Seahorse Issues

Definitive Evidence on Eelgrass Habitat

BORG does not believe claims by the Seahorse Trust that the decline in seahorse sightings in Studland Bay is caused by loss of eelgrass habitat. We believe the aerial photography and other evidence that shows the eelgrass is actually increasing in the areas where the seahorses were seen, and BORG has now been  able to confirm this by shooting underwater video with a pole-mounted camera 1.5 metres, 5 ft, below the surface. See and the full report at , which show abundant, thriving eelgrass, enough for any number of seahorses. Also, the full report demolishes the speculation that disruption of a “rhizome mat” by anchors allows a progressive disruption of the eelgrass bed. Inspection of the images show that this just has not happened.

It should be pointed out that the Seahorse Trust has produced no evidence to back its claims beyond a few images of uncertain provenance showing some localised damage somewhere, and a YouTube video entitled “Anchor Chain Damage at Studland Bay” showing what is a (very) heavy ground chain to a fixed mooring, terminating in a riser chain and mooring buoy. Everybody is aware that fixed moorings can cause scouring of the seabed and that this is a very different effect to the action of a relatively light anchor chain in place for a few hours at most, yet in this video the mooring ground chain is cynically described as an anchor chain. ( ).

BORG has now produced GPS-located video evidence from over 300 metres of seabed, and it shows the Seahorse Trust claims to be utterly untrue.

BORG calls for publication of secret seahorse database

The SHARK TRUST, the SEA WATCH FOUNDATION, the HEBRIDEAN WHALE AND DOLPHIN TRUST, also ORCAWEB and the BRITISH TRUST FOR ORNITHOLOGY: all these bodies compile lists of sightings by their volunteers of their relevant species, and then publish online the numbers and locations of sightings for the benefit of the public and of scientific understanding.

On the other hand, the SEAHORSE TRUST (SHT) compiles lists of sightings by its volunteers and then keeps them secret!  The SHT refuses to publish them. It calls its list of 1500 sightings the “National Seahorse Database”, but a more accurate name would be the Secret Seahorse Database.

Why? Do they have something to hide? What is the point of asking people to report sightings and then shutting the results away in a secret file? In fact by concealing this information they hinder genuine progress in understanding seahorse behaviour, since scientific progress depends on the open publication and sharing of data and results. And what is more –

– Why does the SHT, a registered charity which benefits from public money through tax concessions, as well as from charitable donations from the public, deliberately fail to comply with its own declared charitable objective to “conduct research and enquiry into ….. seahorses and related species and to publish the results for the benefit of the general public”? (see )

BORG and others have asked to see the secret database, but the SHT Director, Neil Garrick-Maidment, has always refused on the grounds of “copyright and data protection”. These excuses are pure poppycock, since any copyright would be owned by the SHT, who as copyright holders are of course free to publish if they choose, while the Data Protection Act applies specifically to personal, i.e. human, data, it certainly does not apply to seahorses!

Other organisations such as those listed above actively publish their sightings reports – so what is different about the SHT? Do they have a different agenda?

It is the responsibility of the Trustees of a Trust to ensure compliance with its published objectives, and BORG has written to the Chairman of the Trustees of the Seahorse Trust, Dr David Gibson, pointing out this failure to comply with its objective. No reply has been received after six weeks, so BORG is repeating here on this website its call for the SHT and its Trustees to comply with its declared charitable objectives and make public its list of seahorse sightings, in the interests of proper science and of better and more widespread understanding of seahorse behaviour for the benefit of the general public. If they do not, it is for the public to draw their own conclusions.

We also advise the SHT to publish all its sightings to avoid any suspicion that they might be selectively using (cherry-picking) their data to favour particular outcomes in the ongoing marine conservation zone process, revealing what suits their purpose while keeping the rest under wraps. For example, the SHT Annual Report and Accounts disclose that the secret seahorse database contained over 800 sightings as of January 2014, and over 1500 sightings as of January 2015. The SHT says that there was just one seahorse sighting at Studland Bay in summer 2014, Studland Bay being of particular interest to the SHT. So what were the locations of the other 699 sightings added in 2014? The public would like to know.

Update May 2016: both Dr David Gibson and Mr Neil Garrick Maidment eventually replied and again refused to publish the Seahorse Database. Mr Garrick Maidment declared that he would rather delete the database than let BORG see it, which means he would rather delete it than publish, which makes us wonder what devastating secrets it must contain! (see next item for a clue)

Seahorses in the Poole Area

Recent (autumn 2015) information confirms that seahorses are found in significant numbers in Poole Harbour and in a location 4 or 5 miles out to sea, as well as in Studland Bay. See our article Seahorses Around Poole, which also gives information on the complex tidal flows in the area which could affect the migration of seahorses. Updated in spring 2016, further evidence is presented which suggests that the short-snouted seahorse is widespread out in Poole Bay, as well as inshore, while the true centre of the spiny seahorse population is probably within Poole Harbour, from which some spill out into the surroundings sometimes including Studland Bay. This is perhaps the secret which would be given away by publication of the SHT’s Secret Seahorse Database: they would like to maintain their narrative that Studland Bay is uniquely important in the seahorse world, and we can only suspect that information in the Secret Database shows that it is not.

