Riverscape recruitment: a conceptual synthesis of drivers of fish recruitment in rivers

Abstract

Most fish recruitment models consider only one or a few drivers in isolation, rarely include species’ traits, and have limited relevance to riverine environments. Despite their diversity, riverine fishes share sufficient characteristics that prediction of recruitment should be possible. Here we synthesize the essential components of fish recruitment hypotheses and the key features of rivers to develop a model that predicts relative recruitment strength, for all fishes, in rivers under all flow conditions. The model proposes that interactions between flow and physical complexity will create locations in rivers, at mesoscales, where energy and nutrients are enriched. The resultant production of small prey will be concentrated and prey and fish larvae located (through dispersal or retention) so that the larvae can feed, grow, and recruit. Our synthesis explains how flow and physical complexity affect fish recruitment and provides a conceptual basis to better conserve and manage riverine fishes globally.

A compendium of ecological knowledge for restoration of freshwater fishes in Australia

“…Equations for these growth curves are included in Table 6. species to inform improved natural resource management capability and decision making. This specific ecological knowledge can be readily used in conjunction with broader ecological concepts, such as habitat use, movements, reproduction and population dynamics (see Humphries and Walker 2013;Humphries et al 2020).…”

Relationship of Freshwater Fish Recruitment With Distinct Reproductive Strategies and Flood Attributes: A Long-Term View in the Upper Paraná River Floodplain

“…Long-lasting floods, those longer than 50 days, favor the survival of juveniles by providing higher availability of shelter and food for more extended periods before the waterline recedes FIGURE 7 | Relationship between non-migratory fish with internal fertilization (NIF; CPUE = catch per unit effort) and maximum annual water level (A) and delay of the flood (B) in the Paraná River and duration of flood in the Ivinhema River (C). (Suzuki et al, 2009;Oliveira et al, 2015;Humphries et al, 2020). With lasting floods, the individuals leaving the flooded areas in the ebb period are larger in body size and consequently less susceptible to predation (Agostinho et al, 2004).…”

“…The hydrologic regime is the selective force behind the diverse livelihood strategies of species, including life-history traits (Wootton, 1990;Zeug and Winemiller, 2007;Abrial et al, 2019;Humphries et al, 2020). The reproductive dynamics and flood regime are closely related (Gomes and Agostinho, 1997;Humphries et al, 1999;Bailly et al, 2008).…”

Climate variability regulates population dynamics of a threatened freshwater fish

“…River flows interact with many other attributes including groundwater, geomorphology and biotic factors (e.g. predators) to influence the vital rates of a population (Humphries et al 2019). Furthermore, the specifics of these attributes and their interactions are likely unique to a waterway or reach within.…”