Multi-Parametric Portfolio to Assess the Fitness and Gonadal Maturation in Four Key Reproductive Phases of Brown Trout

Abstract

Brown trout is an environmental freshwater sentinel species and is economically important for recreational fishing and aquaculture. Despite that, there is limited knowledge regarding morpho-physiological variations in adults throughout the reproductive cycle. Thus, this study aimed to analyze the fitness and gonadal maturation of cultured adult brown trout in four reproductive phases (spawning capable—December, regressing—March, regenerating—July, and developing—November). The systematic evaluation of males and females was based on biometric, biochemical, and hormonal parameters, along with a histomorphological grading of gonads and the immunophenotype location of key steroidogenic enzymes. The total weight and lengths reached the lowest levels in December. Gonad weights were higher in December and November, while the opposite pattern was found for liver weights. The lowest levels of cholesterol and total protein were also noted during those stages. The 11-ketotestosterone (11-KT) and testosterone (T) for males, and estradiol (E2) and T for females, mostly explained the hormonal variations. The immunohistochemistry of cytochrome P450c17 (CYP17-I), aromatase (CYP19), and 17β-hydroxysteroid dehydrogenase (17β-HSD) showed sex and site-specific patterns in the distinct reproductive phases. The sex- and season-specific changes generated discriminative multi-parameter profiles, serving as a tool for environmental and aquaculture surveys.

Liver and Plasma Fatty Acid Characterization in Cultured Brown Trout at Distinct Reproductive Stages

“…Brown trout (3-4 years old) of both sexes were reared and maintained in a statecontrolled aquaculture facility (Torno Station, Amarante, Portugal), according to the detailed description in a previous study [18]. Fish were kept under a natural photoperiod and fed with commercial trout pellets (ICNF7MM, AQUASOJA) throughout the study time.…”

“…A sampling of six fish per sex that were of the same age cohort was performed along each of the four reproductive stages: December (2017, 3-year-old cohort), spawning capable; March (2018, age cohort 3+), regressing; July (2018, age cohort 3+), regenerating; and November (2018, new 3-year-old cohort), developing. These stages were established according to reported criteria [19] and as previously used in brown trout [18]. The sampling was executed on site, and animal handling followed the Portuguese Decree-Law No.…”

“…The mean fish lengths were as follows: December, 41.0 ± 1.5 cm (males) and 38.9 ± 3.8 cm (females); March, 45.3 ± 4.3 cm (males) and 47.2 ± 4.9 cm (females); July, 50.8 ± 4.4 cm (males) and 46.8 ± 6.2 cm (females); and November, 41.4 ± 4.3 cm (males) and 41.0 ± 1.9 cm (females). The details of the measurement and characterization procedures of the fish along the distinct stages were previously published [18].…”

“…This work expands on a previous one that proposed the analysis of (sic.) "the fitness and gonadal maturation" of these animals using histological, biometric, biochemical, and hormonal parameters [18]. Differently, the present study comprises the first detailed fatty acid profile and temporal follow-up of fatty acid dynamics in both types of biological matrices, serving the goal of identifying the classes and individual fatty acids that can be used as biomonitoring tools to discriminate the reproductive status of male and female brown trout.…”

Effect of Day Length on Growth and Gonadal Development in Meishan Male Pigs

“…The following supporting information can be downloaded at: , Table S1: The cross-reactivity of every antibody. Referencecs [ 93 , 94 , 95 , 96 , 97 ] are cited in the Supplementary Materials File.…”