Kinship relationship of Uroteuthis chinensis in the waters of western Kalimantan and northern Java based on morphometric characters and genetic structure

Abstract

Uroteuthis chinensis was a squid species with a wide distribution and rapid reproduction. It was commonly found in the waters of western Kalimantan and northern Java, which were the highest squid fishing grounds in Indonesia. Exploitation of U. chinensis in these waters was intensive and increasing, which might have affected the sustainability of U. chinensis squid resources. Therefore, proper and responsible management was needed to maintain the sustainability of this squid resource. For exploitation to be sustainable and optimal, management based on stock units of the managed resources was required. Therefore, information was needed on the stock units of U. chinensis squid in the western waters of Kalimantan and northern Java. Currently, the Indonesian government has separated the management of these two interconnected waters. The method used was to analyze 12 morphometric characters and genetic structures with COI and Rhodopsin markers. Sampling locations included the Sungailiat and Pontianak, for the waters of western Kalimantan, Jakarta, Pekalongan, and Lamongan for the waters of northern Java. Morphometric data were analyzed using Principal Component Analysis (PCA) and Discriminant Analysis (DA) approaches. Genetic analysis (COI and Rhodopsin) included genetic diversity, AMOVA, and haplotype distribution. The results of the morphometric analysis showed that the 12 morphometric size characters in this study showed a close relationship between the five U. chinensis sample populations. Genetic variation between populations and FST values on COI and Rhodopsin showed very low values; P-values also showed results that were not significantly different between populations. The haplotype distribution of both COI and Rhodopsin showed almost the same composition in both observed waters. The results of these analyses suggested that U. chinensis species in both waters showed indications of connectivity and close kinship or could be regarded as a single stock. Therefore, collaborative management across fisheries management areas in both waters (western Kalimantan and northern Java) was required.