Growth pattern and abundance of Varuna Literatta (Fabricius, 1798) in the new industrial area in the north coast of Gresik, East Java

Abstract

Varuna literatta (Fabricius, 1798) is one of the organisms that inhabit the estuary area facing the sea and will enter the estuary area at high tide. V. literatta has been caught throughout the year in its whole form or its eggs are used to meet human consumption needs as a source of animal protein, besides that V. literatta has a very important role in maintaining the balance of aquatic ecosystems. The presence of V. literatta in the waters as a decomposer which is able to provide the nutrients needed by primary producers in these waters. On the other hand, there has been no attempt to domesticate V. literatta, because according to the IUCN 2021 V. literatta in Southeast Asia is a species that has not been evaluated. This status can cause a decrease in the population of V. literatta because there is no regular evaluation and there are no rules that regulate the catch of V. literatta. This is reinforced by information obtained from fishermen that the catch of V. literatta from year to year is decreasing. This study aims to obtain information including reproductive aspects of V. literatta in an industrial area located on the coast of Gresik Regency. Sampling was carried out at three stations (Kalimireng river, Mengare river, Kalilamong river) at each high tide from June-August 2021. The samples obtained were then counted and differentiated between males and females, then body length and weight were measured to determine growth patterns and abundance. The results showed that the male and female V. literatta had a negative allometric growth pattern. The growth of V. literatta is also differentiated by sex. The highest abundance of V. literatta was obtained from Manyar station.