The design and development of the Windermere Profiler. An instrument for measuring how various environmental parameters vary with depth in lakes, reservoirs and rivers

A review article detailing the background, development and functionality of the Windermere Profiler, a multi parameter environmental monitoring instrument for use in lakes, reservoirs and rivers. The article explains the requirement for regular data collection by the Freshwater Biological Association at Windermere. The article covers the requirements of a profiling instrument, the design considerations, the electronic circuitry, the computer program, the operation of the computer software, the profiler in use and further developments to the design. A number of figures and images accompany the article.

Experimental design in fluvial ichthyology: getting the most for your money

In field biology, cost efficiency is an essential element of experimental design, with ramifications extending well beyond the basic monetary considerations associated with labour and equipment acquisition. Current economic constraints often require scientists to undertake many technical, secretarial and managerial tasks in addition to those associated with data collection, analysis, interpretation and publication. Because the time spent to process material in the laboratory can rarely be shortened without compromising the integrity of the results, it is imperative that field experiments be well-organised, addressing as many aspects of the problem as possible during the same sampling excursion. The sampling strategy employed should provide a maximum of good field data with a minimum cost of time and effort.

Geomorphological considerations for the introduction of boulders and groynes for fisheries enhancement: assessment of River Eden at Carhead

This report seeks to briefly provide geomorphological guidance over the introduction of 'habitat enhancement' features for fisheries improvement which is an expanding area of interest throughout the region. This document is a primary attempt to draw together the salient details from the large quantity of literature published in recent years with reference to boulder introduction and to groyne/deflector placement in NW rivers. Secondly the potential introduction of such features is assessed, with reference to the proposed works at Carhead on the Eden.

A prior for steepness in stock-recruitment relationships, based on an evolutionary persistence principle

Priors are existing information or beliefs that are needed in Bayesian analysis. Informative priors are important in obtaining the Bayesian posterior distributions for estimated parameters in stock assessment. In the case of the steepness parameter (h), the need for an informative prior is particularly important because it determines the stock-recruitment relationships in the model. However, specifications of the priors for the h parameter are often subjective. We used a simple population model to derive h priors based on life history considerations. The model was based on the evolutionary principle that persistence of any species, given its life history (i.e., natural mortality rate) and its exposure to recruitment variability, requires a minimum recruitment compensation that enables the species to rebound consistently from low critical abundances (Nc). Using the model, we derived the prior probability distributions of the h parameter for fish species that have a range of natural mortality, recruitment variabilities, and Nt values.

Participatory research in giant clam farming

Research into developing farming methods for giant clams at the ICLARM Coastal Aquaculture Centre in the Solomon Islands has proceeded in parallel with a program of village-based trials. This program is an attempt to involve the envisaged recipients of technology at a very early stage. The considerations, design and initial implementation of this program from 1988 to 1990 are described in this article. The expansion, impact and results of the program will be the subject of future publications by the scientists involved.

A Comparison of Two Stratification Schemes Used in Sampling Canadian Atlantic Cod, Gadus morhua

Sampling is a key element in the assessment of any fish stock. It is often one of the most expensive activities of the management process; thus, improved efficiency can result in significant cost savings. In most cases a two-phase sampling strategy is employed. Two commonly used versions of such stratified random schemes were simulated using a test population based on Atlantic cod, Gadus morhua. A 1 otolith per 1 cm length frequency currently used for many flatfish and some smaller gadoids and a 3 otolith per 3 cm length frequency currently used for many of the larger gadoids. No difference was detected in the age composition or mean length at age for either scheme; however, 10 percent fewer otoliths were collected in 1 for 1 sampling than 3 for 3. There was an improvement of between 30 and 60 percent in the coefficient of variation of the estimated catch numbers at age using the 1 for 1 compared with the 3 for 3 stratified sampling. For these reasons and other operational considerations, the 1 for 1 stratified random design of sampling appears to be superior.

Considerations about effective dissemination of improved fish strains

Aquaculture production systems in developing countries are largely based on the use of unimproved species and strains. As knowledge and experience are accumulated in relation to the management, feeding and animal health issues of such production systems, the availability of genetically more productive stock becomes imperative in order to more effectively use resources. For instance, there is little point in providing ideal water conditions and optimum feed quality to fish that do not have the potential to grow faster and to be harvested on time, providing a product of the desired quality. Refinements in the production system and improvement of the stock used must progress hand in hand. In this paper we deal separately with genetic and non-genetic issues pertaining to the multiplication and dissemination of improved strains. The separation is somewhat arbitrary, and as will be evident from our discussion, there is frequent interaction between the two.

Water Resources in West Cumbria November 1976

This is the Water Resources in West Cumbria November 1976 report produced by the North West Water Authority. The report focuses on the provision of additional supplies of water in West Cumbria. In certain areas of West Cumbria difficulties arose in meeting peak demands. Moreover British Nuclear Fuels Ltd. (B.N.F.L) required additional water supplies. The area under consideration forms the western edge of the Lake District National Park and all the sources considered in this report, apart from the aquifer in the immediate vicinity of Calder Hall, lie wholly or partly within the National Park boundaries. The Rivers Ehen, Calder and Irt support migratory trout and salmon and are angling streams of a high quality. Amenity considerations therefore play an important part in determining the location and extent of any development.

The Crown-of-Thorns starfish Acanthaster planci (Linne') in Ceylon

The Crown-of-Thorns starfish Acanthaster planci is a predator of coral and has been responsible for the widespread destruction of coral reefs. In Sri Lanka this starfish was first reported by Clarke in 1915. Recently skin-divers reported that Acanthaster planci was present in very large numbers in the coastal waters off Trincomalee, especially on the coral formations around Pigeon Island. It is well known that the multiplication of the starfish to plague proportions is a serious threat to the coral reef formations round the Island. If it were allowed to continue its depredations the entire coral reef belt round the Island might be destroyed in a short time. The monsoon waves would then convert the dead coral to rubble. In the absence of a barrier against the advancing waves during the monsoon it would also lead to serious erosion of the shoreline. The coral reef fish would also disappear with the destruction of the coral formations. On account of these considerations it was decided to conduct a survey of the Crown-of-Thorns starfish in eastern coastal waters in order to estimate the magnitude of the population of the starfish in these waters.