Hydrology and water temperature influence recruitment dynamics of the threatened silver perch Bidyanus bidyanus in a regulated lowland river

2019 ◽  
Vol 70 (9) ◽  
pp. 1333 ◽  
Author(s):  
Zeb Tonkin ◽  
Ivor Stuart ◽  
Adrian Kitchingman ◽  
Jason D. Thiem ◽  
Brenton Zampatti ◽  
...  
Keyword(s):  
Juvenile Fish ◽  
High Water ◽  
River Regulation ◽  
Fish Populations ◽  
Extrinsic Factors ◽  
Spawning Period ◽  
Murray Darling Basin ◽  
Class Strength ◽  
Age Structured ◽  
Key Aspects

Understanding the influence of extrinsic factors such as hydrology and hydraulics on recruitment provides essential insight to inform management of fish populations. The critically endangered silver perch Bidyanus bidyanus is a long-lived, potamodromous pelagophil endemic to Australia’s Murray–Darling Basin. Declines of this species are often attributed to river regulation, although quantitative studies linking hydrology and hydraulics to key aspects of its life cycle are sparse. We used a multidecadal age-structured dataset collected from a locally abundant population of silver perch to quantify the relative importance of different abiotic drivers on year-class strength (recruitment). Silver perch recruited across highly variable hydrological conditions. The strongest year classes were associated with a combination of low to average river discharge (i.e. within channel) and high water temperatures over the peak spawning period, followed in the next year by extended high flows and widespread flooding that promoted survival of age-1+ juvenile fish. We suggest that conditions affecting the growth and dispersal of juvenile fish, in addition to the spawning period, are critical in governing recruitment dynamics. This highlights the need for multiyear flow plans for freshwater fish populations.

Reproduction and year-class strength of the Atlantic tomcod (Microgadus tomcod) in the Sainte-Anne River, at La Pérade, Quebec

1990 ◽  
Vol 68 (7) ◽  
pp. 1350-1359 ◽  
Author(s):  
Réjean Fortin ◽  
Martin Léveillé ◽  
Paul Laramée ◽  
Yves Mailhot
Keyword(s):  
High Water ◽  
Environmental Variable ◽  
Downstream Migration ◽  
Water Levels ◽  
Upstream Migration ◽  
Spawning Period ◽  
Saint Lawrence River ◽  
Spawning Stock ◽  
Class Strength ◽  
Microgadus Tomcod

Experimental catches of a fyke-net fishery operated in the Sainte-Anne River during the 1980–1981 to 1983–1984 spawning seasons showed that although the majority of adult tomcod migrate upstream during rising tide, significant numbers do so against the tidal current. Most spawners return to the Saint Lawrence River during a falling tide. In the first 2 years, peak upstream migration occurred during the second half of December, and in the last 2 years, early in the second half of January. The date of peak upstream migration is significantly correlated with September and October air temperature in the summer habitat. Peak downstream migration of spawned-out adults occurred during the second half of January in 3 years and on 1 February in 1 year. The peak of the upstream and downstream migration of males and females generally occurred on the same dates. The spawning period extends minimally from mid-December to mid-February, but probably peaks close to the maximum of the downstream migration. The length and age composition of the Sainte-Anne River tomcod spawning stock remained relatively stable between the 1980–1981 and the 1983–1984 seasons. For the 1975–1976 to 1981–1982 period, the environmental variable to which year-class strength showed the highest parametric correlation was mean December Sainte-Anne River discharge. Stronger year-classes were produced in years of high water levels and discharge during the spawning period.

scholarly journals Indicators of AEI Applied to the Delaware Estuary

2002 ◽  
Vol 2 ◽  
pp. 169-189 ◽  
Author(s):  
Lawrence W. Barnthouse ◽  
Douglas G. Heimbuch ◽  
Vaughn C. Anthony ◽  
Ray W. Hilborn ◽  
Ransom A. Myers
Keyword(s):  
Meta Analysis ◽  
Juvenile Fish ◽  
Fish Populations ◽  
Weight Of Evidence ◽  
Data Sets ◽  
Delaware Estuary ◽  
Fish Stocks ◽  
Trends Analysis ◽  
Definition Of

