Diet composition changes in tigerfish of Lake Kariba following an invasion by redclaw crayfish

Abstract

The present study used a combination of stable isotope techniques and stomach content analyses to examine the diet and ontogenetic diet shifts of tigerfish, Hydrocynus vittatus, in the Sanyati basin of Lake Kariba, Zimbabwe. We compared tigerfish diet shifts in the presence of an invasive crayfish, Cherax quadricarinatus, with previous studies before invasion. Here, we assessed whether tigerfish now had a preference for C. quadricarinatus leading to a shift in its main dietary food sources from cichlids to crayfish. The dominance of cichlids has remained generally high when compared with historical assessments. Stable isotope analyses showed that tigerfish fed on a variety of food sources including those that may be temporarily unavailable. Results of stable isotope analyses also highlighted that C. quadricarinatus was now becoming an important food source across all tigerfish size classes. In conclusion, tigerfish in Lake Kariba showed remarkable dietary plasticity and ontogenetic shifts, identified by both stomach content and stable isotope analyses.

A Review of Freshwater Crayfish Introductions in Africa

“…The pied kingfisher Ceryle rudis has been seen eating juvenile crayfish on the middle Zambezi River (Douthwaite et al 2018) and crayfish have been found inside the guts of largemouth bass caught at the Claw and Mazvikadei dams in Zimbabwe (Douthwaite et al 2018). In Lake Kariba, Zimbabwe, results of stable isotope analyses highlighted that C. quadricarinatus was now becoming an important food source across all tigerfish size classes (Marufu et al 2017). In Lake Kariba C. quadricarinatus was also found to be present in gut contents of C. gariepinus and Heterobranchus longifilis (AT Chakandinakira, Department of Fisheries, Zimbabwe pers.…”

The redclaw crayfish: A prominent aquaculture species with invasive potential in tropical and subtropical biodiversity hotspots

“…Martin et al . (2010) and Buřič et al . (2011)] with growth allometry between sexes mentioned above.…”

“…Similar reports were made for other predatory fish species such as the African sharp tooth catfish Clarias gariepinus (Burchell, 1822), nembwe Serranochromis robustus (G€ unther, 1864) and the thin-faced bream Serranochromis angusticeps (Boulenger, 1907) (Tyser & Douthwaite 2014). Further, the tigerfish Hydrocynus goliath (Boulenger, 1898) has also been noted as an emerging predator (Marufu et al 2017). Local residents in Kantunta even reported seeing the clawless otter Aonyx capensis (Schinz, 1821), reed cormorant Phalacrocorax africanus (J. F. Gmelin, 1789), marabou stork Leptoptilos crumeniferus (Lesson, 1831), hadada ibis Bostrychia hagedash (Latham, 1790), fish eagle Haliaeetus vocifer (Daudin, 1800), various catfish of the genus Clarias, silver barbel Schilbe intermedius R€ uppell, 1832, and largemouth bream Serranochromis spp., feeding on redclaw populations (Douthwaite et al 2018).…”

Bifurcation Analysis of a 5D Nutrient, Plankton, Limnothrissa miodon Model with Hydrocynus vittatus Predation

“…According to Bell-Cross [4], the tigerfish is an efficient and extremely active predator which preys on fish of up to 40% its length. A number of studies have been done to assess the diet of Hydrocynus vittatus [5][6][7][8]. Results from the study by Mhlanga [7] showed that Limnothrissa miodon is the dominant food item in the diet of the piscivorous Hydrocynus vittatus.…”

“…Results from the study by Mhlanga [7] showed that Limnothrissa miodon is the dominant food item in the diet of the piscivorous Hydrocynus vittatus. Stable isotope analysis by Marufu et al [8] showed that Limnothrissa miodon is still the dominant food item consumed by tigerfish. Mhlanga [9] obtained a natural, fishing, total mortality, and exploitation rate of 0.66, 0.335, 0.995, and 0.337, respectively, of tigerfish from the Bumi Basin of Lake Kariba and the Ume River.…”