Reproductive behavior and mating system of Spotted Seatrout (Cynoscion Nebulosus)

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Spotted Seatrout Cynoscion nebulosus is an important estuarine-dependent finfish along the Texas Gulf coast. Sound production is an important component of Spotted Seatrout reproductive behavior and could potentially serve as a useful metric in monitoring the reproductive output of Spotted Seatrout spawning aggregations. My objective was to assess the relationship between sound production and egg production in captive breeding population of Spotted Seatrout. I used a hydrophone to monitor Spotted Seatrout production tank during the 2013 spawning season. Eggs were collected daily using a surface skimmer and counted. I was able to identify four types of calls characteristic of spawning described in previous literature. Multiple-pulse calls and long grunts were produced more frequently than paired dual-pulse calls during the spawning season, while staccato call was the least common among the four call types. The number of eggs produced was positively correlated to the sound production, and sound production varied between spawning nights and non-spawning nights. The quantity of paired dual-pulse calls were correlated to egg production, and that of long grunts also indicated the similar pattern, while multiple-pulse calls and staccato calls showed little effect on egg production. This may suggest that paired dual-pulse calls and long grunts are courtship-related calls and multiple-pulse calls and staccato calls are associated with agonistic behavior among males and/or attract females to lek. In terms of the quality of each call type, Spotted Seatrout produce lower, softer but higher pitched calls on nights where eggs were discovered compared to the nights where no eggs were discovered, indicating that males produced more intensive calls aiming for potential females from far way when the ones nearby did not respond. My study provided more detailed analysis of Spotted Seatrout acoustic behavior and could potentially lead to non-invasive methods to evaluate reproductive output in the field.

Passive hydroacoustics, Mating displays, Sciaenidae