Fish larger than 40cm ‘very scarce’, report finds

Academics at the University of Strathclyde have found stocks of fish in the Firth of Clyde at their highest level since 1927 – but most are too small to be landed. Professor Mike Heath and Dr Douglas Speirs of the University’s Marine Population Modelling Group in the Department of Mathematics and Statistics have statistics on fish numbers dating back to 1973, when the landings of whitefish in the Clyde peaked. From that point, Professor Heath says, the stocks went down until ‘the fishery became uneconomic in the mid-2000s.’

This does not mean that the Clyde is now devoid of fish. Since 1995, many of the once-common kinds have dwindled and are now in short supply, so the balance of species has changed. Numbers are growing again, but most of the fish are too small to be legally landed. The Strathclyde study identifies the Firth of Clyde as a region where changes have been more pronounced than elsewhere. ‘Recovery has been underway since about 2000,’ Professor Heath says, ‘but the big question is – how long it will take for before the fish community could once again support a commercial fishery for whitefish, and how productive could that fishery be in the future?’ He continues, ‘A combination of factors is probably responsible for what has happened. These could include both fishing and climate change. We are currently planning research that will help to untangle these factors and discover what is controlling the fish size composition. Then we will be able to recommend actions to hasten the restoration process and advise on sustainable levels of fishing.’

The study was funded by the Marine Alliance for Science & Technology Scotland (MASTS) and its co-author, Dr Speirs, says this organisation is promoting co-operation between Universities and Research Institutes, making Scotland a world leader in marine science.