CV17018

This report provides the main results of the 2017 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 20-21. This was the fourth survey to achieve full coverage of the full area. The 2017 survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. A total of 86 UWTV stations were completed at 6 nmi intervals over a randomised isometric grid design. The mean burrow density was 0.44 burrows/m2 compared with 0.18 burrows/m2 in 2016. The 2017 geostatistical abundance estimate was 4.4±0.01 billion a 236% increase on the abundance for 2016 with a CV of 4% which is well below the upper limit of 20% recommended by SGNEPS 2012. Highest densities were generally observed throughout the ground, and there were also high densities observed close to boundaries. Using the 2017 abundance estimate and updated stock data implies catch of 8,673 tonnes and landings of 6,553 tonnes in 2018 when MSY approach is applied (assuming that discard rates and fishery selection patterns do not change from the average of 2014–2016). One species of sea-pen were recorded as present at the stations surveyed Virgilaria mirabilis. Trawl marks were observed at 32% of the stations surveyed

A review of new and existing non-extractive techniques for monitoring marine protected areas

Publication history: Accepted - 23 June 2023; Published - 19 July 2023.Ocean biodiversity loss is being driven by several anthropogenic threats and significant efforts are required to halt losses and promote healthy marine ecosystems. The establishment of a network of Marine Protected Areas (MPAs) can help restrict damaging activities and have been recognised as a potential solution to aid marine conservation. When managed correctly they can deliver both ecological and socio-economic benefits. In recent times, MPA designations have increased rapidly while many countries have set future MPA targets for the decades ahead. An integral element of MPA management is adequate monitoring that collects data to assess if conservation objectives are being achieved. Data acquired by monitoring can vary widely as can the techniques employed to collect such data. Ideally, non-destructive and non-invasive methods are preferred to prevent damage to habitats and species, though this may rule out a number of traditional extractive sampling approaches such as dredges and trawls. Moreover, advances in ocean observation technologies enable the collection of large amounts of data at high resolutions, while automated data processing is beginning to make analyses more logistically feasible and less time-consuming. Therefore, developments to existing marine monitoring techniques and new emerging technologies have led to a diverse array of options when choosing to implement an MPA monitoring programme. Here, we present a review of new and existing non-extractive techniques which can be applied to MPA monitoring. We summarise their capabilities, applications, advantages, limitations and possible future developments. The review is intended to aid MPA managers and researchers in determining the suitability of available monitoring techniques based on data requirements and site conditions.This research was funded through the Marine Protected Area Monitoring and Management (MarPAMM) project, which is supported by the European Union’s INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB) with matching funding from the Government of Ireland, the Northern Ireland Executive, and the Scottish Government. This research was also carried out with the support of the Marine Institute under the Marine Research Programme with the support of the Irish Government

Larval transport dynamics in Nephrops norvegicus

Transport of meroplankton larvae in the ocean is a crucial process as it enables connectivity between populations and determines larval supply for species with narrow habitat requirements and sedentary adult stages. The Norway lobster (Nephrops norvegicus), Europe’s most important commercial crustacean, has a patchy distribution across the Northeast Atlantic Ocean and Mediterranean Sea. Adults inhabit areas of muddy substrate where they excavate and spend most of their time within burrows. The pelagic larval phase enables connectivity between populations separated by uninhabitable substrate. Larvae rely on settlement on suitable mud habitat for survival. Therefore, larval settlement, driven by local hydrography, may act as a constraint on recruitment. Biophysical models offer a method of simulating larval transport, which is extremely difficult to observe in-situ due to the inherent difficulties in tracking miniscule larvae in vast areas of the ocean. In the current study, a biophysical larval transport model was used to estimate larval retention, dispersal distance and connectivity for N. norvegicus grounds around Ireland. Models parameters were supported by empirical data in order to accurately represent the biological and behavioural processes of larvae. In Chapter 2, the vertical distribution and occurrence of a Diel Vertical Migration (DVM) in N. norvegicus larvae was examined. Larval vertical distribution was influenced by the vertical temperature differential in the water column, zooplankton biomass and the potential energy anomaly. A twilight DVM was identified and involved two ascents and two descents per day. In Chapter 3, historical zooplankton datasets were used to identify an earlier larval phenology shift in N. norvegicus by 19.1 days from 1982 - 1995 to 2000 - 2010. Ocean warming was identified as the most likely cause as increasing temperatures led to a contraction of the embryo incubation period and earlier hatching of larvae. The phenology shift appeared to have a limited effect on larval duration and transport. Only large variations in modelled larval retention and dispersal distance were observed between larvae released very early and very late in the season. In Chapter 4, a 20-year time series of modelled larval retention, dispersal distance and connectivity estimates for 6 N. norvegicus Functional Units (FUs) demonstrated their capacity to retain, import and export larvae. Smaller FUs had a decreasing trend in retention over the time series which appeared to be as a result of strengthening currents. On the Aran grounds, a link between modelled larval retention and dispersal distance and empirically observed burrow densities from underwater television with a 3-year lag was observed. The findings indicate that larval transport may act as a constraint on recruitment for N. norvegicus populations like the Aran grounds with low and variable larval retention and limited larval imports due to spatial isolation from other grounds. It demonstrates the potential of using larval transport estimates to identify instances of poor recruitment, due to low larval settlement, early in the life cycle before its effects manifest in the adult population. It can also be applied to similar species with defined habitat and planktonic life stages and may assist in limiting overexploitation for commercial species, particularly in the face of climate change and the likely impacts on oceanography.2022-02-0

