Sea slugs – one more risk. .stuff.co.nz. Setember 03, 2009. Signs with pictures of sea slugs are to go up on North Shore beaches in the wake of poisoning that has killed five dogs and made many others ill.Beaches were closed to dogs and toddlers for much of August, but the warnings were eased last Friday by the Auckland Regional Public Health Service.But North Shore City Council spoksewoman Kelly Gunn says this does not mean beaches have been given the all clear.“We are being careful not to say the warnings have been lifted.”Warning signs on beaches, notably at Narrow Neck and Cheltenham, look set to stay, but will be modified to feature pictures of sea slugs. [ See ]