May 8, 2024 • 13 mins
Are seals the fishermen's friends or foes? The UK is home 35% of the world’s grey seals and we know they like to get their flippers on many of the same fish as we do. So, how are seals impacting the fishing industry?
In our latest podcast, Dr Claire Tanner from the Department of Biology explores the unseen conflict beneath the waves and the complex dynamics between these marine mammals and fisheries.
Tune in to find out how understanding more about the behaviour of the UK’s seal populations can shape marine management policies.
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:06):
>> When it comes to seals living around the UK,
there are some scientific blind
spots. Anecdotally, we know stuff like,
they like
>> to eat the same fish that we
>> do, but we don't know a lot about how they go about
finding their next meal.
>> Well, that's until now.
>> On this episode of the Oxford Sparks Big Questions
podcast, we're asking �how are
(00:28):
>> seals affecting fish fishing catches?�
>> Hello, I'm Emily Elias and this is the show
where we seek out the brightest minds at the University of Oxford
and we ask them the big
questions. And for this one, we have found a researcher
who is excellent at counting and
(00:49):
hungry for some data sets.
>> So, I'm Claire Tanner, I'm a postdoc in
the Marine Conservation Ecology and Management
group in the Department of Biology at the University of
Oxford, and I study the human
wildlife interactions between seals and
fisheries linked to animal behaviour.
>> Okay, so maybe I just have this, like, weird thing where I didn't think
(01:11):
there were tonnes of seals around in the
UK. Are there, like, how many are we talking
about?
>> Yes. So in the UK, we've got two species of
seals. We have harbour seals and grey
seals. The grey seals are the most numerous and
the population is increasing at the moment, but it was
previously declining from hunting, which is now
(01:31):
illegal. Harbour seal population
is generally stable, although we've got
some sub populations, some groups
that are declining, but it's the greys
that are increasing. At the moment, we've
got 35% of the world's
population of grey seals. And for harbour
seals, we've got
(01:53):
22% of the world's population in northern
Europe. So not just in the UK. So
that's still quite a lot of seals. And compared to
other countries, we have a lot of seals,
but we don't know what the historic population counts were
before hunting. So it's difficult to say if
we're back up to that population size,
(02:13):
but it's really good that the populations are increasing
after the hunting ban.
>> So, yeah, that is a lot of seals.
>> And what are these seals doing?
>> A lot of the time they're in the water, they hunt in the
water and move quite a lot between
sites, but they also haul out. So
they spend a lot of time resting to digest their
food and also to reproduce. So we have quite a
(02:36):
lot of sites around the UK that are
reproductive sites.
>> And with all of these seals hanging about and
resting, they must have some pretty full
bellies. So where are they getting their food
from?
>> Yeah, so there's quite a bit of human wildlife
interactions with this. So they're a generalist
predator, so they eat
(02:58):
basically anything that they can get their hands
on or their flippers on. There have been some
diet studies to say that they prefer
sand eels and fish like
that when they're actually fishing for themselves. But
there's a lot of anecdotal evidence from fishes that
they hang around the nets, take fish from the
nets and will follow fishers
(03:20):
around.
>> And obviously those fish would be the ones that have the high value for
them to sell onto the markets. People wanting to
eat bass and cod and
all those wonderful things that we put in a deep fat
fryer.
>> Yes, yes, exactly. So seals are tending to
want the same fish that we're wanting,
which is where the conflict is arising
(03:42):
from, really. The fishers have been saying that they
follow the fishing boats from the harbour all the
way to the fishing ground and then back again. Why would they do
that, potentially to get an easy meal.
If you've got nets in the water, then the seals won't
have to dive down as far to get their fish, they
won't have to follow them or chase the fish
(04:03):
to catch them.
>> You've used the words anecdotally. You've
potentially. It seems like there's a couple question
marks about what we actually know and what we
don't know. What are the sort of gaps of knowledge that
we have?
>> Yes. So there was a paper recently in
preprint from Jackson et al, and they were doing
a big meta analysis on the severity
(04:25):
of these seal fisher interactions around
the world and the conflicts that had
arisen from this. So they predicted
that the UK would have this really high potential
for seal fisheries conflict. But we didn't have a
data point for the commercial fisheries. All
the previous research in the UK has focused
on recreational fishers, so
(04:47):
anglers or fish farms.
