TRANSCRIPT - Dr. Les Watling
Watling is a Professor of Oceanography at the Darling Marine
Center, part of the University of Maine.
Can you describe your research with regard to monitoring the
effects of bottom trawls on sea floor ecosystems?
been doing is looking at what happens when a trawl actually passes
over the surface of the sediment. This is a little bit different
than looking for large things that have been crushed and smashed,
but rather looking at the structure of the sediment itself and how
its altered. And Im particularly interested in how habitat
gets altered for all of the small things that live in this muddy
I got started
in this whole business actually in mid-1990s. Because I had found
this place where these large sponges were present and I had a friend
who was a sponge taxonomist and I took him out on a cruise with
a submersible and put him down on the bottom and asked him to collect
the sponges, take them home and identify them, so we would know
who they were. And when they came back up, they had no sponges.
And so I asked to see the videotape. You know what had happened?
Could we have been in the wrong place or whatever? And it was clear
that the whole place had been trawled. All the large sponges that
we had seen in the tape from 1987 were gone.
Weve actually had fishermen tell us that since theyve
heard that trawls passing over rocky areas and knocking over structures
is bad news, they think that dragging over a muddy floor is okay.
It sounds to me like that might not be the case?
There is this
general perception that when trawls or scallop drags or whatever
goes across sandy bottoms that those devices only do what storms
do. They stir the sediment up and everyone gets kicked up into the
water and they settle back down and think, "okay were
But in fact,
a large number of things happen. Even in sandy bottoms, the sediment
is structured in such a way that the good stuff to eat. If youre
an animal living in the sandy bottom youre looking for high
quality food otherwise you have to eat a lot in order to
digest out of this sediment what you need so the high quality
stuff is all the stuff that has settled from the water column onto
the surface of the sediment.
The key for
understanding what happens when scallop drags or trawls go over
this bottom is that it kicks all that stuff back up into the water
and the tide carries it away. Weve in fact documented this
very well here next to the Darling Center using a scallop drag.
And doing a lot of careful chemical measurements and what not, we
see that the top two to three inches of the sediment is completely
carried away. So all the good food value is gone.
In muddy sediment,
you have the additional complication of the fact that to live in
mud, animals have to make burrows or tubes. They have to do this
because they need to breathe oxygen. And there is no oxygen in the
sediment. So they have to maintain an opening to the overlying water
in order to get enough oxygen to live. When the trawl comes along,
we know from all the work weve done with x-rays that the entire
upper 3-5 inches of the sediment all the tubes and burrows
and everything gets obliterated completely. A lot of that
mud gets kicked up into the water and settles back down again. So
youve lost food value. Youve lost dwelling structures,
homes, for all these animals. All these things have been changed.
Then on top
of that, sediment that has sat there and gradually lost the water
just due to settling by gravity has suddenly all this water back
in it. And what most people dont realize is that the reason
why animals live in sediment rather than up in the water is that
they are not swimming. If you put all that water back into the sediment,
youre essentially forcing an animal to swim in this mud. And
they cant do it. And so an awful lot of animals die under
in muddy and sandy habitats is not benign. It actually makes a very
big difference to the habitat; its just not so visible.
A realist might say, in terms of trade-off, well maybe its
more important for us to be able to catch the fish in an efficient
way with a bottom trawl. Is that so bad?
so bad about it is two things really. One is that part of our objectives
as scientists is to document, monitor, and preserve marine
biodiversity. And clearly, were losing biodiversity when these
habitats are altered in this way. From the fishermans point
of view, there is also a reason they should be concerned. And that
is that all this small life is basically the food for the very young
stages of all the fish they are trying to catch. Its like
disturbing over a cornfield two weeks or three weeks after youve
planted the corn. Whats the point? The corn will never grow.
And young fish need someplace to feed and some food to feed on.
And this is basically the food source. But besides that, there is
this question of habitat integrity and whatever services that those
habitats might perform which we dont know about at the present
How are you actually seeing an area that has been trawled versus
one that hasnt? Are you actually seeing the sea floor somehow?