Seahorse Numbers and Eelgrass Habitat in Studland Bay                                                          (note general Seahorse Q&A’s below this article)

Sensationalist (and sensationally untrue) headlines like “Rich Yotties Wipe Out Precious Seahorse Colony” appeared in the Press in Summer 2013. These are debunked at this link: Great Seahorse Deception.

A BORG statement based on an analysis of Seahorse Trust reports and further information, issued in January 2014 reads:

The seahorse lobby has been claiming that numbers of spiny seahorses in the “colony” in StudlandBay are dropping because of loss of their eelgrass habitat – despite the lack of any evidence of loss of eelgrass in the area (which is regularly dived and observed by conservationists). This non-existent loss is blamed by the seahorse lobby on boats anchoring in the Bay.

The Boat Owners’ Response Group (BORG) has examined the Seahorse Trust’s own figures, which show that over the 5 seasons 2008 – 2012 the average number of seahorses sighted in the Bay on days in which diving (to count seahorses) took place was just two. The numbers varied widely, but on only 13 out of 89 dive days were more than two seahorses sighted. On half of all the dive days there were zero or one sighting.

The population in the Bay is better represented by the number of sightings in a day than by annual totals – the sightings on a day are a measure of the actual observed population on that day.

These low and variable numbers can hardly be considered to make up a “colony”, and the nearly one hundred hectares (about 200 football pitches) of dense eelgrass in the Bay can in no way be considered as a scarcity of habitat for two seahorses – or even for two hundred or more – if there were 200, that’s still a football pitch of eelgrass each!

Interestingly, a 2010 survey of spiny seahorses in the Ria Formosa, Portugal, shows a population density over one hundred times that of Studland in an area with no seagrass, and the data indicate no preference for areas with or without seagrass in the Ria.

Supporting documents are attached, and BORG contends that in the light of these, the argument that low numbers of seahorses are due to “habitat loss” due to visiting boats is totally baseless and would in future amount to wilful misinformation. (Document links: Studland Seahorse Population and Ria Formosa Seahorse Survey ).

These generally low population numbers also raise the question whether there really is anything special about Studland as a seahorse habitat, other than the high number of diving surveys carried out there.

These conclusions are further reinforced by a 2014 report of a site in Italy which describes seahorse populations also about 100 x the density of the Swanage population in two different habitats completely devoid of seagrass of any type: details in Studland Seahorse Population.

Q&A’s on Seahorses in Studland Bay

Q: How many are there?

A: In the best year, 40 individuals were identified. It’s generally less, in 2011 just 11 seahorses, in 2012,  just 9.

Q: Is there enough eelgrass habitat for them?

A:  Yes, about 200 times more than 40 seahorses would need.

(A pair of seahorses was found to occupy about 200 sq m of territory, 100 per seahorse. There are over 900,000 sq m of eelgrass at Studland, enough for 9000 seahorses, which is 200 times the highest observed population.)

 So there is plenty, and even if the amount were to be halved by some hypothetical disaster, there would still be plenty.

Update: the Seastar Survey (see Latest News) concludes there is “no consistent evidence of boat anchoring impacting the seagrass habitat at Studland Bay” so it seems that anchoring is not going to significantly affect the eelgrass habitat anyway.

Q: Do they mind bare patches of seabed?

A: That pair of seahorses lived in the eelgrass right next to a patch of bare seabed swept by a mooring chain. There is even a picture of one with its tail hooked onto the chain. To them, it was a des res.

We have a separate opinion page which expands on this important point here.

Also, a detailed study in Portugal found that seahorses “significantly preferred grasping holdfasts over barren surfaces”.

An OSPAR article says spiny seahorses seem to “prefer staying close to the edge of seagrass beds leaving large areas unoccupied”.

Q: Do they actually need eelgrass?

A:  Figures from the Seahorse Trust show only 3% of short-snouted seahorses were found in eelgrass, leaving 97% not in eelgrass. However 50% of spiny seahorses were recorded in eelgrass, so they probably do like it.

Q: Could boats anchoring cause harm to the seahorses?

A: The fact that boats have been anchoring at Studland for decades, and that there has been no decline, but an ongoing steady increase in eelgrass area, shows that anchoring does not cause a significant irreversible loss of eelgrass, and so would be very unlikely to cause any significant loss in the huge area of available habitat.

Their apparent tolerance to bare or barren seabed around their holdfasts suggests that any small-scale localised damage would not be a problem.

Q: Is Studland Bay special for seahorses?

A: It is certainly special for seahorse naturalists – the relatively clear, shallow sheltered water and easy access mean that hundreds of dives have taken place there, with support from £42,000 of Lottery funding. Nowhere else has been so thoroughly surveyed. However, seahorses have been reported from Greenwich on the River Thames, round the south coast to the south west, and up the west coast to as far north as the Shetlands. It is not known if other sites would show similar populations to Studland if they had the same intense seahorse-hunting activity.

Q: Where do they go in the winter?

A: Nobody knows for sure, but it is thought they move into deeper water.

Q: Where did you get the information?

A: The sources for most of the answers are given in the BORG Studland-evidence paper.

Seahorse distribution information comes from a Natural England document . Information on National Lottery funding for the seahorse tagging project from a most interesting  Daily Telegraph article in July 2011.