>> So a lot of what we knew
>> before I started this study was all
anecdotal, people saying they are having
interactions, but there wasn't any
empirical evidence or data points to say, this
is definitely happening and this is the
severity of it.
>> And so what have you done for the past year? I've
(05:10):
been looking at the partially
eaten fish that come out of the
nets. and I've been going around the UK
talking to fishers and collecting data
on the amounts of partially eaten catch they
get compared to their total catch, their damage to
gear and other information from the vessel, such as,
like the target fish species or the
(05:31):
gear type.
>> What are you hoping to piece together?
>> So we're hoping to link this back to the
severity and try and get a
extent of the conflict. So is it UK wide,
is it specific to certain areas? And
also the severity. So are there certain types of
gear that have more severe partially eaten
(05:52):
catch? Are there certain fish
species that fishers are catching that are
worse than others for this partially eaten
catch, and then potentially looking at
more mitigation measures and helping
policy decision makers with some
management strategies.
>> So is this a big issue for people who are
(06:12):
fishing?
>> Yeah, so a lot of the fishers that we're
talking to are small scale fisheries. So they're under
ten metre boats. They don't fish very far
from the shore, and they tend to be
individuals or families in
fishing communities that have been fishing for
generations. So they're not big
(06:33):
corporate companies, they're
families and family owned businesses.
They can be quite hard hit, depending on
the gear and the fish that they're targeting. So
we've had a range from no fish lost
to almost 100% lost. So, like,
like 90% of the fish that they're
(06:53):
pulling up in the nets have been lost.
>> Wow, that's a lot of fish.
>> Yeah. So that's quite a lot of the fish that
they're losing, but also they can't do anything with the damaged
catch. So if there's a bite taken out of it,
it's not sellable or usable for anything other than
bait for more fishing.
>> And so what were the preliminary results?
(07:13):
>> So we have shared the preliminary results with
the MMO, who have then shared them with fishers.
So at the moment, the extent of the
seal fisher interactions is UK
wide. So there's very few places and
people that are unaffected, and the amount
of catch that's partially eaten
is affected by both the gear type
(07:36):
that the fishes are using and
the, target fish that they're trying to
fish. So if you're fishing with the
netting, then it's more heavily
depredated. There's more partially eaten catch
than any other gear types, and the seals
also prefer the higher value
fish. So fish like bass and monkfish
(07:57):
were more eaten than
other species, and shellfish and crustaceans
were rarely targeted at all by
seals. So there's quite a difference
between fishers depending on their gear
and their target species.
>> So they're figuring out what these seals are doing. How
would that be able to help?
(08:17):
>> So we've collected this data
to produce results on the
extent and severity of this partially eaten
catch. The depredation. We've recently received
a Oxford Policy Engagement Network
funding, and this is in collaboration with the Marine Management
Organisation who are the policymakers.
So we're going to be running management strategies
(08:40):
workshops around the UK. And for this we can
look into the factors within management strategies that
are feasible and appealing to both fishers
and also feasible from a policy
side to assist the MMO with
policymaking decisions. So hopefully we
can help reduce that human wildlife conflict.
(09:00):
>> And, like, what would that kind of look like? Oh, this type
of fishing gear is better to buy
because it means that seals have a harder
time getting into it or what?
>> Yeah, so they're looking at� the MMO have been looking
at acoustic deterrents, potential
changes of gear types, changes
in different target fish species. So
(09:21):
it's a range of different factors within the management
strategies that they're looking into. And then,
we're hoping to help to
categorise these to best to worst for
appealing for the fishers so that the MMO can
find a management strategy that's helpful for
fishers as well as seals.
>> Yeah, I mean, the seals themselves. It sounds like
(09:43):
you also want to learn about them, right?
