Author
 |
Radomski, Andrew |
|
Submitted to: Catfish Farmers of America Research Symposium
Publication Type: Abstract Only Publication Acceptance Date: 11/30/2005 Publication Date: 2/24/2006 Citation: Radomski, A.A. 2006. Catfish pond characteristics and cormorant use – can manipulating one negatively influence the other [abstract]. Catfish Farmers of America Research Symposium. p. 49. Interpretive Summary: Technical Abstract: Recent advancements in studies on the acuity of avian visible spectrum and remote sensing have allowed wildlife and fisheries biologists a unique opportunity to conduct field experiments within the birds’ perceived environment. Past USDA-ARS research suggests a bias in pond use by piscivorous birds but no management strategies were developed to link the potential pond characteristics to bird use. This study was an attempt to assess double-crested cormorants’ (Phalacrocorax auritus) use and avoidance of commercial catfish ponds. To manipulate several pond variables, Aquashade TM, a U.S. Environmental Protection Agency approved dye for use in aquaculture, was used as the treatment. During the winters of 2003-2004 and 2004-2005, cormorants were quantified at 3 commercial fish farms in Arkansas (USA). Selected farms were typical of commercial production, in that the farms had >40 fishponds, ponds were 6 ha, and stocked with single- or multiple-age class channel catfish (Ictalurus punctatus). A pretreatment phase included 5 weeks of cormorant counts to classify ponds as preferred or avoided. After classifying the ponds, the treatment (Aquashade was applied to 4 ponds (2 preferred, 2 avoided) at each farm. Subsequently, cormorants were quantified for 2 months post-treatment and pond variables were measured every other week. Changes were measured in bird use along with a suite of physical and chemical pond variables. Commercial catfish pond variables that were measured prior to treatment were: surface condition, secchi reading, depth, pH, temperature, salinity, dissolve oxygen, total phosphorus, TAN, nitrite, nitrate, hardness, chlorophyll a, and algae species composition and density. These variables were linked with remote sensing data that included visible spectrum digital values from pond images obtained using low-altitude aerial digital video. The preliminary findings of this study indicate that: (1) long-term cormorant use were not deterred from aquaculture ponds treated with Aquashade TM during the winter months and (2) discriminant function analysis for cormorants using ponds only predicted 60% of the cormorant choice could be addressed from the digital values of pond reflectance. Further analyses of the data, particularly with bird avoidance ponds will be discussed along with the temporal changes occurring within catfish ponds during the winter months. This later topic has largely been an ignored component of catfish research that may have broad implications for future farm management strategies. |
