Studies on the seasonal cycle of sea surface temperatures, salinities and phytoplankton in Puttalam Lagoon, Dutch Bay and Portugal Bay along the west coast of Ceylon.

The monthly average temperatures at Puttalam Lagoon, Dutch Bay, Portugal Bay towards Kovilmunai and Portugal Bay towards Pallugaturai showed a distinct annual cycle. The peak was in April and values gradually fell till September. There was a further gradual fall in temperature from October to January. The highest temperatures in all four stations were in April. The highest salinities in all the stations were from May to October i.e., during the south-west monsoon. The salinities at Dutch Bay and Portugal Bay were high in March and April corresponding to the highest temperatures reached during these months. Two maxima have been observed in phytoplankton production. A primary maximum in May-June and a secondary maximum in October. The primary and secondary maxima are due to the influx of nutrient laden waters from the rivers Kal Aru and Pomparippu Aru. The phytoplankton producing blooms were Rhizosolenia alata. Rhizosolenia imbricata, Chaetoceros lascinosus, Chaetoceros pervianus, Ch,aetoceros diversus, Coscinodiscus gigas, Thallasionema nitzschioides, Thalassiosira subtilis, Thallassiothrix frauenfeldii, Asterionella japonica, Sceletonema costatum, Bacteriastrum varians and Biddulphia sinensis. Sudden outbursts of a single species were common. These diatoms were species of Chaetoceros and Rhizosolenia, and Thallassiothrix frauenfeldii. Wide fluctuations have been observed in the distribution of phytoplankton but no definite conclusions can be drawn as the period of observation was only one year.

Sediment Quality in Puget Sound Year 3 - Southern Puget Sound

As a component of a three-year cooperative effort of the Washington State Department of Ecology and the National Oceanic and Atmospheric Administration, surficial sediment samples from 100 locations in southern Puget Sound were collected in 1999 to determine their relative quality based on measures of toxicity, chemical contamination, and benthic infaunal assemblage structure. The survey encompassed an area of approximately 858 km2, ranging from East and Colvos Passages south to Oakland Bay, and including Hood Canal. Toxic responses were most severe in some of the industrialized waterways of Tacoma’s Commencement Bay. Other industrialized harbors in which sediments induced toxic responses on smaller scales included the Port of Olympia, Oakland Bay at Shelton, Gig Harbor, Port Ludlow, and Port Gamble. Based on the methods selected for this survey, the spatial extent of toxicity for the southern Puget Sound survey area was 0% of the total survey area for amphipod survival, 5.7% for urchin fertilization, 0.2% for microbial bioluminescence, and 5- 38% with the cytochrome P450 HRGS assay. Measurements of trace metals, PAHs, PCBs, chlorinated pesticides, other organic chemicals, and other characteristics of the sediments, indicated that 20 of the 100 samples collected had one or more chemical concentrations that exceeded applicable, effects-based sediment guidelines and/or Washington State standards. Chemical contamination was highest in eight samples collected in or near the industrialized waterways of Commencement Bay. Samples from the Thea Foss and Middle Waterways were primarily contaminated with a mixture of PAHs and trace metals, whereas those from Hylebos Waterway were contaminated with chlorinated organic hydrocarbons. The remaining 12 samples with elevated chemical concentrations primarily had high levels of other chemicals, including bis(2-ethylhexyl) phthalate, benzoic acid, benzyl alcohol, and phenol. The characteristics of benthic infaunal assemblages in south Puget Sound differed considerably among locations and habitat types throughout the study area. In general, many of the small embayments and inlets throughout the study area had infaunal assemblages with relatively low total abundance, taxa richness, evenness, and dominance values, although total abundance values were very high in some cases, typically due to high abundance of one organism such as the polychaete Aphelochaeta sp. N1. The majority of the samples collected from passages, outer embayments, and larger bodies of water tended to have infaunal assemblages with higher total abundance, taxa richness, evenness, and dominance values. Two samples collected in the Port of Olympia near a superfund cleanup site had no living organisms in them. A weight-of-evidence approach used to simultaneously examine all three “sediment quality triad” parameters, identified 11 stations (representing 4.4 km2, 0.5% of the total study area) with sediment toxicity, chemical contamination, and altered benthos (i.e., degraded sediment quality), 36 stations (493.5 km2, 57.5% total study area) with no toxicity or chemical contamination (i.e., high sediment quality), 35 stations (274.1 km2, 32.0% total study area) with one impaired sediment triad parameter (i.e., intermediate/high sediment quality), and 18 stations (85.7km2, 10.0% total study area) with two impaired sediment parameters (i.e., intermediate/degraded quality sediments). Generally, upon comparison, the number of stations with degraded sediments based upon the sediment quality triad of data was slightly greater in the central Puget Sound than in the northern and southern Puget Sound study areas, with the percent of the total study area degraded in each region decreasing from central to north to south (2.8, 1.3 and 0.5%, respectively). Overall, the sediments collected in Puget Sound during the combined 1997-1999 surveys were among the least contaminated relative to other marine bays and estuaries studied by NOAA using equivalent methods. (PDF contains 351 pages)

Die Fangmengen an Nordseegarnelen und fischereilicher Aufwand im europäischen Vergleich - Langzeitserien und saisonale Übersicht

