Modelling Potential Fishery Pressures Facing Western Scotland's Cold Water Coral Reefs

Introduction

Cold water coral reefs (Figure 1) are of enormous importance to
science and society. They are biodiversity hotspots, providing
shelter and feeding opportunities for over 1,300 species (Baxter
et al, 2011), are suggested to be a potential source of medicines
and can be indicators of past climate (Hovland, 2008). The existence of cold water coral reefs is under threat from a
number of pressures, including climate change, deep sea mining
and the oil and gas industry (Roberts et al, 2009). In western
Scotland, the greatest threat is the fishing industry due to the
productivity of the waters; in 2012, £419m worth of fish was
caught in Scotland's seas (Scottish Government, 2013).

This dissertation aimed to model the potential pressure posed by the fishing industry to cold water coral reefs in Scotland in order to produce a better understanding of its impacts, consequently improving marine conservation policy and strategies.

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Methodology

Gear-specific fishing activity data in the form of quantity of fish caught was sourced from the Marine Management Organisation and used to indicate potential pressure posed by fisheries. A literature review was conducted in order to determine the potential impacts that different types of fishing gear operating in western Scotland pose to cold water coral reefs. Each type of gear was then weighted in accordance with the results of the literature review using the Analytical Hierarchy Process (Malczewski, 1999). Weighted GIS layers were combined to create cost surfaces covering the years of 2008 to 2012 inclusive for 3 scenarios:

• All gear types and all five years of study combined
• All gear types combined for individual years of study
• Individual gear types combined for all years of study

These cost surfaces revealed spatial and temporal patterns of potential pressure on an index of 1 to 10, where 1 indicated very low potential pressure, 2 to 4 indicated low potential pressure, 5 to 7 indicated moderate potential pressure and 8 to 10 indicated strong potential pressure. This index allowed cold water corals which are most, least and moderately suitable for marine protection to be identified. It also allowed fishing gear restrictions and regulations to be recommended and determined the extent of fishing activity within existing marine protected areas.

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Key Findings & Discussion

The results showed that the use of less harmful types of
fishing gear warrants greater concern than more
destructive types of gear because of their greater usage.
The results also revealed that inshore reefs, such as
those shown in Figure 2, face greater pressure than
offshore reefs. However, pressure facing offshore reefs
was shown to be increasing, possibly reflecting the
movement of fisheries further offshore as inshore
fishing grounds are exhausted.

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Conclusions

This dissertation demonstrates that gear-specific fishing activity data can be used to develop a more detailed picture of pressures, thus allowing the implementation of better informed marine conservation strategies in order to protect and restore western Scotland's cold water coral reefs. The results could be improved by the inclusion of datasets which take into account natural disturbances such as storms which are argued to increase coral resilience (Diesing et al, 2013).

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Key References