Individual spawning performance and mating pair combinations in captive grouper aggregations

• Published in: Environmental biology of fishes Vol. 105; no. 3; pp. 385 - 401
• Main Authors: Okuyama, Junichi, Yamaguchi, Tomofumi
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.03.2022; Springer Nature B.V
• Subjects: Animal Systematics/Taxonomy/Biogeography; Biomedical and Life Sciences; Captivity; Data loggers; Ecological aggregations; Environment; Females; Fish; Freshwater & Marine Ecology; Life Sciences; Lipids; Males; Marine fishes; Mating; Nature Conservation; Reproduction; Reproductive behavior; Reproductive behaviour; Spawning; Zoology; Spawning duration; White-streaked groupers; Lipid density; Spawning frequency; Bio-logging
• ISSN: 0378-1909; 1573-5133
• DOI: 10.1007/s10641-022-01232-w

Spawning aggregations have been widely observed in fish. However, individual reproductive performance in aggregations has rarely been measured because of the lack of techniques for individual identification throughout the spawning period. Here, we investigated the individual reproductive performance of four male and 12 female white-streaked groupers ( Epinephelus ongus ) in simulated spawning aggregations in captivity. Reproductive behaviour was observed by monitoring the simultaneous ascending rush by a pair or group of fish with a fine-scale depth data logger. In this study, we defined verified spawning events as synchronised ascents that met the extraction conditions based on night observations and a complementary experiment. During the experiment, 37 verified spawning events were extracted between four males and ten females; twenty-nine of the verified spawning events involved a single female and a single male, and eight events involved a single female and two males. One presumed and seven false spawning events were also identified. Individuals with higher lipid densities engaged in more verified spawning events, resulting in a longer spawning period. Moreover, the males spawned more (11.3 ± 4.6 as the first or second male) than the females (3.7 ± 1.8). The entire spawning period lasted 6 days; however, each individual was active only for a few days, and the timing varied among individuals. There were no specific mating pair combinations for the multiple verified spawning events. Further application of our technique would be instrumental in understanding the reproductive performance of fish with spawning aggregations.