Temporal and spatial variations in the abundance and population structure of the spined loach (Cobitis taenia), a scarce fish species: implications for condition assessment and conservation

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Abstract
Effective conservation of protected species requires accurate estimates of the status of their populations. In the UK, this led to the production of a series of sampling protocols to establish the status of designated species against predetermined conservation objectives: a process known as ‘condition assessment’. Condition assessments involve comparisons of various parameters, invariably including abundance and/or population structure, of the target species against criteria that are judged to be indicative of viable populations. This study investigated temporal and spatial variations in the abundance and population structure of spined loach (Cobitis taenia), a scarce species indigenous to Europe and central Asia. Specifically, the study compared the density, number of age classes and percentage contribution of the 0+ year age class of spined loach between day and night, months, years and locations. There were marked diel, seasonal, annual and spatial variations in the density, number of age classes and percentage contribution of 0+ year spined loach. Such phenomena are important because monitoring programmes conducted at inappropriate times of day or year, or with insufficient frequency or geographical coverage, could lead to inaccurate assessments of the condition of protected populations and, consequently, to inadequate conservation measures. Notwithstanding, there were few impacts on the condition assessments of the spined loach populations because at least one of the parameters invariably failed to satisfy the population condition assessment criteria. A prerequisite for successful conservation is an effective monitoring programme. It is therefore essential that surveys to assess the condition of populations of protected species are designed with due consideration of their diel behaviour, breeding season, life span and habitat use. It is recommended that the monitoring protocol and condition assessment criteria for spined loach are amended, and that surveys are conducted by trawling, in late summer, at least every 3–4 years. Copyright © 2014 John Wiley & Sons, Ltd.
Funding Information
  • Fisheries Society of the British Isles
  • Natural England
  • Environment Agency

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