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 between loudness (sound pressure level and maximum sound pressure level) of the advertisement call and body size (mass and standard length; rs>0.8). In addition, an asymptotic relationship was observed between the harmonic frequencies (f0–f10) of the advertisement calls and male body condition, with harmonic frequencies initially increasing with body condition indices, but then plateauing when body condition measures were high. Taken together, our results suggest that type I male advertisement calls provide reliable honest information about male quality regarding size and body condition. Such condition-dependent information of calling males could potentially be used by receptive females to help facilitate mate choice decisions.

Contains the data used in the manuscript titled, "Long duration advertisement calls of nesting male plainfin midshipman fish are honest indicators of size and condition" published in the journal of experimental biology. https://doi.org/10.1242/jeb.243889

In brief, this dataset contains overnight acoustic recordings from hydrophones placed on top of a type I male's nest, one minute call segments used to compute spectral features of the advertisement calls, spreadsheets containing data on the dates of acoustic recording and morphometric measures for each type I male, and codes used for data analysis. Please read the methods section on the manuscript for a detailed protocol on how the data was collected and processed.