Abstract

At least twenty species of wrasses (Labridae) mate in temporary resident spawning aggregation site at Finger Reef, Guam. I observed and recorded the reproductive behavior of species (number in parentheses) in the following genera: Anampses (1), Cheilinus (4), Cheilio (1), Epibulus (1), Gomphosus (1), Halichoeres (2), Hemigymnus (2), Macropharyngodon (1), Novaculiththys (1), Oxycheilinus (1), Stethojulis (1), and Thalassoma (4). Mating systems varied from lek-like to haremic, promiscuous or group, and facultative monogamy. Some species utilized only a single mating system while others were variable depending upon the number of males and females present. Regardless of the mating system used, all species utilized a suite of courtship behaviors, and spawned pelagically with a release of gametes after an ascent into the water column. Details of eight of species are described here. The rate, height, and mechanics of the ascent varied between species and between mating systems. Ascents of Cheilinus trilobatus, Epibulus insidiator, and Oxychelinus unifasciatus were relatively slow and pairs often spiraled high into the water column. The ascent rate of Gomphosus varius was slow to moderate, while Hemigymnus melapterus ascents were high and extremely rapid. Cheilio inermis and Thalassoma hardwicke spawned in pairs but more commonly in groups. Paired ascents for both species were usually quite rapid as well, with C. inermis spawning just above the substratum and T. hardwicke spawning high in the water column. Similarly, group spawns by C. inermis were just above the substratum while those of T. hardwicke were near the surface. Halichoeres trimaculatus and Stethojulis bandensis spawned in groups only, with multiple rapid dashes just above the substratum. A comparison of similarities in behavioral repertoires of these species is given in Figure 1. Males and females engaged also in behaviors intended to maximize reproductive success while avoiding egg predation by egg predators at the site.

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