Recruitment patterns of freshwater amphidromous fishes (Pisces: Gobiidae, Eleotridae) to the Cimaja estuary, Palabuhanratu Bay

Abstract

The sustainability of amphidromous fishes is determined by the success of the larval recruitment process from marine to freshwaters habitats. This study aimed to determine the recruitment pattern of freshwater amphidromous fish to the Cimaja River estuary, Palabuhanratu Bay in terms of season and daily. Amphidromous fish were caught monthly on the 25th of Hijri or waning crescent from December 2020 to August 2021. Sampling in one whole day with observation intervals every 4 hours was carried out in June 2021 to reveal the time of larvae and juveniles of the amphidromous fish recruit to the Cimaja River estuary. A total of 13 species of amphidromous fishes representing five genera and two families was captured. The recruitment of amphidromous fishes into the Cimaja River occurs between the peak of the rainy season to dry season. Generally, amphidromous recruit into the estuary waters of the Cimaja River is at the juvenile stage (11.9-21.8 mm body length). However, the recruitment of some amphidromous fish species appears at the postflexion stage (6.9-11.9 mm BL). Based on diel observations, larvae and juveniles of amphidromous fish are generally preferred to recruit to the Cimaja River estuary in the early morning (03:00 am) and afternoon (03:00 pm). Recruitment of amphidromous fish larvae to the Cimaja River follows a semi-diurnal tidal cycle which is a tidal type in Palabuhanratu Bay. Amphidromous fishes use tidal flux to recruit and migrate upstream of the Cimaja River through estuaries.

Temporal variation in abundance of bully sleepers (Pisces: Eleotridae) larvae and juveniles in Cisolok Estuary, Palabuhanratu Bay, Indonesia

“…It is interesting to note that the result also uncovers that bully sleeper or Bunaka gyrinoides recruit and migrate to freshwater during daylight and nighttime associated with tidal fluxes. In another study, it was also mentioned that the success rate of the recruitment process of amphidromous fish in estuary is utterly determined by tides [36]. This is related to the swimming ability of larvae and juveniles to move towards freshwater.…”

Migratory freshwater fish in Indonesia: Threats and conservation efforts

“…Some migratory freshwater fish that live in Indonesia from all types of migration are Tor spp., Anguilla spp., Rasbora spp., bilih fish Mystacoleucus padangensis, redtail catfish Hemibagrus nemurus, goby fish Glossogobius giuris, Awaous melanocephalus [11], several anadromous fishes [12], Polynemus melanochir, Pangasius krempfi, Arius sumatranus, and Boesemania microlepis (Table 1). Simanjuntak et al [13] found 13 species of amphidromous fishes in Cimaja River West Java, and provided a list of several amphidromous fish from several regions in Indonesia (Table 2). All these fish have economic and ecological values, and some of them are endemic species.…”

The Aquatic Environment of Bengawan Solo Estuary, Gresik, East Java As The Basis for Fisheries Development

“…Several research activities in the Ujung Pangkah area and the Bengawan Solo River estuary have also been carried out by several researchers, including the use of water birds, ecotourism, community participation related to mangrove forests [7]. heavy metals in sediments [8], eastern estuary water quality [9], fish biology [10][11][12][13][14][15], small crustaceans, wave studies, sediments, and plankton [16]. However, a general study of waters covering three river mouths has never been carried out.…”