The unexpected octopus influx is causing a ripple effect in the marine ecosystem of south-west England, with deep-sea dolphins like Risso's choosing to stay inshore for longer periods. This phenomenon, as observed by marine biologist Josh Symes, is a fascinating yet complex interplay of food availability and habitat choice.
Symes, who runs the Risso's Dolphin Photo ID project for Exeter University, notes a significant increase in the number of dolphin sightings, with over 20 reported in 2025 compared to fewer than 10 in previous years. This surge in sightings coincides with an abundance of cephalopods, including octopuses and cuttlefish, which are the primary food source for Risso's dolphins. The biologist attributes this to an octopus bloom and the increasing presence of cuttlefish.
The dolphins' preference for inshore waters is a strategic move, allowing them to feed on the abundant cuttlefish that spawn in these areas. With the additional food source of octopuses, the dolphins have more reasons to linger in these waters. Symes suggests that the increase in sightings might also be due to heightened awareness among locals and tourists on how to spot these dolphins.
Risso's dolphins, known for their intelligence and stealth, can be challenging to distinguish from Orcas due to their size. Symes finds this aspect particularly intriguing, as it highlights the complexity of marine life identification. The biologist has documented over 700 individual Risso's since 2011 across Devon, Dorset, Cornwall, and the Isles of Scilly, indicating a thriving population in the region.
This octopus-driven shift in dolphin behavior raises questions about the long-term impact on the marine ecosystem. As the octopus population continues to flourish, it could potentially disrupt the balance of the food chain, affecting not only the dolphins but also other marine species. The story of the Risso's dolphins and the octopus bloom is a reminder of the intricate relationships within marine ecosystems and the importance of understanding these dynamics for conservation efforts.
