2015 Volume 63 Issue 1 Pages 49-58
To ascertain the feeding characteristics of the introduced catfish Ictalurus punctatus, the stomach contents of 268 specimens (14.7-59.1 cm in standard length, SL), collected at night time (19:30-21:00) by bait fishing and casting net in the littoral zone (< 1.2 m in water depth) at Tsumagi and Ofunatsu, Lake Kitaura, Ibaraki Prefecture, Japan, from April to October 2013, were examined. Mean numbers of catfish individuals collected per 30 minutes by fishing were significantly greater in reed areas than in bulkhead areas. Overall food items included small fishes, benthic and epibenthic crustaceans, fragments (flesh, scales, ovary and bones) of large fish, terrestrial plants, aquatic and terrestrial insects, and filamentaous algae. In particular, native species, such as the gobiid Tridentiger brevispinis, cyprinid Pseudorasbora parva, oriental river prawn Macrobrachium nipponense and several sessile chironomids (e.g., Glyptotendipes tokunagai, Dicrotendipes pelochloris and Cricotopus sp.), were frequently observed, such mainly inhabiting the reed areas. The results indicated that I. punctatus mainly utilized food items available in the reed areas at night time, such possibly impacting upon co-occurring native fishes by predation and competition for food resource.
