Composition, abundance and diversity of the Family Cichlidae in Oyan Dam, Ogun State, Nigeria

Abstract

Olopade OA, Rufai OP. 2014. Composition, abundance and diversity of the Family Cichlidae in Oyan Dam, Ogun State, Nigeria. Biodiversitas 15: 195-199.This study was conducted to determine status of the family Cichlidae in Oyan Dam, Nigeria, during the wet and dry seasons of 2011. Samples were collected using multi-mesh gillnets ranging between 30 mm to 80 mm. Simpson's Diversity Index was used to determine the species richness, while dominance and evenness were given by Shannon's index. A total of 547 individuals were caught from Imala (S1) and Ibaro (S2) sites of the dam. Species collected include Sarotherodon galilaeus (42.60%), Oreochromis niloticus (17.92%), Tilapia zillii (25.41%), Hemichromis fasciatus (10.61%) and Tilapia mariae (3.48%). Juveniles and sub-adults and adults were among the catch, the sizes were as big as 12.85±0.29cm SL, 109.22±6.00g BW in Tilapia zillii and small as 6.09±0.05cm SL and 8.07±0.15g BW in Hemichromis fasciatus. The diversity indexes showed that the diversity of Cichlids was lower in the two sites observed in Oyan Dam. The estimates of diversity indexes showed lower value for site 1 (0.284) than for site 2 (0.294); Simpson's diversity index was 0.716 for site 1 and 0.703 for site 2 while reciprocal indexes for site 1(3.521) was slightly lower than site 2 (3.367). Shannon-Wiener's Index recorded in the site 1 (1.36) was slightly lower than site 2 (1.37). Pielou's Index value recorded for site 1 was 0.845 and 0.852 for site 2. Sarotherodon galilaeus, Oreochromis niloticus, Tilapia zillii and Tilapia mariae exhibited a positive allometric growth pattern while only Hemichromis fasciatus showed a negative allometric growth.

Assessment of Ichthyofaunal Assemblage of Erelu Reservoir, Oyo, Nigeria

“…Also, Ayoola and Ajani (2009) recorded higher catches in number and biomass during dry season in Eleyele Wetland while Omitoyin and Ajani (2007) reported more catches during the dry seasons at Asejire and Eleyele lakes and attributed it to low level of water at that time. However, this result contradicts the findings of Olopade and Rufai (2014) who reported more catch in wet season in Oyan dam. The spatial differences recorded in fish species showed a much higher number of fish in lower and upper part of the reservoir.…”

“…This dominance of Cichlidae in Nigerian lakes and reservoirs has been well documented by various workers including Edward (2013), Dan-Kishiya et al (2012), Olopade and Rufai (2014), Mustapha (2010), Komolafe and Arawomo (2008), Ikenweiwe et al (2007), Balogun (2005) and Oso and Fagbuaro (2004). These authors attributed the preponderance of Cichlids to their ability to thrive on a wide range of food items and their prolific breeding nature.…”

Diversity and abundance of the family mugilidae in the New Calabar River, Nigeria

“…Simpson's index values range from 0 to1, with 1 representing perfect evenness which signifies the presence of all species in equal number. In this study the values recorded were less than 1 which indicates imperfect evenness (Olopade and Rufai, 2014). The Simpson's Index of Diversity was 0.63, 0.62 and 0.59 for station 1, 2 and 3 respectively.…”

“…The number of species will vary depending on the differences in the sampling methods and sampling effort (gear type, fishing time etc. ), as well as fish abundance which is usually affected by migration (Olopade and Rufai, 2014). Therefore, all three species were present in each of the sample months although, the monthly abundance of each Mugilid species varied from month to month.…”

Species composition and diversity of cast net fisheries in New Calabar River, Niger Delta, Nigeria

“…This could probably be due to duration of sampling and selectivity of gear used in the present study. The number of species could vary depending upon differences in the sampling methods and sampling effort, as well as fish abundance (Olopade and Rufai 2014). The area of operation of a gear, the inconsistant behavior of the fish relative to the gear, and the size of the fish determine the part of a stock that can be caught by a gear.…”