We use cameras
primarily on remotely operated vehicles or ROVs. And also weve
used cameras mounted on sleds, which on muddy bottoms, is a fairly
efficient way to get a good picture. No matter what kind of camera
system you use, you can see a number of effects of a trawl having
passed over an area.
The most obvious
things are what are called doormarks, which is where the doors that
are used to haul the auto-trawls open make fairly large gouges in
the sediment. Theyre basically like a plow going across the
mud, turning up the mud on one side and leaving a huge trough on
the other. And those are quite visible. So as soon as you see those,
you know youre in trawled area.
discovered some other smaller things with shrimp trawls, for example,
on muddy bottom where the mud seems to go into the net even though
many shrimp fishermen will tell you that theyre not dragging
the bottom very hard. What you see when you go in an area that is
freshly trawled are a bunch of little mud pyramids. These mud pyramids
seem to be mud that has gone into the net and then been squeezed
out through the mesh. And one place where we investigated this we
saw that these mud pyramids lasted for about a week or ten days
and then gradually got worn down probably by the animal activity
in the area. But its quite obvious visually when you go across
an area thats been trawled.
at a lot of stuff in the Gulf of Maine in particular. I can pretty
well tell anywhere in the Gulf of Maine I can tell an area thats
been trawled just from camera pictures.
Can you describe the other impacts of trawling besides on the organisms
that live on sandy bottoms or in muddy bottoms?
A good example
is where rock hopper gear is used. And youve probably seen
this video of roller gear, rock hopper gear going across the surface.
And every once in awhile, the foot-roll with one of the large rollers
on it will get caught on a large rock of say, 2 to 3 feet in diameter.
Instead of going over it, it gets caught on it then it pushes it
over the bottom. Eventually that large rock will hit something else
and then roll and the whole gear will go up over it.
You can see
these kinds of marks when youre diving on the bottom, either
in a submersible or with a ROV. You can see large troughs or gouges
behind big rocks. You can see rocks that are standing up on end
in what would seem to be a rather unnatural position. You can see
rocks where all the life that was on the top of the rock is now
sort of under the rock and now the top of the rock is bare.
There is lots
of visual evidence that you can use to determine whether an area
has been trawled or not. Weve gotten pretty good over the
years now that weve looked at so much videotape. Weve
been doing so much diving with these devices that we can pop down
into an area and we can tell within a few minutes whether the place
has been trawled or not.
How long does it take for these organisms to grow and why is that
of concern to you?
a big problem here and that most of the animals we know something
about in cold water are long-lived. Unfortunately, we dont
know very much about very many animals. So were guessing that
it will take these communities of sponges and corals a very long
time to recover. We dont see rapid re-colonization in areas
that weve studied.
In fact, one
place in the Gulf of Maine, the place was trawled somewhere between
1987 and when I went back there in 1993. In 1987, it had very large
barrel sponges, foz** sponges all sorts of large organisms
living on the rocks. Every possible area of surface of the rock
had some living thing attached to it. When I went there in 1993
that was all gone. It was completely gone. And Ive been back
as late as 1997, and there is still no sign of any recovery of any
of that large stuff.
What we do have
in fact is like you would see in an old field. You have all the
little weedy species, small things call hydroids. But instead of
having 10 or 15 species, you have one that covers completely the
surface of the rock. So we found that the biodiversity of the trawled
area was about half of the un-trawled area. And none of it was large
things. I have no idea how long it will take for the larger things
to gradually come back to that area.
And what is the importance of this kind of structure for the recruitment
of juvenile fish or of cod?
One of the concerns
that we have about losing this large structure is we actually know
very little about nursery grounds of the commercial fisheries. In
fact until a few years ago, we didnt even know where cod went
when they landed on the bottom after leaving the plankton when they
were a month or two old. No one actually knew where one-year old
cod were. And I think that can safely be said for many other species
as well. So we dont know what their habitat requirements are.
