Is there early evidence of the Lamlash Bay No Take Zone providing scallop fishery benefits?

Abstract:
Despite the implementation of several precautionary management measures in Scotland, evidence suggests that scallop fisheries based in the Firth of Clyde may not reach long-term sustainability. It is argued that only the establishment of No take Zones (NTZs) can restore the age structure and spawning biomass of scallop stocks.

The aim of this study was therefore to look for early evidence of the Lamlash Bay NTZ providing scallop fishery benefits by testing for differences in the density, body size, age structure and biomass of Pecten maximus and Aequipecten opercularis between sites located in and outside the NTZ. This was achieved by conducting a combination of diver surveys and scallop dissections.

Accompanying Leigh Howarth on the majority of surveys was COAST chairman Howard Wood with over 37 years experience of diving the waters of the Clyde.  Whilst Leigh heads back to York University to write up all data collected, Howard gives you here his initial thoughts on his summer’s experience.

Visiting marine biologist Leigh Howarth is currently (July -Aug 2010) conducting the first diver scallop survey in Lamlash Bay to monitor the health of the scallop population since the introduction of Scotland’s first No Take Zone (NTZ). This will hopefully provide an important baseline for future monitoring of the Lamlash Bay NTZ.

"Preparation for the scallop survey has been hands-on. My first working day began with learning how to operate the dive boats and planning our survey procedures. We have since then been out diving every day, weather permitting of course."

No-Take Zones (NTZs) have proved highly beneficial for improving the stocks of UK scallop  fisheries by providing protection from scallop dredgers. As a consequence of Lamlash Bay’s  status as an NTZ, we expect the scallop population within Lamlash Bay to rise dramatically  over the next 10 years. We also expect populations in surrounding areas to become enhanced because as reproduction  within the NTZ increases, more scallop larvae will be generated each year which will drift  with the currents and settle in surrounding areas outside the NTZ boundaries. Furthermore,  a larger proportion of individuals will reach older ages and larger sizes as they will no  longer be removed or damaged by fishing. Older, larger scallops generate massively more  sperm and eggs than smaller, younger scallops, thereby further enhancing recruitment inside  and outside the NTZ.

Following the establishment of the No Take Zone (NTZ) in Lamlash Bay, the Cabinet Secretary requested that monitoring work take place to assess the benefits derived from the NTZ. This monitoring covers two elements: (1) general biodiversity and (2) scallops. These work areas are being led by Scottish Natural Heritage (SNH) and Marine Scotland Science (formerly Fisheries Research Services) respectively, but with the organisations collaborating on each element.

Claire Youdale describes helping COAST with dive surveys around Arran.

Arran may not be the first place that comes to mind when planning a dive holiday, as a lot of divers head straight past the Clyde to areas like the Sound of Mull or Scapa Flow, but the variety of underwater life around these shores is astounding. When the seas are caught on good days it’s possible to see up to 15m rivalling many other temperate destination. Plumose anemones waft in the current, wrasse dart in and out of nooks and crannies and the occasional basking shark filters away with each leisurely sweep of its tail.

During the summer of 2009 I took part in a series of Seasearch dives around Arran, recording the types of marine habitats off these shores and the variety of life found there.

Lamlash Bay NTZ Sea Chart

Bower (2012) Awareness of and attitudes to the Lamlash Bay NTZ Read

Howarth et al (2011) Complex habitat boosts scallop recruitment in a fully protected marine reserve -  Read

Mapping of Marine Habitats and Species within the
Community Marine Conservation Area at Lamlash Bay, 2008- Read

The Arran Marine Regeneration Trial April 2004 - Read

Millport Survey Proposed Sewage Outfall Maerl Report  Read

Arran Seasearch Report 2003 - Read

Changes in the Clyde Marine Ecosystem over the past 100 Years  - Read

Ecological Meltdown in the Firth of Clyde Read