Pattern and scale in latitude–production relationships for freshwater fishes

Abstract

Abstract. Empirically understanding spatial variation in secondary production rates is central to ecology. Yet for most taxa, such patterns are rarely examined, especially at different levels of ecological organization (e.g., species-vs. community-level patterns). We compiled data on biomass, production, and P/B rates of freshwater fish communities and species across latitudes and contrast patterns observed at the community level with those observed for species. At the community level, and at two distinct spatial scales (global vs. continental-North American), negative or neutral relationships were apparent between biomass, production, and P/B with latitude; however, there was substantial scatter in these data. Yet at the species level in North America, production was often closely linked to latitude, but in the opposite direction: Many species showed improved production with latitude. Latitudinal increases in species-level production rates were strongest for cool-and cold-water species, and species rarely showed the opposite trend. Species-level increases in production with latitude strengthened when production rates were normalized by the thermal opportunity for production, suggesting potential adaptations of individuals and populations to shorter growing seasons (i.e., "countergradient" production) at high latitudes. At the global scale, there were apparent unimodal relationships between community fish production measures and species richness; however, these patterns became linearized or non-significant at the continental scale. Decreased interspecific competition at northern latitudes combined with genetic adaptations (e.g., countergradient growth) could explain a tendency for increased species production in northern populations, while total community production remains reduced. Latitude has contrasting effects on fish production at different spatial scales and levels of biological organization. Thus while freshwater fish communities are somewhat more productive and diverse at lower latitudes, species production in northern populations is often surprisingly high.

Fish assemblage production estimates in Appalachian streams across a latitudinal and temperature gradient

“…States and, in some cases, worldwide (Table 3; see also Rypel & David, 2017). For example, the upper range of our production estimates were also above estimates for foothill streams in north New Zealand (Hopkins, 1971), tropical rainforest streams in northern Borneo (Watson & Balon, 1984), lowland trout streams in south-eastern Minnesota (Kwak & Waters, 1997) and low altitude neotropical streams in Brazil (Mazzoni & Lobón-Cerviá, 2000).…”

Eroding productivity of walleye populations in northern Wisconsin lakes

“…For example, habitat restorations might improve production D r a f t (Sass et al 2012;Sass et al 2017), whereas environmental degradations might decrease fish production (Sass et al 2006;Valentine-Rose et al 2007;Valentine-Rose et al 2011;Gaeta et al 2014). Secondary production provides a lens through which the production of walleye and other fish populations might be quantified and considered explicitly by managers (Randall and Minns 2000;Rypel and David 2017). For example, whereas production of most walleye populations in northern Wisconsin is low, the few productive walleye populations might be those most important for future walleye conservation.…”

“…Production D r a f t estimates integrate critical vital rates such as abundance, recruitment, growth, and mortality (Waters 1977;Downing 1984;Kwak and Waters 1997). Resultantly, production variables are sensitive indicators of ecological change (Waters 1992;Valentine-Rose et al 2007;Benke 2010;Myers et al 2017;Rypel and David 2017). Production is also a measure specifically well-suited to the study of exploited fish populations (Ricker 1946;Waters 1992;Dolbeth et al 2012;Rypel et al 2015).…”

“…Production is based in first principles, and is a direct estimate of energy fixation by organisms, energy flow through food webs, and fisheries services for human societies (Lindeman 1942; Roell and Orth 1993;Benke and Wallace 1997). In many fisheries, managers already track changes in population numbers, size, and growth (i.e., the component parts of production), but production itself is rarely calculated (Rypel et al 2015;Rypel and David 2017).…”

Flexible Classification of Wisconsin Lakes for Improved Fisheries Conservation and Management

“…For lakes in particular, there is dramatic diversity in the physical, chemical, and biological attributes of these ecosystems over landscapes (Mcdonald et al 2012;Verpoorter et al 2014;Oliver et al 2016). Correspondingly, lake fisheries also express wide spatial heterogeneity in virtually all fisheries metrics (Eadie and Keast 1984;Lester et al 2003;Rypel and David 2017). Lake classification frameworks are foundational for lake fisheries management because they simplify this high degree of landscape complexity, allow better "apples-to-apples" comparisons, and thus encourage more direct evaluations of fisheries data (Austen and Bayley 1993;Kelly et al 2012;Olin et al 2013).…”