Microhabitat association and population status of the Luwuk introduced Banggai cardinalfish (Pterapogon kauderni Koumans, 1933) population

Abstract

The Banggai cardinalfish Pterapogon kauderni is the Indonesian national marine ornamental fish mascot, and an object of national and international conservation concern. The endemic population of this species is limited to the Banggai Archipelago in Central Sulawesi, Indonesia and a few nearby islands in North Maluku. In addition, introduced populations have become established, mainly along ornamental fish trade routes. The National Action Plan for Banggai Cardinalfish Conservation (NAP-BCFC) calls for monitoring and management of all P. kauderni populations. A survey of the Luwuk introduced P. kauderni population was carried out in October 2021. Data were collected at three sites with established P. kauderni populations: the ferry harbour, public harbour (Teluk Lalong) and a recreational area on the nearby coast (Kilo 5). P. kauderni were recorded by microhabitat association and size class (recruits, juveniles, adults). Data collected were compared with data from previous surveys where available. With the exception of one group in a sea anemone at Kilo 5, all P. kauderni were associated with Diadema sea urchins (D. setosum at all sites; D. savignyi at Kilo 5). At Kilo 5 P. kauderni the population structure indicates the possible capture of market-sized juveniles. Overall abundance was also lower compared to the polluted but unfished harbours. The proportion of recruits was significantly negatively correlated with the ratio of adult P. kauderni to Diadema urchins. The results will inform regional legislation currently in preparation to support sustainable management of P. kauderni populations, habitat and microhabitat in Central Sulawesi, as well as contributing to NAP-BCFC targets.Keywords:Banggai cardinalfishEndangered speciesDiademaMicrohabitat,MonitoringOrnamental fisheryLocal regulation

Banggai cardinalfish (Pterapogon kauderni) monitoring in Bokan Kepulauan (2017-2021) highlights the need for the “BCF Garden” approach

“…Six replicates of the 20 m x 5 m belt transect (Figure 2) were surveyed at each site by two observers using snorkelling equipment (total area 1137 (2023) 012059 IOP Publishing doi:10.1088/1755-1315/1137/1/012059 4 600 m 2 ). Along each transect, the observers recorded the number of Banggai cardinalfish by size class based on standard length (SL) in mm (recruit: SL 18; juvenile: 18 < SL < 35; adult: 35) [30,33,46] and microhabitat association (sea urchin, sea anemone, hard coral, soft coral, seagrass, other) [45]. The observers also recorded the number and species of sea urchins and sea anemones.…”

“…Diadematid sea urchins of the genera Diadema and Echinothrix can support the entire Banggai cardinalfish lifecycle. Flocks of Diadema urchins are the most common microhabitat for most endemic and introduced Banggai cardinalfish populations [5,8,[32][33][34]. Sea anemones are mainly used by recruits and small juveniles, while sub-adults and adults can use a wide range of microhabitats, particularly hard corals with complex growth forms [1,5,26,35,36].…”