A large-scale experiment finds no evidence that a seismic survey impacts a demersal fish fauna

Examining the effect of intensive seismic surveys on abundance and behaviour of groundfish species along a continental slope of Newfoundland and Labrador, Canada

This study investigated changes in the abundance and behaviour of groundfish species at a relatively deep-water site along the eastern continental slope of Canada, when exposed to a commercial seismic survey that lasted 100 consecutive days. Baited cameras were deployed at control and impact sites, before and after seismic exposure, consisting of 323, 5-h long, videos. Changes in abundance were not explained by seismic surveying noise for any of the five commonly observed fish species. However, Atlantic cod were found to have significantly longer arrival-times to baited camera stations and it took longer for available bait to be consumed immediately after seismic surveying occurred. This effect occurred when fish were exposed to a daily mean sound pressure level >120 dB re 1 μPa2 prior to the experimental measurements. The study contributes towards a better ecological understating of noise-related impacts over a wide range of conditions where groundfish occur.

The effect of seismic air gun shots on physiology and behaviour of fish lake communities

Alterations in the acoustic environment owing to anthropogenic sound are recognised as global pollution and strengthening studies in freshwater. This study focuses on the impact of lake seismic surveys on fish. First, we measured individual stress responses, i.e. cortisol levels and oxidative stress, morphological parameters, and stomach contents of juvenile roaches (Rutilus rutilus) captured by trawling prior to and during the seismic survey. Second, using hydroacoustics, we analysed individual fish and school behaviour before, during, and after the shots. We collected environmental DNA (eDNA) and analysed the concentrations of three species to assess their littoral refuge. Finally, using hydroacoustics, we assessed pelagic fish density before, during, and after the shots. We demonstrated that the shots noticeably impacted juvenile roaches, from the molecular and cellular level to individual morphological characteristics. During the seismic shots, changes in school characteristics were observed. At the onset of the seismic survey, a sharp decrease (> 30%) in pelagic fish density was observed, and no increase in fish density in the littoral area was noted for the three species. These responses suggest that sound disturbances due to air gun shots affect fish in multiple ways (physiology, morphology, behaviour, and habitat use) and across multiple biological scales.

Population genomics informs the management of harvested snappers across north-western Australia

Failure to consider population structure when managing harvested fishes increases the risk of stock depletion, yet empirical estimates of population structure are often lacking for important fishery species. In this study, we characterise genetic variation in single nucleotide polymorphisms (SNPs) to assess population structure for three harvested species of tropical snappers across the broad (up to 300 km wide) and extensive (~ 4000 km) continental shelf of north-western Australia. Comparisons across ~ 300 individuals per species, showed remarkably similar patterns of genetic structure among Lutjanus sebae (red emperor), L. malabaricus (saddletail snapper) and Pristipomoides multidens (goldband snapper) despite subtle differences in biological and ecological traits. Low levels of genetic subdivision were reflected in an isolation by distance relationship where genetic connectivity increased with geographic proximity. This indicates extensive but not unlimited dispersal across the north-western Australian shelf. Our findings provide evidence of connectivity between current management areas, violating the assumption of multiple independent stocks. Spatial stock assessment models may be more suitable for the management of these species however demographic connectivity rates cannot be accurately estimated from the conventional population genetic approaches applied in this study. We recommend that managers aim to maintain adequate spawning biomass across current management areas, and assess stocks at finer scales, where practical.

A large-scale experiment finds no consistent evidence of change in mortality or commercial productivity in silverlip pearl oysters (Pinctada maxima) exposed to a seismic source survey

High-intensity, impulsive sounds are used to locate oil and gas reserves during seismic exploration of the seafloor. The impacts of this noise pollution on the health and mortality of marine invertebrates are not well known, including the silverlip pearl oyster (Pinctada maxima), which comprises one of the world's last remaining significant wildstock pearl oyster fisheries, in northwestern Australia. We exposed ≈11,000 P. maxima to a four-day experimental seismic survey, plus one vessel-control day. After exposure, survival rates were monitored throughout a full two-year production cycle, and the number and quality of pearls produced at harvest were assessed. Oysters from two groups, on one sampling day, exhibited reduced survival and pearl productivity compared to controls, but 14 other groups receiving similar or higher exposure levels did not. We therefore found no conclusive evidence of an impact of the seismic source survey on oyster mortality or pearl production.

Sounding the Call for a Global Library of Underwater Biological Sounds

Aquatic environments encompass the world’s most extensive habitats, rich with sounds produced by a diversity of animals. Passive acoustic monitoring (PAM) is an increasingly accessible remote sensing technology that uses hydrophones to listen to the underwater world and represents an unprecedented, non-invasive method to monitor underwater environments. This information can assist in the delineation of biologically important areas via detection of sound-producing species or characterization of ecosystem type and condition, inferred from the acoustic properties of the local soundscape. At a time when worldwide biodiversity is in significant decline and underwater soundscapes are being altered as a result of anthropogenic impacts, there is a need to document, quantify, and understand biotic sound sources–potentially before they disappear. A significant step toward these goals is the development of a web-based, open-access platform that provides: (1) a reference library of known and unknown biological sound sources (by integrating and expanding existing libraries around the world); (2) a data repository portal for annotated and unannotated audio recordings of single sources and of soundscapes; (3) a training platform for artificial intelligence algorithms for signal detection and classification; and (4) a citizen science-based application for public users. Although individually, these resources are often met on regional and taxa-specific scales, many are not sustained and, collectively, an enduring global database with an integrated platform has not been realized. We discuss the benefits such a program can provide, previous calls for global data-sharing and reference libraries, and the challenges that need to be overcome to bring together bio- and ecoacousticians, bioinformaticians, propagation experts, web engineers, and signal processing specialists (e.g., artificial intelligence) with the necessary support and funding to build a sustainable and scalable platform that could address the needs of all contributors and stakeholders into the future.