>> Yes, so we also do population
data on the seals. So we'd be monitoring
the Isles of Scilly and the Farn Isles for
full population counts of inaccessible
islands. So we were in the civvies this past
year and, we've been flying drones from the boats
to get an accurate count of seals
(10:06):
from the air. Because you can't see these
sites from the boat, it's really difficult.
And some of the seals can be in the centre of the island
and to get to the centre you have to be able to
land on some of these really inaccessible islands
and potentially disturb a load of seals
to get to the centre. So we've been
trying to use drones to fill in these
(10:28):
population gaps and to monitor them more
effectively. There are some areas which are very
well monitored, especially by conservation
organisations and volunteers. But the fishers have
brought up some locations that were not known as haul
out sites and these are inaccessible by
land and, like, not visible at all from land
surveys. So potentially there are, extra
(10:50):
populations that we don't know about that would be
useful to also monitor by
drones.
>> That's wild, that there's just all these seals hanging
around and we don't even know how many there are.
>> Yeah. So we've got some estimates which have been made
by groups up in St Andrews, but obviously we don't
know exactly how many there are
(11:10):
because most of them do spend the majority of their time
in the water. So when they come on land, we're just getting
a snapshot of their life.
>> Did you think that your life was going to take this twist and turn, that you'd
be, counting seals all day?
>> So my background's from animal behaviour
as well as from� I've done some fisheries bycatch
work as well. So it's kind of a mix
(11:32):
of my two backgrounds together
and I just find the animal behaviour very
interesting. And also
working in the UK, I normally do field work
abroad, so being able to have a project in the
UK and learn more about
the coast of where I live has been really,
really good as well. And to be able to talk to
(11:54):
fishers and give them a voice
for and put a data point where the
anecdotal evidence is, is really
rewarding as well. To be able to get some actual
input and to help a policy
decision maker to move
forward with some actual action is quite
rewarding.
(12:14):
>> Oh, I bet your phone is just filled with really cute seal
pictures.
>> I try, but my phone camera isn't that
good.
>> This podcast was brought to you by Oxford
Sparks from the University of Oxford with music
(12:34):
by John Lyons and a special thanks to Dr
Claire Tanner.
Tell us what you think about this podcast.
You can rate and review us on whatever app you are using
or you can find us on the internet
@OxfordSparks. We've got a website,
Oxfordsparks.ox.ac.uk
and get in touch with your big questions.
I'm Emily Elias.
(12:54):
Bye for now.
>> When it comes to seals living around the UK,
there are some scientific blind
spots. Anecdotally, we know stuff like,
they like
>> to eat the same fish that we
>> do, but we don't know a lot about how they go about
finding their next meal.
>> Well, that's until now.
>> On this episode of the Oxford Sparks Big Questions
podcast, we're asking �how are
(00:28):
>> seals affecting fish fishing catches?�
>> Hello, I'm Emily Elias and this is the show
where we seek out the brightest minds at the University of Oxford
and we ask them the big
questions. And for this one, we have found a researcher
who is excellent at counting and
(00:49):
hungry for some data sets.
>> So, I'm Claire Tanner, I'm a postdoc in
the Marine Conservation Ecology and Management
group in the Department of Biology at the University of
Oxford, and I study the human
wildlife interactions between seals and
fisheries linked to animal behaviour.
>> Okay, so maybe I just have this, like, weird thing where I didn't think
(01:11):
there were tonnes of seals around in the
UK. Are there, like, how many are we talking
about?
>> Yes. So in the UK, we've got two species of
seals. We have harbour seals and grey
seals. The grey seals are the most numerous and
the population is increasing at the moment, but it was
previously declining from hunting, which is now
(01:31):
illegal. Harbour seal population
is generally stable, although we've got
some sub populations, some groups
that are declining, but it's the greys
that are increasing. At the moment, we've
got 35% of the world's
population of grey seals. And for harbour
seals, we've got
(01:53):
22% of the world's population in northern
Europe. So not just in the UK. So
that's still quite a lot of seals. And compared to
other countries, we have a lot of seals,
but we don't know what the historic population counts were
before hunting. So it's difficult to say if
we're back up to that population size,
(02:13):
but it's really good that the populations are increasing
after the hunting ban.
>> So, yeah, that is a lot of seals.
