scholarly journals Individual energy dynamics reveal nonlinear interaction of stressors threatening migratory fish populations

2021 ◽  
Author(s):  
Perla Catalina Chaparro‐Pedraza ◽  
André M. Roos
Keyword(s):  
Nonlinear Interaction ◽  
Fish Populations ◽  
Migratory Fish ◽  
Energy Dynamics

scholarly journals Low marine food levels mitigate high migration costs in anadromous populations

2019 ◽  
Author(s):  
P. Catalina Chaparro-Pedraza ◽  
André M. de Roos
Keyword(s):  
Lower Energy ◽  
Fish Populations ◽  
Migratory Fish ◽  
Environmental Threats ◽  
Freshwater Streams ◽  
Risk Of Extinction ◽  
Ecological Success ◽  
Marine Food ◽  
Migration Costs ◽  
High Migration

AbstractMigratory fish populations, like salmon, have dramatically declined for decades. Because of their extensive and energetically costly breeding travel anadromous fish are sensitive to a variety of environmental threats, in particular infrastructure building in freshwater streams and food declines in the ocean. Here, we analyze the effects of these two threats combined. Unexpectedly, we find that low marine food availabilities favor, as opposed to threaten, the ecological success of endangered populations. This counterintuitive effect results from an aspect of individual energetics that individuals switching to higher food levels reach larger sizes with concomitant larger migration costs but have lower energy densities. Surprisingly, the decline of food levels in the ocean after the completion of dams may thus mitigate the risk of extinction of migratory fish populations. This highlights the need of a mechanistic understanding integrating individual energetics, life history, and population dynamics to accurately assess biological consequences of environmental change.

scholarly journals The ichthyofauna of the Rio Carinhanha basin, one of the main tributaries of the Rio São Francisco

2020 ◽  
Vol 51 (4) ◽  
pp. 31-44
Author(s):  
Gilberto Nepomuceno Salvador ◽  
Ruanny Casarim ◽  
Gustavo Ribeiro Rosa ◽  
Yuri Malta Caldeira ◽  
Paulo Santos Pompeu
Keyword(s):  
Endangered Species ◽  
Native Species ◽  
Catchment Area ◽  
Entire Length ◽  
Fish Populations ◽  
Migratory Fish ◽  
River Channels ◽  
Middle Section ◽  
Long Distance ◽  
Main River

The ichthyofauna of the Rio São Francisco basin is relatively well-documented. However, most of this knowledge is concentrated at the upper stretch of its catchment area. In this study, we compile a list of species encompassing almost the entire length of the Rio Carinhanha, an important tributary from upper-middle section of the Rio São Francisco, including a comprehensive diversity of environments. A total of 99 species from 8 orders and 27 families were recorded. Five species are considered non-native, six classifieds as long distance migrants, and three as vulnerable. The orders with the greatest richness of native species were Characiformes and Siluriformes. Characidae was the most represented family, followed by Loricariidae. The main river channels were the richest environments sampled, followed by floodplain lagoons, veredas, and streams. The Carinhanha basin has important lotic remnants, thus it has several migratory fish populations as well as endangered species. This study demonstrates the importance of cataloguing the still poorly explored tributaries of the upper-middle section of the Rio São Francisco basin.

scholarly journals Preventing overexploitation of migratory fish stocks: the efficacy of marine protected areas in a stochastic environment

2009 ◽  
Vol 66 (9) ◽  
pp. 1919-1930 ◽  
Author(s):  
Christopher D. West ◽  
Calvin Dytham ◽  
David Righton ◽  
Jonathan W. Pitchford
Keyword(s):  
Protected Areas ◽  
Marine Protected Areas ◽  
Environmental Stochasticity ◽  
Fish Populations ◽  
Stochastic Environment ◽  
Migratory Fish ◽  
Deterministic Analysis ◽  
Fish Stocks ◽  
Harvest Control Rule ◽  
Stable Equilibria

Abstract West, C. D., Dytham, C., Righton, D., and Pitchford, J.W. 2009. Preventing overexploitation of migratory fish stocks: the efficacy of marine protected areas in a stochastic environment. – ICES Journal of Marine Science, 66: 1919–1930. Marine protected areas (MPAs) have been widely proposed for protecting overexploited fish populations. It has been suggested that fisheries may be enhanced by spillover of individuals from MPAs into fishing grounds. However, traditional spillover studies fail to account for the seasonal migrations of many populations. Most fisheries models also fail to include the stochasticity inherent in marine environments explicitly. Here we assess MPA efficacy using a simple population model simulating the migration of fish populations between a spawning ground MPA and a fishery. Including realistic environmental stochasticity in our model allows the population to deviate from, and shift between, positive stable equilibria, something that is impossible in a deterministic analysis. This deviation may result in population collapse in cases where deterministic analysis predicts population persistence. We show that, although effective at low migration levels, the ability of MPAs to protect stocks from collapse generally decreases as migration increases. However, an MPA provides greater protection and greater expected fisheries yield than a system without an MPA, irrespective of migration level. Combining MPAs with a harvest control rule may further increase protection and yield. We therefore argue that MPAs can play a role in the protection of migratory species.

The nonlinear interaction of the whistler wave with the inertial alfven wave in the magnetosphere of the Earth

2002 ◽  
Vol 8 (5-6) ◽  
pp. 96-101
Author(s):  
V.N. Fedun ◽  
◽  
A.K. Yukhimuk ◽  
A.D. Voitsekhovska ◽  
О.К. Cheremnykh ◽  
...  
Keyword(s):  
Nonlinear Interaction ◽  
Whistler Wave ◽  
Alfven Wave ◽  
Inertial Alfvén Wave ◽  
The Earth
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