Assessment of interspecific interactions between the invasive red-claw crayfish (Cherax quadricarinatus) and the Mozambique tilapia (Oreochromis mossambicus)

Abstract

The Australian red-claw crayfish, Cherax quadricarinatus, has been introduced for aquaculture purposes worldwide and consequently colonized natural environments, where it might cause ecosystem services losses or adversely affect native species and the local environment. This species was first found in Pequenos Libombos Reservoir in Maputo Province, Southern Mozambique in the late 2009 and is linked to reduction in tilapia fisheries. This study, conducted in 2015 under controlled conditions, aimed to assess the interspecific relationships between the Mozambique tilapia (Oreochromis mossambicus) and the alien crayfish. For both species, no significant differences in growth and survival rates were found between animals reared in the presence versus the absence of heterospecifics, indicating no direct deleterious interspecific effects. Behavioural observations revealed that fish and crayfish competed for shelter and food. Both species reduced the foraging in the presence of heterospecifics during feeding period, in the daytime. Crayfish seemed to have an advantage in competition for shelter, suggesting that they may interfere with tilapia sheltering activity and make tilapia vulnerable to predators in natural habitats.

A Review of Freshwater Crayfish Introductions in Africa

“…The first observation of C. quadricarinatus was in the Pequenos Libombos reservoir, Maputo Province, southern Mozambique during late 2009, early 2010 (Chivambo et al 2019). Assuming this was not the result of an exceptional translocation event, the species probably spread naturally from the Inkomati Basin in Swaziland through the Mbuluzi River until the Pequenos Libombos Dam (Nunes, Zengeya, Hoffman et al 2017;Chivambo et al 2019). Another population of C. quadricarinatus was confirmed in the Garganta basin of Lake Cahora Bassa in 2015 (Douthwaite et al 2018).…”

“…In the Kafue River, Zambia, Zambia, Weyl et al (2017) reported observations that C. quadricarinatus predation on fish entangled in gill nets could result in losses of up to 30% of the catch, as well as considerable damage to the fishing gear. In Mozambique, predation by and competition with C. quadricarinatus is hypothesized to have contributed to a decline in tilapia fisheries in Pequenos Libombos Reservoir (Chivambo et al 2019). Many fishermen in Madagascar expressed that P. virginalis was destroying their fish catches as they perceive that crayfish can prey upon juvenile fishes (Andriantsoa et al 2019).…”

Trophic relationships among three species of ornamental fish from the region of Lake Amanã, Amazon

“…In the present study, the similarity of diets does not mean complete overlap of trophic niches, probably due to the great diversity of insects available in the environment. Specialized techniques of food capture, for example, can cause segregation of niches and allow the coexistence of the species (Peroni and Hernández, 2011;Chivambo et al, 2019). On the other hand, Motta (1989) reported that teeth morphology and some characteristics of the skull anatomy can indicate a feeding specialization based on the efficiency of exploitation of certain types of food.…”