Vessel Monitoring Systems (VMS) automatically collect positional data from fishing vessels. The VMS data can be linked to catch data from logbooks to provide a census of spatially resolved catch and effort data. We explore and validate the most appropriate and practical method for integrating Irish VMS and logbook data. A simple speed rule is applied to identify VMS records that correspond to fishing activity. These data are then integrated with the catch data from the logbooks using date and vessel identifier. A number of assumptions were investigated and the resulting distribution maps of catch and effort appear to be unbiased. The method is illustrated with an example of a time-series of spatially explicit catch per unit effort estimates. The proposed method is relatively simple and does not require specialist software or computationally intensive methods. It will be possible to generalise this approach to similar data sets that are available within the EU and many other regions. Analysis of integrated VMS and logbooks data will allow fisheries data to be analysed on a considerably finer spatial scale that was possible in the past which opens up a range of potential applications.

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Gerritsen, H. D., Minto, C., and Lordan, C. 2013. How much of the seabed is impacted by mobile fishing gear? Absolute estimates from Vessel Monitoring System (VMS) point data. – ICES Journal of Marine Science, 70: 523–531. Demersal trawling impacts extensively on the seabed, and the extent and frequency of this impact can be assessed using Vessel Monitoring System (VMS) data (positional data of fishing vessels). Existing approaches interpolate fishing tracks from consecutive VMS locations (track interpolation) and/or aggregate VMS point data in a spatial grid (point summation). Track interpolation can be quite inaccurate with the current 2-hour time interval between VMS records, leading to biased estimates. Point summation approaches currently only produce relative estimates of impact and are highly sensitive to the grid size chosen. We propose an approach that provides absolute estimates of trawling impact from point data and is not sensitive to an arbitrary choice of grid-cell size. The method involves applying a nested grid and estimating the swept area (area covered by fishing gear) for each VMS point. We show that the ratio of the swept area to the surface area of a cell can be related to the proportion of the seabed that was impacted by the gear a given number of times. We validate the accuracy of this swept-area ratio approach using known vessel tracks and apply the method to international VMS data in the Celtic Sea.

Lordan, C., Ó Cuaig, M., Graham, N., and Rihan, D. 2011. The ups and downs of working with industry to collect fishery-dependent data: the Irish experience. – ICES Journal of Marine Science, 68: 1670–1678. Working with the fishing industry to collect fishery-dependent data for scientific and advisory purposes is essential in most countries, but despite the many advantages of working with fishers, it is not without challenges. The objectives and the ups and downs of 16 recent projects in Ireland are described, and four case studies are discussed in detail. Some common themes that characterize both successful and unsuccessful experiences are identified. One critical aspect is industry's sometimes unrealistic time-horizons and expectations when engaging in scientific data collection. Detailed communication of objectives, procedures, results, and relevance not only to industry representatives, but also to vessel owners and crew, is required throughout the life cycle of a project. For some projects, there is a clear need to include incentives in the design, but for others this is less critical. The critical needs for ongoing quality control and assurance, validation of data, and appropriate project design are discussed, along with the link between successful management systems and participatory research. Finally, comment is provided on how the expected reforms of the EU's Common Fisheries Policy will place new demands on joint research.

The stomach contents of seven male sperm whales Physeter macrocephalus (Odontoceti: Physeteridae) from the north-east Atlantic were examined. One animal was stranded on 27 November 1997 near Wassenaar (the Netherlands). Four became stranded the following day, 28 November 1997, on the island of Ameland (the Netherlands); three of these had food remains in the stomach. Samples were also examined from a whale stranded in August 1998 at Bettyhill (Scotland) and one live-stranded in March 1996 at Tory Island, Co. Donegal (Ireland). Finally, a sample of the stomach contents from a whale stranded near Terneuzen (Scheldt Estuary, the Netherlands) in February 1937 was also examined.All samples consisted almost entirely of cephalopod beaks. Some fish remains were also found in the stomach of the Wassenaar and one of the Ameland whales. The cephalopod prey were mainly oceanic species: Gonatus sp. (probably Gonatus fabricii, Oegopsida: Gonatidae) was the main prey for all the animals stranded in the Netherlands. The specimen stranded in Ireland had consumed a wider range of prey, mainly Histioteuthis bonnellii (Oegopsida: Histiotetuhidae), but also Architeuthis sp. (Oegopsida: Architeuthidae), Chiroteuthis sp. (Oegopsida: Chiroteuthidae), Teuthowenia megalops (Oegopsida: Cranchiidae) and the octopod Haliphron atlanticus (Incirrata: Alloposidae). The fish remains from the Wassenaar whale were saithe (Pollachius virens, Gadiformes: Gadidae), while remains of monkfish (Lophius sp., Lophiiformes: Lophiidae) and an unidentified fish were recorded from one of the Ameland animals.

