Understanding the life histories of amphidromous fish by integrating otolith‐derived growth reconstructions, post‐larval migrations and reproductive traits

Egan, E.M.; Hickford, Michael J. H.; Schiel, David R.

doi:10.1002/aqc.3145

Cited by 8 publications

(3 citation statements)

References 47 publications

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“…We chose to monitor post-recruit (late juvenile and adult) demography because larval and post-larval stages of G. maculatus occur at sea, are largely unknown and challenging to monitor. Furthermore, post-recruit demography may inherently reflect the demography of early life stages [ 29 ] and consequently their survival to adulthood.…”

Section: Introductionmentioning

confidence: 99%

Interacting effects of density and temperature on fish growth rates in freshwater protected populations

2022

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Despite the demonstrated benefits of marine protected areas, there has been relatively little dialogue about freshwater protected areas (FPAs) even though some have been established to protect freshwater species from recreational and commercial fishers. After populations recover from fishing pressure, abundances and densities of formerly fished species increase, and we should therefore expect changes in demographic traits compared to those in exploited populations. To test this, we used capture-mark-recapture data for 10 Galaxias maculatus populations across a density gradient mediated by different degrees of fishery closure. We examined the extent to which density-dependent (DD) and density-independent (DI) effects interact to affect specific growth rates in post-recruit populations. We found that population density, stream temperature and individual size interact to affect growth rates. When population densities were high, compensatory responses of far slower growth rates were strongest, indicating that DD growth is a key mechanism regulating post-recruit populations of G. maculatus . This study emphasizes the importance of understanding DD and DI processes, their interactions, function and effectiveness for freshwater fisheries management. For FPAs to be effective, the extent and quality of target species' habitats must serve as key criteria for protection to alleviate competition for limited resources that underpins DD processes.

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Section: Introductionmentioning

confidence: 99%

Interacting effects of density and temperature on fish growth rates in freshwater protected populations

2022

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“…Egan, Hickford, & Schiel () consider the inter‐relationship between marine and freshwater phases of the amphidromous Galaxias maculatus (Jenyns, 1842) an ‘At risk’ species of Galaxiidae that is harvested seasonally as upstream migrating larvae. Using otolith analysis, they reconstructed early growth histories and found that hatch season affected marine growth rates, suggesting that migrants arriving early in fresh water have the potential for higher reproductive output.…”

Section: Articles In This Issuementioning

confidence: 99%

Mountains‐to‐the‐sea conservation: An island perspective

Collier

Pilditch

Lundquist

2019

Aquatic Conservation

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1. Island nations such as New Zealand provide valuable insights into conservation challenges posed by strongly connected and recently developed or exploited freshwater and marine ecosystems.2. The narrow land mass, high rainfall, and steep terrain of New Zealand, like many other island nations, mean that land-based stressors are rapidly transferred to freshwater habitats and propagated downstream to coastal environments via short, fast-flowing river systems.3. Freshwater and marine environments are linked through faunal life histories; for example, diadromous fishes, many of which are considered threatened or at risk of extinction, and require cross-ecosystem conservation to ensure survival of critical life stages and persistence of source populations. Recent invasions of marine and freshwater environments by non-indigenous spe-cies reveal rapid impacts on a naïve biota and highlight conservation conundrums caused by management aimed at enhancing native biodiversity by improving habitat connectivity. Understanding and managing interconnected freshwater and marine ecosystems isa key concept for local indigenous communities, and highlights socio-cultural connectivity and sustainable local harvesting of traditional resources as key elements of contemporary marine and freshwater conservation planning in New Zealand.

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“…Therefore, assessing the contributions of these areas, and the connectivity between populations, is necessary for efficient restoration (Jansson, Nilsson & Malmqvist, 2007; Zeigler & Whitledge, 2010). Moreover, identifying spawning areas and migration patterns will help with a better understanding of the species' life‐history traits, which is a central goal in any species conservation strategy (Takada & Tachihara, 2009; Egan, Hickford & Schiel, 2019).…”

Section: Introductionmentioning

confidence: 99%

Spawning areas and migration patterns in the early life history of Squalius cephalus (Linnaeus, 1758): Use of otolith microchemistry for conservation and sustainable management

Bounket

Tabouret

Gibert

et al. 2021

Aquatic Conservation

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In the context of the River Rhône restoration programme, the objective of this study was to assess the dispersal and population connectivity of the European chub, Squalius cephalus (Linnaeus, 1758) in a section of the natural, free‐flowing part of the lower River Rhône. The elemental water signatures for Sr:Ca and Ba:Ca were measured at seven stations within the river section, including its tributaries and backwaters, to determine whether they could be differentiated by microchemistry. From August to October the signatures differed among three sectors of the study reach: the Rhône; the Ardèche; and the backwaters. The elemental signatures of the otoliths of 178 young‐of‐the‐year (YOY) chub from the stations were measured to assess spawning areas and identify early migratory life histories. Analyses of otolith microchemistry identified the natal origin of 95% of the fish. Sr:Ca signatures of otoliths showed early downstream migration for 30.4% of the YOY chub; however, 70% of the fish recruited relatively close to their spawning origin suggesting a potential inshore retention of fish. The results showed (i) a non‐negligible contribution of the tributaries and backwaters in the recruitment of fish into the main channel; and (ii) the ability of chub to migrate over several kilometres during their first few months of life. This study shows that the combination of water and otolith microchemistry analyses of fish growth increases the understanding of fish life history. Moreover, the study revealed that half of the YOY fish from this river section came from the tributaries and the other half came from reproduction in the River Rhône (despite its high anthropization). These methods offer promising future applications of otolith microchemistry for river management in the context of ecological rehabilitation, especially to assess the effectiveness of measures applied in the restoration of floodplain connectivity for riverine fish population conservation.

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Understanding the life histories of amphidromous fish by integrating otolith‐derived growth reconstructions, post‐larval migrations and reproductive traits

Cited by 8 publications

References 47 publications

Interacting effects of density and temperature on fish growth rates in freshwater protected populations

Interacting effects of density and temperature on fish growth rates in freshwater protected populations

Mountains‐to‐the‐sea conservation: An island perspective

Spawning areas and migration patterns in the early life history of Squalius cephalus (Linnaeus, 1758): Use of otolith microchemistry for conservation and sustainable management

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