scholarly journals Environmental Variation and Habitat Use Affect Blue Catfish Low‐Frequency Electrofishing Catch Rates

2021 ◽  
Author(s):  
Zachary S. Moran ◽  
Joseph N. Stoeckel ◽  
Brandon K. Peoples
Keyword(s):  
Habitat Use ◽  
Low Frequency ◽  
Environmental Variation ◽  
Blue Catfish ◽  
Catch Rates

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
Low Frequency ◽  
The United States ◽  
Key Factors ◽  
Blue Catfish ◽  
Biological Variables ◽  
Natural Reproduction ◽  
Gill Net ◽  
Successful Establishment ◽  
Weak Negative Correlation ◽  
Catch Rates

<em>Abstract</em>.—The blue catfish <em>Ictalurus furcatus</em> is the largest ictalurid in the United States and is present in many reservoirs throughout Texas. While some populations are native, many fisheries are the result of introductions through stocking programs. These stockings can result in established fisheries while others fail to produce established populations. It is possible that a combination of physical, chemical, and biological variables produce an ideal environment for the successful establishment and survival of this species. The objective of this study was to identify the key factors that influence the success of blue catfish populations in Texas reservoirs. Thirty reservoirs distributed across Texas were sampled using gill nets and low-frequency electrofishing. Blue catfish abundance, condition, and natural reproduction were compared with multiple physicochemical and biological variables collected at each reservoir. Factor analysis indicated that both gill-net catch rates and low-frequency electrofishing catch rates were positively correlated to measures of primary productivity. The analysis also showed that gill-net catch rates increased with increasing reservoir surface area. The occurrence of natural reproduction showed a weak negative correlation to length of growing season. The results of this study provide further insight into the biology of blue catfish and provide managers with information that can be used to prioritize future stocking efforts.

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
Size Structure ◽  
Low Frequency ◽  
Relative Standard Error ◽  
Limited Information ◽  
Blue Catfish ◽  
Frequency Distributions ◽  
Gill Nets ◽  
Pulsed Dc ◽  
Gill Net ◽  
Catch Rates

<em>Abstract</em>.—Despite increasing popularity of blue catfish <em>Ictalurus furcatus</em> with anglers, effective management of blue catfish has been hindered by limited information on appropriate sampling methods. We compared the efficiency, precision, and accuracy of low-frequency pulsed-DC electrofishing and experimental gill nets for use in estimating relative population abundance and size structure in 12 reservoirs. Electrofishing yielded greater catch rates and lower mean relative standard error (RSE) than gill nets. Similarly, the number of samples necessary to achieve a RSE = 0.25 was lower with electrofishing in most reservoirs. Gill-net catch per unit effort (CPUE) and electrofishing CPUE were strongly correlated (<EM>P</EM> < 0.01), and length-frequency distributions were also similar between gear types in many reservoirs examined. Where they differed, there was no consistent pattern, suggesting that differences were due to low precision (caused by low numbers of fish captured) rather than gear bias. Our analysis indicated that both low-frequency pulsed-DC electrofishing and gill netting effectively measured relative abundance of blue catfish. In most cases, electrofishing was more efficient at estimating CPUE and size structure (requiring fewer samples to achieve comparable precision); thus, we recommend using this gear when estimating these parameters for reservoir blue catfish populations.

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
Population Dynamics ◽  
Channel Catfish ◽  
Mississippi River ◽  
Upper Mississippi River ◽  
Catch Per Unit Effort ◽  
Blue Catfish ◽  
Resource Monitoring ◽  
Flathead Catfish ◽  
Unit Effort ◽  
Catch Rates

<em>Abstract</em>.—Using Long Term Resource Monitoring Program data collected from impounded (Pool 26) and unimpounded (Open River) reaches of the upper Mississippi River, we investigated population dynamics of flathead catfish <em>Pylodictis olivaris</em>, channel catfish <em>Ictalurus punctatus</em>, and blue catfish <em>I. furcatus</em> from random sites located in side channel border (SCB) and main channel border (MCB) habitats. Objectives were to (1) compare trends (1993–2007) of three catfishes collected in Pool 26 and Open River reaches of the upper Mississippi River, and (2) provide needed information to managers on population dynamics through time using a binary gear approach of active (i.e., daytime electrofishing) and passive gears (hoopnetting). Active gears resulted in a higher catch per unit effort (CPUE) of all catfishes in each habitat–reach combination as compared to passive gears. Passive gears resulted in negligible catches of blue catfish and flathead catfishes (e.g., mean of <1 fish/net night). Catch per unit effort using active gear resulted in a greater number of channel catfish captured in Pool 26 compared to the Open River, with Open River SCB habitat having the lowest CPUE in most years. Blue catfish in the Open River had a higher CPUE using active gear as compared to Pool 26, with the Open River MCB having the greatest CPUE. Flathead catfish had a higher CPUE in MCB habitat compared to SCB habitat, with the Open River MCB having the highest CPUE in most years. However, declining trends in flathead catfish appears to be occurring in Open River habitats while trends in flathead catfish appear to be slightly increasing in Pool 26. The most common length-classes captured were substock and stock-sized fish regardless of habitat, species, or reach. Trends for channel catfish were easily determined due to high catch rates; however, more monitoring and enhanced sampling is needed to accurately assess flathead catfish and blue catfish trends and to accurately determine demographics for all three species.