We evaluated the impacts of entrainment and impingement at the Salem Generating Station on fish populations and communities in the Delaware Estuary. In the absence of an agreed-upon regulatory definition of “adverse environmental impact” (AEI), we developed three independent benchmarks of AEI based on observed or predicted changes that could threaten the sustainability of a population or the integrity of a community.Our benchmarks of AEI included: (1) disruption of the balanced indigenous community of fish in the vicinity of Salem (the “BIC” analysis); (2) a continued downward trend in the abundance of one or more susceptible fish species (the “Trends” analysis); and (3) occurrence of entrainment/impingement mortality sufficient, in combination with fishing mortality, to jeopardize the future sustainability of one or more populations (the “Stock Jeopardy” analysis).The BIC analysis utilized nearly 30 years of species presence/absence data collected in the immediate vicinity of Salem. The Trends analysis examined three independent data sets that document trends in the abundance of juvenile fish throughout the estuary over the past 20 years. The Stock Jeopardy analysis used two different assessment models to quantify potential long-term impacts of entrainment and impingement on susceptible fish populations. For one of these models, the compensatory capacities of the modeled species were quantified through meta-analysis of spawner-recruit data available for several hundred fish stocks.All three analyses indicated that the fish populations and communities of the Delaware Estuary are healthy and show no evidence of an adverse impact due to Salem. Although the specific models and analyses used at Salem are not applicable to every facility, we believe that a weight of evidence approach that evaluates multiple benchmarks of AEI using both retrospective and predictive methods is the best approach for assessing entrainment and impingement impacts at existing facilities.

Hudson River Fishes and their Environment

2006 ◽  
Keyword(s):  
Anthropogenic Impact ◽  
Juvenile Fish ◽  
Hudson River ◽  
Plant Macrofossils ◽  
Organic Content ◽  
Fish Populations ◽  
Estuarine Ecosystem ◽  
Staten Island ◽  
Jamaica Bay ◽  
Pollen And Spores

<em>Abstract.</em>—Hudson riverine and coastal marshes provide a paleoecological archive consisting of information on climate and land use at both the local and watershed scales. The timing of formation of these marshes is documented using accelerator mass spectrometry (AMS) <sup>14</sup>C dating of identified plant macrofossils in basal marsh organic sediments. While the Staten Island marsh is oldest and dates to 11,000 years before present (BP), Piermont, Iona, and Croton marshes date to the mid-Holocene, and the Jamaica Bay marshes formed most recently. Pollen and spores, charcoal, and plant macrofossils in the marsh sediments document marked climatic shifts as well as anthropogenic impact in the region. Assessment of the inorganic and organic content of the sediments in the marshes reveals a pattern of decreasing inorganic supply with the arrival of the Europeans, possibly due to the construction of numerous Hudson River tributary dams. Piermont Marsh, because of its sensitive location in the Hudson River, records droughts and wet intervals through species which have specific salinity affinities. Throughout the marsh records, the ragweed <em>Ambrosia </em>pollen rise marks the anthropogenic impact at the landscape scale. The recorded changes in hydrology and salinity that occurred throughout the centuries and millennia would have had profound effects throughout the food web and estuarine ecosystem. Fish populations would have been affected by changes in the food supply due to shifts in runoff affecting turbidity and light penetration in the river. Local vegetation changes within marshes may also have affected juvenile fish populations.

