Effects of Fishing on the Population of Speckled PavonCichla temensisin the Middle Negro River (Amazonas State, Brazil): A Decrease in the Size of the Trophy Fish?

Abstract

Fishing acts selectively on exploited fish stocks, catching larger individuals and altering age and size structure. Thus, the objective of this study was to evaluate the impacts of a multi-use fishery in regards to the size truncation of populations of Speckled Pavon Cichla temensis. Data collection was carried out in the middle Negro River region, where the two modalities of recreational and commercial fishing occur with greater intensity. Questionnaires were administered to fishers in order to collect information on fishing. Individual fish were captured by recreational fishers in different rivers, were measured and weighed, and were released back into their environments. Weight (g) and TL (mm) data were used to assess the size structure at different fishing intensities. Asymmetry measurements were performed, and kurtosis of the distribution curve of the population was assessed. Linear models were also performed for both fisheries. The analysis of length distribution, asymmetry, and kurtosis showed a trend toward a decrease in the mean length of Speckled Pavon in line with the increase in fishing intensity. In linear models, the average distance (km) between fishing grounds and the fleet headquarters showed a positive relationship only for recreational fishing, which indicates that with an increasing distance from the municipality, the possibility of catching larger individuals increases and, consequently, the fishing yield also increases. The number of fishers presented a negative relationship, indicating a decrease in mean size and mean yield with increasing numbers of fishers in both modalities. The model predicted that low exploitation would cause a decline in the abundance of trophy fish. The results suggest that the Speckled Pavon population of this region exhibits signs of high exploitation and that fisheries management measures should be implemented to ensure the sustainability of stocks and fisheries that have high socioeconomic importance in the region.

Effects of volitional emigration timing and smolt size on survival and age-at-return in a Pacific salmon hatchery population

“…Additionally, older, larger fish increase biomass in natal streams as they contain more marine-derived nutrients that are important to maintaining primary productivity and overall ecosystem health (Bilby et al 1998(Bilby et al , 2003Oke et al 2020). Finally, larger fish are more desirable in subsistence, cultural, commercial, and recreational fisheries (Fenberg and Roy 2008;Zhou et al 2010;Lubich et al 2021).…”

Freshwater sport fishing: characterization of operations in the middle Negro River, Amazonas, Brazil

“…In the middle Rio Negro region of the state of Amazonas, more precisely in the municipalities of Barcelos and Santa Isabel do Rio Negro, the main sport fishing destinations are located (Freitas and Rivas, 2006). According to Barroco and Freitas (2014), sport fishers mainly explore the Aracá, Demeni, Cuiuni, Caurés, Jurubaxi, Padauari and Unini Rivers due to their specimens of peacock bass (Cichla temensis Humboldt 1821), which have sizes of greater than 62 cm and are known as "trophies" (Holley et al, 2008;Lubich et al, 2021).…”

“…This last species is distinguished from the others by reaching greater lengths (Jepsen et al, 1999;Hoeinghaus et al, 2003;Holley et al, 2008;Campos et al, 2015), growing at a faster pace than their congeners (Jepsen et al, 1999;Holley et al, 2008). In general, species of the genus reach medium to large sizes (Santos et al, 2006;Soares et al, 2007;Campos et al, 2015;Lubich et al, 2021) and are of great economic importance for commercial and sport fishing that occurs in the Rio Negro region (Inomata and Freitas, 2015;Lubich et al, 2021). Winemiller et al (1997) highlighted that peacock bass is the most widespread and abundant predatory fish in clear and black water systems of the Amazon and Orinoco basins.…”

“…Despite envolving a wide production chain, due to the consumption of goods and services necessary to carry out the activity, which result in a great economic contribution (MPA, 2010), there is a scarcity of studies on several aspects involving this activity. However, there are reports of a decrease in fishery yields and in the sizes of peacock bass (C. temensis) caught as a result of the high rates of fish exploitation in the middle Negro River region (Holley et al, 2008;Lubich et al, 2021).…”

Isotopic niche alteration of a predator fish in a dammed Amazonian black water river

“…Therefore, larger C. temensis in natural environments are expected to exhibit lower isotopic niche widths than smaller individuals (Aguiar‐Santos et al ., 2018). Furthermore, this species is targeted by subsistence, commercial and recreational fisheries in the Amazon basin, and the increase in fishing intensity has led to overexploitation of their stocks (Lubich et al ., 2021). Considering its key trophic and socio‐economic role in Amazonian rivers, it is important to understand how damming can affect the isotopic niche of Cichla .…”