Making the most of monkfish and megrim: survey-based assessments and sustainable exploitation

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Anglerfish (Lophius spp.), also known as monkfish, and megrim are two of the most valuable fish resources in Europe. In this fully funded PhD studentship, the student will take to sea to survey anglerfish and megrim, and use a 15 year time series of survey data, to determine the status and advise on the sustainable management of these enigmatic fish species. The studentship is part of the MASTS SUPER DTP and is based at the University of Aberdeen. Located in the North East of Scotland, with good links to the rest of Europe through an international airport, the university is home to a vibrant marine biology research community, which includes Marine Scotland Science (MSS), the principal advisory agency to the Scottish government and a partner in this project. The university is located close to the city centre, which is right on the coast with miles of sandy beaches. It is also close to the UK's biggest national park, offering a fantastic lifestyle for students interested in wildlife and the marine environment. The anglerfish caught by most UK fishermen have no accepted scientific assessment of their abundance on the northern shelf; nor are there reference points available for use in their sustainable management. A series of surveys, dedicated to anglerfish have been carried out annually by MSS since 2005 (Fernandes et al. 2007). These surveys are unique in being carried out in collaboration with, and using vessels from, the fishing industry. They are also unique in providing an absolute abundance estimate of anglerfish (Reid et al. 2007) and also include another valuable species, the megrim (Lepidorhombus spp.), for which there is only a relative scientific assessment. A recent international benchmark exercise for the scientific assessment of anglerfish was inconclusive and the stock is still managed on the basis of the survey biomass estimates ("category 3 stock") such that appropriate exploitation rates are unknown. MSS are developing length based approaches to improve the scientific basis of the advice on anglerfish. In this studentship the aim is to complement this work by developing an age-based assessment model, previously proposed by Fernandes (ICES 2013), paying particular attention to the sensitivity of the model to any age reading bias and error. Sensitivity of the model to survey coverage will also be considered, by analysing appropriate data from the International Bottom Trawl Survey. These assessment approaches will be complemented by incorporating an examination of maturity at age, length and sex; as well as investigating the natural mortality at age, length and sex. Once the age based model has been refined, the student will also conduct a management strategy evaluation (MSE) to determine appropriate fishing and biomass reference points in accordance with ICES procedures. There is also scope to apply the length based method to megrim. Finally, there is good reason to suspect that anglerfish, particularly the black bellied species (Lophius budegassa) which is a Lusitanian (warm water) species, may also benefit from increasing temperatures due to climate change. So there is also scope to detect changes in the abundance and distribution of these species in relation to changes in sea temperature. Data will be taken from the time series of anglerfish surveys available from MSS (Clarke). Training will be provided in modelling and statistical programming (R) by Fernandes, through dedicated courses at the University of Aberdeen, and at ICES training courses (MSE). The student will participate in the anglerfish surveys in the first two years of the studentship which will augment the time series available. The student will also attend the ICES Celtic Seas Working Group at ICES HQ in Copenhagen to present their work.