The Ecology and Conservation of Goldsinny Wrasse (Ctenolabrus rupestris) in Coastal Marine Ecosystems

Applications are open to UK Students Only

Applications are invited for a 3.5-year PhD studentship with the University of Plymouth and the Ocean Conservation Trust’s National Marine Aquarium. Starting on 1st October 2025.

Project Description

A significant number of fish species have become endangered due to the impacts of climate change and overexploitation (IUCN, 2023). The Goldsinny wrasse (Ctenolabrus rupestris), last assessed in 2014 as Least Concern (Pollard, 2014), has seen its populations increasingly threatened by overfishing and exploitation, primarily driven by its role in the salmon aquaculture industry. This exploitation is detrimental to their populations, necessitating urgent conservation measures.

Goldsinny wrasse are small, colourful fish that inhabit rocky substrates, which provide them with shelter from predators. They can grow up to 18 cm in length (Treasurer & Feledi, 2014). Their ecological role as cleaner fish on rocky reefs involves removing ectoparasites, so wrasse species like Goldsinny can be used to feed on sea louse (Lepeophtheirus salmonis) from salmon (Salmo salar) (Powell et al., 2018). This cleaning behaviour benefits the salmon, improving the health and commercial value of the farmed fish, and, while also providing food supply for the wrasse, high mortalities of wrasse species have been observed when used in salmon farming (Geitung et al. 2020). Additionally, the heavy reliance on wild-caught Goldsinny wrasse in aquaculture has led to severe overfishing (Halvorsen et al., 2017).

The importance of the Goldsinny wrasse's cleaning behaviour extends beyond salmon. This species also cleans other commercially important fish such as cod (Gadus morhua) and haddock (Melanogrammus aeglefinus), as well as a variety of reef fish (Skiftesvik et al., 2014). By removing parasites, the wrasse contribute to the health and well-being of these fish, which in turn affects their growth rates, reproductive success, and survival. The presence of cleaner fish like the Goldsinny wrasse can reduce stress levels in fish populations, leading to improved immune responses and overall better health. This symbiotic relationship is crucial for maintaining the balance and health of marine ecosystems (Powell et al., 2018).

The wrasse fishery on the Swedish West Coast, for example, has highlighted the need for ecosystem-based management to ensure sustainable practices (Bourlat et al., 2021). Similarly, the need for improved management and conservation strategies is evident in the UK, where significant numbers of wrasse are harvested annually for use in salmon farms. The increasing exploitation pressures call for a thorough understanding of their ecology, the development of captive breeding techniques, and the implementation of effective conservation policies.

If you wish to discuss this project further informally, please contact Professor Richard Preziosi (Richard.preziosi@plymouth.ac.uk)

Person specification

We seek an enthusiastic individual with an interest in fish ecology and marine conservation. Prior experience of fieldwork (especially in the marine environment), alongside aquaculture or fish husbandry would be advantageous. A diving qualification (e.g. PADI Divemaster or equivalent) is desirable along with experience conducting underwater visual surveys, operating BRUVS, using GIS and working in a laboratory setting.   

Eligibility and Funding

For further details on Eligibility and Funding and to apply for this position, please click the 'Apply' button.

The closing date for applications is 12 noon 14 March 2025. 

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