Freshwater, Fish and the Future: Proceedings of the Global Cross-Sectoral Conference

2016 ◽  
Keyword(s):  
Fish Populations ◽  
Native Fish ◽  
Partnership Model ◽  
European Settlement ◽  
Southeastern Australia ◽  
Murray Darling Basin ◽  
Wide Range ◽  
Funding Opportunities ◽  
Funding Cuts

<em>Abstract</em> .—The Murray–Darling basin (MDB) in southeastern Australia, covers 1.1 million km<sup>2</sup>, involves six partner jurisdictions with a myriad of different government agencies, and, hence, provides an excellent example of the complexities of multijurisdictional management across a range of social and political tiers. In the MDB, fish and fisheries compete for water with agriculture, which is the traditional water user and is driven by national economics. Murray–Darling basin rivers are now highly regulated and generally in poor health, with native fish populations estimated to be at only about 10% of their pre-European settlement abundances. All native commercial fisheries are now closed, and the only harvest is by a recreational fishery. The six partner jurisdictions developed a Native Fish Strategy (NFS) to rehabilitate native fish populations to 60% of pre-European settlement levels after 50 years of implementation by addressing priority threats through a coordinated, long-term, whole-of-fish-community (all native fishes) approach. As there are a wide range of stakeholders, broad engagement was needed at a broad range of government and community levels. The NFS funding was discontinued after 10 years, not because of its lack of successes or project governance, but due to jurisdictional political changes and funding cuts that resulted in a failure of the collaborative funding structure. The withdrawal of considerable funding by one jurisdiction led to collective decline in monetary contributions and posed a threat to the multijurisdictional structures for both water and natural resource management (NRM) within the MDB. As a consequence, there was a review and reduction in NRM programs and a subsequent reduction in focus to the core business of water delivery. Reflection on the NFS, however, provides some useful insights as to the successes (many) and failures (funding) of this partnership model. Overall, the strategy and its structure was effective, as exhibited by an audit of outputs, outcomes, and networks; by the evident ongoing advocacy by NRM practitioners and the community; and by the continuation of ideas under other funding opportunities. This has provided a powerful legacy for future management of fishes in the MDB.

Conservation of an inauspicious endangered freshwater fish, Murray hardyhead (Craterocephalus fluviatilis), during drought and competing water demands in the Murray–Darling Basin, Australia

2013 ◽  
Vol 64 (9) ◽  
pp. 792 ◽  
Author(s):  
Iain M. Ellis ◽  
Daniel Stoessel ◽  
Michael P. Hammer ◽  
Scotte D. Wedderburn ◽  
Lara Suitor ◽  
...  
Keyword(s):  
Freshwater Fish ◽  
Environmental Water ◽  
River Regulation ◽  
Isolated Populations ◽  
Conservation Units ◽  
European Settlement ◽  
Water Demands ◽  
Murray Darling Basin ◽  
Conservation Concern ◽  
Australian Freshwater

Approximately 40% of Australian freshwater fish species are of conservation concern, largely because of the impacts of river regulation, habitat fragmentation and alien fishes. Murray hardyhead is a threatened fish endemic to the southern Murray–Darling Basin in Australia, which has declined significantly in range and abundance since European settlement. Conservation of the species has relied largely on environmental watering of off-channel wetlands where isolated populations persist. This became problematic during recent drought (1997–2010) because of competing demands for limited water, and resentment towards environmental watering programs from communities that themselves were subject to reduced water entitlements. In response, emergency conservation measures prioritised the delivery of environmental water to minimise applied volumes. Captive maintenance programs were established for fish rescued from four genetically distinct conservation units, with varying levels of breeding success. Several translocations of wild and captive-bred fish to surrogate refuge sites were also conducted. Future recovery of the species should secure existing natural and stocked populations and translocate fish to additional appropriate sites to spread risk and reinstate natural pathways for dispersal. The approach to the conservation of Murray hardyhead during extreme environmental conditions provides insights to inform the management of fishes in other drought-prone regions of the world.

Does the quantity and timing of fresh water flowing into a dry tropical estuary affect year-class strength of barramundi (Lates calcarifer)?

