Causal fermion systems are a candidate for a unified physical theory, giving relativistic quantum mechanics, general relativity and quantum field theory as limiting cases. They are based on the Dirac equation, a first order differential equation, which describes the fermions, the particles matter consists of. Fundamental for causal fermion systems is the so-called causal action principle. This determines the physically admissible objects like spacetimes defined in the setting of causal fermion systems, similar to the way the Einstein equations determine the relevant Lorentzian manifolds in general relativity. In this thesis the mass and energy of black holes are investigated in the theory of causal fermion systems based on the Euler-Lagrange equations and so-called surface layer integrals. More explicitly, the main goal of this thesis is to introduce the notions ”mass” (and to this end ”area”), ”momentum” and ”energy” in the setting of causal fermion systems, where ”energy” is given by an energy-momentum four-vector with the energy as first component and momentum in the three spatial directions as the other components. Moreover we will show an analogy to the ”Positive Mass Theorem” adapted to the theory of causal fermion systems. Finally these notions are made manifest by calculating the energy vector for a boosted Schwarzschild black hole and we discuss how to generalize these calculations to Lorentzian Manifolds
