Chemical contaminants, pathogen exposure and general health status of live and beach-cast Washington sea otters (Enhydra lutris kenyoni)

Analyses of blood and liver samples from live captured sea otters and liver samples from beachcast sea otter carcasses off the remote Washington coast indicate relatively low exposure to contaminants, but suggest that even at the low levels measured, exposure may be indicated by biomarker response. Evidence of pathogen exposure is noteworthy - infectious disease presents a potential risk to Washington sea otters, particularly due to their small population size and limited distribution. During 2001 and 2002, 32 sea otters were captured, of which 28 were implanted with transmitters to track their movements and liver and blood samples were collected to evaluate contaminant and pathogen exposure. In addition, liver samples from fifteen beachcast animals that washed ashore between 1991 and 2002 were analyzed to provide historical information and a basis of reference for values obtained from live otters. The results indicate low levels of metals, butyltins, and organochlorine compounds in the blood samples, with many of the organochlorines not detected except polychlorinated biphenyls (PCBs), and a few aromatic hydrocarbons detected in the liver of the live captured animals. Aliphatic hydrocarbons were measurable in the liver from the live captured animals; however, some of these are likely from biogenic sources. A significant reduction of vitamin A storage in the liver was observed in relation to PCB, dibutyltin and octacosane concentration. A significant and strong positive correlation in vitamin A storage in the liver was observed for cadmium and several of the aliphatic hydrocarbons. Peripheral blood mononuclear cell (PBMC) cytochrome P450 induction was elevated in two of 16 animals and may be potentially related to aliphatic and aromatic hydrocarbon exposure. Mean concentration of total butyltin in the liver of the Washington beach-cast otters was more than 15 times lower than the mean concentration reported by Kannan et al. (1998) for Southern sea otters in California. Organochlorine compounds were evident in the liver of beach-cast animals, despite the lack of large human population centers and development along the Washington coast. Concentrations of PCBs and chlordanes (e.g., transchlordane, cis-chlordane, trans-nonachlor, cis-nonachlor and oxychlordane) in liver of Washington beach-cast sea otters were similar to those measured in Aleutian and California sea otters, excluding those from Monterey Bay, which were higher. Mean concentrations of 1,1,1,- trichloro-2,2-bis(p-chlorophyenyl)ethanes (DDTs) were lower, and mean concentrations of cyclohexanes (HCH, e.g., alpha BHC, beta BHC, delta BHC and gamma BHC) were slightly higher in Washington beach-cast otters versus those from California and the Aleutians. Epidemiologically, blood tests revealed that 80 percent of the otters tested positive for morbillivirus and 60 percent for Toxoplasma, the latter of which has been a significant cause of mortality in Southern sea otters in California. This is the first finding of positive morbillivirus titers in sea otters from the Northeast Pacific. Individual deaths may occur from these diseases, perhaps more so when animals are otherwise immuno-compromised or infected with multiple diseases, but a population-threatening die-off from these diseases singly is unlikely while population immunity remains high. The high frequency of detection of morbillivirus and Toxoplasma in the live otters corresponds well with the cause of death of stranded Washington sea otters reported herein, which has generally been attributable to infectious disease. Washington’s sea otter population continues to grow, with over 1100 animals currently inhabiting Washington waters; however, the rate of growth has slowed over recent years. The population has a limited distribution and has not yet reached its carrying capacity and as such, is still considered at high risk to catastrophic events. (PDF contains 189 pages)

The proposed Lune net limitation order 1999 and associated byelaws

The River Lune rises in the hills around Tebay in thje North of England and runs through rural farming country to Morecambe bay. It is generally considered as a river of high purity and unspoiled nature. The salmon fishery was at one time considered amongst the best in England and Wales, with very high catches to both rod and net fishermen. During the late 1960's the disease UDN decimated the stock. Since then there has been a recovery of the stock, but this is considered by most anglers and netsmen to be a partial recovery of some of the previous stock components. In recent years anglers and netsmen have voiced their concerns over the Lune stock and have lobbied for action to improve the Lune fishery. This net limitation order (NLO) and the separate byelaw in conjunction with habitat improvement are proposed as part of the strategy for future conservation and management of this salmon fishery. The fishery is currently exploited by 37 licensed netsmen, the highest number of any single estuary in England and Wales. There are 26 haaf, 10 drift and 1 seine nets available. Current estimates of the rod fishery are that 1100 to 1400 anglers fish 14 000 days per year. The River Luhe is one of the few rivers within England and Wales that has the benefit of an accurate fish counter. The counter is at Forge Weir approximately 4 km upstream of the tidal limit. The counts, together with records of the catches from the rod and net fishery, enable a reasonably accurate assessment of both rod and net exploitation. Extensive surveys of the juvenile population, carried out in 1991 and 1997, provide additional information. The purpose of this document is to describe and explain the current state of the salmon population in the River Lune and in doing so, demonstrate the current need for stock conservation. A second purpose is to demonstrate that the proposed NLO and byelaw package should allow the salmon population to reach its conservation target (spawning escapement target).

Seaweed industry in India

The seaweed industry in India is mainly a cottage industry and is based only on the natural stock of agar yielding red seaweeds, such as Gelidiella acerosa and Gracilaria eduli and algin yielding brown seaweed species such as Sargassum and Turbinaria. India produces 110-132 t of dry agar annually utilizing about 880-1100 t of dry agarophytes, and 360-540 t of algin from 3600-5400 t of dry alginophytes.

Clam farming in the Mekong Delta, Vietnam

The Mekong Delta region in southern Vietnam has high potential for coastal aquaculture, including mollusc culture. Many mollusc species are cultured for domestic and export markets including white clam (Meretrix lyrata Showerby) and blood cockle (Arca granosa). Techniques for clam farming include the nursery and grow-out phases. At present, there are approximately 600 coastal families engaged in clam farming over a total area of 1,870 ha, of which 82.63% is used for the grow-out phased and 17.7% for the nursery phase. Nursery areas are near the coast and receive less than 5 hours of sunlight per day. The average area for a nursery is 3-4 ha and it is fenced with a net or bamboo stakes to prevent clams from escaping and to prevent water currents from carrying them away. Grow-out farm areas are further from the coast and are exposed to sunlight for only 2-3 hours/day. Average farm area for grow-out is 5-6 ha, and may or may not be fenced. Average operating cost is US$1100 per ha for nursery and US$757 per ha for grow-out (the cost of capital assets are not included) with loans being the main source of financial. Problems for clam farmers in the area include natural phenomena, inadequate culture techniques, lack of financing or credit systems, and marketing. Environment-related problems that cause clam mortality include flooding, and freshwater effluent and siltation or sedimentation from Mekong River. Other problems that constrain the development of clam culture in the area are: marketing problems such as lack of buyers and price fluctuations; exploitation of the natural clam populations.