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

2011 ◽  
Keyword(s):  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Size Structure ◽  
Management Strategies ◽  
Growth Increment ◽  
Stocking Rate ◽  
Lake Productivity ◽  
Growth Increments ◽  
The Many ◽  
Stocking Rates

<em>Abstract</em>.—Large fingerling (>175 mm total length) channel catfish<em> Ictalurus punctatus </em>are usually stocked to maintain put-grow-take channel catfish fisheries in small lakes and impoundments. Because these stockings are costly, stocking the appropriate number of fish is essential in minimizing costs and creating a desirable fishery. Appropriate stocking rates may vary among lakes due to differences in lake productivity, fishing and natural mortality of channel catfish, and other factors. Growth rate is responsive to the many processes that exist in lakes and is commonly density-dependent, making it a desirable parameter for assessing stocking rates. Two growth-increment indices were developed that compared size-specific growth increments within a population to statewide growth-increment percentiles for Missouri. These indices were used to determine responses in channel catfish growth rates in seven lakes where stocking rates had been either substantially reduced or increased. Sampling channel catfish populations after 3 years under the new stocking rate showed that growth increments and size structure did not substantially change. Both indices were correlated with growth increments and provided a way to assess growth relative to other populations. The lack of response of channel catfish populations to the new stocking rates suggests that these populations will not quickly respond to changes in stocking rate. The growth increment indices should assist managers in determining appropriate stocking rates and other management strategies.

Bio-economic evaluation of grazing-management options for beef cattle enterprises during drought episodes in semiarid grasslands of northern Australia

2021 ◽  
Vol 61 (1) ◽  
pp. 72
Author(s):  
M. K. Bowen ◽  
F. Chudleigh ◽  
D. Phelps
Keyword(s):  
Beef Cattle ◽  
Management Strategies ◽  
Grazing Management ◽  
Economic Modelling ◽  
Stocking Rate ◽  
Northern Australia ◽  
Management Scenarios ◽  
Management Options ◽  
Herd Management ◽  
Stocking Rates

Context The large inter-annual and decadal rainfall variability that occurs in northern Australian rangelands poses major challenges for the profitable and sustainable management of grazing businesses. Aims An integrated bio-economic modelling framework (GRASP integrated with Breedcow and Dynama (BCD)) was developed to assess the effect of alternative grazing-management options on the profitability and sustainability of a beef cattle enterprise in the central-western Mitchell grasslands of Queensland over a multi-decadal time period. Methods Four grazing-management strategies were simulated over a 36-year period (1982–2017) in the GRASP pasture-growth model, using historic climate records for Longreach in central-western Queensland. Simulated annual stocking rates and steer liveweight-gain predictions from GRASP were integrated with published functions for mortality and conception rates in beef-breeding cattle in northern Australia, and then used to develop dynamic BCD cattle-herd models and discounted cash-flow budgets over the last 30 years of the period (1988–2017), following a 6-year model-equilibration period. The grazing-management strategies differed in the extent to which stocking rates were adjusted each year, from a common starting point in Year 1, in response to changes in the amount of forage available at the end of the summer growing season (May). They ranged from a low flexibility of ‘Safe stocking rate’ (SSR) and ‘Retain core herd’ (RCH) strategies, to a moderate flexibility of ‘Drought responsive’ (DR), to a ‘Fully flexible’ (FF) strategy. The RCH strategy included the following two herd-management scenarios: (1) ‘Retain herd structure’, where a mix of cattle were sold in response to low pasture availability, and (2) ‘Retain core breeders’, where steers were sold before reducing the breeder herd. Herd-management scenarios within the DR and FF strategies examined five and four options respectively, to rebuild cattle numbers and utilise available pasture following herd reductions made in response to drought. Key results Property-level investment returns expressed as the internal rate of return (IRR) were poor for SSR (–0.09%) and the three other strategies when the herd was rebuilt following drought through natural increase alone (RCH, –0.27%; DR, –1.57%; and FF, –4.44%). However, positive IRR were achieved when the DR herd was rebuilt through purchasing a mix of cattle (1.70%), purchasing pregnant cows (1.45%), trading steers (0.50%) or accepting cattle on agistment (0.19%). A positive IRR of 0.70% was also achieved for the FF property when purchasing a mix of cattle to rebuild numbers. However, negative returns were obtained when either trading steers (–2.60%) or agistment (–0.11%) scenarios were applied to the FF property. Strategies that were either inflexible or highly flexible increased the risk of financial losses and business failure. Property-level pasture condition (expressed as the percentage of perennial grasses; %P) was initially 69%P and was maintained under the DR strategy (68%P; average of final 5 years). The SSR strategy increased pasture condition by 25% to 86%P, while the RCH and FF strategies decreased pasture condition by 29% (49%P) and 65% (24%P) respectively. Conclusions In a highly variable and unpredictable climate, managing stocking rates with a moderate degree of flexibility in response to pasture availability (DR) was the most profitable approach and also maintained pasture condition. However, it was essential to economic viability that the property was re-stocked as soon as possible, in line with pasture availability, once good seasonal conditions returned. Implications This bio-economic modelling analysis refines current grazing-management recommendations by providing insights into both the economic and sustainability consequences of stocking-rate flexibility in response to fluctuating pasture supply. Caution should be exercised in recommending either overly conservative safe stocking strategies that are inflexible, or overly flexible stocking strategies, due to the increased risk of very poor outcomes.

