Resetting marine environmental baselines for the United Kingdom: what have we really lost?

The systematic collection of data on fish stocks now used to inform fisheries management began only a few decades ago, however, these data do not provide a true picture of change as commercial fishing began many centuries earlier. Historical information such as that found within old photographs, naturalists’ records, witness testimonies, government data and nautical charts can be used to reconstruct past environments thus providing a baseline from which to judge the state of the seas today. This study explores both historical and modern data for fish stocks and habitats around the United Kingdom and documents some of the changes that have occurred as a result of fishing, as well as investigating the potential of non-consumptive activities to degrade marine environments. Witness testimonies from the 1860s and 1880s reveal that bottom trawling had a devastating and immediate impact upon marine habitats as it expanded around the British Isles. Data sets of demersal fish landings from the 1880s to the present day reveal that technological improvements have masked fish stock decline and that the UK fishing fleet now has to work 17 times harder to catch the same quantity of fish. Comparisons of historical records with the results of recent survey activities show that bottom trawling has fundamentally altered shellfish habitats and extirpated oyster populations at several sites around the UK. At a global scale, wild fish landings have been in decline since the late 1980s. However, growth of the global human population means that wild fish availability per capita has in fact been decreasing since 1970, raising concerns regarding meeting nutrition requirements for those countries dependent upon fish protein. A rapid growth in aquaculture is currently compensating for declines in wild fish availability, however this current rate of increase is unlikely to be sustained in the future. Highly protected marine reserves (HPMRs) are spatial tools that aim to protect habitats and marine wildlife within their boundaries from the direct effects of extractive and depositional activities. HPMRs provide a picture of the marine environment in the absence of activities such as fishing, and offer another way of establishing environmental baselines. However, these areas are often used for non-consumptive activities which may also negatively impact upon habitats and wildlife if inadequately managed. An examination of 91 HPMRs from around the world show that many permit potentially damaging non-consumptive activities, such as SCUBA diving or motorised boating, with few regulations in place. Recommendations are made on how to mitigate or manage for these activities so that HPMRs can provide the high levels of ecosystem protection intended whilst still allowing people to use and enjoy these areas. This thesis demonstrates that reliance on recent fisheries data alone is flawed and that knowledge of marine ecosystems prior to fishing is necessary to evaluate the true success of marine management efforts and to set appropriate baselines for recovery.