Geology topics

Guillermo Figueroa-Munoz

Publications and source records attributed to Guillermo Figueroa-Munoz.

4 recordsLinked to original sources

USGS2025

Infection by the marine cestode Hepatoxylon trichiuri in returning Chinook salmon (Oncorhynchus tshawytscha) spawners in Patagonia: Implications for a novel fishery

Parasitological information may be useful for managing economically important fisheries by providing insights into population dynamics and health effects. The Chinook salmon ( Oncorhynchus tshawytscha ), an invasive species with high socio-ecological importance in South America, supports recreational and incipient artisanal fisheries. In Southern Chile, the recent approval of coastal fisheries for returning Chinook salmon in some regions highlights the importance of understanding salmon foraging, habitat use, and commercial value. However, such information is lacking. Parasites have been extensively used as cost-effective biological tags to identify fish stocks. We conducted the first parasitological examination of the marine tapeworm Hepatoxylon trichiuri larvae in returning adult Chinook salmon from the Cisnes River to assess its potential as a biological tag for returning Chinook salmon in Patagonia. Of 61 Chinook salmon from the Cisnes River, 52.46% were infected by H. trichiuri , with 1.65 ± 1.26 parasites per infected salmon (mean ± SD). Infection prevalence and intensity did not differ significantly between males and females. Infection intensity was higher in larger salmon but decreased with increasing salmon condition. Infection intensity was not significantly related to length, mass, or body condition. Infection prevalence and intensity of H. trichiuri varied spatially among Patagonian river-basin populations of Chinook salmon, thereby supporting the use of H. trichiuri as a biological tag. Our findings provide important parasitological metrics that may enhance future management practices by informing geographic variability in foraging locations of adult salmon and their commercial value for human consumption.

Cisnes River, Patagonia↗

USGS2025

Cleaner cuts: Farmed fish and skin-off fillets are lower in per- and polyfluoroalkyl substances (PFAS)

The ubiquitous occurrence and persistence of per- and polyfluoroalkyl substances (PFAS) in all environmental matrices and biota poses significant health risks to humans. Fish consumption is one of the main pathways humans are exposed to PFAS, yet general patterns in factors influencing PFAS content in fish fillets remain unknown. We assembled information on PFAS content (total quantified PFAS, PFOS, PFOA, and others) in fish fillets to assess the effect of fish origin (marine, freshwater, wild, or farmed), fillet type (skin-on or skin-off), and lipid content on PFAS variation across environments at a global scale. We found that these factors influenced PFAS contents in fish fillets, with concentrations reaching up to 2149 ng•g wet mass −1 (WM). Specifically, PFOS and PFOA in skin-off fillets were consistently lower in farmed than wild fish across freshwater and marine environments. In freshwater wild fish, PFOS was lower in skin-off fillets than skin-on fillets at group and species levels, and multiple PFAS showed an inverse relationship with the lipid content of skin-off fillets, though the slopes showed varying steepness depending on the carbon chain length and functional group of the PFAS. However, the high variability of PFAS content across sites in aquatic environments and the complexity of PFAS bioaccumulation mechanisms in fish tissues may lead to variable results at a fine scale (i.e. , species level); this highlights general patterns of factors influencing PFAS bioaccumulation that may inform the management of human exposure to PFAS through dietary consumption.

Science of the Total Environment↗

USGS2023

Seven dam challenges for migratory fish: Insights from the Penobscot River

More than a century of impoundments in the Penobscot River, Maine, USA, has contributed to population declines in migratory fish in the system. A decade of change, research, and monitoring has revealed direct and indirect ways that dams have influenced the river habitat, connectivity for migratory fish, and the food web. The removal of two main-stem dams (in 2012 and 2013) and bolstering of fish passage have been part of coordinated restoration efforts in the watershed. Integral to this undertaking was support for short- and long-term monitoring and research that included physical habitat, fish passage, and broad scale ecological assessments. Herein we discuss the seven interconnected and complex ways that dams have affected the Penobscot River ecosystem, particularly for migratory fish. These include familiar influences ascribed to dams: i) impaired access to habitat, ii) injury and mortality, and iii) delays of migration. Other ecological influences are less studied and more subtle: iv) facilitation of predation, v) community shifts, and vi) demographic shifts. Lastly, dams result in vii) a loss of ecosystem services that would otherwise be intact in an unimpounded system. We draw on both direct examples from the Penobscot River and broader information to characterize how impoundments have transformed this ecosystem for more than a century. Recent dam removals and mitigation efforts have reestablished some of these ecological functions.

Maine↗

USGS2023

Contemporary distribution of non-native Chinook salmon (Oncorhynchus tshawytscha) in South America

Chinook salmon represent one of the most successful salmonid introductions in South America, and today multiple naturalized populations exist across Patagonia. Here, we present an updated regional distribution of Chinook salmon that includes new records of occurrences collected between 2006 and 2022. We found a significant range expansion in terms of occurrences for adult (18 new basins; 2,854,108 km 2 ) and adult spawners or juvenile (12 new basins; 53,262 km 2 ) salmon extending both to the north and south of the previously known colonized range in South America. This range expansion (38% of the area considering only occurrences indicating reproduction via adult spawners or juvenile salmon) included major basins draining to both the Pacific Ocean and Atlantic Ocean coasts of the continent. Adult Chinook salmon are currently reported from 48 large basins (33.62°–54.97° S) covering a total drainage area of 3,047,197 km 2 . The observed expansion we document here has been likely driven by the dispersal of straying adults from historically naturalized populations. Our findings provide evidence that the invasion of Chinook salmon in South America is ongoing and updated information relevant to the management of this invasive and socio-ecologically important fish.

Biological Invasions↗