scholarly journals A Comprehensive Annotation of the Channel Catfish (Ictalurus punctatus) T Cell Receptor Alpha/Delta, Beta, and Gamma Loci

2021 ◽  
Vol 12 ◽  
Author(s):  
Jonathan Crider ◽  
Sylvie M. A. Quiniou ◽  
Kristianna L. Felch ◽  
Kurt Showmaker ◽  
Eva Bengtén ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Gene Annotation ◽  
Gene Segment ◽  
Cell Receptor ◽  
Gene Duplications ◽  
The Many ◽  
Segment Database

The complete germline repertoires of the channel catfish, Ictalurus punctatus, T cell receptor (TR) loci, TRAD, TRB, and TRG were obtained by analyzing genomic data from PacBio sequencing. The catfish TRB locus spans 214 kb, and contains 112 TRBV genes, a single TRBD gene, 31 TRBJ genes and two TRBC genes. In contrast, the TRAD locus is very large, at 1,285 kb. It consists of four TRDD genes, one TRDJ gene followed by the exons for TRDC, 125 TRAJ genes and the exons encoding the TRAC. Downstream of the TRAC, are 140 TRADV genes, and all of them are in the opposite transcriptional orientation. The catfish TRGC locus spans 151 kb and consists of four diverse V-J-C cassettes. Altogether, this locus contains 15 TRGV genes and 10 TRGJ genes. To place our data into context, we also analyzed the zebrafish TR germline gene repertoires. Overall, our findings demonstrated that catfish possesses a more restricted repertoire compared to the zebrafish. For example, the 140 TRADV genes in catfish form eight subgroups based on members sharing 75% nucleotide identity. However, the 149 TRAD genes in zebrafish form 53 subgroups. This difference in subgroup numbers between catfish and zebrafish is best explained by expansions of catfish TRADV subgroups, which likely occurred through multiple, relatively recent gene duplications. Similarly, 112 catfish TRBV genes form 30 subgroups, while the 51 zebrafish TRBV genes are placed into 36 subgroups. Notably, several catfish and zebrafish TRB subgroups share ancestor nodes. In addition, the complete catfish TR gene annotation was used to compile a TR gene segment database, which was applied in clonotype analysis of an available gynogenetic channel catfish transcriptome. Combined, the TR annotation and clonotype analysis suggested that the expressed TRA, TRB, and TRD repertoires were generated by different mechanisms. The diversity of the TRB repertoire depends on the number of TRBV subgroups and TRBJ genes, while TRA diversity relies on the many different TRAJ genes, which appear to be only minimally trimmed. In contrast, TRD diversity relies on nucleotide additions and the utilization of up to four TRDD segments.

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

2011 ◽  
Keyword(s):  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Management Strategies ◽  
Missouri River ◽  
The United States ◽  
Common Species ◽  
Main Stem ◽  
Commercial Fishing ◽  
Commercial Species ◽  
Fish Harvest