What we do know
is that in the 80s when we were diving in these areas that had these
complex habitats is that we saw all these small fish. And now when
we dive in areas that are un-trawled because the boulders are too
large or something like that for rolling gear to get in there, what
we see are very large numbers of small red fish. For example on
our most recent cruise, that was probably the key organism that
we found in these rough bottom areas were hundreds and hundreds
of really tiny red fish. And I think if you go to a few remaining
areas, where you have this kind of complex habitat structure and
were able to have a look at it, you would see these kinds
But since so
much time has gone by with all of this roller gear being used, we
have very few of these places left. We dont know how they
were used as refuges. But my guess is they were probably very important.
I personally think that the final collapse of ground fishing in
New England was due to the introduction of roller gear and the destruction
of what were otherwise natural refuges.
Would you care to speculate as to how much more area was opened
up with the advent of rock hopping technology?
a little bit of a hard number to come up with, but I think we can
take a sort of broad-brush look. The Gulf of Maine is unusual for
the East Coast of the United States because it has so many different
kinds of habitat. If you go from the top of Georges Bank all the
way to Florida, by in large youre dealing with sand. But in
the Gulf of Maine you have muddy basins. You have rocky ledges and
ridges. You have old gravel moraines left by the glaciers that have
rocks of varying sizes on them. Then on top of that, you have very
different kinds of water types.
So if you take
sort of the cold water layer in the Gulf of Maine which covers the
middle 1/3 depth-wise, say from 50 meters down to 200 meters, within
that layer you have most of the bottom that supports the ground
fishery. And I would say about 2/3 of that was trawl-able before
rock hopper gear came along. Meaning that it had either fairly small
cobble pebbly bottom or was mud.
Of the remaining
third, some of it is just open rock ridge where you couldnt
really drag a trawl up. So were down to probably that might
make up 5 or 10% of that remaining third. And so, most of the remaining
third has been opened up to trawling as a result of the development
of rock hopper gear.
So, if you take
the Gulf of Maine as a whole, you would have had about 65% of the
bottom area that would have been available to trawling before rock
hopper gear came along. With the advent of rock hopper gear, about
90% of the Gulf of Maine bottom is available for trawling. That
leaves 10% that is untrawlable; that is not very much.
How important is it to the long-term success of cod stocks and other
ground fish to have 10 percent? Is 10% enough?
not a fisheries biologist. But common sense would tell me that you
cant raise a large stock that would be under significant fishing
pressure on a very small area of the bottom of the Gulf of Maine.
You have to just step back for a second and think about what these
fish need when they arrive on the bottom, out of the plankton. Theyre
small, a few inches, an inch or two long. They are easy prey for
other fish, particularly silver hake. But all of the other fast
swimming cod-like fishes all prey on small fish. So they need a
place to hide. They need things to eat. Fish have to eat everyday.
So there has to be available prey in very large numbers to support
young fish when they arrive from the plankton.
It seems to
me that if you take a very large area like the Gulf of Maine and
you have in it these little tiny islands of untrawlable bottom,
its going to be very hard for the fish to find them. First
of all, those little islands are not going to support very many
fish. So, just from that, just as a total common sense you
dont have to do any mathematical modeling here its
fairly simple to think about the fact that you need larger patches
of bottom that are undisturbed to support these young fish.
People in Iceland and people that catch fish in the North Sea were
talking about how the advent of technology the more powerful
engines and stronger netting materials has allowed them to
drag in deeper areas. And that the cod was such a prolific fishery
in the North Atlantic for so long because large areas in the North
Atlantic were not fishable; the cod had these vast sanctuaries.
A good part
of the problem is that as all these fisheries were fished out in
shallow water, people moved more and more into deeper water. Moving
into deeper water meant the development of larger, heavier gear.
