Hotspot traffic is common in metro ring networks connecting access networks with backbone networks, and these metro rings are also expected to support a mix of unicast, multicast, and broadcast traffic. Shortest path routing, as employed in the Resilient Packet Ring (RPR), is widely considered for metro rings as it maximizes spatial reuse and thus the achievable packet throughput (capacity) for uniform traffic. In this paper we analyze the capacity of bidirectional optical ring networks, such as RPR, employing shortest path routing for multicast (non-uniform) hotspot traffic (whereby unicast and broadcast are considered as special cases of multicast). We find that when the traffic originating at the hotspot exceeds a critical threshold, then shortest path routing leads to substantial reductions in capacity to a value close to one simultaneous packet transmission. To overcome this limitation of shortest path routing, we propose a simple combined shortest path/one-copy routing strategy that provides a capacity of at least two simultaneous packet transmissions.