Abstract.—Channel catfish <em>Ictalurus punctatus</em> are an important recreational and commercial species in much of the United States. Catfish species accounted for a large portion of angler harvest in the years prior to, and immediately after, main-stem reservoir construction on the Missouri River. Since impoundment, fish communities and angler preferences have shifted. Although channel catfish have remained abundant and are among the most common species in population surveys, they are no longer heavily targeted by anglers. We compared channel catfish population metrics, management, and angler creel surveys among the six main-stem Missouri River reservoirs in order to better understand and promote these fisheries. Proportional size distributions ranged from 35 to 79, and relative weights ranged from 84 to 93 among reservoirs in 2009. Channel catfish mean lengths at age were highest in Gavins Point, the lowermost reservoir, and tended to decrease upstream. Estimates of total annual mortality from catch-curve analysis ranged from 12% to 25%. Several reservoirs had a channel catfish population consisting of fish with all year-classes present through age 20, suggesting low exploitation, and one channel catfish from Garrison Reservoir was estimated to be age 28. Gavins Point and Fort Peck are the only reservoirs regulated with harvest limits and bans on commercial fishing. Percentage of interviewed anglers specifically targeting channel catfish ranged from less than 1.0% to 9.5% among reservoirs, and catfish accounted for less than 3.0% of overall estimated fish harvest for all reservoirs combined. These reservoirs could support significant increases in channel catfish harvest. Additional research and creative management strategies are needed to better promote these underutilized fisheries.

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

2011 ◽  
Keyword(s):  
Size Distribution ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Pearson Correlation ◽  
Supply And Demand ◽  
Relative Weight ◽  
Growth Index ◽  
Multiple Regression Model ◽  
Continuous Variables ◽  
Stocking Rate

<em>Abstract</em>.—Most channel catfish <em>Ictalurus punctatus </em>management in Iowa has revolved around annual maintenance stockings. Issues with supply and demand of advanced fingerling channel catfish necessitate a more proactive approach to Iowa channel catfish management. We performed mark–recapture population estimates on 17 channel catfish populations during summer from 2004 to 2008 using tandem set hoop nets baited with soybean cake. We used Pearson correlation analysis to test potential relationships between lake population density and biomass and numerous continuous variables, including channel catfish size distribution indices (proportional size distribution and proportional size distribution-preferred), catch per unit effort (CPUE), relative weight (<em>W<sub>r</sub></em>), and stocking rate. Channel catfish CPUE was significantly correlated with density. Channel catfish size distribution was negatively correlated with density, and negative density-dependent effects on growth (as indexed by the relative growth index [RGI]) were observed. Both density and CPUE were negatively correlated with RGI. Relative weight throughout the length range of channel catfish populations was positively correlated with RGI. A multiple regression model significantly explained channel catfish density, whereby <em>W<sub>r </sub></em>of channel catfish less than 508 mm total length and channel catfish stocking rate explained 60% and 17% of the variability, respectively. The ability to anticipate channel catfish density and how it relates to population characteristics such as stocking rate will be a valuable asset to fishery managers.

An evaluation of three aerial pasture development methods on the Northern Tablelands of New South Wales, in terms of herbage on offer, botanical composition and animal performance

1987 ◽  
Vol 27 (3) ◽  
pp. 389 ◽  
Author(s):  
PM Dowling ◽  
GG Robinson ◽  
RD Murison
Keyword(s):  
Management Strategies ◽  
Late Summer ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Sheep Grazing ◽  
South Wales ◽  
Dead Material ◽  
The Difference ◽  
Development Methods ◽  
Stocking Rates

Herbage mass on offer, botanical composition and livestock production of sheep grazing 3 types of pastures developed by 'aerial' methods at 3 stocking rates (5, 7.5 and 10 sheep/ha) were compared in a 3-year grazing trial at Glen Innes, N.S.W., during 1972-75. The pastures were: resident grass-white clover (F), resident pasture plus surface sown grass (SF), and as for SF but with herbicide application prior to surface sowing ofgrass (HSF). All pasture treatments had equivalent rates of superphosphate applied. The sowing effect and the herbicide effect were statistically analysed by contrasting the pasture treatments: SF-F, HSF-SF, respectively. The SF-F contrast showed that herbage on offer of the sown grasses on the SF pasture was greater, and this difference increased with time. Legume herbage on offer was greater on the SF pasture though it declined with time, and exhibited seasonal variation. The HSF-SF contrast indicated that herbage on offer: of sown grass was greater on the HSF pasture and increased with time; of the herbs component was greater on the HSF pasture during the initial and final stages of the experiment; oflegume was greater on the HSF pasture but the difference declined with time; of resident grass was greater on the SF pasture but the difference declined with time; and of dead material was consistently greater on the SF pasture. The contrasts for the resident grasses and dead material components varied seasonally. Herbage on offer of all pasture components declined as stocking rate was increased. Patterns of decline varied with pasture component and pasture treatment. Mean sheep liveweights were influenced by pasture treatment, with sheep on the HSF pasture being the heaviest, and those on the F pasture, the lightest. Increasing stocking rate decreased mean sheep liveweights on pastures F and SF but increased mean sheep liveweights on the HSF pasture. Liveweight declines were least for sheep grazing the F and SF pastures and liveweight increases were greatest on the HSF pasture during late summer-autumn. Greasy wool production per sheep was greatest on the HSF pasture during 1972-73 but thereafter there were no significant differences between treatments. We conclude that, although animal production was increased by the introduction of sown grasses in the short term, the level of superiority was not as great as expected. Changes in management strategies may be required if the greater production achieved is to be sustained.

