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

2011 ◽  
Keyword(s):  
Size Structure ◽  
Management Strategies ◽  
Northwestern Part ◽  
Blue Catfish ◽  
Conservation Ecology ◽  
Catch Data ◽  
Annual Survey ◽  
Gill Net ◽  
Glass Slides ◽  
Similar Survey

<em>Abstract</em>.—In Georgia, blue catfish <em>Ictalurus furcatus</em> are native in the Coosa River drainage in the northwestern part of the state. However, they were first detected outside this range during an annual gill net survey of Lake Sinclair conducted by the Georgia Department of Natural Resources in 1996, then again in a similar survey of Lake Oconee during 1997. Catch of blue catfish in annual surveys of Lake Oconee continued to increase, but demographics of the populations are unknown. We used annual survey data for the period 1989–2009 to identify trends in catch of blue catfish in the lake. Age and size structure of the blue catfish population in Lake Oconee was assessed based on catch data from the 2008 survey. Mean length for blue catfish captured (<em>n</em> = 121) was 330 mm (SD = 132 mm), and mean weight was 468 g (SD = 683.9 g); the largest fish was 740 mm and weighed 5078 g. Otoliths from the blue catfish collected were cross-sectioned, mounted on glass slides, and examined under a dissecting microscope, and annuli on each section were counted independently by two readers. Catch data indicated that blue catfish catch increased rapidly after 1997. Seven year-classes (2001–2007) were represented in the 2008 sample, and most fish were from the 2003 year-class (mean age: 3.7 years; SD = 1.4 years). These data document a rapidly expanding blue catfish population in Lake Oconee and could serve as the basis for developing management strategies in this reservoir system and others across North America where blue catfish are expanding their range.

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):  
North Carolina ◽  
International Symposium ◽  
Maximum Size ◽  
Large Fish ◽  
Blue Catfish ◽  
Conservation Ecology ◽  
Size Limit ◽  
Catch And Release ◽  
The North ◽  
Gill Net

<em>Abstract</em>.—Blue catfish <em>Ictalurus furcatus </em>were introduced into North Carolina reservoirs in the mid-1960s and have recently become a popular target for anglers pursuing large catfish. In 2008, the North Carolina Wildlife Resources Commission enacted a maximum size limit for blue catfish at Badin Lake and Lake Norman where only one fish greater than 813 mm could be harvested daily. Surveys indicated that few fish larger than 813 mm were present in either system and that the time to reach the size limit was 12 years in Badin Lake and 20 years in Lake Norman, on average. Although few large fish were present in either system, tournament anglers at Lake Norman kept larger fish in a higher proportion than found in gill-net surveys or harvested during a recent creel survey. Modeling results suggested that the regulation would have little or no impact on increasing the number of large catfish in either population. However, the regulation will protect some rare fish that grow to the maximum size limit and potentially allow recapture opportunities if catch-and-release mortality is low.

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 ◽  
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):  
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.

scholarly journals Links between Phenology of Large Phytoplankton and Fisheries in the Northern and Central Red Sea

2021 ◽  
Vol 13 (2) ◽  
pp. 231
Author(s):  
John A. Gittings ◽  
Dionysios. E. Raitsos ◽  
Robert J. W. Brewin ◽  
Ibrahim Hoteit
Keyword(s):  
Red Sea ◽  
Phytoplankton Bloom ◽  
Size Structure ◽  
Management Strategies ◽  
Trophic Levels ◽  
Cell Diameter ◽  
Food Web Structure ◽  
Marine Management ◽  
Fisheries Resources ◽  
Phytoplankton Size

Phytoplankton phenology and size structure are key ecological indicators that influence the survival and recruitment of higher trophic levels, marine food web structure, and biogeochemical cycling. For example, the presence of larger phytoplankton cells supports food chains that ultimately contribute to fisheries resources. Monitoring these indicators can thus provide important information to help understand the response of marine ecosystems to environmental change. In this study, we apply the phytoplankton size model of Gittings et al. (2019b) to 20-years of satellite-derived ocean colour observations in the northern and central Red Sea, and investigate interannual variability in phenology metrics for large phytoplankton (>2 µm in cell diameter). Large phytoplankton consistently bloom in the winter. However, the timing of bloom initiation and termination (in autumn and spring, respectively) varies between years. In the autumn/winter of 2002/2003, we detected a phytoplankton bloom, which initiated ~8 weeks earlier and lasted ~11 weeks longer than average. The event was linked with an eddy dipole in the central Red Sea, which increased nutrient availability and enhanced the growth of large phytoplankton. The earlier timing of food availability directly impacted the recruitment success of higher trophic levels, as represented by the maximum catch of two commercially important fisheries (Sardinella spp. and Teuthida) in the following year. The results of our analysis are essential for understanding trophic linkages between phytoplankton and fisheries and for marine management strategies in the Red Sea.

