Publicaties

Full catch monitoring in the Dutch Norway lobster fishery (2018-2020) : Results of a science-industry partnership to improve information for Nephrops norvegicus stock assessments

Bleeker, Katinka; Bangma, Tom; Overzee, Harriet van; Chen, Chun; Broekhoven, Wouter van; Ras, David; Boer, Emma de; Trapman, Brita; Steins, Nathalie A.

Samenvatting

The full catch monitoring in the Dutch Norway lobster fishery was part of a science-industry research collaboration project (Onderzoekssamenwerking 2.0) and aimed to improve data for the stock assessments of Norway lobster stocks. The International Council for the Exploration of the Seas (ICES) has divided the discrete patches of mud Norway lobster inhabit into so-called Functional Units (FUs). The Dutch fishery for Norway lobster mainly takes place in FU5, FU33 and outside FUs (outFU). The ICES Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK) has expressed concerns about data limitations, including lack of representative discards data in FU33. This project was set up to address these issues. To improve data for Norway lobster stock assessments, the project comprised of three phases: 1. Development of a Fully Catch-Monitored system (FCM), 2. Implementation of the FCM scheme by a reference fleet and 3. Data analysis and reporting including data sharing with ICES WGNSSK. The FCM system comprised of so-called load cells, installed to measure the total catch of a haul. In addition, the reference fleet participates in a self-sampling scheme in which discard samples 80 kg are taken from two hauls during a fishing trip. A sample of approximately 5 kg of Norway lobster landings is taken from these same hauls for length measurements. The self-sampling scheme is validated with observer trips. The reference fleet (2018-2020) consisted of three vessels. In 2019 two observer trips were executed and one in 2020. Due to COVID-19 restrictions, more observer trips were not possible. A total of 34 self-sampling trips have been carried out (12 in 2019 and 22 in 2020). The collected data provides valuable insight in catch composition, including in the length-frequency distribution, and fishing effort of the reference fleet in regard to the FUs. WGNSSK has raised some concerns about how representative participating vessels are for Dutch fishing effort on nephrops, as they are Dutch owned but foreign flagged. While skippers believe that in a 'regular year' (no COVID-19, no temporary Brexit quota) there are no differences, the question whether or not the current reference fleet is a good representation of the Dutch Norway lobster fishing fleet warrants further investigation. The full catch monitoring in the Dutch Norway lobster fishery will be continued in a follow-up programme in which outcomes of the current project will be taken into consideration. This includes expansion of the current reference fleet with three Dutch registered vessels. The research collaboration also provides an opportunity for improved exchanges with nephrops fishers on developments in the fishery and how these affect landings. This is of particular importance to current assessments as they rely heavily on landings data. The skippers pointed out that fishing effort on nephrops, and hence catch composition and landings in 2020 was influenced by COVID-19 and by the temporary Brexit quota allocations. This project was funded under a science-fisheries partnership grant (Partnerschappen Wetenschap en Visserij) under the Dutch Operational Programme of the European Maritime and Fisheries Fund.