A telephone survey of eel fishermen regarding external lesions and mortalities of American eels (Anguilla rostrata) from Lake Ontario and the St. Lawrence River basin, Canada.
Signs of decreasing landings and recruitment have been observed during the last decade in American eels (Anguilla rostrata) from the St. Lawrence River basin, Canada. A study was undertaken to examine whether important manifestational diseases among commercial catches could be associated with these declines. During this survey, 56 fishermen from Lakes Ontario, Saint-François and Saint-Pierre, the Richelieu River, the Québec City area and the St. Lawrence Estuary were interviewed. Most fishermen from every area reported decreasing catches since the 1980s. Eel mortalities were reported from 1990 to 1992 in Lake Saint-François, Lake Saint-Pierre and the Québec City area, but in apparently lower magnitude than in the past decades. The lesions observed on dead eels in Lake Saint-François indicated that the cause of the mortalities might be associated with the upstream hydroelectric dam. Eels with 'scratches all over the body' were only observed in the St. Lawrence Estuary. Fishermen from almost every area reported that they had observed eels with 'crooked tail', 'humpback' and 'cut tail' in low frequency in 1992. The questionnaire data were validated by comparing some of the results of the questionnaire survey and a processing plant survey in 1992. The use of questionnaires for assessing fish diseases in commercial species is discussed. The results of this survey do not indicate that the health of the American eels from the St. Lawrence River basin is severely impaired. However, the magnitude of diseases and mortalities was probably underestimated.
A comparison of metal concentrations in the tissues of yellow American eel (Anguilla rostrata) and European eel (Anguilla anguilla).
Historically abundant and widespread, populations of Atlantic eels have suffered a sharp decline in recent decades, in the ranges 40-80% and 90-99% for American and European eels, respectively. As a result, American eels are now classified as threatened, whereas European eels are considered to be in critical danger of extinction. Several causes have been identified as likely contributors of this decline, including overfishing, obstacles to migration (hydroelectric dams), climate change and habitat contamination. In the context of a larger project investigating the role of organic and inorganic contaminants in this decline, in this study, we measured the liver, kidney and muscle concentrations of essential (Cu, Se and Zn) and non-essential (Ag, As, Cd, Cr, Hg, Ni and Pb) metals in eels sampled at four sites in the South-West of France and four sites in Eastern Canada varying in contamination. Tissue concentrations of Cd, Hg and Se increased with fish size and age. Tissue metal concentrations generally reflected the contamination of their sampling sites. This was the case for Ag, As, Cd, Cu, Hg, Pb and Se. Comparison of tissue concentrations of these metals with the toxicological literature suggests that all of them except As could pose a risk to the health of eels from the most contaminated sites. In particular, European eels may be particularly at risk of Cd and Pb toxicity. Globally, our study suggests that a substantial accumulation of inorganic contaminants in the tissues of both eel species at sites contaminated by historical anthropogenic inputs may play a role in their decline.
Evaluation of Analgesic Effect of Caudal Epidural Tramadol, Tramadol-Lidocaine, and Lidocaine in Water Buffalo Calves (Bubalus bubalis)
Aim of this study was to compare the analgesic effect of tramadol and a combination of tramadol-lidocaine with that produced by lidocaine administration in the epidural space in buffalo calves. In a prospective randomized crossover study, ten male buffalo calves were used to compare the epidural analgesic effect of tramadol (1 mg/kg) and tramadol-lidocaine combination (0.5 mg/kg and 0.11 mg/kg, resp.) with that produced by 2% lidocaine (0.22 mg/kg). Loss of sensation was examined by pin-prick test. Onset time, duration, and degree of analgesia and ataxia were recorded after each treatment. Heart rate (HR), respiratory rate (RR), rectal temperature, and haematobiochemical parameters were recorded after all treatments. Time to onset and duration of analgesia, respectively, were as follows: tramadol 11 ± 2 min and 208 ± 15 min; tramadol-lidocaine 6 ± 2 min and 168 ± 9 min; lidocaine 4 ± 1 min and 67 ± 13 min. Onset time and duration were significantly longer with tramadol than the other treatments. Duration was significantly longer with tramadol-lidocaine than lidocaine. Ataxia was mildly observed in tramadol-lidocaine and was moderate in lidocaine. HR, RR, and rectal temperature did not differ significantly from baseline after any treatment. Haematobiochemical parameters returned to basal levels by 24 h after all treatments. This combination might be clinically useful to provide analgesia in buffalo for long-duration surgical procedures.