International Tribunal for the Law of the Sea : 1998 Survey

1999 ◽  
Vol 14 (4) ◽  
pp. 453-465
Author(s):  
Shabtai Rosenne
Keyword(s):  
United Nations ◽  
Law Of The Sea ◽  
General Assembly ◽  
International Tribunal ◽  
Annual Survey ◽  
United Nations General ◽  
Similar Survey ◽  
United Nations General Assembly ◽  
The Law ◽  
Previous Volume

AbstractThis article continues the annual survey of matters connected with the International Tribunal on the Law of the Sea during the year 1998. It follows on the similar survey published in a previous volume of this journal. It is structured in the same way, dealing in order with the 1998 Meeting of States Parties and relevant matters from the 53rd session of the United Nations General Assembly, and is concluded with an account of the Tribunal's work in 1998.1

Balancing Fisheries Management and Water Uses for Impounded River Systems

2008 ◽  
Keyword(s):  
Size Structure ◽  
Management Strategies ◽  
Historical Context ◽  
Lepomis Macrochirus ◽  
Large Body ◽  
Early Maturation ◽  
Reservoir Species ◽  
Clear Identification ◽  
Management Approaches ◽  
Underlying Mechanisms

<em>Abstract</em>.—Although stunting is a fairly common phenomenon in fishes, confusion remains about underlying mechanisms and appropriate management strategies. Herein, I summarize current literature to provide a synthetic look at factors that can cause stunting and consider associated management strategies. First, I provide historical context by reviewing early literature, much of which is focused on density-dependent slow growth as the cause of stunting. A brief summary of more recent literature, however, suggests that stunting is often more complex than early investigations might indicate, and mechanisms such as early maturation and overexploitation of adults are considered. Because the bluegill <em>Lepomis macrochirus </em>is an extremely common reservoir species, a large body of literature related to its population size structure and associated management strategies is available. Therefore, I use bluegill as a model system to describe how various mechanisms might lead to stunting and indicate important considerations from a management standpoint. In the final section, I review management strategies and argue, among other things, that consistent language, clear identification of underlying mechanisms, and multifaceted management approaches are necessary for robust results when dealing with stunted populations.

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

2011 ◽  
Keyword(s):  
International Symposium ◽  
Size Structure ◽  
Pylodictis Olivaris ◽  
Social Event ◽  
Conservation Ecology ◽  
Party Size ◽  
Catch And Release ◽  
Flathead Catfish ◽  
Creel Survey ◽  
Total Effort

<em>Abstract</em>.—Hand grabbing for catfish has been practiced in Mississippi for many years; however, few studies have addressed this fishing technique. Ross Barnett Reservoir is a<em> Abstract</em>.—Hand grabbing for catfish has been practiced in Mississippi for many years; however, few studies have addressed this fishing technique. Ross Barnett Reservoir is a 13,360-ha impoundment located in central Mississippi that supports a substantial hand grabbing fishery. A roving creel survey was conducted during the 2007 and 2008 Mississippi hand grabbing season (May 1–July 15). Objectives were to estimate catch, harvest, and effort of hand grabbers and to solicit information concerning techniques used by these anglers. A total of 37 parties was interviewed, consisting of 150 total anglers. Seventy percent of the parties interviewed targeted flathead catfish <em>Pylodictis olivaris</em>. Ninety-five percent of the parties used a probe, and all parties fished boxes located at depths of 1–2 m. Average party size was four anglers, indicating that hand grabbing is a social event. For 2007 and 2008, anglers spent an estimated 4,424 and 5,259 h hand grabbing, respectively. An estimated 3,313 and 2,589 catfish were harvested in 2007 and 2008, respectively. Based on size structure of harvested catfish, hand grabbing anglers at Ross Barnett Reservoir do not appear to be size-selective. Most anglers were harvest-oriented, with catch-and-release estimates making up only 12% and 9%, respectively. Future creel surveys should be directed at the total effort allocated toward catfishing, in an effort to determine the effect of hand grabbing on Ross Barnett Reservoir.

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