The biology and control of Caligus sp., an ectoparasite of the adult milkfish Chanos chanos Forskal

One unidentified species of copepod belonging to the genus Caliqus of the family Caigidae was found to infest the adult milkfish broodstock. To control the parasites infesting the adult milkfish, tests were made using the chemical (2,2,2-trichloro-1-hydroxyl)-phosphonic acid-dimethylethol (Neguvon) at a concentration of 0 . 25 ppm. It is noted that a concentration of 0 . 25 ppm of Neguvon maintained for 12-24 hours in the sabalo-containing tanks in a closed water system but with aeration is effective in controlling the parasites. Fish mortality during the experiment was due to inadequate aeration in the tanks.

Fishery resource assessment and monitoring in the development and control of fisheries in the Lake Volta

Gill-netting and rotenoning have been used for assessing and monitoring fish stock abundance in Volta Lake. The lake and the main gear types used on it have been described. Before a gill-net sampling plan was set up, a preliminary survey was undertaken which largely determined the final form of the plan. An investigation as to whether or not the lake was being overfished concluded that it was being underfished. Commercial and experimental catch data analyses disclosed that the adults of the small species were being little utilized. Commercial sized species were also not being harvested according to their apparent proportion in the population. Production is presently fluctuating between approximately 37,000 and 40,000 tonnes. A high correlation between commercial and experimental catch was realized. Developments which have followed in the wake of stock assessment and monitoring studies include: introduction of monofilament nylon net, development of a special scoop net to permit mass harvest of clupeids after they have been attracted to light, and the design of a larger canoe which would help to extend the fishery into open water. New regulation and management policies will have to be formulated in the light of new findings before a rational exploitation of all the species can be achieved.

The Siem Reap Meet Proceedings: Asserting Rights, Defining Responsibilities: Perspectives from Small-scale Fishing Communities on Coastal and Fisheries Management in Asia

This publication is a record of the proceedings of the Siem Reap Workshop and Symposium. It provides a bottom-up perspective on how rights are understood, and what rights are seen as important by small-scale fishing communities, if they are to fulfil their responsibilities for managing resources in a sustainable and equitable manner. It is hoped that these proceedings, and the Statement from the Workshop-the Siem Reap Statement-are found useful by those engaged in policy making and advocacy in support of small-scale fisheries, as well as researchers, non-governmental organizations (NGOs), fishworker organizations, and multilateral and regional organizations

Using productivity and susceptibility indices to assess the vulnerability of United States fish stocks to overfishing

Assessing the vulnerability of stocks to fishing practices in U.S. federal waters was recently highlighted by the National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration, as an important factor to consider when 1) identifying stocks that should be managed and protected under a fishery management plan; 2) grouping data-poor stocks into relevant management complexes; and 3) developing precautionary harvest control rules. To assist the regional fishery management councils in determining vulnerability, NMFS elected to use a modified version of a productivity and susceptibility analysis (PSA) because it can be based on qualitative data, has a history of use in other fisheries, and is recommended by several organizations as a reasonable approach for evaluating risk. A number of productivity and susceptibility attributes for a stock are used in a PSA and from these attributes, index scores and measures of uncertainty are computed and graphically displayed. To demonstrate the utility of the resulting vulnerability evaluation, we evaluated six U.S. fisheries targeting 162 stocks that exhibited varying degrees of productivity and susceptibility, and for which data quality varied. Overall, the PSA was capable of differentiating the vulnerability of stocks along the gradient of susceptibility and productivity indices, although fixed thresholds separating low-, moderate-, and highly vulnerable species were not observed. The PSA can be used as a flexible tool that can incorporate regional-specific information on fishery and management activity.