Comparing river basins world‐wide and contrasting inland fisheries in Africa and Central Amazonia

Abstract

An analysis of covariance relating basin area (A, km2) to river length (L, km) and discharge rate (D, m3 s–1) was performed for two continents and showed that the two covariates (L and D) were highly significant and that the strength of the relationship changed between continents. For comparison, D was excluded but the result remained the same. Although geomorphological models are useful for establishing global levels of production, these regressions should be applied with caution. Historically, simple statistical models were developed to predict fish catches in rivers. These, based upon regression of catches on channel length or basin area for Africa and Central Amazonia, are contrasted in this paper because of their generally similar approach.

Geomorphic controls on lacustrine isotopic compositions: Evidence from the Laney Member, Green River Formation, Wyoming

“…Consequently, the captured river was probably larger than the minimum discharge that satisfi es the mass-balance model. Although large rivers commonly have higher δ 18 O than small tributaries due to the mixing of water from different parts of the catchment, rivers with discharges as great as 3000 m 3 /s (90 × 10 9 m 3 /a) are abundant in a survey of world rivers and commonly carry water across distances of 1500 km or more (e.g., Petrere et al, 1998). The modern Columbia River is one such river that easily meets the high discharge-low δ 18 O required by the model.…”

Reservoir Attributes Display Cascading Spatial Patterns Along River Basins

“…Considering that the combination of topography and climate can make river basins highly dissimilar, we suspect that for the majority of attributes, the Type 2 pattern (i.e., similar gradients among basins) could be generated by the high variability in attribute estimates within basins, resulting in inability to detect statistical differences in slopes (i.e., b 3 in Equation ) among basins. Thus, we suggest that with an increased sample size, most Type 2 patterns are in effect Type 3 patterns; however, some of the attributes that displayed Type 2 patterns, such as discharge, residence time, and siltation, are directly tied to the hydrological properties of watersheds and may remain as Type 2 patterns even with an increased sample size (Petrere et al., 1998; Simons, 1979). The innate relationships between these attributes and catchment area are so direct that statistical tests cannot find enough power to differentiate similar slopes among basins.…”

“…Across continents, river basins display similar lengthwise characteristics (Petrere et al., 1998). Just as river networks show linear patterns, our results suggest that many reservoir attributes also display lengthwise patterns from upstream to downstream.…”

“…The drivers causing Type 2 and Type 3 patterns are many, but unlike the Type 1 pattern, they are likely to be catalyzed mostly by dynamics operating at the basin scale. Cascading spatial patterns are dictated by landscape characteristics shaped in geological time by runoff and are also evident in rivers (Fang et al., 2017; Petrere et al., 1998; Vannote, et al., 1980) and chains of natural lakes (Kratz et al., 1997; Martin & Sorrano, 2006). Basin‐scale catalysts are rarely controllable but constrain the expression of processes that drive the attributes observed at the reservoir scale.…”

Landscape variables affecting fishery yield in lake systems of the Central Amazon region, Brazil

“…In the tropics, some authors tested fishery and environmental variables, e.g. Melack (1976) with relationships of fish yields and primary production; Petrere (1983) relating yield to river morphology and fishing effort; Welcomme (1990) relating yield to river basin area, floodplain area and length of the river; and Petrere et al (1998) modeling fishery yields of inland waters in Africa and the Central Amazon with the variables of discharge rate, basin area and length of the rivers. However, the effects of variables associated with lake morphology were not considered, although the diversity of lake types exploited by the regional fishery fleet is large enough to give an appropriate basis for testing its effect on the fishery yield.…”