>> And what are these seals doing?
>> A lot of the time they're in the water, they hunt in the
water and move quite a lot between
sites, but they also haul out. So
they spend a lot of time resting to digest their
food and also to reproduce. So we have quite a
(02:36):
lot of sites around the UK that are
reproductive sites.
>> And with all of these seals hanging about and
resting, they must have some pretty full
bellies. So where are they getting their food
from?
>> Yeah, so there's quite a bit of human wildlife
interactions with this. So they're a generalist
predator, so they eat
(02:58):
basically anything that they can get their hands
on or their flippers on. There have been some
diet studies to say that they prefer
sand eels and fish like
that when they're actually fishing for themselves. But
there's a lot of anecdotal evidence from fishes that
they hang around the nets, take fish from the
nets and will follow fishers
(03:20):
around.
>> And obviously those fish would be the ones that have the high value for
them to sell onto the markets. People wanting to
eat bass and cod and
all those wonderful things that we put in a deep fat
fryer.
>> Yes, yes, exactly. So seals are tending to
want the same fish that we're wanting,
which is where the conflict is arising
(03:42):
from, really. The fishers have been saying that they
follow the fishing boats from the harbour all the
way to the fishing ground and then back again. Why would they do
that, potentially to get an easy meal.
If you've got nets in the water, then the seals won't
have to dive down as far to get their fish, they
won't have to follow them or chase the fish
(04:03):
to catch them.
>> You've used the words anecdotally. You've
potentially. It seems like there's a couple question
marks about what we actually know and what we
don't know. What are the sort of gaps of knowledge that
we have?
>> Yes. So there was a paper recently in
preprint from Jackson et al, and they were doing
a big meta analysis on the severity
(04:25):
of these seal fisher interactions around
the world and the conflicts that had
arisen from this. So they predicted
that the UK would have this really high potential
for seal fisheries conflict. But we didn't have a
data point for the commercial fisheries. All
the previous research in the UK has focused
on recreational fishers, so
(04:47):
anglers or fish farms.
>> So a lot of what we knew
>> before I started this study was all
anecdotal, people saying they are having
interactions, but there wasn't any
empirical evidence or data points to say, this
is definitely happening and this is the
severity of it.
>> And so what have you done for the past year? I've
(05:10):
been looking at the partially
eaten fish that come out of the
nets. and I've been going around the UK
talking to fishers and collecting data
on the amounts of partially eaten catch they
get compared to their total catch, their damage to
gear and other information from the vessel, such as,
like the target fish species or the
(05:31):
gear type.
>> What are you hoping to piece together?
>> So we're hoping to link this back to the
severity and try and get a
extent of the conflict. So is it UK wide,
is it specific to certain areas? And
also the severity. So are there certain types of
gear that have more severe partially eaten
(05:52):
catch? Are there certain fish
species that fishers are catching that are
worse than others for this partially eaten
catch, and then potentially looking at
more mitigation measures and helping
policy decision makers with some
management strategies.
>> So is this a big issue for people who are
(06:12):
fishing?
>> Yeah, so a lot of the fishers that we're
talking to are small scale fisheries. So they're under
ten metre boats. They don't fish very far
from the shore, and they tend to be
individuals or families in
fishing communities that have been fishing for
generations. So they're not big
(06:33):
corporate companies, they're
families and family owned businesses.
They can be quite hard hit, depending on
the gear and the fish that they're targeting. So
we've had a range from no fish lost
to almost 100% lost. So, like,
like 90% of the fish that they're
(06:53):
pulling up in the nets have been lost.
>> Wow, that's a lot of fish.
>> Yeah. So that's quite a lot of the fish that
they're losing, but also they can't do anything with the damaged
catch. So if there's a bite taken out of it,
it's not sellable or usable for anything other than
bait for more fishing.
>> And so what were the preliminary results?
(07:13):
>> So we have shared the preliminary results with
the MMO, who have then shared them with fishers.
