The maturity and breeding season of the bellybarred pipefish, Hippichthys spicifer, in Okinawa-jima Island rivers

Abstract

We investigated the breeding season and size at maturation and described the morphology of newly released Hippichthys spicifer larvae collected from the estuaries of four rivers on northern Okinawa-jima Island, southern Japan. The minimum size of brooding males was 108 mm standard length (SL). The smallest mature female, as estimated from gonadosomatic index (GSI) analysis and histological observations of gonads, was about 100 mm SL. Histological observations showed the gonad of H. spicifer to be a cylindrical tube with a sequential pattern of follicle development and a single germinal ridge. We surmised that the breeding season is year-round, as shown by monthly changes in female GSI, gonad histology, and monthly changes in the occurrence of brooding males. The monthly changes in female GSI and proportions of brooding males were small in winter. The number of eggs in the male brood pouch ranged from 114 to 1,764 (604.4 ± 322.8, mean ± standard deviation; n = 25). The SL of the released larvae was 9.9 mm. All fins except the pectoral fins were formed, the body was elongated, and the developmental stage was similar to that of other Urophori species. The smallest individual present in the mangrove areas of estuaries was 78.0 mm SL.

Basic reproductive biology of the barbed pipefish Urocampus nanus (Syngnathidae) under laboratory conditions

“…Some species (e.g. Hippichthys spicifer, Syngnathus scovelli, S. typhle) have ovaries that consist of a single germinal ridge at one edge of the follicular sheet, and produce mature eggs continuously and asynchronously (Begovac and Wallace 1987;Ishihara and Tachihara 2009;Sogabe and Ahnesjö 2011). On the other hand, others (e.g.…”

The ovarian structure and mode of egg production in two polygamous pipefishes: a link to mating pattern

“…Some species, e.g . bellybarred pipefish Hippichthys spicifer (Rüppell 1838) and gulf pipefish Syngnathus scovelli (Evermann & Kendall 1896), have a single germinal ridge at one edge, with the most advanced follicles at the other, so‐called, mature edge (Begovac & Wallace, 1987; Ishihara & Tachihara, 2009). In contrast, others, e.g .…”