Bioenergetics of cannibalism in juvenile barramundiLates calcarifer(Bloch): exploring growth advantage of fish fed live prey and formulated diet

Abstract

The present study investigated the growth performance of juvenile barramundi Lates calcarifer (Bloch) fed conspecific prey (CP), formulated diet (FD) and a mix of both (MIX) using a bioenergetics approach. Fish in the MIX treatment ingested significantly more CP than FD by dry mass. However, prey mass ingestion and cannibalism rate in the MIX treatment were significantly lower than in the CP treatment. This indicates that the provision of alternative food does not complete mitigate cannibalism, but it can significantly reduce cannibalism in barramundi. Fish in the FD treatment showed a significantly higher daily food intake than fish in the CP or MIX treatments. However, fish fed conspecifics showed significantly better feed conversion efficiencies, apparent digestibility rates and growth performances. Exclusive cannibalistic barramundi assimilated significantly more energy consumed, with 1.5% of energy lost in faeces comparing with 7.3% of siblings feeding exclusively on FD. Consequently, exclusive cannibals channelized more energy consumption into growth (57.1%) than those fed solely on FD (43.9%). Therefore, high energy allocation into growth promoted better feed conversion efficiency and growth performance of cannibalistic barramundi than siblings fed solely on FDs. This study implies that fastgrowing cannibals may continuously prey on slow-growing conspecifics due to growth advantage through cannibalism. Therefore, size heterogeneity should be reduced at initial stocking and controlled as fish grow to avoid the emergence of new cannibals.

Intracohort cannibalism and methods for its mitigation in cultured freshwater fish

“…Size-sorting regarding type I cannibalism is connected mainly with maintaining the ontogenetically homogenous stock, because sorting does not reduce type I cannibalism, as this form is independent of larval sizes. At early stages, intraspecific predation is not greatly limited by size heterogeneity, as cannibals ingest conspecific prey (Ribeiro and Qin 2016). Synchronization of hatching and initial diversity of larval sizes play an important role among many fish species in maintaining a homogenously-sized stock.…”

“…However, rearing period and feeding schedule, specific for each species, are equally important (such as daily feed ration, feeding frequency, feed access surface and transition from live feed to commercial feed) (Jobling et al 1993;Folkvord and Otterå 1993;Francis and Bengtson 1999;Baras et al 2000a;Kestemont et al 2003;Szczepkowski 2009;Conceição et al 2010;Altaff and Janakiraman 2013;Piotrowska et al 2013;Król and Zieliński 2015). This is important, because any type of feeding restriction not only promotes forage activities by hunger motivation, encounter rates of conspecifics and prey vulnerability (Hecht and Pienaar 1993;Baras et al 2013;Ribeiro and Qin 2016), but can also lead to food competition, variability in food intake and establishment of a dominant hierarchy. Every situation which leads to inequities in food intake, results in growth depensation and size heterogeneity (Hecht and Pienaar 1993;Baras and Jobling 2002;Kestemont et al 2003;Baras et al 2013;.…”

The use of different 17β-estradiol hormone doses and water temperatures to control cannibalism in catfish Clarias gariepinus seed

“…According to Conceicao et al (2010), the interval of a feeding schedule that is too far can trigger cannibalism. Besides, Ribeiro & Qin (2016) and Baras et al (2013) also added that all forms of feeding restrictions not only encourage foraging activities with hunger motivation but can also lead to food competition, variability in food intake, and the formation of a dominant hierarchy. In the growth parameters, the administration of 20 mg/ kg 17β-estradiol at 31°C has a higher growth in length and weight than other treatments, while administration of 50 mg/kg 17β-estradiol has a low growth value.…”

Ameliorative Effects of Monoammonium-Glycyrrhizinate on Liver Lipid Metabolism and Antioxidant Capacity in Laying Hens

“…The existence of size heterogeneity contributed to the natural selection within the population (Conner and White, 1999). Cannibalism eliminated the individuals who were stunted by the above reasons of internal and external factors in the early stage of development, making the whole population develop away from recession and improving the survival ability of them (Baras et al, 2013;Ribeiro and Qin, 2016).…”