An evaluation of the survival of Atlantic salmon (Salmo salar L.)fry stocked in eight streams in the North West of England.

Eight streams from the North West of England were stocked with Atlantic salmon (Salmo salar L.) fed fry at densities ranging from 1 to 4/m2 over a period of up to three years to evaluate survival to the end of the first an d second growing periods and hence assess the value of stocking as a management practice. Survival to the end of the first growin g period (mean duration of 108 days) was found to vary between 7.8 and 41.3% with a mean of 22% and CV of 0.44. Survival from the end of the first growing period to the end of the second growing period (mean duration of 384 days) ranged from 19.9 to 34.1% with a mean of 26.3% and CV of 0.21. Survival was found to be positively related to 0+ trout density (P < 0.05) and negatively related to altitude (P < 0.05). A comparison of the raw survival data (non standardised with respect to duration of experiments) with that from other studies in relation to stocking densities revealed a negative relationship between fry survival and stocking density (P < 0.05). Densities in excess of 5/m2 tended to result in lower levels of survival. Post stocking fry dispersal patterns were examined for the 1991 data. On average 86.7% of the number of fry surviving remained within the stocked zone by the end of the first growing period. With the exception of one stream there was little in the way of dispersal beyond the stocked zone. The dispersal pattern approximated to the normal distribution (P < 0.05). It was estimated that stocking can result in a net gain of fish to a river system compared with natural productivity, however the numerical significance of this gain and its cost effectiveness need to be determined on a river specific basis.

An evaluation of mark and recapture techniques for estimating tigerfish biomass in Lake Kariba

The effectiveness of 2 mark and recapture techniques was evaluated using tiger fish, Hydrocynus vittatus. The 2 techniques used were: tagging with a plastic tag and fluorescent spray marking. While the tagging method resulted as the logical method to use within the constraints of the tiger fish study, it cannot be considered completely reliable for the estimation of population size in Lake Kariba.

Evaluation of NRA tracking studies. Future projects and technical development

Fish tracking is a valuable technique for the provision of detailed information on the behaviour patterns of individual fish especially during estuarine and riverine migration. 2. Tracking studies help in the provision of a comprehensive description of the variety offish behaviour patterns in response to factors such as water flow, obstructions and water quality. 3. There are advantages to be gained by complementing fish tracking studies with data collected from fish counters and vice versa. 4. An overall evaluation of NRA fish tracking projects is presented in the wider context of NRA strategic research objectives. 5. The requirement for future development of tracking equipment, improved data analysis techniques, better communication and more immediate report preparation is identified. 6. Individual project evaluation is given for NRA (or the appropriate Water Authority predecessor) tracking studies conducted on the Ribble estuary, the River Tamar, River Torridge, Rivers Test and Itchen, River Lodden, the Welsh River Dee, River Glaslyn, River Taff, River Tawe, River Tywi, River Usk, Rivers Avon and Stour and the River Frome. 7. An outline for future strategic research is provided which identifies particular areas for study:- i) Identification of environmental factors which control the entry of fish into rivers. ii) Improvement of the understanding of the relationship between water flow and upstream movement of salmonids. iii) Examination of the detailed movements and behaviour of fish in relation to obstructions. iv) Closer definition of water quality requirements for salmonid fish. v) Definition of habitat preferences of salmonids in rivers. vi) Subsidiary topics such as the movements of non-salmonid fish and the downstream migration of kelts and juvenile salmonids.

Age composition and distribution of red drum (Sciaenops ocellatus) in offshore waters of the north central Gulf of Mexico: an evaluation of a stock under a federal harvest moratorium

