Gillnet fisheries are widely thought to pose a conservation threat to many populations of marine mammals, seabirds and turtles. Gillnet fisheries also support a significant proportion of small-scale fishing communities worldwide. Despite a large number of studies on protected species bycatch in recent decades, relatively few have examined the underlying causes of bycatch, and fewer still have looked at the issue from a multi-taxon perspective. We used three bibliographic databases and one search engine to identify studies by year of publication and taxon. The majority of studies on the mechanisms of gillnet bycatch are not This article is protected by copyright. All rights reserved. 2 accessible through mainstream published literature sources. Many are reported in technical papers, government reports and University theses. We reviewed over 600 published and unpublished studies of bycatch where causal or correlative factors were considered, and identified therein 28 environmental, operational, technical and behavioral factors that might plausibly be associated with higher or lower bycatch rates of the three taxa. Of the factors considered, 11 were found to have been associated with potential bycatch reduction in two out of the three taxa, while three factors (water depth, mesh size and net height) were associated with trends in bycatch rate for all three taxa. These findings provide a basis to guide further experimental work to test hypotheses about which factors most influence bycatch rates, and to explore ways of managing fishing activities and/or improving gear design to minimize the incidental capture of species of conservation concern, whilst ensuring the viability of the fisheries concerned.

ForewordThis 'cruise report' is the third of a short series, reflecting the aspiration of the Clyde Fishermen's Association to establish a rigorous sampling scheme to monitor changes in the abundance and distribution of cod and other gadoid species within the Clyde area. The Scottish Oceans Institute was approached to provide independent scientific support in early 2016. A series of surveys was then conducted in 2016, 2017 and 2018. In each survey the SOI provided observers, collected data and wrote up a cruise report detailing the methods used and the location, numbers, weights, sex and maturity states of fish caught. Trials were halted after 2018 firstly because of pressing issues resulting from Brexit which absorbed any potentially available human and other resources, and secondly because of the COVID pandemic. The reports remained as unapproved and incomplete drafts until 2022. Picking up these reports again in 2022, we have responded to reviewers' comments since made by Marine Scotland Science and have finalised all four reports in the 2016-2018 current series.MSS comments on previous drafts included the observation that there are a number of surveydesign problems that would need to be addressed in any future Clyde surveys, and that there is a lack of important detail on how the surveys were conducted. MSS pointed out that the surveys were intended to be developmental and inform future survey work and as such the design and the implementation of the surveys over the three years is too inconsistent to permit comparative timeseries, and any future survey would probably need to start from scratch.MSS suggested revisions should focus on providing spatial summaries of fish distribution and additional detail regarding the specific gear types used.Changes made to previous drafts of the present report include editorial changes to language and the inclusion of bubble plots to provide more detail on the spatial distribution of fish catches (Figures 13-16) as requested. We were unable to provide any further details on the trawl characteristics used in the demersal trial here. The trawl used was a 'standard nephrops trawl' but unfortunately, we could not recover further details of how this was rigged (Table 1).

ForewordThis 'cruise report' is the second of a short series, reflecting the aspiration of the Clyde Fishermen's Association to establish a rigorous sampling scheme to monitor changes in the abundance and distribution of cod and other gadoid species within the Clyde area. The Scottish Oceans Institute was approached to provide independent scientific support in early 2016. A series of surveys was then conducted in 2016, 2017 and 2018. In each survey the SOI provided observers, collected data and wrote up a cruise report detailing the methods used and the location, numbers, weights, sex and maturity states of fish caught. Trials were halted after 2018 firstly because of pressing issues resulting from Brexit which absorbed any potentially available human and other resources, and secondly because of the COVID pandemic. The reports remained as unapproved and incomplete drafts until 2022. Picking up these reports again in 2022, we have responded to reviewers' comments since made by Marine Scotland Science and have finalised all four reports in the 2016-2018 current series.

[Extract from Foreword] This ‘cruise report’ is the first of a short series, reflecting the aspiration of the Clyde Fishermen’s Association to establish a rigorous sampling scheme to monitor changes in the abundance and distribution of cod (and later other gadoid species) within the Clyde area. The Scottish Oceans Institute was approached to provide independent scientific support in early 2016. A series of surveys was then conducted in 2016, 2017 and 2018. In each survey the SOI provided observers, collected data and wrote up a cruise report detailing the methods used and the location, numbers, weights, sex and maturity states of fish caught. Trials were halted after 2018 firstly because of pressing issues resulting from Brexit which absorbed any potentially available human and other resources, and secondly because of the COVID pandemic. The reports remained as unapproved and incomplete drafts until 2022. Picking up these reports again in 2022, we have responded to reviewers’ comments since made by Marine Scotland Science and have finalised all four reports in the 2016-2018 current series.

No abstract