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

2011 ◽  
Keyword(s):  
Age Estimation ◽  
Early Life ◽  
Age Groups ◽  
Early Life History ◽  
Blue Catfish ◽  
Conservation Ecology ◽  
Flathead Catfish ◽  
Daily Increments ◽  
Daily Ring ◽  
Management And Conservation

<em>Abstract</em>.—We validated methods for estimating daily age of age-0 blue catfish <em>Ictalurus furcatus</em> and flathead catfish <em>Pylodictis olivaris</em>. Larvae of each species were reared in the laboratory and were sampled approximately every 10 d over a 4-month period. Five individuals of each species were randomly selected for daily age estimation from each of nine age-groups, ranging from 40 to 119 d posthatch for blue catfish and 20–121 d posthatch for flathead catfish. Mean daily ring count and known age were related for both species, indicating that daily ring deposition occurred in the otoliths of these fishes. Daily increment counts were accurate through 60 d posthatch for blue catfish and through 72 d posthatch for flathead catfish, with mean deviance of estimated age within 1 d of the known age. For both species, daily increments could be enumerated for older fish; however, accuracy decreased with age. We encourage researchers to utilize our aging technique to estimate hatch dates, the timing and frequency of hatching, and early growth rates of catfishes in wild populations. Such early life history information will be valuable in enhancing the management and conservation of important catfish populations.

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

2011 ◽  
Keyword(s):  
International Symposium ◽  
Pylodictis Olivaris ◽  
Blue Catfish ◽  
Conservation Ecology ◽  
Flathead Catfish ◽  
Tag Loss ◽  
Reward Value ◽  
Exploitation Rate ◽  
Time Correction ◽  
Regulation Changes

<em>Abstract</em>.—The Missouri Department of Conservation suspected that blue catfish <em>Ictalurus furcatus </em>and flathead catfish <em>Pylodictis olivaris </em>were being heavily exploited by anglers in 22,539-ha Harry S. Truman Reservoir in west-central Missouri. A reward tag study was initiated in 2004 to determine angler exploitation rates for both species. Three hundred blue catfish ≥ 482 mm total length (TL) and 194 flathead catfish ≥ 508 mm TL were equipped with transbody Carlin dangler reward tags in 2004 and 2005, respectively. All reward tags displayed a reward value of US$50. A 5-year post-tagging estimate of annual exploitation (<em>u</em>) was calculated with a 25% annual correction for angler nonreporting and a one-time correction for tag loss. The estimated annual exploitation rates for blue catfish ranged from 25.5% to 33.4% with a mean of 28.8%. The estimated cumulative exploitation rate (<EM>U</EM>) at 5-years post-tagging was 81.7% for all sizes of tagged blue catfish and 92.4% for tagged blue catfish ≥ 610 mm TL. The estimated annual exploitation rates for flathead catfish ranged from 0% to 3.9% with a mean of 1.8%. The estimated cumulative exploitation rate at 5-years post-tagging for flathead catfish was 8.8%. These exploitation rates indicate that blue catfish are being heavily exploited while flathead catfish are not. Of all the reward tagged blue catfish that were reported by anglers, 7% were reported as released while 22% of the reported flathead catfish were released. These results are being used to examine possible regulation changes to protect the blue catfish fishery at Truman Reservoir.

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

2011 ◽  
Keyword(s):  
Mississippi River ◽  
Age Estimation ◽  
Fish Population ◽  
High Variability ◽  
Annual Growth ◽  
Age And Growth ◽  
Large Fish ◽  
Conservation Ecology ◽  
Flathead Catfish ◽  
Actual Growth

<em>Abstract</em>.—Characterizing dynamics of a fish population requires accurate age estimation for individual fish, and few studies have collected basic age and growth information for flathead catfish in the upper Mississippi River (UMR). Multiple methods were used to calculate age and growth of flathead catfish from the UMR. Length at age was determined using sectioned otoliths and pectoral spines cut on the articulating process. Most research has shown that otoliths provide the most accurate age when compared to other structures. Otoliths require sacrifice of many fish, including very large fish (i.e.: >762 mm). Otoliths and pectoral spines were collected from commercially harvested flathead catfish from Pools 12 and 13 (river kilometer [rkm] 841.0–938.3), UMR, aged and compared. Growth was similar between genders, and there was little difference in growth predicted by the two aging structures. Spine articulating processes and otoliths both showed high variability in growth starting at age 1. When we compared the two structures, the spine articulating process accurately aged fish up to 17 years old (mean total length = 907 mm) before loss of annuli occurred. Aging flathead catfish with the spine articulating process provides an accurate, reliable, affordable, nonlethal aging technique that may be preferable in many situations as opposed to otoliths. Annual and seasonal growth was calculated from flathead catfish captured from Pool 13 (rkm 841.0–895.9), UMR, tagged with a visual implant tag and subsequently recaptured. Actual growth over the summer was estimated to be 0.25 mm/d, and growth from year to year was estimated to be 32 mm/year. The actual annual growth (31.9 mm/year) calculated from tag returns validates estimates of annual growth derived from otolith (30.2 mm/year) and spine articulating process (31.0 mm/ year) aging techniques.

