In this Issue

Abstract

i IN THIS ISSUE Bruce Osborne Varying perceptions of a non-native introduction The introduction of non-native species and their often negative impacts are of much current concern, although where would we be without many alien introductions,including the majority of crop plants? Clearly we want to be able to harness the benefits of many alien species without any harmful consequences ,although in a number of cases it is a balancing act,given that they may have both a positive and a negative contribution.The European brown hare (Lepus europaeus),which was introduced into Ireland in the 1880s for field sports,has been associated with a marked decline in the numbers of the native Irish Hare (L. timidus hibernicus) in parts of Northern Ireland as well as evidence for hybridisation between the two species.As Caravaggi et al., in this issue, point out,this is a cause of significant concern as the Irish hare is a high priority for conservation and one of the few Irish mammals that predate the Holocene. But how do we manage the conflicting interests of the field sports enthusiast with conservationists? When Caravaggi et al. conducted a survey among members of Countryside Alliance Ireland (CAI) and non-members to ascertain the contrasting attitudes to the lethal control of the European hare, they found some interesting results. Whilst both groups recognised the threats posed to native biodiversity by the European hare, CAI members were both more aware of the presence of non-native species and more prepared to support lethal management interventions. So what are we to make of all of this? One concern could be that the conclusions where based on a relatively small number of respondents (20%),suggesting a more extensive analysis might be required. However, these results may have also identified a more fundamental issue that conservationists are, in general, unwilling to agree to lethal control measures where animals are concerned, particularly those that have become an inextricable part of the regional fauna, irrespective of whether they are native or non-native. Using surrogate metrics to estimate fish weights In biology and ecology research we are often confronted with situations where direct measurements of the parameter(s) of interest are often almost impossible , impractical or uneconomical.This is where surrogate metrics become invaluable.We often, for instance, estimate leaf area from length and breadth measurements in plant growth and photosynthesis studies.Another such case relates to the estimates of fish stocks,where the recording of a sufficient number of individual weights is often very difficult or could result in significant mortality. Not only is this important for assessing fish stocks per se, it can also provide information on fish health and growth rate for both commercial and research purposes. What is required is a simple, cheap and effective method that provides reasonable estimates of fish weights. Connor et al., in this issue, provide an assessment of the use of length-weight relationships to estimate the weights of a range of fish species found in contrasting Irish lakes and rivers using a data set spanning a period of approximately 10 years.Their conclusions, based on an analysis of approximately 230,000 individuals, indicate that fish length is a good predictor of weight and provides a simple way of routinely assessing fish stocks in Irish lakes and rivers.In truth,the use of length as a surrogate measure of fish weights is not new, but significant variations can be found due to environmental factors and because of non-linearity in the relationship between weight and length, making general relationships difficult. What Connor et al. have done is to provide improved length-weight relationships that can be specifically applied to common fish species found in Irish lakes and rivers. The most feared spider in Britain and Ireland? The false widow spider (Steatoda nobilis) is widely regarded as the most feared spider in Britain, although it may often be confused with its much more dangerous cousin, the black widow spider (Latrodectus sp.), which has a venom reportedly fifteen times more toxic than a rattlesnake! The false widow can, however, still give you a nasty bite that could become infected if not properly treated.The first record...