About Marine Fisheries

Protein from seafood is an important source for nutrition for over a billion people worldwide. Marine fisheries (both commercial and recreational) are known to to cause impacts to the marine environment by ‘fishing down the food web’ by removing large individuals (targeted), as well as non-targeted species (by-catch). To truly attain a balance between conservation and fishing to ensure sustainable fishing practices, understanding must of the current status of biodiversity, understanding of ecosystem level effects and level of marine fisheries pressure on species and habitats.

List of Dissertations

The following are the abstracts from past dissertations at the University of Gibraltar.

Understanding the specific pressures and methodologies of marine recreational fishing and impact to demersal fish species in British Gibraltar Territorial Waters and mapping marine recreational fishing hotspots

Clive Crisp

Marine Recreational Fishing (MRF) is an extremely popular leisure activity at a global scale, it is an area of fisheries which has been, until recently, overlooked as having an impact on commercially important fish stocks. Recent studies suggest that it may have the same impact on demersal and pelagic fish species as that of small-scale fisheries, artisanal fisheries, and subsistence fisheries. Gibraltar has no commercial fishing fleet but has an element of local artisanal/ subsistence fishing, its national legislation prohibits any commercial fishing activity, or the methods employed within this modality of fisheries. The main form of fishing in Gibraltar is that of marine recreational fishing, undertaken as shore fishing, fishing from a vessel and underwater fishing. Although MRF is considered well regulated in Gibraltar no methodologies for monitoring or the collection of data for marine recreational fishing has been implemented. Data reporting in the form of a creel survey was designed to collect specific data of MRF activity in British Gibraltar Territorial Waters. MRF methods were listed and analysed in terms of bait used, specific location, use of anchor, season, and target species. The MRF methods were individually assessed and assigned an impact score of low, medium, or high depending on several factors based on research already carried out in the field of MRF. The impact scores were colour coded (Traffic light system) for ease of reference and visualisation. Geographical Information System Software (GIS) QGIS was utilised to collect and interrogate the data. The results were analysed to evaluate the different MRF methods, what fishing areas they are carried out in, and their impact, also producing a heat map of MRF fishing intensity in British Gibraltar Territorial Waters (BGTW). It was found that MRF methods utilised have a linear relationship to skill and experience, which has a direct output in the effectiveness of the catch of the desired or targeted fish species. MRF fishing is location specific and the fishing intensity and impacts on the benthic environment need to be studied and researched further. This study shows location specific MRF impact upon rocky reefs and rocky outcrops, the impact of continuous fishing over the same area will have consequential repercussions on important demersal fish population and abundance. The methodology designed in this study should be continued by the Department of the Environment, Sustainability, Climate Change and Heritage on a regular basis to be able to make informed decisions in the near future on its policy with regards to fishing, creation and management of Marine Conservation Areas and the protection of the marine environment.
Primary Supervisor:               Dr Awantha Dissanayake
Secondary Supervisor:          Dr Darren Fa

Atlantic Bluefin Tuna (Thunnus thynnus) in the Straits of Gibraltar: from historical to recreational fisheries, and recommendations for implementing a catch-and-release fishery via stakeholder engagement

Francine Pons

The Atlantic Bluefin Tuna (Thunnus thynnus) has been a highly prized species for millennia. A review on the existing literature has been carried out in order to understand the ecology and life-history of the species, including oceanographic processes relating to their distribution. In addition, the history of tuna fisheries, dating back to 3rd century B.C. are discussed, as well as management challenges faced by ICCAT and its epistemic community, such as the Pluri-Annual Recovery Plan (PARP) for the eastern stock. The second part of the study focuses on the Gibraltar recreational tuna fishery. Current policies and regulations are discussed, under the Tuna Preservation Regulations 2014 and Marine Regulations, 2014. In addition, a statistical analysis for the Gibraltar catch data is carried out, demonstrating that the fishing method employed (Trolling, Popping and Live bait) can have a significant effect on the size (weight, kg) (fork length, cm) of the tuna caught. Moreover, an online survey was distributed to tuna anglers in Gibraltar, in order to devise local perceptions towards catch-and-release. Our results show that 92% of respondents are interested in implementing a catch and release fishery. Potential implications, as well as best-practices for catch-and-release and tagging are discussed, including recommendations to increase compliance, sustainability and animal welfare.
Read more about Francine’s research here.
Atlantic Bluefin Tuna, Thunnus thynnus, ecology, Recreational fisheries,
Catch-and-Release, Tag-and-release, management, ICCAT
Primary Supervisor: Dr Awantha Dissanayak
Secondary Supervisor: Dr Darren Fa
In conjunction with:
Stephen Warr and Clive Crisp: Department of Environment, Sustainability, Climate Change and Heritage (DESCCH)

The effects of climate variability on a top pelagic predator assessed through stable isotope and stomach content analyses

Samantha Slisarenko

The effects of climate change and oceanographic shifts have significant implications for marine ecosystems, particularly for keystone pelagic predators such as Atlantic bluefin tuna, which play critical ecological and economic roles. Despite their importance, knowledge of the effects of climatic variability on these species still needs to be improved, underscoring the need for additional empirical inquiry. To address this knowledge gap, this project aimed to investigate the impact of oceanographic oscillations on the feeding behaviours and body condition of Atlantic bluefin tuna in both the Atlantic and Mediterranean regions, utilising a systematic literature review, meta-analysis, and preliminary experiments. While the results of this study are pending, understanding the relationship between climatic variability and Atlantic bluefin tuna is essential for the effective conservation and management of this species. Further research is required to fully comprehend the impact of climate change on Atlantic bluefin tuna and other marine life, as well as to understand the relative influence of environmental factors better to make informed decisions in managing and conserving these species amidst a rapidly changing world.
Keywords: ¨Climatic Variability ¨Atlantic bluefin tuna ¨ Oceanic Oscillations ¨ Stable Isotope Markers ¨ Stomach Content Analysis ¨ Feeding Phenology ¨ Meta-Analysis.

Thematic Leader

Dr Awantha Dissanayake
Head of School (Marine Science)