So we've just published this new report on the 2025 octopus
bloom. So hi, I'm Doctor Bryce Stewart.
I'm a Senior Research Fellow at the Marine Biological
Association and associate Professor at our University of
Plymouth. So we've just published this new
report on the 2025 octopus bloom.
This is the common octopus, as it's known by its scientific
name, Octopus vulgaris. In the coastal waters of
southwest UK, we've seen this incredible increase in numbers.
So we were commissioned to do some research into why this has
happened, what the consequences might be, particularly for the
fishing industry, and then also what the future might hold.
So we're lucky enough to receive funding from Defra, from
Plymouth City Council and from Devon County Council to be able
to do this study. So it's led by the Marine
Biological Association. But we're also doing that work,
importantly with partners at Plymouth Marine Laboratory, the
University of Plymouth, and also an independent consultant called
Doctor Simon Thomas. Yeah.
So what we've discovered, well, we've really confirmed how
unusual this event is. We've looked back through
history over 150 years. There's only a few instances
where this sort of thing has happened before.
So this is probably now the best documented, particularly because
of the reservations from fishermen.
A, this is a really unusual event, but B, we think we found
a really clear link with climate change.
So we looked at both the environmental conditions around
this bloom in octopus, but also those are the previous ones over
the last 100 years or so. But during the year of the
bloom, but also the year before when the octopus would have been
breeding, we saw unusually warm temperatures in the sea water
and in the atmosphere compared to the sort of other years
around that period, what we call a marine heat wave.
So that was consistent with all of those other blooms.
And this one sort of makes sense because this is a warm water
species, right? So when the water's warmer here,
you expect to see them here. The other thing that we've done
is actually model the dispersal of the young octopus after
they've hatched from eggs. So octopus are pretty cool.
Anyone who's seen My Octopus Teacher will know the females,
once they've been fertilised, actually lay eggs in a den.
They'll guard those until they hatch.
And then those little tiny baby octopus actually disperse in the
ocean currents. And we were able to show that if
there had been lots of breeding, say in the Channel Islands,
Guernsey in particular, where we know there was lots of octopus
last year, those baby octopus would have actually come on the
ocean currents to the southwest coast of the UK, exactly where
they've been found. So we're pretty clear that
there's this link with warmer temperatures and also that they
can actually have come from other waters as well.
The octopus, once they've sort of arrived near our coasts, have
obviously been moving around. That's very difficult to study.
And that's something we'd like to look at more in the future.
Yeah. So obviously what I've said is
the fishermen were the first ones to detect these octopus,
but to begin with it And it wasn't very positive, to be
honest. Particularly crab and lobster
fishermen were finding that the octopus were getting into their
pots and they were eating everything in there.
It was like a seafood buffet for them, you know.
So fishermen were pulling out pots and they'd find bits and
pieces of crabs and lobsters and even scallop shells that the
octopus seemed to have brought into the pots to eat later.
So they're, you know, they're quite the connoisseur.
That was obviously very disturbing.
Catches of crabs and lobsters were really down for the first
few months. Then at least some of the
fishermen, unfortunately not all, were able to actually focus
on catching the octopus instead. Some of them did quite well out
of that and offset their the loss of their catches of crabs
and lobsters. And so for a period of time,
probably short of four or five months, you know, the earnings
were still relatively good. Not for everyone, as I said, and
that's important, but from about August onwards, catches of
octopus have dropped off quite a lot, but catches of crabs and
lobsters and scallops haven't come back.
So we're really in a, in a sort of, I guess, an uncertain future
and a worrying time for the fishermen because if those
populations of crabs and lobsters and scopes don't
recover, obviously that's going to affect what is a long
standing fishery for those species.
But also if the octopus don't come back either, then they've
kind of got almost nothing to catch.
Now that leads us to the question of will the octopus
come back? They are still here.
We're still getting reports of fishermen catching them.
Divers are seeing them as well. One diver last week.
So six of them in a single dive. So they're obviously around.
We know they've been breeding as well.
There's lots of observations of that and of the eggs as well.
And even some small baby octopus have been seen here.
So chances are they will be here again, particularly if we have a
relatively warm winter. So they'll survive over the
winter and we'll see them again. Exactly how big the numbers will
get, I guess that remains to be seen.
But I think we do have to get used to this almost new reality
that climate change is bringing. It's disrupting marine food
webs, it's causing these changes.
And for us, as I guess both fishermen and divers, that's
something that we're going to just need to adapt to.