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Lyme Bay Closed Area, a Marine Protected Area success? Part 2.

Lyme Bay Closed Area, a Marine Protected Area success? Part 2.

This post follows on from Lyme Bay Closed Area, a Marine Protected Area success? Part 1, which described the damage first noted on rocky reefs in Lyme bay, Southwest England, from scallop dredging during the 1990s. This post describes the voluntary agreements set up and the ongoing problems.
As described in Part 1, the condition of the reefs in Lyme Bay had begun to deteriorate markedly by the early 1990s, and this deterioration continued more or less unchecked over the next 12 or 13 years. It would however, be wrong to suggest that all reefs were suffering equally or that nothing was happening to change this situation. Some reefs were simply too rugged for any sort of mobile fishing gear to ever be towed across them, however even they suffered from degradation around the edges. Others that were more easily worked were devastated.

The Devon Wildlife Trust had been working hard with local fishermen since the early 1990s, and voluntary agreements had been set up voluntary agreements whereby trawlers and scallop dredgers would not work in the most fragile reef habitats. The first such agreement extended voluntary protection to two reefs (known locally as Lane’s Ground, a boulder reef rich in sponges, and The Saw-Tooth Ledges, a series of limestone ledges supporting abundant seafans, soft corals and sponges). Two additional reefs were added to this agreement in 2006, The East Tennants Reef, a boulder reef supporting high densities of large seafans, and Beer Home Ground, a reef of ledges and rocky promentories composed of softer mudtstone and sandstone amongst harder limestone that had suffered quite badly from reef erosion through the action of scallop dredges. However problems remained. The first was that however sincere most local fishermen were, there was always the problem that some from further afield would see no need to abide by this agreement and, it has to be said, not all local fishermen agreed with the closure. It only took one vessel operating within the voluntary closures, maybe late at night or early morning when they were unlikley to be spotted, to cause damage that would last for years. The second problem was that the four voluntary areas were small and in no way enclosed all of even the most vulnerable reefs. An example of this is the West Tennants Reef. This is an very extensive reef in Lyme Bay terms. It is a low limestone ledge, or series of ledges, that runs parallel to the shore, about 4 miles offshore and roughly 29 metres below sea level. Although only around 10-30 metres wide over much of its length, it runs east-west for over two miles. The ledge is fairly level and free of rocky protrusions, and drops less than a metre to the surrounding seabed, thus it was very easily worked from the top of the ledge, dredges running along, parallel to the edge before eventually dropping of the edge. Strong currents sweep along this ledge, and in the early 1990s a dense band of very large seafans grew along this ledge, along with significant numbers of large axinellid sponges.

Large Axinellid sponge (Axinella dissimilis) and seafans. Most of the West Tennants Reef used to look like this.

The band was not wide, perhaps no more than 8-10 metres across, but extended for nearly two miles East-West. Although the East Tennants Reef nearby had higher densities of seafans but, simply due to its size, the west Tennants Reef supported more large seafans than any other reef in Lyme Bay. Indeed it was one of the most extensive continuous beds of large seafans in UK waters. Unfortunately, by 2007 most of these large seafans (and large sponges) had gone. As part of a wider study, I conducted a remote video survey along the reef in the summer of 2007. Instead of a dense continuous bed of seafans we found isolated patches and extensive areas of bare reef. We also saw many recently detached large seafans lying flat on the seabed and scallop dredgers working nearby. We returned a couple of days later to dive the reef and capture some better video. This can be seen here: West Tennants Reef, 2007.

 

It was clear that the situation in Lyme bay was continuing to deteriorate. Fortunately major changes to rectify this were also happening. Following a lengthy consultation process, with proposals submitted by the Natural England, Conservation NGOs (in particular the Wildlife Trusts) and the fishing industry, DEFRA announced that an area of some 60 square nautical miles in the central part of Lyme Bay was to be closed to mobile fishing gear by Statutory Order. There have undoubtedly been a few vessels that continued to work inside the closed area at night, especially during the first couple of years. However it’s fair to say that by and large this has been a success, in terms of maintaining an area free from the impacts of mobile bottom fishing gear. So how has that been reflected in changes, or recovery, of the fauna of the reefs within the closed area. In order to assess this two parallel studies were set up, one by Plymouth University using remote video, and one conducted by ourselves (that is my consultancy Marine Bio-images) with divers recording life at fixed stations. Data was collected over three summers; 2008, 2009 and 2010, and the findings of these studies have now been analysed and are about to be published. The next part of this blog will look in more detail at what we found and what seems to have changed since the closed area was established.

Update 10th July 2012, New blog: Lyme Bay, what makes it special?
All images and text (C) Colin Munro Photography.

Diving the trawl 2: filming the trawl

Diving the trawl 2: filming the trawl

A couple of years ago I wrote a piece called lessons is stupidity: diving the trawl , describing the first time I dived on a trawler’s net.  I’ve done this a few times over the years, most recently a couple of days ago.  We re-did this because cameras improve and the quality of images improves, so we need to re-shoot.  We also wanted to get some slightly different images this time; in particular we wanted to get images as the trawl net was being hauled, when it was just below the surface.

