  Baryon - anti-baryon photoproduction off a proton target is being studied in
detail at Jefferson Lab with the GlueX Experiment. We observe $p\bar{p}$ and,
for the first time, $\Lambda\bar{\Lambda}$ photoproduction (with $\Lambda
\rightarrow \pi^- p$, $\bar{\Lambda} \rightarrow \pi^+ \bar{p}$) from
thresholds up to $E_{\gamma} = 11.4$ GeV. Preliminary spectra from data
accumulated during the GlueX Phase-I period are shown. Angular distributions of
the photoproduced hyperons indicate more than one production mechanism in the
reaction channel $\gamma p \rightarrow \Lambda\bar{\Lambda}p$. A Monte Carlo
simulation with four mechanisms, tested through comparison between simulation
and experimental data, is presented.