So at the moment, the extent of the
seal fisher interactions is UK
wide. So there's very few places and
people that are unaffected, and the amount
of catch that's partially eaten
is affected by both the gear type
(07:36):
that the fishes are using and
the, target fish that they're trying to
fish. So if you're fishing with the
netting, then it's more heavily
depredated. There's more partially eaten catch
than any other gear types, and the seals
also prefer the higher value
fish. So fish like bass and monkfish
(07:57):
were more eaten than
other species, and shellfish and crustaceans
were rarely targeted at all by
seals. So there's quite a difference
between fishers depending on their gear
and their target species.
>> So they're figuring out what these seals are doing. How
would that be able to help?
(08:17):
>> So we've collected this data
to produce results on the
extent and severity of this partially eaten
catch. The depredation. We've recently received
a Oxford Policy Engagement Network
funding, and this is in collaboration with the Marine Management
Organisation who are the policymakers.
So we're going to be running management strategies
(08:40):
workshops around the UK. And for this we can
look into the factors within management strategies that
are feasible and appealing to both fishers
and also feasible from a policy
side to assist the MMO with
policymaking decisions. So hopefully we
can help reduce that human wildlife conflict.
(09:00):
>> And, like, what would that kind of look like? Oh, this type
of fishing gear is better to buy
because it means that seals have a harder
time getting into it or what?
>> Yeah, so they're looking at� the MMO have been looking
at acoustic deterrents, potential
changes of gear types, changes
in different target fish species. So
(09:21):
it's a range of different factors within the management
strategies that they're looking into. And then,
we're hoping to help to
categorise these to best to worst for
appealing for the fishers so that the MMO can
find a management strategy that's helpful for
fishers as well as seals.
>> Yeah, I mean, the seals themselves. It sounds like
(09:43):
you also want to learn about them, right?
>> Yes, so we also do population
data on the seals. So we'd be monitoring
the Isles of Scilly and the Farn Isles for
full population counts of inaccessible
islands. So we were in the civvies this past
year and, we've been flying drones from the boats
to get an accurate count of seals
(10:06):
from the air. Because you can't see these
sites from the boat, it's really difficult.
And some of the seals can be in the centre of the island
and to get to the centre you have to be able to
land on some of these really inaccessible islands
and potentially disturb a load of seals
to get to the centre. So we've been
trying to use drones to fill in these
(10:28):
population gaps and to monitor them more
effectively. There are some areas which are very
well monitored, especially by conservation
organisations and volunteers. But the fishers have
brought up some locations that were not known as haul
out sites and these are inaccessible by
land and, like, not visible at all from land
surveys. So potentially there are, extra
(10:50):
populations that we don't know about that would be
useful to also monitor by
drones.
>> That's wild, that there's just all these seals hanging
around and we don't even know how many there are.
>> Yeah. So we've got some estimates which have been made
by groups up in St Andrews, but obviously we don't
know exactly how many there are
(11:10):
because most of them do spend the majority of their time
in the water. So when they come on land, we're just getting
a snapshot of their life.
>> Did you think that your life was going to take this twist and turn, that you'd
be, counting seals all day?
>> So my background's from animal behaviour
as well as from� I've done some fisheries bycatch
work as well. So it's kind of a mix
(11:32):
of my two backgrounds together
and I just find the animal behaviour very
interesting. And also
working in the UK, I normally do field work
abroad, so being able to have a project in the
UK and learn more about
the coast of where I live has been really,
really good as well. And to be able to talk to
(11:54):
fishers and give them a voice
for and put a data point where the
anecdotal evidence is, is really
rewarding as well. To be able to get some actual
input and to help a policy
decision maker to move
forward with some actual action is quite
rewarding.
(12:14):
>> Oh, I bet your phone is just filled with really cute seal
pictures.
>> I try, but my phone camera isn't that
good.
>> This podcast was brought to you by Oxford
Sparks from the University of Oxford with music
(12:34):
by John Lyons and a special thanks to Dr
Claire Tanner.
Tell us what you think about this podcast.
You can rate and review us on whatever app you are using
or you can find us on the internet
@OxfordSparks. We've got a website,
Oxfordsparks.ox.ac.uk
and get in touch with your big questions.
I'm Emily Elias.
(12:54):
Bye for now.
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