Todarodes sagittatus (N=1131) were opportunistically sampled from commercial and research trawling in Irish and Scottish waters between 1993 and 1998. The results suggest that the species is common in deep waters (>200 m) to the west of Ireland and Scotland, particularly in late summer and autumn. The size of squid caught was related to depth, with larger squid caught deeper, and is indicative of an ontogenetic, bathymetric migration. Females were more common (sex ratio 1·00:0·46), and attained a larger maximum size (520 mm mantle length (ML)) than males (426 mm ML). Mature females (360–520 mm ML) were caught in deep water (>500 m), between March and November, with a large catch of mature females taken off the west coast of Ireland in August 1996. Mature males (300–426 mm) were found from August to November. Potential fecundity was estimated to range from 205,000–523,500 eggs female−1. Putative daily increments in statoliths indicated a life cycle of slightly over a year, with rapid growth of approximately 1·8 mm d−1 during subadult and adult life. Fish were the most important prey of T. sagittatus and 17 fish prey taxa were identified, of which pelagic species were the most important.

The vertical distribution of pelagic marine larvae can greatly influence their dispersal due to depth-varying currents, which can determine larval retention or transport away from critical habitat. Vertical distribution of commercially important lobster Nephrops norvegicus larvae was examined over fishing grounds off the west and east coasts of Ireland. Larval vertical distribution for both grounds was significantly influenced by the temperature differential between the surface and 60 m depth, zooplankton biomass and, to a lesser extent, stratification, measured using the potential energy anomaly. Fixed station sampling was conducted over 3 d in the western Irish Sea (WIS) to investigate the occurrence and extent of a diel vertical migration (DVM). Larvae performed twilight DVM with an ~10 m ascent prior to sunset and sunrise and a descent at midnight and after sunrise. Particle-tracking model simulations were used to examine the effect of DVM behaviour on larval retention over mud habitat. The presence of a DVM actually reduced the likelihood of retention on both the Aran and WIS grounds. Predicted larval retention was unusually low over the Aran grounds in 2018, which is potentially significant in the context of historic stock fluctuations in this area. These findings suggest that understanding larval dynamics could be crucial in managing N. norvegicus stocks on fishing grounds, in particular those with variable interannual oceanography and a low rate of larval donation from other grounds.

Seafloor multiparametric fibre-optic-cabled video observatories are emerging tools for standardized monitoring programmes, dedicated to the production of real-time fishery-independent stock assessment data. Here, we propose that a network of cabled cameras can be set up and optimized to ensure representative long-term monitoring of target commercial species and their surrounding habitats. We highlight the importance of adding the spatial dimension to fixed-point-cabled monitoring networks, and the need for close integration with Artificial Intelligence pipelines, that are necessary for fast and reliable biological data processing. We then describe two pilot studies, exemplary of using video imagery and environmental monitoring to derive robust data as a foundation for future ecosystem-based fish-stock and biodiversity management. The first example is from the NE Pacific Ocean where the deep-water sablefish (Anoplopoma fimbria) has been monitored since 2010 by the NEPTUNE cabled observatory operated by Ocean Networks Canada. The second example is from the NE Atlantic Ocean where the Norway lobster (Nephrops norvegicus) is being monitored using the SmartBay observatory developed for the European Multidisciplinary Seafloor and water column Observatories. Drawing from these two examples, we provide insights into the technological challenges and future steps required to develop full-scale fishery-independent stock assessments.