Interactions between biology, environmental and anthropogenic factors on the exploitation of pelagic species by the Scottish fleet

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This PhD will seek to demonstrate the importance of a holistic approach to better understand how fish stocks are exploited within the face of both a changing environment and due to the influence of economic and societal change and technological advance. These interlinking factors are important when considering the importance of the fishing industry to remote and rural communities, to food security and, for pelagic fisheries which are known to have a low carbon footprint – the carbon cost of food.

Herring Clupea harengus and mackerel Scomber scombrus are migratory species and targeted seasonally during spawning and/or feeding aggregations. These species comprise 80% by weight of the Scottish pelagic fisheries, and account for >55% by weight, and >40% by value of the entire Scottish fishing sector. The Scottish fleet is 21 large (>40-85m) modern trawlers based in Shetland, Peterhead and Fraserburgh. The fishing efficiency, combined with both restricted quotas and the migratory behaviour of the species result in relatively short seasonal fisheries that are mainly: herring July-Aug and mackerel Jan/Feb and Oct/Nov.

Large fluctuations in annual fishing quota together with a mis-match between fisher observations and assessment outputs led to industry calls for improved science on these stocks. As part of this, the industry through the SPFA, have worked in partnership with UHI and MSS since 2018 to develop fisher self-sampling and fisher/science co-sampling programmes that have been adopted as the route through which the Scottish Government collects pelagic data [1]. These programmes collect data on a haul-by-haul resolution and are providing biological data on previously unobtainable resolution. The data-set continues to grow and is ripe for the analysis of biological factors.

In addition to immediately apparent seasonal and inter-annual variations within the catch data, there are a range of external factors that affect the fishing choices that skippers make in relation to when to fish, what they are targeting regarding fish size, maturity and condition, and where to land their catches (Scottish processors or abroad). These are influenced by market forces and have in recent years been significantly affected by Russian sanctions (since 2019) and in 2022 by the Ukraine war.

The development of pelagic fisheries from 1945 until 2000 has been documented [2] but since 2000 there has been a complete fleet renewal and significant technological advances that have improved fishing efficiency. Additionally, the introduction of vessel visibility through AIS and VMS has resulted in skippers being able to track where the fleet are, has eliminated fishing location secrecy – a huge change in culture, and has cut the amount of time vessels spend searching for shoals such that the altered fishing behaviour will have further increased catching efficiency and may have reduced carbon footprint through fuel consumption.

There are multiple factors that determine how a stock is fished and for pelagic stocks, where fisheries are seasonal, targeting either spawning or feeding aggregations, there is clearly an interplay between the variable biological and environmental factors and fisher behaviour, particularly where the fisher behaviour is influenced by numerous factors including external market forces. Fisheries research is normally narrow in focus, concentrating on aspects of the biology, or stock assessment or within socio-economic or social history disciplines but rarely pull these together or incorporate fisher knowledge and perspectives to take a holistic approach to understanding a fishery in the whole.

 Objective 1 Investigating seasonal and annual variations and trends in biological factors.

Recent and emerging data from the Scottish pelagic sampling programme, together with historical data will allow the investigation of intra- and inter-annual changes in fish size, condition and fat content, all are biologically important and of key importance to fishers. Data will be mapped to understand spatio-temporal changes, and correlations to environmental drivers such as temperature can be investigated. For herring, the shift in spawning time and presence of ‘roe herring’ will be quantified.

Objective 2 Mapping and analysis of fleet movements and landings

Intra- and inter-annual changes in fisher behaviour as recorded through the timing, frequency and numbers of trips/hauls will be analysed and mapped along with changes in use of landing ports/factories over time. A combination of existing data together with the collection of fisher knowledge through interviews and diary information will be used.

Objective 3 Influences of economics and market drivers on the pelagic fisheries

Drivers that have influenced the markets for herring and mackerel will be investigated. These will include, for example, product changes and demand in size and quality of mackerel for Japanese markets, the shift to focus on herring roe, MSc certification and revocation, Brexit, Covid, fuel costs, Russian sanctions since 2019, Ukraine conflict. Through fisher and processor interviews, the relative importance of these drivers and their impacts on how the fisheries were operated will be determined.

Objective 4 Integration of biological, environmental, and economic drivers

The outputs of the previous objectives will be brought together in a holistic approach to describe the changes and the relative importance of their drivers within the herring and mackerel fisheries. From this, future potential stock scenarios will be described along with predictions of how changes may impact their fisheries. 

The start date of this project is: 2 October 2023

The 3½ year studentships cover:

• Tuition fees each year at Home (UK) rate. For International students, there may be funding available to cover the full international tuition fee and this will be discussed at interview.
• A maintenance grant each of around £15,000 per annum (for full-time study)
• Funding for research training
• Part-time study is an option, with a minimum of 50% of full-time effort being required.

Applicants should normally have, or be studying for:

• A postgraduate Master’s degree from a degree-awarding body recognised by the UK government, or equivalent, or
• A first or upper second class honours degree from a degree awarding body recognised by the UK government, or equivalent, or
• Other qualifications or experience that affords sufficient evidence of an applicant’s ability to work at the academic level associated with doctoral study.

A full UK driving licence would be highly advantageous.

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