Effect of monsoon on coastal fish diversity of Goa: an example from the gillnet fishery

Abstract

The dynamics of fauna in coastal ecosystems are influenced by seasonal patterns in the oceanographic environment. It is well known that the monsoon along south-west coast of India influences the movement and spawning of fishes. Thus, they have direct effect on the richness, abundance and evenness of fish diversity in the ecosystem. This study investigates how the monsoon affects the commercial gillnet fishery along the coast of Goa. Fishing experiments were conducted in popular gillnet fishing grounds and the temporal pattern in diversity indices between October 2013 and September 2014 was assessed. A total of 124 fish species (40 families), 16 crustacean species (4 families) and 9 molluscan species (8 families) were recorded. The species diversity was found to be significantly different during the monsoon season and the species abundance distribution followed a geometric series during this period indicating signs of ecosystem perturbations. The economic and biological aspects of gillnet fishing in relation to the monsoon season in Goa are also discussed.

Seasonal fish species composition, catch rate and catch value in the small scale fishery of a tropical monsoon estuary along southwest coast of India

“…In the present study, four distribution models namely broken stick, geometric, log-series and log-normal models were used for comparing the species abundance between the seasons (May, 1975). These species abundance curves were generated using the 'PROC SGPLOT' procedure of SAS software (SAS Institute, 2012;Sreekanth 2016). …”

“…Journal of Environmental Biology, January 2017 abudance plot were took from the recently published research paper (Sreekanth , 2016). The abundance, CPUE and VPUE demonstrated great variations and in a day's fishing operation and an average of 2870 organisms of 43.8 kg were caught with a VPUE of Rs.…”

“…Zuari estuary gets a large fresh water influx (9 km ) from the upper et al E. thoracta M. cephalus S. longiceps F. indicus P. pelagicus et al, et al, et al, et al, et al, et al, et al, et al, 3 reaches in monsoon (Sreekanth 2016) and this causes seasonal fluctuation in salinity and temperature. Thus, the seasonal fluctuations in the species composition may be attributed to the distinct seasonal patterns in salinity and temperature (Harrison and Whitfield, 2006;Rojo-Vazquez 2008;Rajesh 2015;Sreekanth 2015a;Sreekanth 2016).…”

“…The fish species composition exhibited high diversity and abundance in post-monsoon and premonsoon while seasonal species dominated in monsoon. This may be attributed to seasonal migrations of species for breeding, larval development and feeding, as a result of variations in salinity and temperature (Sreekanth 2015a;Sreekanth 2016).…”

“…This monsoon phenomenon causes et al., et al, et al, et al, et al, et al, et al, et al, et al, seasonality in the coastal environment which is generally classified into three seasons, namely pre-monsoon (February-May), m o n s o o n ( J u n e -S e p t e m b e r ) a n d p o s t -m o n s o o n (October-January) seasons (Shamsan, 2008;Sreekanth 2015a). Therefore, monsoon mediated environmental fluctuations in the coastal ecosystem are expected to affect the spawning and movement activities of aquatic species and thus, influences the diversity of fish species (Ansari 1995;Sreekanth 2015a;Sreekanth 2016). These environmental fluctuations cause seasonal migrations of fish species like movement of young fish from deeper waters to estuarine regions and movement of mature adult fish to spawning grounds and thus bring out seasonal variations in the fish assemblages (Harrison and Whitfield, 2006;Costa 2007;Barbone and Basset, 2010).…”