PICRC Researchers collect valuable reproductive and age information on commercially-important reef fish

Over the past two years, the research team at the Palau International Coral Reef Center (PICRC) have been sampling melangmud (longnose emperor) as part of a larger project, which looks at the reproductive activity of this species. More recently, this project has expanded to include other key reef species, such as grouper (tiau, mokas, temekai), parrotfish (otord, ngesngis, mesekelat, mellemau), rabbitfish (meyas, kelsebuul, reked), snapper (keremlal), emperor (mechur), and unicornfish/surgeonfish (um, mesekuuk, chesengel).

Fish are purchased from the JR5 fish market, Surangel, BOFI, or independent fishers and brought to PICRC for sampling. The researchers then collect the gonads (reproductive organs) and otoliths (ear bones) and note down the length and weight of the fish. PICRC is also collaborating with The Nature Conservancy (TNC) and Coral Reef Research Foundation (CRRF) to gather the otolith samples and to sample species with limited or no information. Samples are sent to the University of Hawai’i and Poseidon Fisheries Research in Hawai’i for processing, with some otolith samples being processed at PICRC.

By looking at the gonads it is possible to tell if the fish is mature enough to spawn or still immature, while the otoliths provide information on the age of the fish. This information is then combined with fish length data collected during fish market surveys to assess whether the species is being fished sustainably. Sampling of gonads has previously been carried out in Palau in the northern reefs, from 2012 to 2016, and in Koror, from 2017 to 2019, which provided the size of maturity for some important reef fish species. However, valuable information is still lacking for many reef fish.

“The results of this study will help to inform fisheries managers about whether minimum size limits should be implemented to protect immature fish, or if a species should be protected during its spawning period,” stated Geraldine Rengiil, Director of PICRC’s Research Department.  

“This project will allow for more accurate assessments of Palau’s reef fish stocks in the future,” added PICRC’s Chief Executive Officer, Roxanne Siual Blesam.

PICRC is grateful to the CRRF and TNC for contributing samples to this effort and the Marine Institute in Galway/Irish Aid’s Our Shared Ocean Programme and the University of Guam Sea Grant for their support with funding this project.