Because of a lack of fishery-dependent data, assessment of the recovery of fish stocks that undergo the most aggressive form of management, namely harvest moratoriums, remains a challenge. Large schools of red drum (Sciaenops ocellatus) were common along the northern Gulf of Mexico until the late 1980s when increased fishing effort quickly depleted the stock. After 24 years of harvest moratorium on red drum in federal waters, the stock is in need of reassessment; however, fisherydependent data are not available in federal waters and fishery-independent data are limited. We document the distribution, age composition, growth, and condition of red drum in coastal waters of the north central Gulf of Mexico, using data collected from a nearshore, randomized, bottom longline survey. Age composition of the fishery-independent catch indicates low mortality of fish age 6 and above and confirms the effectiveness of the federal fishing moratorium. Bottom longline surveys may be a cost-effective method for developing fishery-independent indices for red drum provided additional effort can be added to nearshore waters (<20 m depth). As with most stocks under harvest bans, effective monitoring of the recovery of red drum will require the development of fishery-independent indices. With limited economic incentive to evaluate non-exploited stocks, the most cost-effective approach to developing such monitoring is expansion of existing fishery independent surveys. We examine this possibility for red drum in the Gulf of Mexico and recommend the bottom longline survey conducted by the National Marine Fisheries Service expand effort in nearshore areas to allow for the development of long-term abundance indices for red drum.

Evaluation of the contribution of fisheries and aquaculture to food security in developing countries

Fish contain important nutrients such as essential fatty acids, iron, zinc, calcium, vitamin A and vitamin C. Production of freshwater fish depends on the strategic application of various management techniques. The demand for fish products has increased beyond the natural supply, resulting in a high pressure on fisheries. Development of aquaculture is necessary for a rapid growth in fish production. A number of constraints hamper the development of aquaculture. Introduction of polyculture technologies in some countries is a way of maximizing production from different levels of the food chain. The roles of women in making fish products available to consumers is frequently over-looked by policy makers. Gender equity in policy-making and management of fisheries and in capacity building is an important issue. Fish production from inland waters and coastal areas can be increased by adopting cage and pen culture systems. Input subsidies and loans to resource poor farmers can boost fish production.

Evaluation of the carcass and commercial characteristics of carps

The role of carcass evaluation techniques in aquaculture research programs, especially in genetics, breeding, production management, feeding and nutrition, cannot be overemphasized. Knowledge of production efficiencies and growth potentials in relation to desired carcass attributes has provided an impetus to improvements in genetic selection techniques and management of aquatic food animals. Accurate, standard and uniform methods of carcass evaluation are critically important. A standard format developed for collection of data on carps is presented in this paper.

Economic evaluation of marine fisheries in India for sustainable production and coastal zone development

The article highlights briefly the economics of different types of fishing units operating along the Indian coast; analyzes the exploitation trend of major marine fishery resources in relation to its potential yield; and suggests policy measures for optimum exploitation of resources, conservation and management.

Economics and management strategies for restocking sandfish in Vietnam

This paper assesses the costs and benefits of a proposed project for restocking sandfish (Holothuria scabra) in Khanh Hoa Province, Vietnam. It identifies the key stakeholders, institutional framework, management and financing required for its implementation. The recommended management strategy includes a 50 percent harvest at optimum size. Limiting the number of boats fishing an area, possibly through licensing, can control the number of sandfish removed. The easiest way to prevent harvesting of undersized sandfish is to control the size of processed sandfish from processors. The potential benefits of restocking are shown by the rapid changes in selected indicators, particularly the net present value, the internal rate of return, and the benefit-cost ratio. Probability analysis is used to estimate the uncertainties in the project calculations. Based on a conservative estimate, the restocking of sandfish is expected to be profitable, although cost-benefit analyses are sensitive to the survival of restocked sandfish and their progeny, and the number of boats fishing for sandfish in the release area.

A standard format for design and evaluation of pond experiments

Details are given of a standard format used by the Pond Dynamics/Aquaculture Collaborative Research Support Program of the US Agency for International Development for the communication of experimental ideas. An example is given of the "Preliminary Proposal Format," which contains a list of information categories or headings as follows: Title; Objectives: Significance; Experimental design; Pond facilities; Stocking rate; Other inputs; Sampling plan; Hypotheses; Statistical methods; Duration; Water management; and Schedule.

