A technique for detection of larval fish in the digestive tract of predators by otolith marking

Abstract

The aim of the present study was to develop a method to unequivocally detect pre-flexion fish larvae in the digestive tracts of fish predators, even several hours after their ingestion. For this purpose, we evaluated larval mortality and the quality of the marks generated in sagitta otoliths after 0.5- or 2-h immersion in 50–800mg L–1 alizarin red S stain. The optimal condition (2h, 200mg L–1) was chosen to stain Prochilodus lineatus larvae, which were offered to single predators at 5 or 12 days after marking (DAM). The otoliths were searched in the digestive tract of predators killed 1–17h after ingestion of the prey, and were then examined for mark presence. Otolith recovery rates were high (>70%) and mark detection was above 80% up to 3h after ingestion, but even after 9h, 20–40% of the otoliths were recovered, with mark detection levels of 65%. A higher number of DAM was associated with a higher success in otolith recovery and mark detection. Otolith marking constitutes a single and inexpensive technique that could be applied in both laboratory and field experimental studies of predator–prey interactions.

Yayın Balığı (Silurus glanis L., 1758)’nın Otolit Morfometrisi

“…Otoliths are often used in stomach content studies of predator animals such as seabirds, mammalia, and fishes (Pascoe 1986;Kemp et al 2011;Polito et al 2011), in paleontological studies (Bosnakoff 2011), and in the detection of larval fish in the digestive tract (Gómez et al 2017). But the sex and length of the prey fish are not known (Echeverria 1987).…”

Effects of calcein on the levels of antioxidant enzymes and lipid peroxidation in juvenile silver carp, Hypophthalmichthys molitrix

“…This method has been evaluated in both teleosts and elasmobranchs (Gelsleichter et al., 1997). To date, fluorochrome labelling dyes mainly include tetracycline (TC) (Kobayashi et al., 1964; Krumme & Bingel, 2016), oxytetracycline (OTC) (Brooks et al., 1994; Hundt et al., 2016), calcein (CAL) (Becker et al., 2017; Wilson et al., 1987), alizarin red S (ARS) (Beckman & Schulz, 1996; Gómez & Fuentes, 2017) and alizarin complexone (ALC) (Arai & Chino, 2017; Tsukamoto, 1988). CAL (2, 4‐bis‐[ N, N' ‐di (carboxymethyl)‐aminomethyl] fluorescein) is a frequently used fluorescent compound that binds to bony structures when applied by immersion or injection (Lü et al., 2014).…”