Workshop on Age Estimation Methods of Deep-Water Species (WKAMDEEP2), 17 -21 September 2018. Cadiz, Spain

Type Scientific report
Date 2019
Language English
Ref. ICES CM 2018/EOSG:27
Other localization
Author(s) ICES
Contributor(s) Mahe KeligORCID, Bled--Defruit Geoffrey
Publisher ICES

Based on the previous work realized during the WKAMDEEP1 (2013), the Working Group on Biological Parameters (WGBIOP 2017) identified the need for an age reading Workshop on age estimation methods of deep-water species (WKAMDEEP2). This workshop was hosted by IEO (Cádiz, Spain; 1721 September 2018). The workshop was chaired by Ole Thomas Albert (Norway), Kélig Mahe (France), Juan Gil Herrera (Spain). During this workshop, the ageing of several deepwater species were reviewed: Blackspot seabream (Pagellus bogaraveo), Tusk (Brosme brosme), Greater silver smelt (Ar-gentina silus), Blue ling (Molva dypterygia), Ling (Molva molva), Greater forkbeard (Phycis blennoides) and Black scabbardfish (Aphanopus carbo). The aims of the present workshop (WKAMDEEP2) were to assemble this group of experts in order to further develop the ageing protocol for all species and to estimate the precision of readings.

For each species, an easy to use ageing manual was agreed by all participants. These manuals are considered necessary and sufficient for a generic age reader of deepwater fish to provide reasonably accurate and precise age estimates of all the species. An ex-change of 50 images by species was organized using the SmartDots tool. The results from all age readers showed relatively low precision, with a mean CV of 24%. How-ever, this was mainly due to the inclusion of new age readers in early training phase. The expert readers showed precision that is considered adequate for stock assessments (mean CV 9%).

WKAMDEEP2 recommends that small exchanges of all species are scheduled in two and four years, followed by WKAMDEEP3 in 5 years in order to continue to improve both the quality and the capacity of age readings for deepwater species.

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