Bottom trawl fishing footprints on the world’s continental shelves

Bottom trawlers land around 19 million tons of fish and invertebrates annually, almost one-quarter of wild marine landings. The extent of bottom trawling footprint (seabed area trawled at least once in a specified region and time period) is often contested but poorly described. We quantify footprints using high-resolution satellite vessel monitoring system (VMS) and logbook data on 24 continental shelves and slopes to 1,000-m depth over at least 2 years. Trawling footprint varied markedly among regions: from 50% in some European seas. Overall, 14% of the 7.8 million-km2 study area was trawled, and 86% was not trawled. Trawling activity was aggregated; the most intensively trawled areas accounting for 90% of activity comprised 77% of footprint on average. Regional swept area ratio (SAR; ratio of total swept area trawled annually to total area of region, a metric of trawling intensity) and footprint area were related, providing an approach to estimate regional trawling footprints when high-resolution spatial data are unavailable. If SAR was ≤0.1, as in 8 of 24 regions, there was >95% probability that >90% of seabed was not trawled. If SAR was 7.9, equal to the highest SAR recorded, there was >95% probability that >70% of seabed was trawled. Footprints were smaller and SAR was ≤0.25 in regions where fishing rates consistently met international sustainability benchmarks for fish stocks, implying collateral environmental benefits from sustainable fishing

Growth of monkfish (Lophius vomerinus) in Namibian waters based on length frequency analysis

A multiple approach to the growth of Lophius vomerinus is presented for the first time, based on age estimation of 2282 illicia (first dorsal fin ray) sections, length-frequency analyses (SLCA, ELEFAN, Bhattacharya) and corroborated by tracking cohorts. The growth is studied based on the widest time series (2000–2017) and the largest sample analyzed to date. Individuals ranging from 3 to 109 cm, representing the whole range commercially landed, were collected from annual research surveys in Namibian waters. Modification in the age interpretation using illicia is presented, suggesting a new more accurate criterion at early ages. Two main different growth patterns were obtained, being that of the length-frequency analyses faster than from illicia age estimation. Both growth patterns estimated here are faster than those from previous studies. Possible causes of differences among all studies are discussed. The von Bertalanffy growth parameters from illicia age estimation (L∞ = 110, k = 0.08, t0 = - 1.16) are proposed to be used in age-structured models for the annual assessment of this population. Growth pattern provides tracking of cohorts in the abundance-at-age matrix, with high correlation values obtained between the age abundance indices of the same year-class for most of the age groups compared. Greater lengths and ages were found in females, showing a slightly higher growth rate than males in older specimens.Namibian Ministry of Fisheries and Marine Resources and the Spanish Agency for International Development CooperationEn prens