Yellowfin Sole, Pleuronectes asper, of the Eastern Bering Sea: Biological Characteristics, History of Exploitation, and Management

Yellowfin sole, Pleuronectes asper, is the second most abundant flatfish in the North Pacific Ocean and is most highly concentrated in the eastern Bering Sea. It has been a target species in the eastern Bering Sea since the mid-1950's, initially by foreign distant-water fisheries but more recently by U.S. fisheries. Annual commercial catches since 1959 have ranged from 42,000 to 554,000 metric tons (t). Yellowfin sole is a relatively small flatfish averaging about 26 cm in length and 200 g in weight in commercial catches. It is distributed from nearshore waters to depths of about 100 m in the eastern Bering Sea in summer, but moves to deeper water in winter to escape sea ice. Yellowfin sole is a benthopelagic feeder. It is a longlived species (>20 years) with a correspondingly low natural mortality rate estimated at 0.12. After being overexploited during the early years of the fishery and suffering a substantial decline in stock abundance, the resource has recovered and is currently in excellent condition. The biomass during the 1980's may have been as high as, if not higher than, that at the beginning of the fishery. Based on results of demersal trawl surveys and two age structured models, the current exploitable biomass has been estimated to range between 1.9 and 2.6 million t. Appropriate harvest strategies were investigated under a range of possible recruitment levels. The recommended harvest level was calculated by multiplying the yield derived from the FOI harvest level (161 g at F = 0.14) hy an average recruitment value resulting in a commercial harvest of 276,900 t, or about 14% of the estimated exploitable biomass.

Biological Analysis of Two Management Options for the Atlantic Menhaden Fishery

Biological implications of two managment options (the closed corridor and the recommended shortened season (Option 7) options) for the Atlantic menhaden, Brevoortia tyrannus, fishery are reported based on purse-seine landings and port sampling data from 1970 to 1984 and captain's daily fishing reports from 1978 to 1982. Large catches of age-O menhaden raise concern for growth overfishing. Area-specific yield-per-recruit analyses are used to investigate the biological consequences of these management options. The closed corridor option indicates coastwide gains in yield-per-recruit ranging from 0.3 to 7.2% depending on changes in fishing activity with most areas showing gains. The shortened fishing season indicates coastwide gains in yield per recruit ranging from O. 4 to 10.2% depending onf ishing year with most geographic areas showing gains. The shortened fishing season option offers the greatest gains when large numbers ofy oung menhaden would be caught late in the fishing year, while gains from the closed corridor option depend on how the fishing fleet responds to that management plan. The shortened season offers greater potential coastwide gains to the fishery, but also may result in greater losses to the North Carolina fall fishery. The analytical approach is applicable to the management of other coastal migratory fish stocks that fall under the Atlantic States Marine Fisheries Commission or other interstate management groups.

River Dart Biological Survey 10th June - 15th July 1968

This is the River Dart Biological Survey from 10th June to 15th July 1968 by the Devon River Authority. This survey was undertaken to investigate the invertebrate bottom fauna of the river and to assess the condition of the river with regard to pollution. It describes the environmental conditions of the River Dart and the biological sampling method used, plus a brief conclusion of the survey. It also contains tables with the different species present and abundance on each sampling stations.

Intensive biological survey of the Glaze Brook catchment May 1981

This is the Intensive biological survey of the Glaze Brook catchment May 1981 report produced by the North West Water Authority in 1981. The aim of this report is to identify those pollution problems not identified during the routine biological water quality surveys, and to check the suitability of the routine biological sampling point. This report looks at an intensive biological water quality survey of the Glaze Brook catchment which was carried out by Biol. (S) on 13th-15th May, 1981. Kick samples of invertebrates were taken at 5 sites and all invertebrates were identified and counted in the field. The most significant water quality observations in the report were from: Borsdane brook, Pennington brook, Glaze brook, Amberswood brook, Cunningham brook, Old Mill brook, Shakerley brook, Astley brook and Shaw brook.

Intensive biological survey of the Glaze Brook catchment. Supplementary report on the water quality as indicated by macrophytes. August 1981

This is the Intensive biological survey of the Glaze Brook catchment: Supplementary report on the water quality as indicated by macrophytes produced by the North West Water Authority in 1981. This report describes the results of the macrophyte survey including data on their distribution and the prevailing water quality (nutrient status and toxic metal contamination) It supplements the initial report,TS-BS-81-3, which described the macroinvertebrate survey. The aim of this project is to describe the distribution of macrophytes within the river, paying attention to areas where weed growth may directly affect water quality or amenity usage, and describe the distribution of toxic metals. In the survey 16 sites of 500 m lengths of river were analysed, noting the relative abundance and percentage cover of the macrophytes present, plant score and Community Description Class (C.D.C.) were computed.

Biological survey: River Teign and tributaries with references to the discharge of ball clay wastes

This is the Biological survey of River Teign and tributaries with references to the discharge of ball clay wastes, document produced by South West Water Authority in 1973. This report focuses on on-site assessment of the benthic macro-invertebrates of the lower River Teign, River Bovey, Ugbrooke Stream and Blatchford Brook was undertaken on 19th and 22nd August 1977 to assess the effects of discharges from ball clay mining premises. Inspection of aquatic fauna in the field is of necessity, less extensive than laboratory identification of sorted samples, so that the resulting data underestimates the water quality. This is more pronounced in the Chandler Score than in the Trent Biotic Index which does not take account of species abundance. Chandler should thus be interpreted by the trends described rather than by absolute values calculated.

Biological survey of the River Teign and tributaries, with reference to the effect of ball clay discharges

This is the Biological survey of the River Teign and tributaries, with reference to the effect of ball clay discharges report produced by South West Water Authority in 1979. A survey of the macroinvertebrate riffle fauna in the Ball Clay mining area of the Bovey Basin, following a period of low rainfall, indicated that the River Bovey and the River Teign between Chudleigh and Teign Bridge, Newton Abbot were of good quality. Further downstream, the R. Teign and the lower reaches of the Ugbrooke Stream were identified as being of doubtful quality with the discharge from ECC Broadway continuing to give cause for concern.