Evaluation of natural annual pastures at Trangie in central western New South Wales. 1. Sheep production

1973 ◽  
Vol 13 (62) ◽  
pp. 238
Author(s):  
RJ Campbell ◽  
DG Saville ◽  
GE Robards
Keyword(s):  
New South ◽  
Management Strategies ◽  
New South Wales ◽  
Grazing Pressure ◽  
Stocking Rate ◽  
Wool Production ◽  
South Wales ◽  
Sheep Production ◽  
Stocking Rates ◽  
Sheep Wool

Natural annual pasture at Trangie, New South Wales, was set stocked from August, 1967 to December 1970 at rates of 2.5, 3.7, and 4.9 merino wethers per ha to determine an optimum stocking rate for the pasture type. All stocking rates were supported without the necessity to hand feed any sheep. Wool production per head was reduced significantly by increased stocking rate in 1968, but not in 1969 and 1970. The suppression of barley grass at the higher stocking rates appeared to benefit animal production in 1969. Substitution of portion of the natural annual pasture with areas of lucerne or natural perennial pasture was also investigated and found to be ineffective in increasing wool production per head above that of wethers at similar rates of stocking on natural annual pasture alone. Possible reasons for the apparent failure of the grazing supplements, particularly lucerne, are discussed in terms of grazing pressure and management strategies.

Supplementary feeding pattern and rate of liveweight gain in winter-spring affect wool production of young Merino sheep on the south coast of Western Australia

1995 ◽  
Vol 35 (8) ◽  
pp. 1093 ◽  
Author(s):  
PT Doyle ◽  
TW Plaisted ◽  
RA Love
Keyword(s):  
Growth Rates ◽  
Management Strategies ◽  
Fibre Diameter ◽  
Supplementary Feeding ◽  
Stocking Rate ◽  
Merino Sheep ◽  
Wool Production ◽  
Wool Growth ◽  
Staple Strength ◽  
Stocking Rates

The effects of different supplementary feeding practices in summer-autumn and management strategies on green pasture on liveweight change, wool growth rate, annual wool production and wool characteristics of young Merino wethers were examined at 2 farms. The grain feeding treatments were lupins (L) or lupins and oats (LO) fed in amounts that were adjusted to try and maintain liveweight, or lupins and oats (LOG) fed at a higher rate. The objectives of liveweight maintenance or gain were not always achieved, but liveweight patterns differed between LOG compared with L or LO during summer-autumn. The sheep used at farm 1 were aged 4.5 months and liveweight 32 kg at the start of the experiment, while those at farm 2 were 6.5 months and liveweight 39 kg. The stocking rate in summer-autumn was 8 wethers/ha at both farms. During supplementation, sheep on LOG had a higher (P<0.05) liveweight change compared with those on L or LO (farm 1, 15 v. -8 g/sheep. day; farm 2, -35 v. -51 g/sheep. day) and clean wool growth rates (farm 1, 7.1 v. 6.4 g/sheep. day; farm 2, 5.1 v. 4.8 g/sheep.day). The sheep on LOG grew broader (P<0.05) wool than those on L or LO (farm 1, 19.0 v. 18.5 �m; farm 2, 21.7 v. 20.8 �m), and at farm 1 length was also greater (P<0.05) (114 v. 111 mm), while at farm 2 staple strength was greater (P<0.01) (22.9 v. 16.4 N/ktex). There were no significant differences in annual clean wool production. There were positive (P<0.01) relationships between staple strength and liveweight change to the time of minimum liveweight in summer-autumn. After green pasture on offer reached 500 kg DM/ha in autumn, different liveweight change patterns were achieved in 2 groups (LS, lower stocking rates; HS, higher stocking rates) of sheep at each farm by adjusting stocking rates. Within a farm, the LS and HS groups were comprised of equal numbers of sheep from each replicate of the supplementary feeding treatments. There were differences (P<0.05 to 0.01) in liveweight change between LS and HS (farm 1, 93 v. 72 g/day; farm 2, 127 v. 60 g/day), the differences being more pronounced at farm 2. The differential stocking rates at farm 2 resulted in differences in clean wool growth rates (P<0.01), in clean wool production (4.22 v. 4.53 kg, P<0.05), and fibre diameter (20.8 v. 21.4 �m, P<0.01), but there were no significant effects on staple length or strength. There were no significant effects of the supplementary feeding treatments imposed in summer-autumn on the responses to the stocking rate treatments on green pasture.

