Preliminary estimates of seabird bycatch by UK vessels in UK and adjacent waters

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Report on CFA Clyde demersal fish survey March 2017: summary report to the Clyde Fishermen's Association

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Report on CFA Clyde demersal fish survey Autumn 2017: summary report to the Clyde Fishermen's Association

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Cod catches from demersal and pelagic trawl gears in the Clyde estuary: results from an industry-led survey in 2016: a report on behalf of the Clyde Fishermen's Association

[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.Publisher PD

Firth of Clyde demersal fish surveys: Spring & Autumn 2018: a summary report on behalf of the Clyde Fishermen's Association

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Passive acoustic methods for fine-scale tracking of harbour porpoises in tidal rapids

The growing interest in generating electrical power from tidal currents using tidal turbine generators raises a number of environmental concerns, including the risk that marine mammals might be injured or killed through collision with rotating turbine blades. To understand this risk, information on how marine mammals use tidal rapid habitats and in particular, their underwater movements and dive behaviour is required. Porpoises, which are the most abundant small cetacean at most European tidal sites, are difficult animals to tag, and the limited size of tidal habitats means that any telemetered animal would be likely to spend only a small proportion of time within them. Here, an alternative approach is explored, whereby passive acoustic monitoring (PAM) is used to obtain fine scale geo-referenced tracks of harbour porpoises in tidal rapid areas. Large aperture hydrophone arrays are required to obtain accurate locations of animals from PAM data and automated algorithms are necessary to process the large quantities of acoustic data collected on such systems during a typical survey. Methods to automate localisation, including a method to match porpoise detections on different hydrophones and separate different vocalising animals, and an assessment of the localisation accuracy of the large aperture hydrophone array are presented.Publisher PDFPeer reviewe

Passive acoustic tracking of the three-dimensional movements and acoustic behaviour of toothed whales in close proximity to static nets

Funding: Department for Environment, Food and Rural Affairs, UK Government (Grant Number(s): ME6052; Grant recipient(s): Jamie Macaulay, Allen Kingston, Simon Northridge, Alexander Coram). University of St Andrews.1. Entanglement in net fisheries (static and drift) is the largest known cause of direct anthropogenic mortality to many small cetacean species, including harbour porpoise (Phocoena phocoena), in UK waters. Despite this, little is known about the behaviour of small cetaceans in proximity to nets. 2. We have developed a passive acoustic monitoring (PAM) system for tracking the fine-scale three-dimensional (3D) movements of echolocating cetaceans around actively fishing nets by localising their acoustic clicks. The system consists of two compact four-channel acoustic recorders with sample-synchronised sensor packages that use 3D motion tracking technology to accurately calculate log orientation, depth, water temperature and ambient light level. Two recorders were used in tandem, with each one attached to and floating above the net floatline. The system can be deployed during normal fishing operations by a trained researcher or experienced fisheries observer. Recordings were analysed in PAMGuard software and the 3D positions of echolocating animals in the vicinity of the system were calculated using an acoustic particle filter-based localisation method. 3. We present findings from four deployments in UK waters (each 1–2 days in duration) in which 12 distinct harbour porpoise encounters yielded a sufficient number of detected clicks to track their movements around the net. The tracks show a variety of behaviours, including multiple instances of animals actively foraging in close proximity to the fishing net. 4. We show that a relatively inexpensive PAM system, which is practical to deploy from active fishing vessels, is capable of providing highly detailed data on harbour porpoise behaviour around nets. As harbour porpoises are the one of the most difficult species to localise, this methodology is likely to be suitable for elucidating the behaviour of many other toothed whale species in a variety of situations.Publisher PDFPeer reviewe

Identification of high-risk areas for harbour porpoise Phocoena phocoena bycatch using remote electronic monitoring and satellite telemetry data

ABSTRACT: The bycatch of harbour porpoise Phocoena phocoena is an issue of major concern for fisheries management and for porpoise conservation. We used high-resolution spatial and temporal data on porpoise abundance and fishing effort from the Danish Skagerrak Sea to identify areas with potentially higher and lower risk of porpoise bycatch. From May 2010 to April 2011, 4 commercial gillnet vessels were equipped with remote electronic monitoring (REM) systems. The REM system recorded time, GPS position and closed-circuit television (CCTV) footage of all gillnet hauls. REM data were used to identify fishing grounds, quantify fishing effort and document harbour porpoise bycatch. Movement data from 66 harbour porpoises equipped with satellite transmitters from 1997 to 2012 were used to model population density. A simple model was constructed to investigate the relationship between the response (number of individuals caught) and porpoise density and fishing effort described by net soak time, net string length and target species. Results showed that a model including both porpoise density and fishing effort data predicted bycatch better than models containing only one factor. We therefore conclude that porpoise telemetry or REM data allow for identification of areas of potential high and low bycatch risk, and better predictions are obtained when combining the 2 sources of data. The final model can thus be used as a tool to identify areas of bycatch risk.Publisher PDFPeer reviewe