Larval transport dynamics in Nephrops norvegicus

Transport of meroplankton larvae in the ocean is a crucial process as it enables connectivity between populations and determines larval supply for species with narrow habitat requirements and sedentary adult stages. The Norway lobster (Nephrops norvegicus), Europe’s most important commercial crustacean, has a patchy distribution across the Northeast Atlantic Ocean and Mediterranean Sea. Adults inhabit areas of muddy substrate where they excavate and spend most of their time within burrows. The pelagic larval phase enables connectivity between populations separated by uninhabitable substrate. Larvae rely on settlement on suitable mud habitat for survival. Therefore, larval settlement, driven by local hydrography, may act as a constraint on recruitment. Biophysical models offer a method of simulating larval transport, which is extremely difficult to observe in-situ due to the inherent difficulties in tracking miniscule larvae in vast areas of the ocean. In the current study, a biophysical larval transport model was used to estimate larval retention, dispersal distance and connectivity for N. norvegicus grounds around Ireland. Models parameters were supported by empirical data in order to accurately represent the biological and behavioural processes of larvae. In Chapter 2, the vertical distribution and occurrence of a Diel Vertical Migration (DVM) in N. norvegicus larvae was examined. Larval vertical distribution was influenced by the vertical temperature differential in the water column, zooplankton biomass and the potential energy anomaly. A twilight DVM was identified and involved two ascents and two descents per day. In Chapter 3, historical zooplankton datasets were used to identify an earlier larval phenology shift in N. norvegicus by 19.1 days from 1982 - 1995 to 2000 - 2010. Ocean warming was identified as the most likely cause as increasing temperatures led to a contraction of the embryo incubation period and earlier hatching of larvae. The phenology shift appeared to have a limited effect on larval duration and transport. Only large variations in modelled larval retention and dispersal distance were observed between larvae released very early and very late in the season. In Chapter 4, a 20-year time series of modelled larval retention, dispersal distance and connectivity estimates for 6 N. norvegicus Functional Units (FUs) demonstrated their capacity to retain, import and export larvae. Smaller FUs had a decreasing trend in retention over the time series which appeared to be as a result of strengthening currents. On the Aran grounds, a link between modelled larval retention and dispersal distance and empirically observed burrow densities from underwater television with a 3-year lag was observed. The findings indicate that larval transport may act as a constraint on recruitment for N. norvegicus populations like the Aran grounds with low and variable larval retention and limited larval imports due to spatial isolation from other grounds. It demonstrates the potential of using larval transport estimates to identify instances of poor recruitment, due to low larval settlement, early in the life cycle before its effects manifest in the adult population. It can also be applied to similar species with defined habitat and planktonic life stages and may assist in limiting overexploitation for commercial species, particularly in the face of climate change and the likely impacts on oceanography.2022-02-0

A Stable Isotope Sclerochronology‐Based Forensic Method for Reconstructing Debris Drift Paths With Application to the MH370 Crash

Abstract A flaperon belonging to Malaysian Airlines flight MH370 washed ashore on Réunion Island covered with the barnacle Lepas anatifera in July 2015, more than a year after the plane's disappearance. Here, we report the first high‐precision δ18Ocalcite versus temperature relationship for L. anatifera reared under laboratory conditions to unlock clues to the flaperon's drift path and origin. Using this experimental relationship and known growth rates for L. anatifera, we also demonstrate a new method for (a) converting δ18O data for one of the MH370 barnacles into a dated time series of sea surface temperatures (SSTs) experienced during the last part of the flaperon's drift and (b) identifying best fits between the observed flaperon SST time series and 50,000 SST histories generated from a particle‐tracking simulation. Our new method identifies a flaperon drift path far south of a previous isotope‐based reconstruction. We conclude with specific recommendations for using our method to continue the search for MH370 and other applications

A review of new and existing non-extractive techniques for monitoring marine protected areas

Ocean biodiversity loss is being driven by several anthropogenic threats and significant efforts are required to halt losses and promote healthy marine ecosystems. The establishment of a network of Marine Protected Areas (MPAs) can help restrict damaging activities and have been recognised as a potential solution to aid marine conservation. When managed correctly they can deliver both ecological and socio-economic benefits. In recent times, MPA designations have increased rapidly while many countries have set future MPA targets for the decades ahead. An integral element of MPA management is adequate monitoring that collects data to assess if conservation objectives are being achieved. Data acquired by monitoring can vary widely as can the techniques employed to collect such data. Ideally, non-destructive and non-invasive methods are preferred to prevent damage to habitats and species, though this may rule out a number of traditional extractive sampling approaches such as dredges and trawls. Moreover, advances in ocean observation technologies enable the collection of large amounts of data at high resolutions, while automated data processing is beginning to make analyses more logistically feasible and less time-consuming. Therefore, developments to existing marine monitoring techniques and new emerging technologies have led to a diverse array of options when choosing to implement an MPA monitoring programme. Here, we present a review of new and existing non-extractive techniques which can be applied to MPA monitoring. We summarise their capabilities, applications, advantages, limitations and possible future developments. The review is intended to aid MPA managers and researchers in determining the suitability of available monitoring techniques based on data requirements and site conditions</p