As events transpired the weather conditions were against us. Strong winds prevailed through most of August and much of September.  It was not until the last week of September, with equinoxal gales just around the corner, that we finally found a brief window of opportunity.  Due to vessel availability and other logistical constraints we had only one day available that week in which everything came together.  The weather was marginal but we were now well into autumn with precious few opportunities remaining this year, so we decided to take a chance and go for it.

Trawl net close up as it is hauled to the surface, Lyme Bay, Southwest England, Colin Munro Photography

Trawl net close up as it is hauled to the surface, Lyme Bay, Southwest England,

We began to load the trawl net on to our vessel on a bright but chilly morning.  A stiff breeze was whipping whitecaps on the sea beyond the shelter of the harbour, but the latest forecast indicated this should die away during the morning.  By the time the net had been hauled aboard and rigged and all our gear on deck it was midday; Lynsey, John and I were hot, dirty and sweaty but pretty satisfied everything was as ready as it could be.  The wind had not abated.  But we were now committed, so warps were unhitched and we nosed out into the bay.  A 60 square mile exclusion area for bottom towed fishing gear (trawls and scallop dredges) has been established within the centre of Lyme Bay to protect the fragile reefs found there (this came about in part due to our earlier work looking at the impacts of bottom-fishing gear).  We therefore had a two hour steam to get to a suitable location beyond this closed area in which to set the trawl.  That gave us two hours for the wind to die down and the sea state to drop away.   If we were lucky the wind would not yet have stirred up the seabed enough to destroy the visibility.  The longer the wind continued the more our chances of success diminished.

Filming the trawl net being deployed

John does all the hard work while I film the trawl net being deployed

We reach a shallow bay outside the closed area, about 20 metres depth, shortly after 2.30p.m.  The wind was still fresh and we knew it was not looking good for getting workable conditions on the seabed.  We decided to have a test dip to check out visibility before deploying the trawl.

A bottom trawl, otter trawl. © Colin Munro

Diagram of the bottm trawl used (not to scale)

I wanted to stay dry in order to do some surface filming of the trawl being deployed, so this task fell to my dive buddy Lynsey.  A quick dip was enough to convince her it was no-go.  Seabed visibility was no more than one metre.  Quite apart from it being impossible to film the trawl operating in such conditions it would also have been too dangerous to be around heavy moving fishing gear.  Reluctantly I called the dive off and we reverted to plan B.

Setting up the Gates camera housing in the trawler’s tiny wheelhouse is always a bit of a challenge.

I also wanted to get footage of the trawl as it was being hauled, a little below the surface.  This we could do as the near-surface visibility, although far from perfect, was much better than that close to the seabed.  However, there were the added logistical problems that the trawl net had to be hauled with the boat steaming forward at a speed of several knots, way too fast to swim or hang on holding a large camera.  We had worked a method where I would be dropped off close to the net as it reached the surface, and drift back alongside it, filming as I went.  It sounded plausible – I mean what could possibly go wrong?  Before this we set up some surface and just below shots at speed, working from a small inflatable.

John and Lynsey in deep discussion as we trawl for a couple of hours.

John and Lynsey in deep discussion as we trawl for a couple of hours.

Poor Lyndsey had the unenviable task of heaving cameras across the tubes to me and hanging on to my legs as I dangled head-down in the water trying desperately to: a) get the vaguest impression of what I was filming through the spray and turbulence, and b) stop my camera from being ripped from my fingers.  From the surface I must have presented a highly comical sight, legs waving and coughing and spluttering to the surface every few seconds.  From a personal perspective it felt rather like what I imagine being waterboarded by a firehose while suspended upsidedown might feel like.   Having had my sinuses thoroughly irrigated at high pressure, it was now time to get into the water, before I had time to ponder the stupidity of my actions and change my mind.  At any rate, the sun was racing toward the horizon and light was fading rapidly, so it was either now or  call it off and wait ’til next year.    In the event the plan worked almost like clockwork; we were even able to repeat the operation so that I could run one haul taking stills and a second taking video footage.  Given the relatively poor visibility (~ 4 metres near the surface) I was quite pleased with the results.

The stupid grin you wear when it all works out.

Nothing got broken (apart from a torn shoulder muscle – my stupidity when the trying to work parallel to the waterflow) and everything worked pretty much as it should.  October gales have now set in so there will be no more dives on fishing gear this year.

Note:  As with my previous blog on this topic, this is NOT in any way designed to be a ‘how to’ guide to diving on trawl nets.  I have deliberately ommitted key elements to try to avoid giving this impression.  Diving around nets and heavy moving fishing gear obviously involves a significant element of risk if not approached with great care and planning.  I have presented this in a fairly light-hearted manner and should be taken as such rather than a technical guide.