Sexual maturity in sea trout, Salmo trutta L., running up the River Calonne (Normandy, France) at the ‘finnock’ stage

Abstract

Sexual maturation in sea trout (Salmo lrutlo L.) running up the River Calonne (Normandy, France), at the finnock stage, is characterized. Autopsy of I18 finnock in summer showed that 87k7Yo aged 2+ and 33_+ 15% aged 1 + were undergoing gametogenesis. In autumn all the fish were maturing. The analysis of plasma levels of 1 1-ketotestosterone, 17~-0estradiol, maturational gonadotropin and vitellogenin showed that only females in vitellogenesis can be well identified in summer (plasma vitellogenin greater than 0.30 mg ml-I). The morphological recognition of females among 134 autumn finnock and the ELISA assay of plasma vitellogenin of 814 summer finnock, demonstrated that vitellogenic females represented 12+2%0 of the 1 + individuals and 46*2%0 of 2+ fish captured during the 1985 run. The question of a possible relationship between the salinity tolerance ofjuvenile trout migrating towards the sea in the spring and their age on first migration in the river is discussed.

Enzyme-Linked Immunosorbent Assay (ELISA) for Rainbow Trout (Oncorhynchus mykiss) Vittellogenin

“…As regards rainbow trout, concentrations increase fiom 0.1 m S / d to 12.9 mdml (20,21) during the year preceding the first spawning. These levels remain within the same range observed for other salmonids (9,12,14).Therefore, the sensitivity of our assay allows the detection of Vtg at the very beginning of vitellogenesis, more than one year before sexual reproduction first takes place.…”

“…A ram serum (7) was used as control. (1) standard Vtg, ( 2 ) male oestrogenised rainbow trout,(3) male oestrogenised brook char, (4) The characteristics of the assay are similar to those described by other authors who have experimented with Vtg assays (13)(14)(15) for sensitivity and variability both within and among assays. We can also compare these characteristics to those obtained with RIAs described for salmonids (9)(10)(11)(12) The processing time of these assays vanes from 6 hours to 4 days for ELISA and from 1 to 4 days for RIA, Several authors have measured the concentration of circulating Vtg among female salmonids.…”

“…Enzyme-linked immunosorbent assays (ELISA) get around these difficulties. In the teleost species, ELISAs for Vtg have been described for sole (13), brown trout (14), catfish (15), striped bass ( 16), sea bass ( 17) and the Japanese sardine (1 8).…”

Gonad histology and vitellogenin concentrations in brown trout (Salmo trutta) from Danish streams impacted by sewage effluent

“…The raised and purified antibodies were specific towards vtg as no protein bands from male plasma were recognised by Western blotting. The quantification limit of the direct sandwich ELISA was below the quantification limits which have been reported so far from two other ELISAs for brown trout vtg (Maisse et al 1991;Sherry et al 1999).…”

Use of Vitellogenin as Biomarker Indicator in Sex Identification of Giant Grouper (Epinephelus lanceolatus)

“…Other reports on the measurement of Vtg by ELISA include the white spotted char Salvelinus leucommaenis Kwon et al [11] sole Sole vulgaris, brown trout Salmo trutta Maisse et al [24] and channel catfish Ictalurus punctatus [25].…”