Chemical narcosing of fish in northern Cross River

Chemical narcosing of fish was found to be one of the fishing techniques used for harvesting fish stocks in the northern Cross River, Cross River State, Nigeria. The preparation of the fish poison is described. The ichthyotoxic plants used for the fish poisoning were identified and Derris elliptica recommended to be used for the development of piscicides for the removal of unwanted fish in the fish farms

Toxic effect of Raphia vinifera on fish leech (Piscicola geometra)

This study examines acute toxicity of Raphia vinifera on fish leech, Piscicola geometra. The leeches with a mean total length of (TL) 4.2+1.0cm were exposed to various concentrations of both crude powdered and ethanolic extracts of the botanical. Median lethal concentration (LC50) was determined with static-renewal tests using logarithmic and arithmetic graphic methods. The LC50 (for 96 hours of crude powdered (aqueous) extracts of the botanical on Piscicola geometra was 1.10 ppm arithmetically and 1.14ppm logarithmically. The 95% confidence limits was 0.10ppm arithmetically and 0.12ppm logarithmically. The LC50 of ethanolic extract of the poison at 96-h was 0.5ppm arithmetically and 0.48ppm logarithmically. The 95% confidence limits were less than 0.10ppm. The use of extracts of R. vinifera in the control of leeches in fish ponds is discussed

Studies of the effects from extracts from two local plants (Tephrosia vogelii and Parkia clappertoniana) on Clarias gariepinus (Tengels)

Studies were carried out using 96hr static toxicity bioassay to determine the effect of lethal concentrations of extracts from two local plants Tephrosia vogelii and Parkia clappertoniana which are known fish poison, on a species of mud fish. Clarias gariepinus Phytochemical analysis of the plant extracts was done and the extract from T. vogelii was found to contain alkaloids, tannins and flavonoids, while the extract from P. clappertoniana was formed to contain alkaloids tannins and saponins. Experimental fish were exposed to test water separately polluted by varying concentrations of extraction of both plant species ranging from 0.50mgl super(-1), 1.50mgl super(-1), 2.50mgl super(-1), 3.0mgl super(-1), 5.00mgl super(-1), 10.00mgl super(-1) in the case of T. vogelii and 5.00mgl super(-1), 7.50mgl super(-1), 10.00mgl super(-1), 15.00mgl super(-1), 20.00mgl super(-1) and 30.00mgl super(-1) in the case of P. clappertaniana. Behavioural hispathological and heamatological examinations were made. Both plant extracts were found to have lethal effects at the higher concentrations, affecting the gills and the central nervous system as well as having a depressive effect on the total count and increasing platelet and white blood cell count. Symptoms of toxicosis observed include, initial inactivation agitated swimming, tumbling movement air gulping, increased opercular beat and period of quiescence/knockdown before death. Marked differences were also observed in the hematological and histopathological analysis of poisoned fish. Lower concentrations of the extracts had sub lethal effects on the fish, which manifested as zigzag movement air gulping increased opercular movement etc. None of these effects were observed in the control experiment

Los fenómenos de marea roja y toxicidad de moluscos bivalvos en el Mar Argentino

Two unusual blooms of dinoflagellates appeared in the Argentine Continental Shelf in spring/summer period of 1980 and 1981, but these differed, one from the other. The first was an intense red-tide with which were associated no signs of toxicity, whereas the second, although; not showing special coloration, was associated with (and doubtless the cause of) intense toxicity in bivalves of the Gulfs of San Matías and San José and of the shelf waters off Península Valdés; the death of two fishermen was atributed to the latter. The first bloom developed as an unusual surface concentration of the predatory dinoflagellate Noctiluca scintillans. It was supposed that this concentration was produced by a particular combination of processes of circulation of water masses. The second bloom was characterizaed by high concentrations of Gonyalax excavata. Investigations at the time determined that toxins in molluscs of the area correasponded to what is called "paralytic shellfish poison". The bloom of G. excavata was associated with a front between well mixed and well stratified water masses. The maximum toxicity centre occured in the mussel bank "Constanza" (42°23'27"S and 62°45'66"W) which coincides with the front referred to above. (PDF contains 93 pages)

Corals, fishermen and tourists

Two major anthropogenic activities that disturb coral reefs are fishing and tourism, even though coral reefs are important for both fishing and tourism. Already more than 60 per cent of all reefs worldwide are endangered. The use of explosives and poison by small-scale fishers, to supply the market for live fish for aquariums and for human consumption, cause irreversible damages to reefs. Similarly, rapid and unmanaged coastal development for marine tourism negatively affects coral reefs in many ways. Though marine parks and marine protected areas are being promoted all over the world, developing countries need assistance in establishing and assessing such reserves and for taking appropriate actions for rehabilitation of reefs. These can be accomplished through partnership projects.

Ciguatera Fish Poisoning: treatment, prevention and management

Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world, and it causes substantial physical and functional impact. It produces a myriad of gastrointestinal, neurologic and/or cardiovascular symptoms which last days to weeks, or even months. Although there are reports of symptom amelioration with some interventions (e.g. IV mannitol), the appropriate treatment for CFP remains unclear to many physicians. We review the literature on the treatments for CFP, including randomized controlled studies and anecdotal reports. The article is intended to clarify treatment options, and provide information about management and prevention of CFP, for emergency room physicians, poison control information providers, other health care providers, and patients.