Cannibalism and protective behavior of eggs in Arctic charr (Salvelinus alpinus).

Marilena Frye,Torvald B Egeland,Ivar Folstad,Jarle Tryti Nordeide

doi:10.1002/ece3.8173

Marilena Frye, Torvald B Egeland + Show 2 more

Open Access

https://doi.org/10.1002/ece3.8173

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Abstract

From video recordings of spawning events, we quantified protective and cannibalistic behavior of Arctic charr occurring immediately after spawning. The number of fish cannibalizing on stray eggs was examined regarding (a) whether more than one male shed milt during the spawning event, that is, whether sperm competition occurred, (b) whether the sperm competition included few or many males, that is, the intensity of sperm competition, and (c) the density of fish at the spawning site. Response behavior toward egg cannibalism was also examined among females and dominant males in order to determine any parental investment toward protecting the eggs after spawning. Cannibalistic behavior was seen in almost 50% of the spawnings, and the multiple spawning events showed the highest numbers of fish cannibalizing on eggs. Both the number of males releasing milt and the number of fish approaching the spawning site were positively correlated with egg cannibalism. Sperm competition was, however, not a prerequisite for egg cannibalism. Although we also observed partial filial cannibalism, protective behavior of eggs was seen both among dominant males and females, suggesting that charr actually conduct parental care.

Highlights

The act of cannibalism among fish has been considered an abnormal and maladaptive type of behavior (Persson et al, 2000; Smith & Reay, 1991)
While most studies on charr are riddled with difficulties in distinguishing between cannibalism and interspecific predation (Pereira et al, 2017; Svenning & Borgstrøm, 2005), this study focuses on the act of spawning and the following egg cannibalism associated with this event, clearly differentiating cannibalism from interspecific predation
We examine three questions related to cannibalism in charr: (a) Does the spawning type affect the probability of cannibalism?; (b) Does, the number of fish approaching the spawning site affect the number of fish showing cannibalistic behavior; And (c) does the spawning female or the spawning dominant male show any behavior that could be related to egg protection?

Summary

| INTRODUCTION

The act of cannibalism among fish has been considered an abnormal and maladaptive type of behavior (Persson et al, 2000; Smith & Reay, 1991). In the best of these cases, cannibalism of eggs with uncertain paternity may reduce the number of future competitors for a male's own offspring (Pereira et al, 2017; Smith & Reay, 1991). We have observed males, not involved in the actual spawning, eating eggs Both cannibalism and filial cannibalism occur in the population. We examine three questions related to cannibalism in charr: (a) Does the spawning type (i.e., paternal certainty) affect the probability of cannibalism?; (b) Does, the number of fish (i.e., potential cannibals) approaching the spawning site affect the number of fish showing cannibalistic behavior; And (c) does the spawning female or the spawning dominant male show any behavior that could be related to egg protection?

| METHODS

Findings

| DISCUSSION