Aphanomycosis of crayfish: crayfish plague

This is the Aphanomycosis of crayfish: crayfish plague report produced by the Environment Agency in 2000. Crayfish plague is an extremely virulent fungal disease of European crayfish species, the white clawed or stone crayfish of Western Europe Austropotamobius pallipes, the Noble crayfish of northern Europe Astacus astacus and the narrow clawed crayfish of Eastern Europe, Astacus leptodactylus. The white claw crayfish A. pallipes is the indigenous native crayfish of the British Isles. Until the early 1980s there were extensive healthy populations of this crayfish in almost all suitable alkaline river and lake environments in England and Wales as far north as Northumberland. The conservation importance of this native crayfish is widely recognised. This report provides a general review of the literature of crayfish plague, including an overview of its spread through the British Isles from CEFAS records. Information on current diagnostic methods from the Office International des Epizooties (OIE) Aquatic Disease Manual is provided. Information on the taxonomy, morphology and physiology of the pathogen is reviewed, together with the pathogenicity and pathology of the disease and current means of prevention and control.

Salmonid and freshwater fisheries statistics for England and Wales,1997

This report is the third collation of salmon and migratory trout catch statistics for England and Wales produced by the Environment Agency. For the years 1989-94, these statistics were published by the National Rivers Authority (NRA) and the years 1983-88 by the Ministry of Agriculture, Fisheries and Food, Directorate of Fisheries Research in its Data Report series. This report is designed to be a reference document of declared salmonid catches in England and Wales and is produced in the autumn following the season. Salmon stock assessment data including provisional catches, counter run estimates and some juvenile data are now published in an annual assessment for the International Council for the Exploitation of the Seas (ICES). The first report in this series was published jointly by the Environment Agency and the Centre for Environment, Fisheries & Aquatic Science (CEFAS) in April 1997 (Anon 1998).

Salmonid and freshwater fisheries statistics for England and Wales,1998

This report is the fourth collation of salmon and migratory trout catch statistics for England and Wales produced by the Environment Agency. For the years 1989-94 these statistics were published by the National Rivers Authority (NRA) and for the years 1983-88 by the Ministry of Agriculture, Fisheries and Food, Directorate of Fisheries Research, in its Data Report series. This report is designed to be a reference document of declared salmonid catches in England and Wales. Salmon stock assessment data including provisional catches, counter run estimates and some juvenile data are now published in an annual assessment for the International Council for the Exploitation of the Seas (ICES). The second report in this series was published jointly by the Environment Agency and the Centre for Environment, Fisheries & Aquatic Science (CEFAS) in April 1998 (Anon 1999).

Salmon stocks and fisheries in England and Wales, 2001. Preliminary assessment prepared for ICES, April 2002

This report presents a preliminary assessment of the state of salmon stocks and fisheries in England and Wales in 2001 to assist ICES in providing scientific advice to NASCO and to provide early feedback to fishery managers and anglers. The chief indicators of the state o f salmon stocks are normally the catches taken by rod and net fisheries. However, in 2001 angling was affected by the outbreak of foot and mouth disease (FMD), which restricted angling opportunities and access to rod fisheries in many parts of the country for lengthy periods. It is impossible to quantify the impact that FMD had on rod catches, although these were undoubtedly significantly reduced; net fisheries were unaffected by FMD. The declared salmon catch for 2001 (including those fish released alive by anglers) is provisionally estimated at 209 tonnes, representing some 57,000 fish, and comprising 153 tonnes (-43,000 fish) by nets and fixed engines and 56 tonnes (-14,000 fish) by rods. For direct comparison with previous years, it should be noted that the declared catch prior to the issue of a second reminder was about 49 tonnes (see below). An estimated 26 tonnes (43%) of the rod catch was released alive. These figures do not take account of catches of salmon which go unreported (including those taken illegally), and it is estimated that there may have been a total of 33 tonnes of additional fish caught in 2001; approximately 15% of all fish killed.

Mortality and movement of Yellowtail Flounder (Limanda ferruginea) tagged off New England

From 2003 to 2006, 44,882 Yellowtail Flounder (Limanda ferruginea) were captured and released with conventional disc tags in the western North Atlantic as part of a cooperative Yellowtail Flounder tagging study. From these releases, 3767 of the tags were recovered. The primary objectives of this tagging program were to evaluate the mortality and large-scale movement of Yellowtail Flounder among 3 stock areas in New England. To explore mortality, survival and recovery rate were estimated from traditional Brownie tag-recovery models fitted to the data with Program MARK. Models were examined with time and sex-dependent parameters over several temporal scales. The models with a monthly scale for both survival and recovery rate had the best overall fit and returned parameter estimates that were biologically reasonable. Estimates of survival from the tag-recovery models confirm the general magnitude of total mortality derived from age-based stock assessments but indicate that survival was greater for females than for males. In addition to calculating mortality estimates, we examined the pattern of release and recapture locations and revealed frequent movements within stock areas and less frequent movement among stock areas. The collaboration of fishermen and scientists for this study successfully resulted in independent confirmation of previously documented patterns of movement and mortality rates from conventional age-based analyses.

Differences in diet of Atlantic bluefin tuna (Thunnus thynnus) at five seasonal feeding grounds on the New England continental shelf

The stomachs of 819 Atlantic bluefin tuna (Thunnus thynnus) sampled from 1988 to 1992 were analyzed to compare dietary differences among five feeding grounds on the New England continental shelf (Jeffreys Ledge, Stellwagen Bank, Cape Cod Bay, Great South Channel, and South of Martha’s Vineyard) where a majority of the U.S. Atlantic commercial catch occurs. Spatial variation in prey was expected to be a primary influence on bluefin tuna distribution during seasonal feeding migrations. Sand lance (Ammodytes spp.), Atlantic herring (Clupea harengus), Atlantic mackerel (Scomber scombrus), squid (Cephalopoda), and bluefish (Pomatomus saltatrix) were the top prey in terms of frequency of occurrence and percent prey weight for all areas combined. Prey composition was uncorrelated between study areas, with the exception of a significant association between Stellwagen Bank and Great South Channel, where sand lance and Atlantic herring occurred most frequently. Mean stomach-contents biomass varied significantly for all study areas, except for Great South Channel and Cape Cod Bay. Jeffreys Ledge had the highest mean stomach-contents biomass (2.0 kg) among the four Gulf of Maine areas and Cape Cod Bay had the lowest (0.4 kg). Diet at four of the five areas was dominated by one or two small pelagic prey and several other pelagic prey made minor contributions. In contrast, half of the prey species found in the Cape Cod Bay diet were demersal species, including the frequent occurrence of the sessile fig sponge (Suberites ficus). Prey size selection was consistent over a wide range of bluefin length. Age 2–4 sand lance and Atlantic herring and age 0–1 squid and Atlantic mackerel were common prey for all sizes of bluefin tuna. This is the first study to compare diet composition of western Atlantic bluefin tuna among discrete feeding grounds during their seasonal migration to the New England continental shelf and to evaluate predator-prey size relationships. Previous studies have not found a common occurrence of demersal species or a pre-dominance of Atlantic herring in the diet of bluefin tuna.