Data for: Long duration advertisement calls of nesting male plainfin midshipman fish are honest indicators of size and condition

The plainfin midshipman fish (Porichthys notatus) has long served as a model organism for neuroethology research on acoustic communication and related social behaviors. Type I or ‘singing’ males produce highly stereotyped, periodic advertisement calls that are the longest known uninterrupted vertebrate vocalizations. Despite the extensive literature on the acoustic behaviour of this species, it remains unclear whether reproductive males signal their quality via their highly energetic, multiharmonic advertisement calls. Here, we recorded the advertisement calls of 22 reproductive type I males at night in a controlled laboratory setting in which males were housed in aquaria maintained at a constant temperature (13.9±0.3°C). The duration of the advertisement calls from type I males was observed to increase from the first call of the night to the middle call after which call duration remained steady until the early morning hours and first light. A strong positive correlation was observed be...