Larval dispersal from an energetic tidal channel and implications for blue mussel (Mytilus edulis) shellfisheries

Abstract Complex coastal currents control early-stage larval dispersal from intertidal populations, and late-stage settlement patterns, but are often poorly resolved in models. Generally, there is high uncertainty the timing of spawning, which markedly affects dispersal. In this study, we describe physical parameters that induce spawning events blue mussel, Mytilus edulis , using a variation Condition Index (which relates mass meat to shell) as proxy. We developed high-resolution Eulerian hydrodynamic model, coupled with Lagrangian particle tracking quantify potential mussel larvae based on differing dates obtained field data. Our results showed (1) timings cannot be explained solely by ‘thermal shocks’ sea or air temperatures (i.e. fluctuations temperature causing stress); (2) larger generally occurred during neap tides; (3) simulated was largely not always predicted averaged current pathways (calculated over two weeks period); (4) self-recruitment low at sites associated strong tidal currents. These have important implications for shellfisheries stock management sustainability. Specific mussels shellfishery beds off North Wales dispersed more than 25 km one week so could feasibly contribute wider population throughout northern part Irish Sea.