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.

Dynamics in 0+ recruitment and early life history for snapper (Pagrus auratus, Sparidae) in South Australia

2003 ◽  
Vol 54 (8) ◽  
pp. 941 ◽  
Author(s):  
A. J. Fowler ◽  
P. R. Jennings
Keyword(s):  
Life History ◽  
Water Temperature ◽  
Early Life ◽  
South Australia ◽  
Early Life History ◽  
Daily Increments ◽  
Successful Recruitment ◽  
Pagrus Auratus ◽  
Temperature Regimen ◽  
New Recruits

The population dynamics of snapper (Pagrus auratus) relate to interannual variation in 0+ recruitment. The focus of the present study was to improve our understanding of this variation for snapper in northern Spencer Gulf, South Australia. The objectives of this study were to describe the distribution and abundance of 0+ juveniles annually from 2000 to 2002 and to determine early life history characteristics through retrospective analysis of otolith microstructure from captured fish. The environmental characteristics differed between years, with 2001 being extremely hot and 2002 the coldest summer recorded. Sampling was undertaken in April after spawning and settlement were complete. The estimates of recruitment were relatively low, suggesting a complex relationship with sea surface temperature. Each year new recruits occurred at the same places that were bare and flat with muddy substratum, suggesting nursery areas are actively selected by the recruits. The sagittae from juveniles had clear daily increments and settlement mark, allowing age and presettlement duration to be determined. Growth rates varied considerably both within and between years, and were related to water temperature, which affected the presettlement duration. Based on spawn dates, successful recruitment resulted from specific periods through the reproductive season that appeared to relate to the specific water temperature regimen in each year.

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

2011 ◽  
Keyword(s):  
Life History ◽  
Body Size ◽  
Habitat Selection ◽  
Early Life ◽  
Early Life History ◽  
Interstitial Space ◽  
Relative Importance ◽  
Limited Information ◽  
Total Length ◽  
Flathead Catfish

<em>Abstract</em>.—Little is known about habitat requirements of juvenile flathead catfish <em>Pylodictis olivaris</em>. Previous studies indicate use of coarse substrates associated with riffle habitats in streams; however, limited information on microhabitat characteristics associated with habitat selection exists. To further our understanding of early life history habitat for flathead catfish, we used polyvinyl chloride half tubes (i.e., tubes cut in half longitudinally) of six different diameters (range, 13–76 mm) and depths (range, 25–152 mm) to simulate interstitial spaces provided by coarse substrates and determine (1) whether juvenile flathead catfish selected for interstice size, (2) relative importance of interstitial diameter and depth, and (3) if interstitial space size selection was related to fish body size. A total of 1,316 selection trials regarding interstitial diameter, depth, and the interaction of these characteristics was conducted using juvenile flathead catfish ranging in total length (TL) from 15 to 128 mm. Utilization of interstice diameters and depths was nonrandom (i.e., selection was occurring). Selection of interstice diameter was positively related to fish body size (i.e., total length), whereas all sizes of juvenile flathead catfish most often selected the greatest depth of interstitial space offered. We observed an ontogenetic shift in relative importance of interstice diameter and depth during interaction trials. Flathead catfish less than 40 mm TL selected for interstitial diameter, fish between 41 and 60 mm TL selected for both interstitial characteristics, whereas individuals larger than 60 mm TL selected for interstitial depth. Results of our study are among the first to identify microhabitat-scale characteristics that influence habitat selection by early life history stages of this species.

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

2011 ◽  
Keyword(s):  
Management Strategies ◽  
Missouri River ◽  
Rapid Expansion ◽  
Movement Behavior ◽  
Radio Tracking ◽  
Blue Catfish ◽  
Spawning Period ◽  
Annual Cycles ◽  
Conservation Ecology ◽  
Flathead Catfish

