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Landa, J., Duarte, R., and Quincoces, I. 2008. Growth of white anglerfish (Lophius piscatorius) tagged in the Northeast Atlantic, and a review of age studies on anglerfish. – ICES Journal of Marine Science, 65: 72–80. Growth of white anglerfish was estimated from the results of a tagging study in south European waters. In all, 1326 fish, caught by bottom trawl and gillnet commercial vessels and on trawl surveys, were tagged from 1995 to 2004; 50 were recovered, and a growth rate of 13.6 cm year−1 was estimated from the four fish at liberty long enough to allow extrapolation of the growth rate to an annual period. Growth patterns were reviewed based on available studies of growth verification of white anglerfish in Atlantic waters, including another tag-recapture study, length-frequency of catches, and microstructure analysis of hard parts. The growth rate estimated from these studies showed many similarities, and an overall growth pattern was estimated: growth rate = 18.24e–0.015length. A von Bertalanffy growth curve fitted to all data yielded the parameter values L∞ = 140 cm and k = 0.11. This growth rate is faster than estimated recently using illicia for age estimation, but similar to that found in the first studies that used illicia and sectioned otoliths. Current estimates of growth based on illicia, which are used in assessing the northern European stock of white anglerfish, seem to be underestimated.

High-quality video observations are very much needed in underwater environments for the monitoring of several ecosystem indicators and to support the sustainable development and management of almost all activities in the ocean. Reliable video observations are however challenging to collect, because of the generally poor visibility conditions and the difficulties to deploy cost-effective sensors and platforms in the marine environment. Visibility in water is regulated by natural light availability at different depths, and by the presence of suspended particles, scattering incident light in all directions. Those elements are also largely variable in time and space, making it difficult to identify technological solutions that can be used in all conditions. By combining state-of-the-art "time of flight" (ToF) image sensors and innovative pulsed laser illumination, we have developed a range-gated camera system (UTOFIA) that enables affordable and enhanced 3D underwater imaging at high resolution. This range-gated solution allows users to eliminate close-range backscattering, improving quality of the images and providing information on the distance of each illuminated object, hence giving access to real-time 3D measurements. Furthermore, as the system is based on pulsed laser light, it is almost independent of natural light conditions and can achieve similar performances at an extended depth range. We use this system to collect observations in different oceanographic conditions and for different applications, including aquaculture monitoring, seafloor mapping, litter identifications and structure inspection. Performances are evaluated by comparing images to regular cameras and by using standard targets to assess accuracy and precision of distance measurements. We suggest that this type of technology can become a standard in underwater 3D imaging to support the future development of the ocean economy.Sustainability 2019, 11, 162 2 of 13 create a turbid environment that strongly increases light scattering and enhances the absorption probability of photons [3]. When the light source is the sun, this process effectively decreases the amount of ambient light present at any depth and limits the range of visual observations. With artificial illumination, the range for underwater vision can be extended (for example we can move deeper) but at the cost of degrading image contrast due to (forward-and back-) scattering generated by suspended particles. The situation is similar to driving a car in foggy conditions with the headlights on: increasing the power of illumination does not improve the visibility, as the backscattering increases proportionally. Image contrast is also lowered with shorter visual range as the light attenuation will reduce the illumination of distant targets. These factors remain the outstanding challenges in underwater imaging and limit the application of visual observations in many sectors [1,2,4].Various optical and acoustic imaging systems for mitigating or solving these problems are under constant develo...

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a b s t r a c tWithin the frame of an international tagging program which has been carried out since 1995, movements of black and white anglerfish (Lophius budegassa and L. piscatorius) in Southern European waters were studied. This is the first large-scale study on movements of tagged black anglerfish. A total of 877 black anglerfish (6-88 cm total length) and 1326 white anglerfish (15-137 cm total length) were tagged. Times at liberty ranged from 1 to 665 days, with recapture rates of 21 (2.4%) and 50 (3.8%), respectively. A description of our tagging procedures is presented, together with the influences of the gear used, fish length and area of tagging on recapture rates. The type of fishing gear was the main factor affecting recapture rates. Fish length was neither related to the displacement distance nor to the time at liberty while the displacement distance was related to the time at liberty. Recapture locations suggested that movements occurred both in-and offshore. The largest displacement recorded was 408 km of a black anglerfish from southern to northern Bay of Biscay. The movements of the anglerfish indicate a mixing between northern and southern populations which may have strong implications for the current geographical boundaries of the stocks from a management perspective. Here, movement of white anglerfish between the Le Danois Bank and the Cantabrian continental shelf is reported for the first time.

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