Ultrasound as a noninvasive tool for monitoring reproductive physiology in male Atlantic salmon (Salmo salar)

Ingun Næve,Jonni Virtanen,Maren Mommens,Augustine Arukwe,Md Enamul Hoque,Elin Kjørsvik

doi:10.14814/phy2.14167

Ingun Næve, Jonni Virtanen + Show 4 more

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https://doi.org/10.14814/phy2.14167

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Abstract

We examined the potential for ultrasound as a noninvasive tool for maturation monitoring in Atlantic salmon (Salmo salar) males. Ultrasound examination and measurements were compared to common practices for maturation monitoring such as gonadosomatic index (GSI), sex hormone analysis, and histological analysis of spermatogenesis. There were significant correlations (R 2 = 0.68, P < 0.01) between ultrasound‐based measurements of the left testis and total testes weight and GSI, and ultrasound could be used for noninvasive GSI measurements. Echogenicity of ultrasound images corresponded to the histological stages observed, which added nuance to ultrasound‐based GSI measurements during final weeks preceding stripping. We propose that ultrasound can be used as an alternative to more invasive methods for sexual maturation monitoring in wild and farmed Atlantic salmon males. Using ultrasound technology, we have established a quick and noninvasive method that could reduce the number of stressful handlings and unwanted sacrifice of broodfish required for maturation monitoring in Atlantic salmon males.

Highlights

The salmonid species are of great cultural and economic value, and knowledge and control of their reproduction is an important step both in management of wild, endangered populations and for commercial production
Gonadosomatic index (GSI) was estimated indirectly using total testis weight calculated from ultrasound measurement and registered body weight, or directly from ultrasound measurement of left testis (Figure 1C and 1, respectively)
We have established a quick and noninvasive method that could reduce number of stressful handlings and unwanted sacrifice of broodfish required for maturation monitoring in Atlantic salmon males

Summary

Introduction

The salmonid species are of great cultural and economic value, and knowledge and control of their reproduction is an important step both in management of wild, endangered populations and for commercial production. During upstream river migration, decreasing photoperiod and water temperature induces final maturation of eggs and sperm and initiates spawning (Heggberget, 1988; Webb and McLay, 1996). Gonadosomatic index (GSI) is an invasive method that is most commonly used to monitor sexual maturation in fish. It is based on gonad weight as a percentage of total body weight, and the method requires unwanted sacrifice of valuable broodfish. In farmed broodstock, it is often performed on deceased fish, which might not be representative for the population

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