<em>Abstract</em>.—Flathead catfish <em>Pylodictis olivaris</em> and blue catfish <em>Ictalurus furcatus</em> thrive in large rivers and constitute large sport fisheries. Defining a spatial scale for new management strategies has become increasingly important due to rapid expansion of the sport fishery. To investigate life history characteristics, migratory pathways, and space use, we used telemetry to monitor the movement behavior of flathead catfish and blue catfish during two complete annual cycles. Individuals were sampled from a 97-km reach of the lower Missouri River and surgically implanted with transmitters during April 2006 (<EM>N</EM> = 77) and again in April and July of 2007 (<EM>N</EM> = 80). Acoustic tracking by boat and radio tracking by helicopter were used on the Missouri, Lamine, Chariton, Little Chariton, and Grand rivers during 2006–2008. The proportion of individuals that used a tributary during the putative spawning period (May 15–July 15) increased from 10% (8 of 77) in 2006 to 18% (14 of 80) in 2007. Flood conditions in May 2007 may have contributed to this increase. Between April 2006 and May 2007, the majority of flathead (51%) and blue catfishes (55%) moved less than 100 river kilometers from where they were tagged. The maximum linear range during 2006–2007 was 347.6 river kilometers for blue catfish and 751.9 river kilometers for flathead catfish. Seasonal structure to annual movements was evident with periods of both restricted movement (December–March; July–September) and migratory behavior (March–June; October–December). The variability in observed behaviors provides a substantial basis for managers to identify and protect distant habitats that are used by adult catfish for spawning, feeding and growth, and overwintering.

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

2011 ◽  
Keyword(s):  
Size Structure ◽  
Management Strategies ◽  
Age Groups ◽  
Missouri River ◽  
Population Characteristics ◽  
Fish Length ◽  
Natural Mortality ◽  
Conservation Ecology ◽  
Flathead Catfish ◽  
Tag Loss

<em>Abstract</em>.—Few studies have been conducted on angler exploitation rates or angler harvest size selectivity for flathead catfish <em>Pylodictis olivaris</em>. However, exploitation of a narrow range of age groups or sizes could affect flathead catfish population characteristics and fisheries, and management strategies may be needed to enhance fisheries if selective angler exploitation is severe. Almost 3,000 flathead catfish (305–1,209 mm total length [TL]) were marked with Carlin dangler reward tags over a 3-year period in a 92-km section of the Missouri River in northwest Missouri. Corrected angler exploitation (accounting for angler nonreporting, tag loss, and natural mortality) ranged from 4.1% to 9.6%. Angler harvest rates of flathead catfish varied by fish length. Tagged fish 305–380 mm TL were harvested in lower proportion than expected. Fifty-six percent of all fish tagged were in this size-group vested in higher proportion (50% of total) than relative abundance (27%) would suggest, as were flathead catfish ≥ 508 mm TL (17% of total tagged and 23% of total harvested). Angler exploitation rates of flathead catfish from the Missouri River did not seem excessive (<10%). However, 77% of flathead catfish harvested by anglers were less than 508 mm TL, and given that logistic regression predicted that flathead catfish between 450 and 650 mm TL had the highest probability of being harvested by anglers, harvest restrictions protecting fish less than 650 mm TL would likely shift the population size structure towards larger-sized individuals, if that was a management goal.

Prey tell: what quillback rockfish early life history traits reveal about their survival in encounters with juvenile coho salmon

2020 ◽  
Vol 650 ◽  
pp. 7-18 ◽  
Author(s):  
HW Fennie ◽  
S Sponaugle ◽  
EA Daly ◽  
RD Brodeur
Keyword(s):  
Life History ◽  
Early Life ◽  
Life History Traits ◽  
Direct Evidence ◽  
Coho Salmon ◽  
Larval Fish ◽  
Early Life History ◽  
In The Wild ◽  
Otolith Microstructure Analysis ◽  
Pelagic Juvenile

Predation is a major source of mortality in the early life stages of fishes and a driving force in shaping fish populations. Theoretical, modeling, and laboratory studies have generated hypotheses that larval fish size, age, growth rate, and development rate affect their susceptibility to predation. Empirical data on predator selection in the wild are challenging to obtain, and most selective mortality studies must repeatedly sample populations of survivors to indirectly examine survivorship. While valuable on a population scale, these approaches can obscure selection by particular predators. In May 2018, along the coast of Washington, USA, we simultaneously collected juvenile quillback rockfish Sebastes maliger from both the environment and the stomachs of juvenile coho salmon Oncorhynchus kisutch. We used otolith microstructure analysis to examine whether juvenile coho salmon were age-, size-, and/or growth-selective predators of juvenile quillback rockfish. Our results indicate that juvenile rockfish consumed by salmon were significantly smaller, slower growing at capture, and younger than surviving (unconsumed) juvenile rockfish, providing direct evidence that juvenile coho salmon are selective predators on juvenile quillback rockfish. These differences in early life history traits between consumed and surviving rockfish are related to timing of parturition and the environmental conditions larval rockfish experienced, suggesting that maternal effects may substantially influence survival at this stage. Our results demonstrate that variability in timing of parturition and sea surface temperature leads to tradeoffs in early life history traits between growth in the larval stage and survival when encountering predators in the pelagic juvenile stage.

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