Celtic Sea Herring Acoustic Survey Cruise Report 2022, 09 - 29 October 2022

In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g and j), herring are an important commercial species to the pelagic and polyvalent fleet. The local fleet is composed of dry hold polyvalent vessels and a smaller number of large purpose built refrigerated seawater vessels (RSW). The stock is composed of both autumn and winter spawning components with the latter dominating. The fishery targets pre-spawning and spawning aggregations in Q3-4. The Irish commercial fishery has historically taken place within 1-20nmi (nautical miles) of the coast. However, since the mid-2000s RSW fleet have actively targeted offshore aggregations migrating from summer feeding in the south Celtic Sea. In VIIj, the fishery is traditionally active from mid-November and is concentrated within several miles of the coast. The VIIaS fishery peaks towards the year end in December, but may be active from mid-October depending on location. In VIIg, along the south coast herring are targeted from October (offshore) to January at a number of known spawning sites and surrounding areas. Overall, the protracted spawning period of the two components extends from October through to February, with annual variation of up to 3 weeks. Spawning occurs in successive waves in a number of well known locations including large scale grounds and small discreet spawning beds. Since 2008 ICES division VIIaS (spawning box C) has been closed to fishing for vessels over 15m to protect first time spawners. For those vessels less than 15m a small allocation of the quota is given to this ‘sentinel’ fishery operating within the closed area. The stock structure and discrimination of herring in this area has been investigated recently. Hatfield et al. (2007) has shown the Celtic Sea stock to be fairly discrete. However, it is known that fish in the eastern Celtic Sea recruit from nursery areas in the Irish Sea, returning to the Celtic Sea as young adults (Brophy et al. 2002; Molloy et al., 1993). The stock identity of VIIj herring is less clear, though there is evidence that they have linkages with VIIb and VIaS (ICES, 1994; Grainger, 1978). Molloy (1968) identified possible linkages between young fish in VIIj and those of the Celtic Sea herring. For the purpose of stock assessment and management divisions VIIaS, VIIg and VIIj have been combined since 1982. For a period in the 1970s and 1980s, larval surveys were conducted for herring in this area. However, since 1989, acoustic surveys have been carried out, and currently are the only tuning indices available for this stock. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989. Since 2004 the survey has been fixed in October and carried out onboard the RV Celtic Explorer. This year, the survey was conducted onboard the RV Tom Crean. Survey design and geographical coverage have been modified over the time series to adapt to changes in stock size and behaviour. Since 2016, the wider core distribution area has been surveyed by means of two independent surveys and supplemented with small high resolution adaptive surveys focusing on areas of high abundance

Exploring environmental and biological drivers of cetacean occurrence in the cross-border region of the Malin Shelf using data from a European fishery survey

Irish and Scottish waters are important habitats for cetaceans in Europe. Yet, little data is available for the region of the Malin Shelf, north of Ireland. Despite a rich species diversity, relative cetacean abundance appears low compared to hotspots documented west of Scotland and Ireland. Whether this perceived low prevalence accurately portrays an ecological discontinuity or arises from a lack of published results and low survey effort in that transborder area remains unclear. Here, we used sighting records from a multi-disciplinary fisheries survey, the Western European Shelf Pelagic Acoustic Survey (WESPAS), to explore cetacean habitat preferences over the Malin and Hebridean shelves. Northern minke whale and common dolphin occurrence was modelled within a Bayesian Additive Regression Trees (BART) framework, against selected environmental and biological variables. No correlation was observed between cetacean presence and in-situ prey biomass. Minke whales distribution was better explained by oceanography, notably proxies for frontal activity, and primary productivity. Common dolphins similarly showed preferences for shelf waters within 5-25km of fronts, but also affinities for fine substrates. Favourable habitats identified by the models were consistent with literature around the Hebrides and shed light on potentially important areas along the Islay front and north of Donegal, so far unreported due to data deficiency. Results will contribute towards informing future monitoring, strategic management and conservation efforts in this cross-border region

