Examination of the present state of the Grimsby trawl fishery Part 1

Part 1 covers the North Sea fisheries, a voyage on a steam trawler, an outline of the rise of trawling in the North Sea and the introduction of trawling at a northern fishing station and its influence on the fishery.

Macroecology of Calanus finmarchicus and C. helgolandicus in the North Atlantic Ocean and adjacent seas

Global climate change is expected to modify the spatial distribution of marine organisms. However, projections of future changes should be based on robust information on the ecological niche of species. This paper presents a macroecological study of the environmental tolerance and ecological niche (sensu Hutchinson 1957, i.e. the field of tolerance of a species to the principal factors of its environment) of Calanus finmarchicus and C. helgolandicus in the North Atlantic Ocean and adjacent seas. Biological data were collected by the Continuous Plankton Recorder (CPR) Survey, which samples plankton in the North Atlantic and adjacent seas at a standard depth of 7 m. Eleven parameters were chosen including bathymetry, temperature, salinity, nutrients, mixed-layer depth and an index of turbulence compiled from wind data and chlorophyll a concentrations (used herein as an index of available food). The environmental window and the optimum level were determined for both species and for each abiotic factor and chlorophyll concentration. The most important parameters that influenced abundance and spatial distribution were temperature and its correlates such as oxygen and nutrients. Bathymetry and other water-column-related parameters also played an important role. The ecological niche of C. finmarchicus was larger than that of C. helgolandicus and both niches were significantly separated. Our results have important implications in the context of global climate change. As temperature (and to some extent stratification) is predicted to continue to rise in the North Atlantic sector, changes in the spatial distribution of these 2 Calanus species can be expected. Application of this approach to the 1980s North Sea regime shift provides evidence that changes in sea temperature alone could have triggered the substantial and rapid changes identified in the dynamic regimes of these ecosystems. C. finmarchicus appears to be a good indicator of the Atlantic Polar Biome (mainly the Atlantic Subarctic and Arctic provinces) while C. helgolandicus is an indicator of more temperate waters (Atlantic Westerly Winds Biome) in regions characterised by more pronounced spatial changes in bathymetry.

Lysosomal And Microsomal Responses To Environmental-Factors In Littorina-Littorea From Sullom-Voe

The marine gastropod Littorina littorea from four sites in the vicinity of the Sullom Voe Oil Terminal was found to display reduced cytochemically determined latency of lysosomal arylsulphatase, β-glucuronidase and acid phosphatase in comparison with snails from a nearby ‘clean’ site. This is interpreted as indicating lysosomal destabilization by environmental factors. Elevated total activities of particular lysosomal hydrolases were recorded at three of the sites in Sullom Voe. Animals from a fourth site (Swarta Taing) showed significant depression of arylsulphatase and β-glucuronidase. Cytochemically determined activity of blood cell NADPH-neotetrazolium reductase, which is a component of microsomal detoxication systems, was stimulated in these same sites in comparison with the ‘clean’ reference site. This stimulation or induction is interpreted as a response to the presence of oil-derived polynuclear aromatic hydrocarbons. These results are discussed in the light of previous work on the effects of hydrocarbons on lysosomes and in terms of the possible physiological consequences for the animals.