Is the Iloilo River still a Nursery Ground for Important Marine Fishery Resources during the Northeast Monsoon?


by: Alexander J. Roth, Nathaniel C. AƱasco,Resurreccion S. Sadaba , Mae Grace G. Nillos, Armi May T. Guzman


Ichthyoplankton and decapod larvae taxonomic composition, density, relative abundance and frequency of occurrence were determined to assess if Iloilo River tidal inlet is still a nursery ground during the Northeast Monsoon. The sampling was conducted during the first quarter moon in the months of December 2016, January and February 2017 by towing a conical plankton net in 3 stations, namely upstream, upper midstream and lower midstream. A total of 7 taxonomic groups of ichthyoplankton and 7 decapod larvae taxa were recorded with densities ranging from 70.8 to 404.2 individuals/100m3 and 112.7 to 1277.6 individuals/100m3 , respectively. Ichthyoplankton in all 3 zones were dominated by Gobiidae (>70%). Sesarmidae and Dotillidae dominated decapod larvae in all 3 zones (>65%). Ichthyoplankton and decapod larvae frequency of occurrence ranged from 0.44 to 0.49 and 0.65 to 0.84, respectively. Compared to other coastal nursery grounds, Iloilo River shows fewer taxa but similar densities. This implies that the river is a nursery ground, but is utilized by very few taxa during the Northeast Monsoon. Clupeids was the only economically important ichthyoplankton group recorded, although, it is unlikely this taxonomic group utilizes the river as a nursery ground. Portunidae, Penaeidae and Palaemonidae were the only economically important decapod larvae taxa utilizing the river as a nursery ground. Based on this information, further research exploring how to improve the ecological condition of the tidal inlet should be conducted to hopefully increase the number of economically important taxa

Keywords: Ichthyoplankton, Decapod Larvae, Iloilo River Tidal Inlet, Nursery Ground, Mangroves