Evaluation of a Pound Net Leader Designed to Reduce Sea Turtle Bycatch

Offshore pound net leaders in the southern portion of Chesapeake Bay in Virginia waters were documented to incidentally take protected loggerhead, Caretta caretta, and Kemp’s ridley, Lepidochelys kempii, sea turtles. Because of these losses, NOAA’s National Marine Fisheries Service (NMFS) in 2004 closed the area to offshore pound net leaders annually from 6 May to 15 July and initiated a study of an experimental leader design that replaced the top two-thirds of the traditional mesh panel leader with vertical ropes (0.95 cm) spaced 61 cm apart. This experimental leader was tested on four pound net sites on the eastern shore of Chesapeake Bay in 2004 and 2005. During the 2 trial periods, 21 loggerhead and Kemp’s ridley sea turtles were found interacting with the control leader and 1 leatherback turtle, Dermochelys coriacea, was found interacting with the experimental leader. Results of a negative binomial regression analysis comparing the two leader designs found the experimental leader significantly reduced sea turtle interactions (p=0.03). Finfish were sampled from the pound nets in the study to assess finfish catch performance differences between the two leader designs. Although the conclusions from this element of the experiment are not robust, paired t-test and Wilcoxon signed rank test results determined no significant harvest weight difference between the two leaders. Kolmogorov-Smirnov tests did not reveal any substantive size selectivity differences between the two leaders.

Cypermethrin use in forestry and its impact on Welsh streams: An evaluation of the impact of cypermethrin use in forestry on Welsh streams

This is the Evaluation of the impact of cypermethrin use in forestry on Welsh streams from the University of Plymouth, published on September 2010 by the Environment Agency South West. The report focuses attention on Cypermethrin, a highly active synthetic pyrethroid insecticide effective against a wide range of pests in agriculture, public health, and animal husbandry. It is also used in forestry to control the pine weevil, Hylobius abietis. Cypermethrin is very toxic to aquatic invertebrates and fish at nanogram per litre concentrations. This project checks the effectiveness of current best practice measures in minimising the risk of pollution associated with the use of cypermethrin in forestry in Wales. Chemical results from the intensive studies show that cypermethrin entered minor watercourses draining treated areas at two of the eight sites. In one of these cases the level was well in excess of the short-term Predicted No Effect Concentration. The absence of a buffer area at the other site resulted in the cypermethrin reaching a main drain. However dilution appeared to be sufficient to prevent any impact on water quality or on the invertebrate community in the main stream. Invertebrate and chemical data from the extensive survey showed little evidence of pollution due to wider use of cypermethrin in Welsh forestry. Finally, a number of recommendations are made for further tightening controls on forestry practice to minimise the risk of cypermethrin entering the aquatic environment.

River habitat survey and geomorphological evaluation of the Glaze Brook Catchment

This is the River habitat survey and geomorphological evaluation of the Glaze Brook Catchment report produced by the Environmental Research and Consultancy of the University of Liverpool in 2002. The major aims of the project were to provide baseline information on river habitats in the Glaze catchment using standard River Habitat Survey (RHS) methods (sampling 25% of the catchment length) and, through the geomorphological audit, to assess the distribution and intensity of geomorphological processes, notably sediment transfer, sources and sinks. This information was then used to develop informed management recommendations. The Glaze catchment is a heavily modified watercourse of generally poor habitat quality. The most important factors contributing to the low quality of the sites are poor bank and channel features; low diversity/absence of channel vegetation; paucity of bankside trees and, to a lesser extent, a lack of channel substrate diversity. The high degree of modification relates principally to extensively resectioned banks and channels plus extensive culverting in the urban parts of the catchment.

1987 ecosystem view of management research in the Myakka River: review of Phase I and Phase II reports

This memorandum has four parts. The first is a review and partial synthesis of Phase 1 and Phase 2 Reports by Dr. Ernest Estevez of the Mote Marine Laboratory to the Board of County Commissioners of Sarasota County, Florida. The review and synthesis emphasizes identification of the most important aspects of the structure of the Myakka system in terms of forcing functions, biological components, and major energy flows. In this context, the dominant primary producers, dominant fish species and food habits, and major environmental variables were of articular interest. A major focus of the review and synthesis was on the river zonations provided in the report and based on salinity and various biological indicators. The second part of this memorandum is a review of a draft report by Mote Marine Laboratory on evaluation of potential water quality impacts on the Myakka River from proposed activities in the watershed. This Memorandum's third part is a review of resource-management related ecosystem models in the context of possible future models of the Myakka River Ecosystem. The final part of this memorandum is proposed future work as an extension of the initial reports.