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- The diversity of fish larvae in the Bons Sinais Estuary (Mozambique) and its role as a nursery to marine fish resourcesPublication . Mocuba, Jeremias; Leitão, Francisco; Teodosio, MariaThe study of assemblages of fish in their early phases in estuaries is an essential approach to understanding the functioning of these types of ecosystems and their role as nursery grounds for some marine fish species. The main aim of this study was to analyze the ichthyoplankton assemblage in the Bons Sinais Estuary, specifically to clarify the use of this area by species of socio-economic interest. This study identified 22 fish larval taxa among families, genera, and species. Gobiidae (54%), a group of resident species, dominated the community. The larval taxa of socio-economic importance (Thryssa sp., Clupeidae, Sillago sihama, Johnius dussumieri, Pellona ditchela, Pomadasys kaakan, Cichlidae, and Mugilidae) accounted for 23% of the total abundance. Larval density (N◦/100 m3 ) varied spatially and temporally, with higher density and diversity values both in the middle zone and in the wet season. Multivariate analyses revealed that salinity, temperature, and water transparency had a strong influence on larval abundance and density. While most fish larvae were in the post-flexion stage, there was a predominance of pre-flexion larvae in the lower estuary and in the post-flexion stage in the middle and upper zones, especially for marine fish resources, showing the role of this estuarine habitat as a nursery area.
- Characterising different artisanal fishing gears catches that operate in distinct habitats to assess ichthyofauna assemblages in Bons Sinais estuary, MozambiquePublication . Jeremias J. Mocuba; Eudriano F.S. Costa; Daniel Oliveira Mualeque; Maria Alexandra Teodósio; Francisco Leitão; Mocuba, Jeremias; Florêncio dos Santos Costa, Eudriano; Teodosio, Maria; Leitão, FranciscoMonitoring the ichthyofauna is crucial to detect changes in aquatic communities for fisheries management and conservation. This study aimed to identify the most effective gear for ichthyofauna studies in the estuary. Thus, the performance of the beach seine (active gear) and chicocota (fixed gear), common fishing gears used by artisanal fishers in the Bons Sinais estuary (BSE), were used to characterise fish assemblage structure. Monthly surveys were conducted at two fixed sample points of the BSE to assess the composition of the fish assemblage. The analysis revealed statistical differences in abundance, biomass, and the presence/absence of different species between gears regardless sampling months. At ecological level, differences among gears were explained by different modus operandi, technological features and also different sampling habitats where gears operate; beach seine is catching bottom-bound and littoral fish while Chicocota is sampling the pelagic assemblage of the mid-channels. The frequency of occurrence of the 13 most abundant species differed between gears. Both gears showed little size-selectivity, with the mean total length and mean body height of these species statistically differing between gears. A total of 92 fish species were identified. No statistical differences were observed among gears for species richness, diversity and evenness. Both fishing gears captured several local socio-economically important species in the BSE. In particular, 13 of the most important species accounted for more than 54% and 60% of the total abundance and biomass in beach seine and chicocota, respectively. The complementary use of fixed and active fishing gears for studying fish community structure in estuaries is recommended. This multi-gear sampling approach enhances the capacity to detect changes in fish communities and provides valuable data for fisheries management and conservation efforts.
- Ichthyofaunal community assemblage and spatiotemporal patterns in the Bons Sinais Estuary, Mozambique: Ecological drivers and conservation implicationsPublication . Mocuba, Jeremias; Florêncio dos Santos Costa, Eudriano; Teodosio, Maria; Leitão, FranciscoUnderstanding the ichthyofaunal assemblage of estuarine and adjacent coastal ecosystems is important for managing fishery resources and implementing conservation actions. This study explored the structure, diversity, and spatial-temporal variations of the ichthyofauna in the Bons Sinais Estuary (Mozambique) and the influence of environmental parameters. Fish sampling was conducted in the lower, middle, and upper zones using beach seine (active) and chicocota (fixed) gears in January 2020 and monthly from July 2020 to June 2021. The study identified 102 fish species, mostly of marine origin, belonging to 51 families. The most abundant families were Sciaenidae, Engraulidae, Clupeidae, Mugilidae, and Gobiidae, contributing over 78 % of the total catch. The most dominant species were Thryssa vitrirostris, Johnius dussumieri, Johnius dorsalis, Sardinella albella, Mugil cephalus, and Hilsa kelee, which accounted for more than half (52.43 %) of the abundance and 48.27 % of the biomass. The study found an ichthyofaunal community characterised by significant spatial variations, primarily influenced by salinity. The dominance of marine species in the lower and middle estuary contrasted with freshwater species in the upper zone. Dominant species showed spatial variations in abundance and biomass, but fewer showed seasonal variations. The middle estuary exhibited the highest species richness, diversity, and average abundance, while the lower zone had the highest biomass average. Threatened species, including Oreochromis mossambicus, comprised 3.4 % of the total abundance. These findings highlight the need for sustainable exploitation of fisheries resources and preserving the ecological functions of the Bons Sinais Estuary, which is important for resident and migratory species.