Shortlist Masterplan Wind. Effect of pilling noise on the survival of fish larvae( pilot study) progress report

Fish can suffer lethal damage to swimming bladder or other organs due to extreme loud impulse sounds caused by e.g. pile driving (Popper & Hastings 2009). Juvenile and adult fish can actively swim away from a sound source, but planktonic larvae are not able to do this. As a result, fish larvae may suffer more from underwater noise than the older life stages. Despite the many indications for adverse effects, detailed information on the effect of different sound levels on fish is still scarce, especially for the early life stages. Within the framework of the Appropriate Assessment of Dutch offshore wind farms, the effect of piling noise on the southern North Sea population of herring, sole, and plaice larvae was simulated (Prins et al. 2009). For this, an existing larval transport model (Bolle et al. 2005, 2009, Dickey-Collas et al. 2009, Erftemeijer et al. 2009) was expanded with crude assumptions on larval mortality caused by pile driving. The model results were extrapolated to other fish species and older life stages, based on “expertjudgment", in an attempt to assess the effect of offshore piling on the prey availability for birds and marine mammals in Natura 2000 areas (Bos et al. 2009). This assessment involved a large number of uncertainties. The first and most important uncertainty was the range around a piling site in which larval mortality occurs. It was assumed that 100% mortality occurs up to a distance of 1 km from the piling site. However, little is known about larval mortality rates in relation to the level of exposure to piling noise. In general, there is an urgent need to obtain more knowledge on the effect of sound on fish (survival, distribution, and behaviour) during different life stages. More particularly, in view of the rapid extension of offshore wind farms, there is an urgent need to fill the knowledge gap on lethal effects of loud impulse noises caused by pile driving. The broader aim of the current project is to examine the effect of piling noise on the survival of fish larvae. However, within the limited resources and time frame of the Shortlist research programme it is not possible to carry out field experiments, nor is it possible to execute elaborate series of experiments. The first goal within the Shortlist programme is to examine the feasibility of laboratory experiments with pile driving noise and fish larvae. The second goal is to use the laboratory set-up in a pilot study aiming at determining the threshold at which mortality of fish larvae occurs. This shortlist study is limited to laboratory experiments, lethal effects, larvae of 1 species (sole, Solea solea) and 3 series of experiments (trials). The study consists of exposure-effect experiments only; the effects of pile driving at the population level will not be modelled, nor will the results be extrapolated to other species or life stages. The progress to date has been documented in a series of memo’s. These memos are included in this report as Appendices and are summarised in the sections of the report.