CE0403

Use the URI link below to search the Marine Institute Data Discovery Catalogue for datasets relevant to this report.Acoustic surveys on northern blue whiting (Micromesistius poutassou) stocks have been carried out since the early 1970s by the Institute of Marine Research (IMR), Bergen. In the early 1980s a coordinated acoustic survey approach was adopted, with both Russia and Norway participating to estimate the size of the stock. The acoustic survey programme is carried out for fishery management purposes, results are presented annually at the ICES led Northern Pelagic and Blue Whiting Fisheries Working Group and from this catch advice is determined for the following year. The highly migratory nature of this stock and its components require a large geographical area to be surveyed during a relatively short spawning window. Acoustic surveys are routinely carried out on specific spawning and pre-spawning aggregations of blue whiting. This can allow for high concentrations of fish to be surveyed in a relatively small geographical and often well defined area, if the timing is synchronised. This survey was conducted as part of a collaborative survey coordinated by the Institute of Marine Research, Bergen, Norway, using the vessel the MRV “Johan Hjort”. Also participating were the MRV “Fridtjof Nansen” (PINRO, Russia) and the MRV “Tridens” (RIVO, Netherlands). The total combined area surveyed in 2004 covered from the Faroe Islands in the north (62º of longitude) to the southern coast of Ireland (50.5º N), area coverage to the west extended from 2º -18º of latitude. The Irish component of the survey was made up of transects covering some 2,080 nautical miles. In addition to the collection of acoustic data fishing hauls were carried out to determine the make up of fish marks recorded by the equipment and to assess the length, weight, age, sex and maturity of the stock. Oceanographic data was collected using a number of spaced hydrograhic stations where salinity and temperature of the water column was recorded at depths of up to 1200 m

Response of cetaceans to fluctuations of pelagic fish stocks and environmental conditions within the Celtic Sea ecosystem

Inshore waters off the south coast of Ireland are an important foraging area for a range of cetacean species. Some of the main prey species of these cetaceans are herring and sprat, two economically valuable fish species in the region. The Celtic Sea herring stock suffered a marked decline in 2013. The present study aimed to investigate potential changes in the ecosystem associated to the herring decline and to determine the potential impacts on predators. Here we analyzed sightings information of common dolphins, fin, minke, humpback and unidentified whale species, acoustic data of herring and sprat, and a range of environmental variables mainly derived from satellites. Firstly, we characterized spatio-temporal patterns in the relative abundance of predator and prey species, and environmental variables, and compared periods before and since the herring decline. Since the 2013 herring decline, (i) the herring stock has mainly concentrated in south-eastern coastal waters and southern offshore Irish waters, (ii) sprat density has increased, (iii) chlorophyll concentration has decreased, (iv) sea surface temperature has risen, and (v) the euphotic layer has extended deeper. Secondly, we modelled the effects of prey density and environmental conditions on the relative abundance and distribution of cetaceans, as well as the effects of environmental conditions on prey density, between 2005-2018 by applying Hurdle Generalized Additive Models. The models for herring and sprat support the idea that these species have different environmental relationships, for example herring tended to be found in shallower waters than was the case for sprat. The presence and relative abundance of common dolphins were significantly affected by both environmental conditions and herring density, whereas whale species presence and relative abundance were found to be correlated with sea surface temperature and prey density. The model results suggest differences in prey choice among whale species. Understanding the dynamic relationships between predators, prey and the environment is important to inform an ecosystem-based approach to fisheries management

CE0504

Use the URI link below to search the Marine Institute Data Discovery Catalogue for datasets relevant to this report.Acoustic surveys on northern blue whiting (Micromesistius poutassou) stocks have been carried out since the early 1970s by the Institute of Marine Research (IMR), Bergen. In the early 1980s a coordinated acoustic survey approach was adopted, with both Russia and Norway participating to estimate the size of the stock. The acoustic survey programme is carried out for fishery management purposes, results are presented annually at the ICES led Northern Pelagic and Blue Whiting Fisheries Working Group and from this catch advice is determined for the following year. The highly migratory nature of this stock and its components require a large geographical area to be surveyed during a relatively short spawning window. Acoustic surveys are routinely carried out on specific spawning and pre-spawning aggregations of blue whiting. This can allow for high concentrations of fish to be surveyed in a relatively small geographical and often well defined area, if the timing is synchronised. This survey was conducted as part of a collaborative survey coordinated by the Institute of Marine Research, Bergen, Norway, using the vessel the RV “G.O. Sars”. Also participating were the RV “Fridtjof Nansen” (PINRO, Russia), RV “Atlantniro” (Russia), RV “Tridens” (RIVO, Netherlands) and the RV “Magnus Heinason” (Faroes). The total combined area surveyed in 2005 covered from the Faroe Islands in the north (62º of longitude) to the southern coast of Ireland (49º N), area coverage to the west extended from 2º -20º of latitude. The Irish component of the survey was made up of transects covering some 2,228 nautical miles. In addition to the collection of acoustic data fishing hauls were carried out to determine the make up of fish marks recorded by the equipment and to assess the length, weight, age, sex and maturity of the stock. Oceanographic data was collected using a number of spaced hydrograhic stations where salinity and temperature of the water column was recorded at depths of up to 1200 m

