The deep sea is a critical component of the marine ecosystem. It can be home to cold water coral reefs and sponge fields; long-living fish and a myriad of other organisms.
These habitats are complex, diverse and beautiful, yet they are vulnerable too. Deep water fish are particularly at threat, having characteristics such as low birth rates, slow growth and small populations. Yet some deep water species are the target for European fisheries.
Evaluating the benefits of deep sea habitats
Sometimes my job as a marine scientist requires me to look for alternative methods to evaluate the benefits of the deep sea, beyond the intrinsic value of the habitats.
Therefore, I was delighted to chair an evening symposium, presenting the views of leading scientists and conservationists, discussing the value of deep sea habitats, with the aim of promoting conservation.
This event was opportunistically timely, with the EU debating proposals to introduce measures to restrict deep-sea trawling in European waters.
Depth based ban under consideration
David Bailey from the University of Glasgow started the evening with a presentation showing how deep trawls have unfavourably impacted deep sea fish species (whether targeted by fisheries or not) of Western Scotland and Ireland.
David documented declines in fish over two decades, many of which are now classified as endangered or vulnerable. Fishing in waters deeper than 600 metres has a strong negative impact on areas of high diversity for very low financial gain. A simple and effective way to protect these species and areas is a blanket ban of bottom trawling at depths greater than 600 metres.
- The EU is considering introducing a depth based ban on bottom trawling below 800 metres
Public support for protecting deep sea habitats
Claire Armstrong, an economist from University of Tromso, The Arctic University of Norway (and the only economist in a room of 144 people), presented her research documenting perceived values of cold water coral habitats based on surveys of the general public.
The research showed that the public (in Norway) place a high value on cold water corals as habitats for fish, and are willing to pay for their protection. Furthermore, there is little public concern for any additional costs this may impose on industry (fisheries, oil & gas).
- The public (at least in Norway) support protecting deep sea habitats
The economic value of deep sea habitats
Clive Trueman from University of Southampton talked about his research valuing the role the deep sea plays as a carbon sink. Clive estimates that the amount of the greenhouse gas carbon dioxide captured by European deep seas is the equivalent to a woodland the size of Greater London. To provide the equivalent service with a man-made carbon capture and storage facility would cost around £1 billion. This ecosystem service of carbon capture is dependent on a healthy environment. The value of this carbon capture services greatly outweighs an uneconomic, heavily subsidised trawl fishery.
- The economic value of healthy deep sea habitats greatly exceeds the value of the trawl fisheries
Progress for deep sea conservation?
Matthew Gianni of the Deep Sea Conservation Coalition spoke on the current negotiations for new regulations to manage deep sea fisheries in the EU. This could be a significant step in the conservation of deep seas.
However, Matt spoke about the watering down of depth-based approach to prohibiting bottom trawling which is currently proposed at 800 metres and even so, there is still opposition from a number of EU countries in the negotiations, notably Spain. Even at 800m a trawl ban would provide greater protection for important deep sea habitats such as certain sponge and xenophyophore species which form important habitats in the deep-sea although roughly half of the cold water coral reefs off the UK and Ireland would still be unprotected (based on work by Kerry Howell).
A bottom trawl ban below 600m would effect no more than a couple of dozen UK fishing vessels fishing part time at these depths (out of more than 5,000 UK fishing vessels) and a few dozen more French and Spanish deep-sea trawlers at most. Nonetheless, fishing industry representatives are lobbying hard against the deep-sea trawl ban and trying to introduce loopholes in the regulation complicating the negotiations. Matt reported that in practice the regulations will be decided by about 10 key countries, and the UK is playing a critical role in the negotiations.
Please find out more about the proposed EU trawl ban
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