scholarly journals Influence of environmental variation on spatial distribution and habitat-use in a benthic foraging marine predator

2021 ◽  
Vol 8 (10) ◽  
Author(s):  
Cassie N. Speakman ◽  
Andrew J. Hoskins ◽  
Mark A. Hindell ◽  
Daniel P. Costa ◽  
Jason R. Hartog ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Habitat Use ◽  
Large Scale ◽  
Environmental Variability ◽  
Southern Oscillation ◽  
Environmental Variation ◽  
Climate Indices ◽  
Marine Systems ◽  
Marine Predators ◽  
Eastern Australia

The highly dynamic nature of the marine environment can have a substantial influence on the foraging behaviour and spatial distribution of marine predators, particularly in pelagic marine systems. However, knowledge of the susceptibility of benthic marine predators to environmental variability is limited. This study investigated the influence of local-scale environmental conditions and large-scale climate indices on the spatial distribution and habitat use in the benthic foraging Australian fur seal ( Arctocephalus pusillus doriferus ; AUFS). Female AUFS provisioning pups were instrumented with GPS or ARGOS platform terminal transmitter tags during the austral winters of 2001–2019 at Kanowna Island, south-eastern Australia. Individuals were most susceptible to changes in the Southern Oscillation Index that measures the strength of the El Niño Southern Oscillation, with larger foraging ranges, greater distances travelled and more dispersed movement associated with 1-yr lagged La Niña-like conditions. Additionally, the total distance travelled was negatively correlated with the current year sea surface temperature and 1-yr lagged Indian Ocean Dipole, and positively correlated with 1-yr lagged chlorophyll- a concentration. These results suggest that environmental variation may influence the spatial distribution and availability of prey, even within benthic marine systems.

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
International Symposium ◽  
Size Structure ◽  
River System ◽  
Population Characteristics ◽  
Blue Catfish ◽  
Growth And Survival ◽  
Conservation Ecology ◽  
Flathead Catfish ◽  
Management Actions ◽  
Catch Rates

<em>Abstract</em>.—Catfish are popular recreational fish in Alabama, and management interest has been rising. We hypothesized that tailwater habitat more closely resembling lotic conditions would provide more suitable conditions for catfishes compared to impounded habitats. We examined and compared population characteristics, including abundance, age and size structure, growth, and survival of blue catfish <em>Ictalurus furcatus</em>, channel catfish <em>I. punctatus</em>, and flathead catfish <em>Pylodictis olivaris</em> between tailwater and reservoir habitats in a section of the Coosa River in 2001–2002. Coosa River system tailwater habitats appear to generally provide higher quality environments for abundance and growth of catfishes than reservoir habitat, although results were often not consistent among species. We found no differences for many comparisons of stock descriptors between tailwater and reservoir habitat. We found that blue catfish were larger (48 mm total length larger) and flathead catfish electrofishing catch rates were higher (13 fish/h greater) in tailwater areas. Catfish populations in the Coosa River were characterized by slow growth and high longevity, findings in accord with other recent otolith-based age analyses from populations in the Southeast. All species had moderate to high annual survival (57–88%), likely indicating light exploitation levels. Catfish populations in this section of the Coosa River appear robust, and the tendency for these dam tailwaters to have higher quality catfish populations may warrant management actions to enhance/sustain these fisheries.

Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
Habitat Use ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Mississippi River ◽  
Early Life ◽  
Anthropogenic Activities ◽  
Main Channel ◽  
Low Velocity ◽  
Middle Mississippi River ◽  
Catch Rates

<em>Abstract</em>.—Channel catfish <em>Ictalurus punctatus</em> are a major recreational and commercially important large river species. However, anthropogenic activities have heavily degraded the majority of riverine catfish habitats. To maintain catfish populations, an understanding of channel catfish early-life habitat use is necessary. We quantified habitat use of juvenile channel catfish in the middle Mississippi River from 2004 through 2007 by trawling in main channel, channel border, island, and artificial structure habitat (i.e., river training structures or wing dikes) features throughout the sampling reach (<EM>N</EM> = 878 trawls; <EM>N</EM> = 538 juvenile channel catfish). Channel catfish occurred most frequently in island and off-channel habitats. Few juvenile channel catfish were trawled in the main channel. All macrohabitat features were used by a broad size range of juvenile channel catfish, with the exception of the main channel, where only larger juvenile channel catfish were captured. Within each habitat, juvenile channel catfish catch rates were highest in sand substrate, low velocity, and shallow depths. Channel catfish in the middle Mississippi River use a variety of habitats during early life. Maintaining existing habitats, creating habitats with these attributes, and coupling this with proper management will foster sustainability of the channel catfish population at current commercial and recreational fishing levels in the middle Mississippi River.