2004 ◽  
Vol 55 (8) ◽  
pp. 787 ◽  
Author(s):  
Jonathan Staunton-Smith ◽  
Julie B. Robins ◽  
David G. Mayer ◽  
Michelle J. Sellin ◽  
Ian A. Halliday
Keyword(s):  
Fresh Water ◽  
River Flow ◽  
Juvenile Fish ◽  
Early Life History ◽  
Relative Strength ◽  
Estuarine Fish ◽  
Causal Mechanism ◽  
Lates Calcarifer ◽  
Nursery Habitats ◽  
Class Strength

The influence of fresh water flowing into estuaries on biological processes, such as recruitment of juvenile fish, is poorly understood, but important if freshwater resources are to be managed sustainably. Typically, lagged correlations between freshwater flows and fisheries production (i.e. catch) are used to support speculation that flows affect the survival of fish (and thus year-class strength) during their first year of life. The present study compares the relative strength of year classes in an estuarine fish population with two indices of fresh water flowing into the estuary, river flow and coastal rainfall. Year-class strength was estimated from a subset of the age structure of commercially caught adult barramundi (Lates calcarifer), which were sampled at seafood processors for three consecutive years. Strong and coherent fluctuations in year-class strength were observed. Positive correlations were found between the abundance of year classes (accounting for age) and quantity of fresh water flowing into the estuary during spring and summer, when barramundi spawn and young-of-the-year recruit to nursery habitats. Regression analysis was used to explore the relationships between year-class strength and environmental variables. A possible, but unproven, causal mechanism for the relationship is that the quantity of fresh water flowing into the estuary during spring and summer influences the survival of early life-history stages of barramundi (i.e. juvenile recruitment) by altering accessibility, productivity and or carrying capacity of nursery habitats.

The role of anthropogenic impact and natural habitat conditions in the reproduction of semi-passable and mass river fish of the lower reaches of the Volga River according to retrospective data

2021 ◽  
pp. 34-46
Author(s):  
Natalia Ivanovna Chavychalova ◽  
Dina Germanovna Taradina ◽  
O.M. Vasilchenko ◽  
Raigul Sadyakhovna Mukhanova
Keyword(s):  
Water Content ◽  
River Flow ◽  
Juvenile Fish ◽  
Natural Habitat ◽  
Hydrological Regime ◽  
High Water ◽  
Food Competition ◽  
Volga River ◽  
Spawning Grounds ◽  
River Fish

A retrospective review of the main factors that caused the decline in the reproduction of semi-passable fish in the lower reaches of the Volga River is given. Long-term data on the yield of juvenile semi-passable and river fish are presented, on the basis of which the current state of natural reproduction of roach, carp is estimated as low; bream, bluefin and perch — satisfactory; crucian carp, gaster and rudd — safe. Overregulation of the Volga River flow near Volgograd violated the natural conjugacy of water and temperature regimes. In the regulated period, the timing of the onset of spawning temperature in most cases is ahead of the flooding of the strips. The lag of the delta spawning grounds begins when the runoff is less than 120 km³ and reaches the maximum values (up to 27 days) in years with extremely low water content. The delay in flooding of spawning grounds in conditions of unsatisfactory water content leads to the accumulation of producers in limited areas of strips and simultaneous spawning of fish with different ecology. This leads to increased food competition of the larvae and reduced survival. After the flow was regulated, the rates of rise and fall of the hollow waters increased by 2 times, the hatching of the larvae, as a rule, coincided with the onset of the flow of the hollow waters. The mass removal of larvae into the delta watercourses at the early stages of ontogenesis, due to their lack of viability in river conditions, leads to a decrease in the productivity of spawning grounds. In the modern period (2003– 2019), due to the predominance of unfavorable hydrological regime, the duration of high water and flooding of the poloi years, and in order to clarify the yield of juvenile fish in the lower reaches of the Volga, its accounting was carried out not only in the poloi of the delta, but also in the coastal watercourses (where a large number of larvae and fry that rolled off the poloi and from local spawning), in the kultuch zone and on the poloi of the lower zone of the Volga-Akhtuba floodplain.

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