Estimación no invasiva del desarrollo gonadal en Salmo salar (Linnaeus, 1758) mediante ecografía y parámetros morfométricos.
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Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
La maduración sexual temprana representa un desafío para la industria salmonicultora chilena, debido a sus efectos negativos sobre el crecimiento, la calidad del producto y el bienestar animal. En este contexto, la presente tesis tuvo como objetivo desarrollar y validar un enfoque no invasivo para estimar el desarrollo gonadal en juveniles de Salmo salar (Linnaeus, 1758), mediante ecografía modo B, como alternativa a los métodos tradicionales que requieren biopsia o sacrificio de los peces. El estudio se realizó sobre un total de 176 ejemplares, en los que se registraron el peso corporal, la longitud furcal y se efectuaron evaluaciones ecográficas con un ecógrafo BMV, modelo PT50C equipado con un transductor lineal de 7–10 MHz. Los resultados demostraron que la ecografía en modo B es una herramienta altamente eficaz para la diferenciación sexual, permitiendo identificar los ovarios como estructuras anecoicas, ovaladas, homogéneas y de mayor diámetro, mientras que los testículos se observaron como bandas hiperecoicas, más delgadas, alargadas y ocasionalmente segmentadas. Uno de los logros principales fue la formulación de un modelo de regresión lineal para la estimación no invasiva del Índice Gonadosomático (IGS) en hembras, basado en la longitud ecográfica de la gónada, con un ajuste estadístico significativo (R² = 0.13, p < 0.05). Asimismo, se observó una correlación positiva y significativa entre el IGS estimado por este modelo y las variables de tamaño corporal (largo furcal y peso corporal) en hembras (r = 0.51, p < 0.05), indicando que los individuos de mayor tamaño tienden a presentar un mayor desarrollo gonadal. También se identificaron diferencias significativas entre sexos en el tamaño relativo de las gónadas (p < 0.05), siendo proporcionalmente más largas en machos, en concordancia con lo reportado en la literatura respecto a la inversión energética diferencial entre sexos. En contraste, no fue posible construir un modelo predictivo confiable para estimar el IGS en machos, lo cual podría atribuirse a una mayor variabilidad morfológica o a una muestra insuficiente. Por otro lado, la evaluación del flujo sanguíneo mediante ecografía Doppler (modo PW) no arrojó datos válidos bajo las condiciones del estudio, probablemente debido al pequeño tamaño de las estructuras vasculares o a velocidades de flujo por debajo del umbral de detección del equipo.
Early sexual maturation poses a challenge for the Chilean salmon farming industry due to its negative effects on growth, product quality, and animal welfare. In this context, the objective of this thesis was to develop and validate a non-invasive approach to estimate gonadal development in juvenile Salmo salar (Linnaeus, 1758) using B-mode ultrasound as an alternative to traditional methods that require biopsy or sacrifice of the fish. The study was conducted on a total of 176 specimens, in which body weight and furcal length were recorded and ultrasound evaluations were performed with a BMV PT50C ultrasound machine equipped with a 7–10 MHz linear transducer. The results demonstrated that B mode ultrasound is a highly effective tool for sex differentiation, allowing the ovaries to be identified as anechoic, oval, homogeneous structures with a larger diameter, while the testes were observed as hyperechoic bands, thinner, elongated, and occasionally segmented. One of the main achievements was the formulation of a linear regression model for the non-invasive estimation of the Gonadosomatic Index (IGS) in females, based on the ultrasound length of the gonad, with a significant statistical adjustment (R² = 0.13, p < 0.05). Likewise, a positive and significant correlation was observed between the GSI estimated by this model and body size variables (furcal length and body weight) in females (r = 0.51, p < 0.05), indicating that larger individuals tend to have greater gonadal development. Significant differences were also identified between sexes in the relative size of the gonads (p < 0.05), which were proportionally longer in males, in accordance with what has been reported in the literature regarding the differential energy investment between sexes. In contrast, it was not possible to construct a reliable predictive model to estimate the IGS in males, which could be attributed to greater morphological variability or an insufficient sample size. On the other hand, the evaluation of blood flow using Doppler ultrasound (PW mode) did not yield valid data under the study conditions, probably due to the small size of the vascular structures or flow velocities below the detection threshold of the equipment.
Early sexual maturation poses a challenge for the Chilean salmon farming industry due to its negative effects on growth, product quality, and animal welfare. In this context, the objective of this thesis was to develop and validate a non-invasive approach to estimate gonadal development in juvenile Salmo salar (Linnaeus, 1758) using B-mode ultrasound as an alternative to traditional methods that require biopsy or sacrifice of the fish. The study was conducted on a total of 176 specimens, in which body weight and furcal length were recorded and ultrasound evaluations were performed with a BMV PT50C ultrasound machine equipped with a 7–10 MHz linear transducer. The results demonstrated that B mode ultrasound is a highly effective tool for sex differentiation, allowing the ovaries to be identified as anechoic, oval, homogeneous structures with a larger diameter, while the testes were observed as hyperechoic bands, thinner, elongated, and occasionally segmented. One of the main achievements was the formulation of a linear regression model for the non-invasive estimation of the Gonadosomatic Index (IGS) in females, based on the ultrasound length of the gonad, with a significant statistical adjustment (R² = 0.13, p < 0.05). Likewise, a positive and significant correlation was observed between the GSI estimated by this model and body size variables (furcal length and body weight) in females (r = 0.51, p < 0.05), indicating that larger individuals tend to have greater gonadal development. Significant differences were also identified between sexes in the relative size of the gonads (p < 0.05), which were proportionally longer in males, in accordance with what has been reported in the literature regarding the differential energy investment between sexes. In contrast, it was not possible to construct a reliable predictive model to estimate the IGS in males, which could be attributed to greater morphological variability or an insufficient sample size. On the other hand, the evaluation of blood flow using Doppler ultrasound (PW mode) did not yield valid data under the study conditions, probably due to the small size of the vascular structures or flow velocities below the detection threshold of the equipment.
Description
Tesis presentada para optar al título de Biólogo/a Marino/a.
Keywords
Salmonicultura, Salmones Identificación, Ultrasonido en biología