Which meant the financing of very large and very powerful vessels
to pull this gear. And now what weve seen is an effort on
the part of not only fishermen but in fact of governments putting
money into the development of these large vessels and this large
gear to fish ever deeper.
think this is an ecological crime. I think that these areas have
been undisturbed for millennia. They are not adapted to any disturbance
regime that we know of. No natural disturbances occur once you get
below 700-800 meters. And we also know that the organisms that live
here are very long-lived. And so one sweep of any of this gear through
this bottom area will leave a mark for centuries probably and maybe
a lot longer. And the fact that people are being encouraged by financial
incentives to fish in these areas I think is really unbelievable
and unconscionable and should be stopped.
Do you think this slow rebuilding of the cod stock has caught everyone
off-guard? What does the outlook look like and to what degree is
there a tie-in to habitat management?
is to say that the reason why the rebound has taken so long is that
there is nowhere for newly recruited cod to go to survive. Thats
because I have a habitat perspective. Mathematical modeling tells
you that you should get a certain percentage of fish. If you have
certain stock of reproductive age animals, they will reproduce a
certain stock of eggs. You will have certain losses, some percentage
loss all the way through this business until you get back to an
there is that as other aspects of the environment have changed you
have things like the North Atlantic oscillation that may determine
aspects of the planktonic food chain. You have habitat loss on the
bottom. You have lots of other sort of externalities that come to
bear on the changing the numbers in this percentage loss trickle
down that everyone uses. Something like 95% of the cod eggs that
are spawned every year are just lost.
is if you ruin the habitat for these young animals as they land
on the bottom do you change that number for 95 to 97? We dont
know those kinds of answers. It may be that its that last
2% or 3% thats going to make all the difference in the possible
rebound of the stock. Thats whats not been looked at.
And I have a hunch that the fact that we lost so much of the habitat
that could be nurseries is going to drag out this recovery for a
very long period.
Could you compare the effects of a scallop trawl versus an auto-trawl?
and auto-trawls actually work in quite different ways in terms of
what they do to the bottom. From what weve documented so far,
when a scallop trawl drags, they are very heavy and they plow along
the surface. Some people think they actually slide along the surface,
but in fact they dig into the bottom a few inches. In doing so,
they actually put quite a bit of sediment up into the water. You
can actually see furrows that are left by the scallop gear after
its gone across the bottom. Theyve been documented in
many instances, not just by us, but also by others, as being about
4 inches deep.
are interesting because they can be rigged in many different ways.
And the degree to which they dig into the bottom really depends
on how theyre rigged and how they fish. Weve looked
now at shrimp gear in the Gulf of Maine area, which is a cold-water
shrimp fishery, which occurs primarily on muddy bottoms and the
mud is very fine, and that gear is supposed to slide along the surface.
But we know in fact that it digs into the bottom from video work
that weve done.
of auto-trawl gear, you can rig the footrope in different ways so
that it basically pulls over the bottom. And clearly rock hopper
gear is just a modification of an auto trawl so that it supposedly
rolls along the bottom and actually rolls over the stones and other
large structures. The problem is that it actually snags onto things
because stones are not perfectly round. They have angles. Theyre
sometimes at a slight angle to the sediment and can get caught.
The other thing
that weve seen with rock hopper gear is that theres
an impact of the net as well. Most people havent really paid
attention to it. And that is that the net acts like sandpaper as
it pulls over the structure. And that, I think, is responsible for
an awful lot of the large things that are knocked off the surfaces
of the rock.
The scallop dredges go 4 inches deep, but in general would you say
that its an even greater impact than trawls?
dredges, the impact is greater on a single pass because the dredge
is so heavy and it literally destroys everything in its path. It
leaves very little structure standing. It may take several passes
of an auto-trawl to do the same thing.
Do you think that fishery managers are taking the scientific concerns
about the impacts on seafloor habitat into account?
no. The biggest problem that I see with the way the fishery
management system works today is that there is no chair at the table
for someone who is interested solely in marine biodiversity. If
I wanted to make a case that an area of the sea bottom should be
protected because there is an unusual, interesting, rare kind of
species that lives there that has no connection that I can establish
whatever to the fishery, there is no way for that to happen.