CE21009

The WESPAS survey program is the consolidation of two existing survey programs carried out by FEAS, the Malin Shelf herring acoustic survey, and the boarfish acoustic survey. The Malin Shelf herring acoustic survey has been carried out annually since 2008 and reports on the annual abundance of summer feeding aggregations of herring to the west of Scotland and to the north and west of Ireland from 53°30’N to 58°30’N. The boarfish survey was conducted from 2011 using a chartered fishing vessel and reported the abundance of spawning aggregations of boarfish from 47°N to 57°N. In 2016 both surveys were combined into the WESPAS survey and have been carried out onboard the RV Celtic Explorer over a 42-day period, providing synoptic coverage of shelf waters from 47°30’N northwards to 58°30’N. Age stratified relative stock abundance estimates of boarfish, herring and horse mackerel within the survey area were calculated using acoustic data and biological data from trawl sampling. Stock estimates of boarfish and horse mackerel were submitted to the ICES assessment Working Group for Widely Distributed Stocks (WGWIDE) meeting in August 2021. Herring estimates are submitted to the Herring Assessment Working Group (HAWG) meeting in March every year. Survey performance will be reviewed at the ICES Planning Group meeting for International Pelagic Surveys (WGIPS) meeting in January 2022

Fine-scale spatial association between baleen whales and forage fish in the celtic sea1

Baleen whales can be regularly observed in the Celtic Sea; however, little is known about their local foraging behaviour. The study objective was to determine whether or not baleen whales selectively prey upon particular forage fish species or, on the contrary, is predation on the Celtic Sea plateau driven by random encounters between prey and predator? Concurrent sighting surveys for fin (Balaenoptera physalus), minke (Balaenoptera acutorostrata), and humpback (Megaptera novaeangliae) whales were carried out simultaneously from 2007 to 2013 during dedicated fisheries acoustic surveys assessing the abundance and distribution of forage fish. Probabilities of spatial overlap between baleen whales and forage fish were analysed and compared with the probability of a random encounter. For estimations of foraging threshold and prey selectivity, mean fish biomass and fish length were calculated when baleen whales and forage fish co-occurred. Whales were dominantly observed in areas with herring (Clupea harengus) and sprat (Sprattus sprattus), while areas with mackerel (Scomber scombrus) were not targeted. A prey detection range of up to 8 km was found, which enables baleen whales to track their prey to minimize search effort. Fish densities within the defined foraging distance ranged from 0.001 to 3 kg . m(-2) and were correlated to total fish abundance. No prey size selectivity according to fish length was found. By linking baleen whale distribution to high-density herring and sprat areas, it was possible to identify the Celtic Sea as a prey hot spot for baleen whales during autumn

Digital Interoperability for the Facilities Management Domain : a Review of Semantic Web-based Approaches

The use of Semantic Web-based Technologies (SWT) to support digital Facilities Management (FM) activities has been shown to address interoperability challenges between disciplinary stakeholders. By establishing shared understanding through ontologies, eliminating precarious file exchanges and democratising participation through non-proprietary technologies, SWTs are receiving growing interest from the research community. Despite this, no comprehensive review exists which analyses works with a specific focus on the FM domain. This paper reviews 35 academic works and provides a broad discussion around academic and industry initiatives in SWTs for the FM domain, identifying research gaps and future directions of interest. We find that SWTs are already being used by FM practitioners and that implementation is highly case-specific and thus, developments need to be flexible and user-oriented in their design. This work towards a comprehensive domain review provides a useful reference for others in the field as well as informing our own future research activities

CE12014

In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989. This survey was undertaken in early October. The geographical confines of the annual 21 day survey program have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complimented since 2004 by detailed hydrographic and marine mammal and seabird surveys