Biodiversity, Distribution, and Abundance of the Tropical Anguillid Eels in the Indonesian Waters

Abstract

In order to understand biodiversity, distribution, and abundance among the tropical anguillid eels in the Indonesian waters, inshore migration mechanism of the juvenile anguillid eel (glass eel) to the estuaries of western, central, and eastern region of Indonesian waters were examined using both morphology and genetic analyses. A total of 9 species/sub species of anguillid eels (Anguilla bicolor bicolor, A. nebulosa nebulosa, A. bicolor pacifica, A. interioris, A. borneensis, A. celebesensis, A. marinorata, A. obscura and A. megastoma) were recognized to recruit at the mouth of 15 rivers through Indonesian archipelago. Species/subspecies diversity and distribution of recruiting juveniles differs in the estuaries of each region. In the western region that represented by estuary of Krueng Aceh, Batang Antokan, Air Kertaun, Cibaliung, Citanduy, Progo, and Pacitan Rivers, three species and sub species (A. bicolor bicolor, A. nebulosa nebulosa and A. bicolor pacifica) were found. In the central region that represented by estuary of Mahakam, Palu, Dumoga, Poigar, Bone, and Poso Rivers, five species and sub species (A. borneensis, A. celebesensis, A. marinorata, A. bicolor pacilica and A. interioris) were found. In the eastern region that represented by estuary of Akelamo and Pami Rivers, four species (A. marinorata, A. interioris, A. obscura and A. megastoma) were found. During the 6 months investigation from May to October 2005, abundance of the juveniles was higher in the central region compared with western and eastern regions. These results were suggested that inshore migration mechanism of tropical anguillid eels recruiting in tropical estuaries of Indonesian waters differs among regions.

Assessing Temporal Patterns and Species Composition of Glass Eel (Anguilla spp.) Cohorts in Sumatra and Java Using DNA Barcodes

“…The present study further highlights the usefulness of DNA barcoding in capturing boundaries between Anguilla species [7,22,[73][74][75][76]. Among the nine species included, seven displayed well-differentiated mitochondrial lineages, with minimum genetic distances to the nearest neighbor largely exceeding maximum intraspecific genetic distance.…”

“…Eels further grow up in freshwaters (yellow eels) until they become sexually mature (silver eels) and return to marine spawning grounds [2][3][4][5][6]. Anguillid eels are a significant food resource around the world, and contribute greatly to many national economies [2,[7][8][9][10]. For example, approximately 150,000 tons of eels were consumed each year both in Japan (2000)(2001)(2002) and China (2012China ( -2013 [11].…”

“…Unfortunately, scientific knowledge regarding eel diversity, distribution and abundance is sparse [15,19]. In particular, little is known about the ecology of anguillid eels in the tropics, even though such regions typically support relatively high abundances and species richness' of anguillid eels [7,[20][21][22]. Indeed, two-thirds of the known species of the genus, Anguilla, occur in the tropical Indian and Pacific Ocean, while the remaining species occur in temperate parts of both the Pacific and Atlantic Ocean [1].…”

“…Indeed, two-thirds of the known species of the genus, Anguilla, occur in the tropical Indian and Pacific Ocean, while the remaining species occur in temperate parts of both the Pacific and Atlantic Ocean [1]. For Indonesia, a total of seven to nine species has been reported, as the biological status of two species pairs (A. bengalensis vs. A. nebulosa, A. borneensis vs. A. malgumora) is still under debate [7,[22][23][24]. This diversity is among the highest in the Indo-Pacific Ocean; however, few attempts have been made to document diversity and distribution of Anguilla spp.…”

“…in Indonesia. Previous studies have mostly focused on either specific life stages or selected species [7,22,25,26]. Therefore, there is a clear and pressing need to assess spatial and temporal patterns of all life stages of tropical anguillid eels to gain a comprehensive understanding of their ecology.…”