Abiotic affinities and spatiotemporal distribution of the endangered smalltooth sawfish, Pristis pectinata, in a south-western Florida nursery

2011 ◽  
Vol 62 (10) ◽  
pp. 1165 ◽  
Author(s):  
Gregg R. Poulakis ◽  
Philip W. Stevens ◽  
Amy A. Timmers ◽  
Tonya R. Wiley ◽  
Colin A. Simpfendorfer
Keyword(s):  
Habitat Use ◽  
Early Life History ◽  
Marine Species ◽  
Population Recovery ◽  
Marine Fish Species ◽  
Recovery Planning ◽  
The Usa ◽  
Catch Rates ◽  
Size At Birth ◽  
Pristis Pectinata

Understanding how endangered marine species rely on coastal habitats is vital for population recovery planning. The smalltooth sawfish (Pristis pectinata) is one of several critically endangered sawfishes worldwide known to use estuaries and rivers during their early life history. In a Florida estuary designated as critical habitat by the USA government, juveniles were monitored to characterise seasonality, recruitment, and habitat use. Stretched total length ranged from 671 to 2172 mm (n = 137, mean = 1248 mm). Sawfish were captured year round. Captures of neonates with embryonic rostral sheaths allowed refinement of the size at birth (671–812 mm) and confirmed a protracted timing of parturition (November–July), which peaked between April and May. Although sampling occurred throughout the estuary, five locations had the greatest catch rates. Most juvenile sawfish had an affinity for water <1 m deep, water >30°C, dissolved oxygen >6 mg L–1, and salinity between 18 and 30. Greater catch rates for sawfish >1 year old were associated with shoreline habitats with overhanging vegetation such as mangroves. These results detail habitat use within a recognised nursery that can be used for conservation of the first endangered marine fish species in the USA.

Summer Bat Habitat Use and Forest Characteristics in Managed Northeastern Forests

2021 ◽  
Author(s):  
Megan E Gallagher ◽  
Shannon L Farrell ◽  
René H Germain ◽  
Vanessa G Rojas
Keyword(s):  
Forest Management ◽  
Habitat Use ◽  
Management Practices ◽  
Low Frequency ◽  
Canopy Cover ◽  
Managed Forests ◽  
Forest Management Practices ◽  
Management Actions ◽  
Mature Stands ◽  
Forest Managers

Abstract There has been limited research investigating summer habitat use of bats in managed forests in the northeastern United States. Consequently, there is limited knowledge to inform forest managers seeking to maintain or enhance bat habitat, particularly for several federally threatened, endangered, or candidate species. In summer 2017–2018, we conducted repeated acoustic surveys to determine what forest characteristics are associated with bat habitat use in managed forests in the Adirondack region of upstate New York. We modeled detection corrected probability of occupancy for bats in three phonic groups: high, mid, and low frequency. Across all phonic groups, probability of occupancy increased with decreasing canopy cover. High-, mid-, and low-frequency bats were more likely to use recently harvested sites (&lt;10 years since harvest). High-frequency bats also used mature stands. Midfrequency bats demonstrated a preference for further distances from forest roads, whereas low-frequency bats preferred areas with a higher percentage of clutter. Our results suggest that tending and regenerating even-aged forest management practices can provide habitat for foraging bats in the Adirondacks. Study Implications: Several northeastern bat species have been granted or are candidates for federal endangered or threatened status; therefore, forest managers may increasingly need to consider how forest management actions affect bats. This research elucidates the effects of forest management practices on summer bat habitat use in northeastern forests. Foresters can use this information to limit negative impacts to bat habitat from management actions and identify management opportunities that protect or enhance bat habitat. All bat species we studied showed higher probability of use in stands with lower percent canopy cover, including stands recently harvested with the shelterwood method. However, special attention is owed to postharvest management to maintain suitable conditions, particularly concerning American beech. It is common in northeastern forests for beech to sprout root suckers following harvesting activities that can result in dense thickets, impeding bat flight abilities and limiting habitat connectivity for bats and other wildlife. Our findings also show that several bat species forage in mature stands that have a natural open understory and in areas around or near waterbodies. Consequently, even-aged tending and regeneration techniques in hardwood and mixed-wood forests, coupled with maintenance of nearby aquatic habitats, can provide habitat for bats.

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