Between November 24 and 28, IFOP researcher Cristián Henríquez Pastene participated in the 3rd International Congress on Physical of Estuarine and Coastal Ocean in Puerto Varas, where he presented the work:
“Hydrographic Variability in Northern Chilean Patagonia (2018–2025): Preliminary EOF Analysis”
At this event, the researcher was able to exchange experiences and knowledge with national and international experts specialized in coastal and estuarine physical oceanography, thus strengthening collaboration networks for our institution.
His research applies the Empirical Orthogonal Function method to hydrographic data collected during autumn between 2018–2025 in the Los Lagos and Aysén regions, in order to understand how interannual environmental variability could influence the distribution of pelagic resources in northern Patagonia.
These analyses complement previous studies based on GIS and GAM models by incorporating temporal variability, and can eventually be applied to other similar projects.
The author thanks the funding provided by the PACAN-PAVAN Program (2025 Agreement) and colleagues from the Direct Assessments Department for their constant support.
Hydrographic Variability in Northern Chilean Patagonia (2018–2025): Preliminary EOF Analysis
Cristián Henríquez-Pastene (1), Javier Legua (1), Alejandro Cárdenas (2), Jairo Gutiérrez (1), Adrián Ibieta (1), Manuel Rojas (1), René Vargas (1) and Jorge Castillo (1)
(1) Direct Assessments Department, Fisheries Development Institute, Valparaíso, Chile. cristian.henriquez@ifop.cl
(2) Sampling Management Department, Fisheries Development Institute, Aysén, Chile.
Northern Chilean Patagonia, between the Interior Sea of Chiloé (MIC) and the Aysén region, supports a highly productive pelagic ecosystem with key fishery species such as southern sardine (Sprattus fuegensis), anchoveta (Engraulis ringens), and common sardine (Strangomera bentincki). From 2018 to 2025, autumn surveys combined hydroacoustic prospection and oceanographic sampling to assess species dynamics in relation to the physicochemical structure of the water column. Previous studies using GIS and Generalized Additive Models (GAMs) helped identify spatial patterns, but their point-based approaches are limited in capturing regional and temporal coherence. This study introduces a complementary methodology based on Empirical Orthogonal Function (EOF) analysis to identify dominant modes of spatiotemporal variability across zones. A common horizontal grid was created for all cruises, and CTD profiles (0–100 m) were interpolated using kriging, masking areas distant from observational data. This standardized matrix enabled EOF analysis on potential temperature (θ), absolute salinity (SA), potential energy anomaly (PEA), freshwater content (FWC), and Brunt–Väisälä frequency (BV), revealing robust vertical and horizontal hydrographic structures. An exploratory EOF applied to θ and SA showed that the first modes explained 50%–70% of the total variance. Temporal signals from leading modes were compared with acoustic biomass of target species to explore physical–biological relationships. However, data gaps from unsampled areas limit EOF’s ability to resolve continuous temporal patterns; this limitation highlights the need to incorporate and validate complementary data from oceanographic models such as GLORYS V12. Despite these gaps, the EOF analysis revealed interannual pulses of stratification and oceanic intrusion. These hydrographic shifts may indirectly modulate pelagic species distributions through effects on water column stability and habitat structure. This approach offers a valuable tool for advancing multiyear physical–biological coupling in complex estuarine systems.
Funding: ASIPA Project (2025): Hydroacoustic Assessment of Small Pelagics in Inland Waters of the Los Lagos and Aysén Regions of General Carlos Ibáñez del Campo.
4 December 2025