I suppose theres
one way, if I could prove that it was in danger of going extinct,
I may be able to get the area protected through the Endangered Species
Act. But the way ocean management has been set up in this country
the fishery management councils almost de facto are responsible
for managing any living thing on the sea floor. And I think I can
say unequivocally that none of those people know very much about
invertebrate zoology and therefore know almost nothing about all
the other organisms that live on the sea floor besides fish. So
theres no way really for me to take a concern that I have
about any small organism and have it dealt with in any way.
Why do you think fishery managers have been disinclined to close
more areas to fishing or to implement sufficiently low quotas over
I think this
has really been the case of sociology trumping biology. I think
that there hasnt been the political will to manage the fishery
as a fishery in terms of the health of the fishery. With fishery
production as the sole goal, there has always been in our system
of managing fisheries, the competing needs of human resources with
natural resources. And my sort of amateur look at this over the
years says that human resources have always won out over natural
resources. That seemed to me to be a recipe for disaster, which
is what we have.
Does the Sustainable Fisheries Act call for the precautionary principle
and start talking about ecosystem-based management?
It does call
for the precautionary principle and it does call for ecosystem-based
management, but I havent seen any evidence of the precautionary
principle being applied. And whats happened with ecosystem-based
management has been the definition of essential fish habitat. And
for the most part, thats single fish species-based. It includes
very little of the natural world outside of fish.
A good example
would be there are lots of maps thats been produced about
where these fish are and the fisheries service, to their credit,
has been very good at documenting where all the fish species are
or have been over the years. What they havent done is documenting
the habitat in those places where those fish are. As a result, we
dont actually know that much about the ecosystem requirements.
So in your opinion whats the best way to catch ground fish?
Is it to use trawls in just certain areas and close larger areas,
or is it to use a whole different kind of fishing method?
I think that
the best thing to do is to match gear to habitat type. And on top
of that, maybe even stay out of some kinds of habitats. See if we
knew where the nursery areas were, I dont think that anyone
would be able to make a compelling argument that we should take
a trawl and trawl through nursery areas. Everyone understands the
importance of nursery areas. We just dont know where they
are. Thats one.
On the other
hand, if you knew that nursery grounds for example were fairly wide
spread and had all this complicated habitat structure, you might
then suggest that you fish in there using some kinds of gear, perhaps
long lines, perhaps not, perhaps traps. There are other ways to
catch fish that are maybe more labor intensive but will still produce
some catch and yet leave an environment that will continue to produce
some fish. It would be a helpful thing to do.
So I think you
could actually do this. There are ways to match gear to habitat
type. I personally think that thats the one single thing that
could done that could make a big difference that hasnt been
done at all. No effort in that way whatsoever. Its just too
In Cape Cod well visit some hook and line fishermen who are
concerned about the effects of trawls and are set up to do long
Well you know
heres the thing, there are lots of areas in the Gulf of Maine
that were too rough to trawl before rock-hopper gear. So what did
they use in those areas? They used hooks and lines. And those areas
produced lots of fish. Thats why they still were in fact refuges.
They were being fished but there were still refuges because the
habitat was still being maintained.
been contacting me about what should we do about gear? Are there
ways we can modify trawls? In fact there was a recent initiative
in front of the New England Fishery Management Council about changing
the size of the rollers on the rock hopper gear. And I just thought
well all right this is an incremental step but it probably isnt
going to do much good. All its going to do is shrink the un-trawlable
area by a very small percentage, a half percent maybe. Its
not going to make that big of a difference.
But if you got
rid of rock hopper gear all together, then you go back that 65%
that was trawlable and you leave 35% thats un-trawlable. Now
weve got a balance in this system that might mean something,
that might make some difference. But I dont see that happening
any time soon, unfortunately.
