Finfish diversity and seasonal abundance in the largest arid mangrove forest of the Indus Delta, Northern Arabian Sea

Abstract

Finfish composition and seasonal abundance was studied in the world largest arid mangrove ecosystem of the Indus Delta, Pakistan. Sampling was done from February 2010 to July 2011 in a narrow creek with thick mangrove forest and in a wide creek with sporadic patches of mangrove forest along its banks. The sampling revealed 84 fish species, corresponding to 2,274 individuals in 60 genera and 29 families, weighing a total of 217 kg. A minimum of 8 species were recorded in December 2010 while a maximum of 32 species were recorded in April 2010 (average 21 ± 5.8). The most speciose families were the Mugilidae (9) followed bythe Sciaenidae (8) and the Ariidae (7), the remaining 26 families being represented by 1-5 species. The average sizes of 28 dominant species in the collection ranged from 76.9 to 284.6 mm (SL), consisting mostly of juveniles. Relative abundance (%) and relative biomass (%) of species was between 0.04 and 9.1 and 0.01-12.14, respectively. The Pearson correlation of 0.52 (r 2 0.27) was observed among the environmental parameters and found significant between temperature and dissolved oxygen (p < 0.03). The canonical correspondence analysis showed strong relationships of different salinity and temperature ranges with the diversity and biomass composition. The species occurrence frequency was 69% in the wide creek and 31% in the narrow creek. We conclude that the Indus Delta is a highly productive zone in terms of fish diversity, providing ideal habitat for a nursery rather than a fishing ground and propose it to be a marine protected area (MPA).

Studies on the Spatial Distribution and Abundance of Selected Estuarine Fish Species in the Indus Delta Creek System Sindh, Pakistan

“…The family Leiognathidae accounts for 6.5% in our study and are widespread throughout tropical waters of the Indo-West Pacific where they live on soft bottoms in coastal marine and estuarine waters (Dianne et al, 2021), a few ranging up into fresh water (Woodland et al, 2001;Sparks et al, 2005). Three species of Leiognathidae is reported at Khober creek near Keti Bander (Amir et al, 2016). This is similar to our study from different creeks.…”

“…Croakers are mostly demersal fishes (Chao, 1995). Amir et al (2016) has found 8 species of family Sciaenidae at Khober creek, near Keti bander, while we found only two species from our study areas. Fish of the family Pristigasteridae is distinguished from other sardines (Clupeidae) by their long anal fin (Berra, 2001), mostly fish that are marine, coastal, or schooling in tropical and subtropical waters (Munroe et al, 1995).…”

“…Migratory periods of this species are varied from 2 to 7 months (Mićković et al, 2010). Amir et al (2016) has found 8 species of family Mugilidae at Khober creek of Indus delta, whereas we only found four species in our study area. The family Leiognathidae accounts for 6.5% in our study and are widespread throughout tropical waters of the Indo-West Pacific where they live on soft bottoms in coastal marine and estuarine waters (Dianne et al, 2021), a few ranging up into fresh water (Woodland et al, 2001;Sparks et al, 2005).…”

“…The low catches of this family in Jhang River, Hajamro and Dabbo creeks might be due to the low temperature due to rains in monsoon season in May to September (Khan and Abbas, 2020). We identified seven species in our study as compared to Amir et al (2016), they reported four species of Engraulidae from Khober creek which includes Coilia dussumieri, Thryssa setirostris, Thryssa mystax, Thryssa hamiltonii. The Family Mugilidae consists of mullets are ecologically, recreationally, and commercially important fishes (Dianne et al, 2021).…”

“…Each of these environments serves as a spawning, feeding, and spawning ground for different kinds of fish and shellfish, and they all sustain distinct food webs (Psomadakis et al, 2015). Amir et al (2016) conducted study on finfish diversity and seasonal abundance at Khober creek near Keti Bander. In this context, the Indus Delta creek survey was conducted in 13 creeks out of total 17 creeks.…”