by Michel Kaiser
(reprinted from the September Fishing News International 
Dr. Michel Kaiser shoots holes in America's trawl ban plan
The main preoccupation of scientists who advise fisheries managers was until recently the issue of stock management. However, over the last few decades, environmental issues connected with fishing activities have become increasingly important and we are now beginning to see a move towards ecosystem based approaches to fisheries management.
What that means are scientists are now being asked to consider not only the consequences of removing the target species from the world's oceans but, also, the ecological implications of by-catches, discarding, ghost fishing and seabed habitat disruptions.
This need for scientific advice on the wider effects of fishing on the marine ecosystem has been driven largely by recent treaties such as the Rio Convention on Biodiversity and legislation such as the Magnuson-Stevens Fishery Conservation and Management Act.
Issues involving the death of cetaceans and sea turtles play on the sensitivities of the public and have tended to be publicized by non-governmental and conservation groups. Therefore it was almost inevitable that the last section of the marine community to be portrayed as the victim of fishing activities by the media were the unseen habitats and creatures living on the seabed.
Much life on the seabed is unknown to the public – and much remains unknown to science as well.
Species such as sea cucumbers and sea squirts have little public appeal. Nevertheless, minimal public appeal does not necessarily mean a lack of scientific importance where ecological and conservation issues are concerned.
Indeed scientists in Europe and Australasia have been studying the impacts of fishing activities on seabed habitats for over ten years.
In contrast this area of research has been studied relatively little in North America until the last five years or so. However, it wasn't long before North American scientists were conducting similar studies and, with their access to a number of marine reserves of which there are few in Europe, were yielding new insights into seabed disturbances.
The response of regulatory authorities to the various studies regarding the impacts of fishing has differed according to individual circumstances. For example, off Tasmania fishing with trawl gears deployed near the seabed has been prohibited around a number of as yet unexploited seamounts.
These deep water seamounts are encrusted by many slow growing corals and sponges which are hundreds of years old in some cases and provide important shelters for commercially important species.
As the trawls sweep over the seamount, they snag the emergent fauna and drag them off the bedrock.
You donut need to be a scientist to realize that it would take many hundreds of years for these organisms to recolonise and attain their former density and size. Yet the Australian authorities have not closed all seamounts to fishing.
Those that have been trawled for some years remain open to fishing as they have been damaged and are no longer pristine. Hence there is little to be gained by restricting fishing activity on these seamounts.
The Australian continental shelf is a vast resource and contrasts sharply with the relatively small continental shelf of Northern Europe which is exploited by member states of the European Union.
The North Sea is the most common hotbed of contention in Northern Europe as it contains more valuable demersal fisheries than either the English Channel or the Irish and Celtic Seas.
Bottom trawling has occurred in the North Sea for many hundreds of years, but bottom fishing took on a new dimension when North Sea fleets started using beam trawls instead of otter trawls to catch flatfish.
Dutch, Belgian, German and UK scientists were concerned about the effects of these gears as long ago as 1970. Yet it is only in the last five years that we have really begun to understand that fishing has caused long term changes to seabed habitats in the North Sea.
However, how great are those changes and are they that important? We can say without doubt that there are certain types of seabed habitats, animals and plants which ar very sensitive to bottom fishing. Towed bottom fishing gears should be excluded where they occur.
These areas are relatively small and few in number. In the southern North Sea, where the majority of bottom fishing occurs for flatfish, we now know that some animals are no longer as common as they were, e.g. dogfishes, whelks and large clams
However, this area of seabed has been disturbed for so many years that any changes would have occurred long ago. What we see today are the animals which can survive this disturbance.
What lives in such a place? Small worms and small clams - less than tile size of your thumbnail - are well adapted to living in heavily trawled areas as they only live for a few months and so can quickly recolonise newly trawled areas of seabed.
We also know from Canadian studies that to be small is advantageous when you live in such an area. A small body size means these animals are pushed aside by a pressure wave which precedes the passing trawl gear over the seabed.
In addition, small worms and clams are exactly the right food for the flatfishes which are the main target of the beam trawl fishery. Another important finding of the European studies was that some areas of the seabed are so greatly disturbed by natural events, such as tidal scour and wave action, that trawling has only negligible effects in comparison.
Closing such areas to fishing would be a waste of time from the environmental point of view.
Scientists in North America have undertaken many similar studies to those in Europe, although the findings have tended to be more pessimistic as in the Australian case.
This may be due largely to the fact that most studies undertaken in the US have made comparisons between fished areas and protected marine parks. The results arc based on sound science but they portray the worst case scenario.
As a result, lobby groups have picked up this data with little or no reference to the science done elsewhere in the world, some of which indicates that towed bottom fishing is perfectly acceptable and environmentally sustainable in certain seabed habitats.
So, I was concerned in read the phraseology of the recent Hefley Bill put before the House of Representatives (see extracts). This Bill proposes a moratorium on towed bottom gear in a number of areas which have ecologically sensitive habitats, animals or plants.
In section 2 of the Bill, points 1, 2 and 3 are not contentious. However, point 4 paints a grim but misleading picture that could have much wider implications for the fishing industry than those highlighted for the bottom fishing moratorium in the Bill.
What point 4 implies is that fishing gears effectively mow the entire seabed at least twice every year, leaving not a single piece of seabed untouched by trawling.
When this is applied to the statement in point 5 that trawling reduces biodiversity, you are left with the impression that the seabed must be a veritable desert
This is utter nonsense and is the gross misuse of fishing effort statistics never intended for this purpose.
Fishermen exploit very specific seabed areas which yield good catches and are free of snags Knowledge about these areas is passed between generations of fishermen
This results in a concentration of fishing effort into limited areas of the seabed which, we know, leaves many other areas which are fished infrequently – if ever.
The first part of point 6 is blatantly misleading. On a worldwide basis we know quite a lot about the recovery of some seabed habitats and which habitats would take many years to recover from fishing activity. Of course only horror stories generate public and political support.
The fishing industry should be concerned about these issues as they begin to impinge more and more on fisheries management practices. These issues are becoming far more prominent in the media and there will almost certainly be future consumer demand for environmentally friendly fisheries that extends beyond concerns about dolphin and turtle bycatches.
As scientists try to fill the gap in our knowledge concerning these issues, environmental lobby groups are happy to fill the knowledge vacuum with extrapolations based on the worst case scenarios, as we see implied in the Hefley bill.
The fishing industry needs to arm itself with existing scientific facts
to ensure a fair and even-minded debate. Science collected in Europe and
Australia is equally valid when applied to situations in North America,
or anywhere else for that matter.
Dr. Michel Kaiser  is a Lecturer in Marine Ecology at the University of Wales-Bangor and formerly worked for the UK Government agency the Centre for Environment, Fisheries and Aquaculture Science. He is the co-author of two books to be published on this subject in the next twelve months by Blackwell Science: The Effects of Fishing on Non-target Species  and Marine Fisheries Ecology.