It seems to me that the best attack to take is that some of these
organisms that these wacky biologists are concerned about are ultimately
important to their fishery and livelihood.
one way to deal with it. But I often dont take that approach
because not all organisms are important to the fishery. And see
thats where I think we have to back away from the ocean as
just a producer of fish and look at the ocean as a body of water
that sustains all life. And it really bothers the hell out of me
that a lot of people dont really care about all these other
things that we have in the ocean. And yet theyre part of the
legacy of evolution. I mean why are we willy-nilly wanting to throw
those things away? Or not even recognize their existence, which
I think is probably even worse. Ill give you my spin on biodiversity
Why is conserving biodiversity so important?
People say well
why should we protect these species? Why do we care whether these
species are going extinct? And everyone comes up with these sort
of well theres ecosystems services and theres the potential
for the cure for cancer and all this stuff. But I think that actually
the issue is much more fundamental. And that is that we live as
far as we know on the only planet that has living things on it.
And we dont know whether in the end if this will be the only
planet or whether there will be others. But in the meanwhile this
is what we have. And were fortunate to be here around at a
time when we can understand what three and a half billion years
of evolution has produced.
So what I use
as my example is the fact that what we see today is the end of a
long series of evolutionary processes. We see all these interesting
very specialized animals who are the product of evolution. Its
a marvelous process thats produced animals that can do some
pretty amazing things. And a lot of them are very, very tiny. And
the analogy I would have is if you took a library that has in it
like the Library of Congress everything thats
been written and if you think of those things as the end point of
centuries of learning, but you said well what do we need this library
for? Its taking up too much space. So were going to
go to the library and were going to take every fifth thing
off the shelf and were going to take it out in the streets
and burn it. People would go nuts.
essentially what were doing when were destroying these
species that are at the long end of evolution. Were losing
our record of how life has evolved on this planet. And I find that
pretty sad that people dont really care that much more about
it. They dont have to understand it. They dont have
to even know it. They dont have to know all these details.
But in the back of their heads, there should be an appreciation
for why this has happened. And they should be willing to take the
steps to protect it. And thats what I dont see which
is too bad. But I find that analogy works with most people that
I talk to sort of on the street or whatever, people who dont
know any biology.
Is fisheries science changing?
By in large,
theres no one really evil in this whole business. You have
a bunch of well-meaning people behaving according to the paradigm
they were taught. Thats what it comes down to. Theyre
behaving according to whatever the ecological system was in the
day that they did their Ph.D. work. Thats what they know.
Thats the framework they operate in. And in science generally
thats the case. Its not just fishery science.
the occasional person who steps outside that framework later in
their career and says maybe were doing things in a completely
wrong way. And we need to take a fresh look. And the whole field
eventually agrees and takes this little turn to the left or right
and on they go in another direction. But either these big advances
are made by graduate students or people right out of their PhDs
or theyre made later on by someone who realizes that the way
things have been done wasnt getting you close to the answer
And what I see
in the fisheries business is a whole bunch of people who are trained
in the 60s. I mean thats why the Ricker Population book. Thats
why we called it the bible for a while. Because everyone learned
their population mathematics from that book and others like it.
And that was it. There was no mention if you look in the index in
that book you wont find the word habitat. I guarantee it.
And in many of those books, the habitat is just not important. Its
this cute little black box that young fish come out when theyre
a certain age and then they become recruits to the fishery, which
is a term that took me a long number of years to learn.
Which is a very
different use of the word "recruit" actually than what
you would use if you study any other marine organism. A "recruit"
to most marine ecologists would be an animal that takes up resided
in an ecosystem that its parent lived in residence in some way either
attaches or whatever settles to the bottom or something like that.
But in fisheries
parlance, a "recruit" is an animal that is almost ready
to be caught. So what the hell has this animal been doing for the
other 4-5 years, right? Thats the question. And there was
no answer to that. Until you get a new generation of fisheries biologists
who understand that you have to go all the way back the day zero
with their biology and know their biology all the way along, the
system is not going to change much.