Métodos de análisis de impactos tróficos de salmónidos en las aguas marinas y continentales de Chile: Sistemas de información geográfica, análisis de contenido estomacal y estimación del índice gonadosomático.
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Date
2025
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Universidad de Concepción
Abstract
Los salmónidos son especies del hemisferio norte que fueron introducidas en aguas continentales y marinas de Chile con el objetivo de desarrollarla pesca recreativa y la acuicultura. Estas especies, ya naturalizadas, han generado impactos ecológicos significativos en los ecosistemas acuáticos de Chile, alterando las redes tróficas nativas tanto en aguas continentales como marinas. Esta habilitación profesional aborda la implementación de tres metodologías que permiten un enfoque multidisciplinario para estudiar salmónidos y sus impactos. La primera metodología fue los sistemas de información geográfica (SIG) para analizar patrones espaciales de coexistencia de trucha arcoíris, salmón Chinook y trucha café con peces nativos; la segunda metodología fue análisis de contenido estomacal para determinar su dieta en aguas marinas; y la tercera metodología fue la estimación del índice gonadosomático (IGS) para evaluar el estado reproductivo de los individuos muestreados. Para los análisis de SIG se usó una base de datos publicada de peces nativos e introducidos en el Neotrópico, de las cuales se tomaron los datos sólo para las aguas continentales de cuatro regiones de Chile; el análisis de contenido estomacal se hizo en individuos de dos especies de salmones, salmón coho y salmón Chinook muestreados en su respectiva campaña de Caleta La Barra, río Toltén; el cálculo del índice gonadosomático se realizó en en gónadas muestreadas en la campaña de Caleta La Barra, habiendo gónadas de tres especies: trucha arcoíris, salmón Chinook y salmón coho, a las cuales se pesaron y midieron. Los resultados de SIG revelaron una alta coexistencia espacial entre salmónidos y especies nativas en cuencas del centro-sur de Chile. Además, el análisis permitió identificar un segmento del río Biobío donde se registra una zona de máximo registro de especies nativas, lo cataloga como un lugar de interés para maximizar esfuerzos de conservación. Los análisis de contenido estomacal revelaron que las principales presas de los salmónidos en su fase marina (en las costas cercanas a la desembocadura del río Toltén) corresponden a sardina y anchoveta, lo que concuerda con estudios pasados y confirma que los salmones Chinook y salmones coho frente al río Toltén tienen una dieta muy parecida a los salmones Chinook nativos del hemisferio norte. Los resultados de índice gonadosomático mostraron una interesante diferencia entre especies, probablemente explicados por diferencias en historias de vida, tales como residentes (trucha arcoíris) y de especies migratorias (salmón coho y salmón Chinook). Las tres metodologías de este estudio aplicadas en varias especies de salmónidos nos entregaron información global de los impactos de los salmónidos en las tramas tróficas, generando una visión a futuro de cómo seguir investigando su impacto en los ecosistemas acuáticos de Chile.
Salmonids are Northern Hemisphere species introduced into the continental and marine waters of Chile to promote recreational fishing and aquaculture. These now-naturalized species have caused significant ecological impacts on Chile’s aquatic ecosystems, altering native trophic networks in both continental and marine waters. This graduation project addresses the implementation of three methodologies that enable a multidisciplinary approach to study salmonids and their impacts. The first methodology involved geographic information systems (GIS) to analyze spatial coexistence patterns of rainbow trout, Chinook salmon, and brown trout with native fish. The second methodology was stomach content analysis to determine their diet in marine waters, and the third was the gonadosomatic index (GSI) to assess the reproductive status of sampled individuals. For the GIS analysis, a published database of native and introduced fish in the Neotropics was used, extracting data only from continental waters in four Chilean regions. Stomach content analysis was performed on individuals of two salmon species—coho and Chinook salmon—sampled during the Caleta La Barra field campaign in the Toltén River. The gonadosomatic index was calculated using gonad samples collected during the same campaign, including gonads from three species: rainbow trout, Chinook salmon, and coho salmon, which were weighed and measured. The GIS results revealed high spatial coexistence between salmonids and native species in south central Chile basins. Additionally, the analysis identified a segment of the Biobío River as a hotspot for native species records, designating it as a priority area for conservation efforts. Stomach content analysis showed that the primary prey of salmonids in their marine phase (near the mouth of the Toltén River) were sardines and anchovies, consistent with past studies and confirming that Chinook and coho salmon in the Toltén River have a diet highly similar to that of native Chinook salmon in their Northern Hemisphere range. The gonadosomatic index results highlighted notable differences between species, likely explained by life-history traits such as residency (e.g., rainbow trout) versus migratory behavior (e.g., coho and Chinook salmon). The three methodologies applied across multiple salmonid species provided comprehensive insights into their impacts on trophic webs, offering a forward-looking perspective for further research on their effects on Chile’s aquatic ecosystems.
Salmonids are Northern Hemisphere species introduced into the continental and marine waters of Chile to promote recreational fishing and aquaculture. These now-naturalized species have caused significant ecological impacts on Chile’s aquatic ecosystems, altering native trophic networks in both continental and marine waters. This graduation project addresses the implementation of three methodologies that enable a multidisciplinary approach to study salmonids and their impacts. The first methodology involved geographic information systems (GIS) to analyze spatial coexistence patterns of rainbow trout, Chinook salmon, and brown trout with native fish. The second methodology was stomach content analysis to determine their diet in marine waters, and the third was the gonadosomatic index (GSI) to assess the reproductive status of sampled individuals. For the GIS analysis, a published database of native and introduced fish in the Neotropics was used, extracting data only from continental waters in four Chilean regions. Stomach content analysis was performed on individuals of two salmon species—coho and Chinook salmon—sampled during the Caleta La Barra field campaign in the Toltén River. The gonadosomatic index was calculated using gonad samples collected during the same campaign, including gonads from three species: rainbow trout, Chinook salmon, and coho salmon, which were weighed and measured. The GIS results revealed high spatial coexistence between salmonids and native species in south central Chile basins. Additionally, the analysis identified a segment of the Biobío River as a hotspot for native species records, designating it as a priority area for conservation efforts. Stomach content analysis showed that the primary prey of salmonids in their marine phase (near the mouth of the Toltén River) were sardines and anchovies, consistent with past studies and confirming that Chinook and coho salmon in the Toltén River have a diet highly similar to that of native Chinook salmon in their Northern Hemisphere range. The gonadosomatic index results highlighted notable differences between species, likely explained by life-history traits such as residency (e.g., rainbow trout) versus migratory behavior (e.g., coho and Chinook salmon). The three methodologies applied across multiple salmonid species provided comprehensive insights into their impacts on trophic webs, offering a forward-looking perspective for further research on their effects on Chile’s aquatic ecosystems.
Description
Tesis presentada para optar al título de Biólogo
Keywords
Salmónidos, Peces Alimentación y alimentos, Peces Ecología