 eddies in Chilean waters during the study period. Of these, 4,511 were cyclonic and 3,952 were anticyclonic. CEs occurred more frequently and peaked during July, while AEs peaked slightly later, in August.

(A) Monthly variations, (C) interannual trends, and (E) relative propagation trajectories of CEs within the study area; (B) Monthly variations, (D) interannual trends, and (F) relative propagation trajectories of AEs within the study area.

Importantly, the study employed Generalized Additive Models (GAMs) and Random Forest analysis to identify environmental variables that most significantly influenced squid abundance. Sea surface temperature (SST) emerged as a crucial factor. In cyclonic eddies, the proportion of SST readings within optimal ranges for D. gigas was markedly higher than in anticyclonic eddies.

“Cyclonic eddies not only increase productivity through upwelling but also create pockets of optimal habitat for D. gigas, including cooler temperatures and higher dissolved oxygen concentrations,” explained co-author Pengchao Jin. This is consistent with previous research showing that D. gigas alters its feeding behavior based on ocean conditions, preferring high-energy prey in nutrient-rich environments.

The spatial distribution of eddy generation locations off Chile from 2015 to 2021.

The spatial analysis revealed that most eddies were generated near the Chilean coastline, propagating westward into the open Pacific. Both CEs and AEs displayed a northward drift pattern, with cyclonic eddies traveling slightly further on average. These movements shape nutrient flows and biological productivity in the region, indirectly influencing squid migration and aggregation.

Moreover, fishing effort and catch data showed a clear pattern: longline vessels consistently recorded higher catch-per-unit-effort (CPUE) values within cyclonic eddy zones. “This underscores the potential for using real-time eddy monitoring to optimize fishing strategies,” said senior author Wei Yu, who emphasized the need for sustainable fishery management practices informed by ocean dynamics.

Monthly and annual variations in the number of eddies and D. gigas CPUE off Chile.

The authors argue that this research has significant implications for both ecological understanding and fisheries policy. “By clarifying how mesoscale eddies affect a key commercial species, our findings offer actionable guidance for adaptive management of squid fisheries,” Yu added. As global fisheries face increasing pressure from climate change and overfishing, such insights are vital to preserving oceanic resources.

This study also contributes to a growing body of literature highlighting the ecological importance of mesoscale eddies in structuring marine life distribution. Similar mechanisms have been documented in tuna, sardines, and plankton communities across global ocean basins.

The spatial distribution of D. gigas CPUE, fishing effort, and catch in CEs and AEs, and their relationship with the distance from the eddy center

In conclusion, the team calls for enhanced satellite monitoring and integration of oceanographic data into fisheries decision-making. Given the variability of eddy formation and intensity under climate change scenarios, understanding their ecological consequences is more crucial than ever.

“This is not just about squid,” said Wu. “It’s about unlocking the dynamics of life in the open ocean.”

Reference: Wu, X., Jin, P., & Yu, W. (2024). The relationship between mesoscale eddies and the abundance and distribution of jumbo flying squid off Chile. Ocean Decade International Cooperation Center (ODCC), Shanghai Ocean University.

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