Post-experimental modelling of grazing systems to improve profit and environmental outcomes using AusFarm

2017 ◽  
Vol 57 (9) ◽  
pp. 1849 ◽  
Author(s):  
K. M. Broadfoot ◽  
W. B. Badgery ◽  
G. D. Millar
Keyword(s):  
Management Strategies ◽  
Grazing Management ◽  
Management Systems ◽  
Stocking Rate ◽  
Management Options ◽  
Experimental Modelling ◽  
Grazing Systems ◽  
Sheep Production ◽  
Flexible Management ◽  
Stocking Rates

Assessments of grazing systems are often constrained by the decisions regarding the management of the grazing systems, including stocking rate, and also the seasonal conditions that occur during the assessment period. These constraints have led to sometimes conflicting results about comparisons of grazing management systems. This paper examines 1-, 4- and 20-paddock (1P, 4P and 20P) grazing management systems to determine how the intensity of grazing management on native pastures influences the financial performance of sheep production systems. The performance of the grazing systems, as part of the Orange EverGraze research experiment, was initially examined using the biophysical data over the 4 years of the experiment and then a more detailed analysis over a longer timeframe was undertaken using the AusFarm simulation modelling software. Flexible management strategies to optimise ewe numbers, sale time of lambs, and adjust ewe numbers based on season, were also assessed to determine which management systems are the most profitable and sustainable. There was higher profit for the 20P grazing system than the 1P system during the experiment. However, when stocking rates were held constant at optimum levels and systems were simulated over 40 years, there was no difference between grazing systems. Modelling strategies used to vary stocking rates showed that flexible management options are better based on optimising ewe numbers and the sale time of lambs rather than changing ewe numbers between years. The sustainability of modelled systems was also assessed using frequency of events where the average herbage mass (0.8 t DM/ha) or ground cover (80%) in autumn dropped below levels that are associated with degradation. Degradation events occurred more so with increasing ewe number than lamb sale time. Overall, the most sustainable systems, when considering profitability and environmental issues, had a stocking rate of 4.2 ewes per ha, with lambs sold in February (2 or 18). Higher stocking rates (5.3 ewes/ha) would need to be run for more intensive grazing management to have higher profitability.

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

2011 ◽  
Keyword(s):  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Size Structure ◽  
Prey Availability ◽  
Relative Weight ◽  
Negative Influence ◽  
River Channel ◽  
Population Characteristics ◽  
Current Status ◽  
Platte River

<em>Abstract</em>.—Catfish angling is popular throughout North America and catfish are the most sought after fish species in the Platte River, Nebraska. However, catfish management in the Platte River is minimal as little is known about current populations. Our objective was to determine the current status of channel catfish <em>Ictalurus punctatus</em> populations in the central and lower Platte River. Specifically, we evaluated population characteristics including relative abundance, size structure and condition. The current Platte River channel catfish population appears to be comparable to many Midwestern rivers. Channel catfish populations in the central Platte River had lower relative abundances (CPUE [catch per unit effort] = 1.1 ± 0.2 versus 2.3 ± 0.2 fish/net-night using 25-mm hoop nets), higher condition (<em>W<sub>r</sub></em> [relative weight] = 92 ± 1.7 versus 83 ± 0.7 using all gears) and greater size structure (PSD [proportional size distribution] = 35 ± 7 versus 24 ± 3 using all gears) compared to lower Platte River channel catfish. Possible factors influencing differences in channel catfish population characteristics are prey availability, flow modifications, habitat characteristics, and angler exploitation. Water manipulation from the Loup River Power Canal was also identified as a possible negative influence on lower Platte River channel catfish populations because hydropeaking is likely creating a stressful environment. However, channel catfish in the central Platte River may have benefited from recent high flows that likely increased productivity and food availability in the central Platte River.

Sign in / Sign up

Export Citation Format

Share Document