Dave Reid

Standard protocols for the analysis of school based data from echo sounder surveys

This paper presents a set of standard extraction parameters and protocols for the use of image analysis techniques in the processing of echo sounder data. The paper includes parameters at the school, elementary distance sampling unit (EDSU) and regional levels. The school level parameters, which are mainly derived from the image analysis, fall into four main categories: positional, morphometric, energetic and environmental. At the sampling unit level (i.e. standard integration units, commonly 1 or 2.5 nautical miles), parameters used include: school structures, protocols for including layers and general scatter plus ancillary (e.g. environmental) variables. These variables are derived mostly from visual examination of the echogram and from ancillary data collected underway. Regional level parameters include those mapped from point samples (e.g. trawls) or which are available as maps. Each school thus has its own unique parameters and is associated with an EDSU and through that to regional data. We discuss the application of such databases to the analysis of echo surveys at a school level in relation to aggregation patterns (school, school cluster and population) and to changes in those aggregation patterns with stock biomass and exploitation pattern.

Prevalence of boreal Atlantic, temperate Atlantic and neritic zooplankton in the North Sea between 1958 and 1998 in relation to temperature, salinity, stratification intensity and Atlantic inflow

The Calanus finmarchicus population of the North Sea has collapsed since the late 1950s, while abundance of temperate Atlantic and neritic species groups has risen. These changes are explored in relation to the changing environment of the North Sea. Non-parametric regression methods are used throughout the study, in order to compare the spatial, long-term and seasonal dynamics of the changes in both biotic (e.g. C. finmarchicus) and physical variables (e.g. temperature, salinity, and stratification). The fall in the population of C. finmarchicus has coincided with a long-term freshening and warming of the eastern North Sea and a long-term increase in the salinity of the western North Sea. At the same time the prevalence of temperate Atlantic and neritic zooplankton species has risen. The changes may be explained by differing origins of Atlantic water entering the North Sea since the late 1950s.

REACTIONS OF COD GADUS MORHUA TO LOW- FREQUENCY SOUND RESEMBLING OFFSHORE WIND TURBINE NOISE EMISSIONS

wild fish. It must be cautioned that there are many species of fish with vastly different hearing capabilities and probable potential differing behavioural responses to distressing stimuli so much work is still required to establish wide-scale impacts. The correlation of behavioural changes in response to an approaching air gun and physiological impacts on fish auditory systems suggest that something had happened to the hearing of fish discussed in McCauley et al. (2003a). These results need to be replicated in a controlled fashion before we can accurately assess their implications.