An investigation into the pathogenesis of blue catfish alloherpesvirus in ictalurid catfish

Abstract.—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 Pylodictis olivaris, channel catfish Ictalurus punctatus, and blue catfish I. furcatus 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.

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

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

10.47886/9781934874257.ch31 ◽

2011 ◽

Keyword(s):

Chesapeake Bay ◽

Fork Length ◽

Atlantic Menhaden ◽

Tidal River ◽

Human Consumption ◽

Apex Predators ◽

Blue Catfish ◽

Brevoortia Tyrannus ◽

Conflicting Demands ◽

Peak Abundance

Abstract.—Rapid increase in abundance and expanded distribution of introduced blue catfish Ictalurus furcatus populations in the Chesapeake Bay watershed have raised regional management concerns. This study uses information from multiple surveys to examine expansion of blue catfish populations and document their role in tidal river communities. Originally stocked in the James, York, and Rappahannock River systems for development of commercial and recreational fisheries, blue catfish have now been documented in adjacent rivers and have expanded their within-river distribution to oligo- and mesohaline environments. Range expansions coincided with periods of peak abundance in 1996 and 2003 and with the concurrent decline in abundance of native white catfish I. catus. Blue catfish in these systems use a diverse prey base; various amphipod species typically dominate the diet of smaller individuals (<300 mm fork length [FL]), and fishes are common prey for larger blue catfish (>300 mm FL). Recent studies based on stable isotope analyses suggest that adult blue catfish in these systems are apex predators that feed extensively on important fishery resources, including anadromous shads and herrings Alosa spp. and juvenile Atlantic menhaden Brevoortia tyrannus. Minimizing effects on Chesapeake Bay communities by controlling high densities of blue catfish populations is a primary goal of management, but conflicting demands of the commercial and recreational sectors must be resolved. Further, low market demand and human consumption concerns associated with purported accumulation of contaminants in blue catfish pose additional complications for regulating these fisheries.

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

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

10.47886/9781934874257.ch56 ◽

2011 ◽

Keyword(s):

Ictalurus Punctatus ◽

Channel Catfish ◽

Large Scale ◽

Growth Data ◽

Blue Catfish ◽

Brown Bullhead ◽

Black Bullhead ◽

Flathead Catfish ◽

The North ◽

Shared Environmental Factor

Abstract.—Growth rates are a core characteristic of catfish populations that are of increasing research interest. However, few studies have synthesized growth data across catfish populations and species to examine large-scale drivers of catfish growth. Here, a metaanalysis of growth was conducted for channel catfish Ictalurus punctatus, blue catfish I. furcatus, flathead catfish Pylodictis olivaris, brown bullhead Ameiurus nebulosus, and black bullhead A. melas, and relationships were documented between growth and climate variables, hydrologic habitats (lentic versus lotic), and latitudinal countergradients (a tendency for faster subannual growth in the north). Blue catfish, black bullhead, and brown bullhead growth correlated significantly and positively with temperature metrics. Blue catfish, flat-head catfish, and brown bullhead growth also correlated significantly and positively with sunshine fraction, wind speed, and evapotranspiration. Channel catfi sh growth did not correlate to any climate metrics. After removal of growth effects related to climate, blue catfish and brown bullhead had significantly faster growth in lotic than lentic habitats. Channel catfish and black bullhead had faster growth in lentic than lotic habitats. Flathead catfish showed no difference in growth between hydrologic habitat types. After standardizing growth by postsexual maturation age and the thermal opportunity for growth, significant and highly predictive countergradient growth relationships (mean r 2 = 0.47) were found for all five species across sites (i.e., faster temperature-standardized growth in more northerly populations). Slopes of these relationships did not differ among species, suggesting similar responses to latitude. There may be a genetic basis for countergradient growth in catfishes that developed over evolutionary scales via selection by a shared environmental factor. Catfish growth is variable within and among species but can be intensely shaped by all three primary factors evaluated in this study.

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