The deep waters found in submarine canyons around the world are a unique ecosystem that attracts the entire food chain. There is an increase in productivity that can sustain even the apex predator of our oceans, the Orca. The topography of the Bremer Canyon allows for downwelling and upwelling of the Leeuwin and Southern Ocean currents. Eddies provide cul-de-sac environments which create perfect spawning or feeding grounds for certain species. The circulation of these currents create a perfect feeding environment for some of the top pelagic predators including Pilot Whales, Sperm Whales, Tuna, Sharks and Orca.
There is a reason for the yearly gathering in the Bremer Canyon of the largest known congregation of Orca in the Southern Hemisphere. These types of mass gatherings in all wildlife will generally indicate one of two things;
- A need to feed
- A need to find a mate
- or both of the above!
We have sighted Orca in the Bremer Canyon feeding on squid. Orca of all age groups with squid in their mouths and also in the beaks of foraging seabirds. This answers one question, the Orca are certainly coming here to feed and it seems most regularly on squid. We must now focus our attention on what is bringing the squid here to the Bremer Canyon. The best time to see Orca in the canyon is between January and March each year with this also being a prime time for spawning to occur.
The research that has been completed in deep sea canyons around the world has found a peak time in the productivity of spawning squid during certain months. Some species will prefer to lay egg cases on relatively shallow and sandy plateaus, while other females will protect their eggs while fasting. These different spawning methods and species will still have the same result in the end, vey weak and immobile squid. Some may die straight after spawning while others who can evade predators might be fortunate to live for a while longer once they regain their strength.
Millions of squid can congregate during these spawning events and the food availability for all species in the food chain who can consume squid sky rockets into enormous proportions. The weakened squid become easy targets for calamari lovers such as Pilot Whales, Sperm Whales and the Orca of Bremer Bay. We suspect that squid are the main purpose for the arrival of the Orca and further research must be completed to understand if feeding on Tuna and Beaked Whales by the Orca is opportunistic feeding or perhaps territorial.
Our study going forward will focus on the West Australian canyons environment and indeed the canyons around the world. It is these environments that cultivates the food types mega fauna are seeking, this we believe is the true ingredient to unravel the mysteries of the Bremer Bay Orca.