Inter-tidal shellfish support important commercial fisheries and also form the principal food base for estuarine wading birds. Balancing the needs of these various interests is a primary consideration for shoreline conservation research and management.   Little is known for example, about the underlying causes of periodic fluctuations in abundance of both cockles and mussels, and the "boom and bust" scenarios experienced by the commercial fishermen who exploit them.

A particular question arising with cockles in recent years has centred upon the cause, as yet unknown, of high summertime mortality amongst maturing 2nd year cockles in certain areas. In the case of mussels, questions arise over the fate of temporary or so called "ephemeral stocks" of juveniles, and the extent to which these can be removed as seed for relaying without compromising natural resettlement and integrity of wild stocks.

Our understanding of shellfish population dynamics is still poor and with management schemes now rapidly emerging based on theoretically sustainable yields and total allowable catch (TAC), there is an increasing requirement for accurate, scientifically based monitoring and exploratory research.

Walkover survey of a typical mussel skear at Morecambe (Old Skear) showing areas of low, medium & high density stocks

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Population assessment & health studies
of shellfish stocks

Hydrosurveys offer experience and resources to undertake surveys and investigative work on wild stocks of cockles and mussels.  We monitored mussel stocks in Morecambe Bay following the population crash in 1994, up until the time of full recovery in 2005.  Monitoring was continued thereafter as part of the Phase III Morecambe Sea Defences scheme.  More recently we undertook a valuation and stock assessment study on behalf of Natural England, of cockle and mussel stocks on the Eastern Side of the Wash

..............Areas of specifc expertise

• Inter-tidal shellfish mapping & stock assessment
• Shrimp population surveys using push-net & trawl
• Valuation of cockle and mussel fisheries
• Valuation of oyster farming sites

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Sampling of cockles using a Day grab