Among other tasks the “Working Group on Crangon Fisheries and Life Cycle” of the “International Council for the Exploration of the Sea” collects data on landings and effort in the North Sea brown shrimp fisheries by country. Landings per unit effort data are calculated and all are compared on basis of long-term series as well as on seasonal basis. The development for each country is described and compared for the year 2001 to the ten-year average from 1992 to 2001 were possible, as some data are missing especially for the Netherlands. While the Dutch and British fleets increased their landings substantially in 2001 compared to the previous years, Danish,German and Belgian fishermen had reduced landings. There are regional differences in fishing pattern between the countries, especially Denmark versus the rest of Europe. Effort measures remain incomparable between the countries, and fluctuations in landings per unit effort data seem to be in a normal biological range, giving no reason for concern at present for the situation of brown shrimp stocks in the North Sea. An improvement of the data basis is required and possibly achievable by the EU logbook system being in force for brown shrimp fisheries as well.

Winterfischerei auf Garnelen. Die Anteile der europäischen Garnelenflotten an den Anlandungen von Crangon crangon im Zeitraum Januar bis März der Jahre 1990 bis 1999

„Winter fishery“ on brown shrimp does not imply a special type of fishery. It merely means the continuation of the standard fishing procedure of parts of the fleet during wintertime, when the majority of the mostly smaller vessels stay in harbour due to generally unfavourable weather conditions for their activity. During 1990 to 1999 mean European wide landings in January and February summedup to 854 tonnes making up to only 4 % of the mean annual landings (21 805 t). While German vessels landed0.7 % (68.7 t) of their mean annual landings during that period, the other countries caught about 7 % of their individual, mean annual landings at the same time. The Netherlands and Denmark contributed highest tonnages of 580and 110 tonnes, respectively, to the total European landings, making up 81 % of them. As about 70 % of brown shrimp may carry eggs in January, the winter fishery took a mean total of about 2.15 x 1012brown shrimp eggs out of the stocks in that period annually. As there is no reliable assessment available concerning the brown shrimp stocks, it is despite of these high losses of eggs not possible to trace a negative effect of the winter fishery in scientific terms. However, precautional catch reductions in winter would be in favour of higher survival rates of eggs, which are the carrying source for the recruitment of brown shrimp stocks and catches in forthcoming summer and autumn seasons according to Dutch investigations.

Saisonale und regionale Unterschiede zwischen den 0-Gruppen-Schollen-Discards in der deutschen Garnelenfischerei

Shrimping in the waddensea is frequently considered to significantly reduce the numbers of juvenile plaice . This investigation aims to reveal the seasonal and regional differences regarding discards in the German waddensea and sets the results in relation to the bycatch projects with German participation. Furthermore, methodological aspects are evaluated to find possible effects on the estimation of the netted numbers. The bycatch problem exists predominantly throughout the summer season, but high catches of juvenile plaice can occur occasionally in autumn. The discard issue seems to be most important in the East Frisian region, while the Elbe and Schleswig-Holstein areas are of lesser importance. Considering the distribution of the fish in the environment is as indispensable as sampling of the shrimp fleet with optimum representativity. There are indices that the contribution of the Dutch shrimp fleet to the discard mortality of juvenile plaice was underestimated in the recent past. A combination of time and area closures as restrictions in combination with the extensive application of selective gears could possibly gain the best protection for the affected species.

Fangmengenbegrenzungen in der Garnelenfischerei - eine Chance fur weitere Biefangreduzierungen

Aiming for price stabilisation Danish, German and Dutch brown shrimp fisheries agreed on weekly catch limitations for the years 1998 and 1999. This resulted in fishing effort reduction of 18 % of the total number of fishing trips in 1998 and up to 24 % in summer. In that period highest abundance of young plaice occurs in the Wadden Sea which is the fishing area of the brown shrimp fleets of Germany and the Netherlands. Consequently as a side effect a reduction of the total annual by-catch especially of young plaice must have occurred. According to formerly conducted EU-studies and investigations the by-catch reduction due to the agreed catch limitations should have led to survival of millions of young plaice. They give a potential of some extra catch in coming years which is 2,5 % of the total TAC of plaice in the North Sea. Compared to the German TAC in year 2000 the gain equals 44 %. The catch limitations effect on by-catch reduction in 1998 was in the same order of magnitude of the one achievable by technical measures in net selection applied in that fishery and research. A combination of both could substantially reduce traditional by-catch levels in brown shrimp fisheries.Aiming for price stabilisation Danish, German and Dutch brown shrimp fisheries agreed on weekly catch limitations for the years 1998 and 1999. This resulted in fishing effort reduction of 18 % of the total number of fishing trips in 1998 and up to 24 % in summer. In that period highest abundance of young plaice occurs in the Wadden Sea which is the fishing area of the brown shrimp fleets of Germany and the Netherlands. Consequently as a side effect a reduction of the total annual by-catch especially of young plaice must have occurred. According to formerly conducted EU-studies and investigations the by-catch reduction due to the agreed catch limitations should have led to survival of millions of young plaice. They give a potential of some extra catch in coming years which is 2,5 % of the total TAC of plaice in the North Sea. Compared to the German TAC in year 2000 the gain equals 44 %. The catch limitations effect on by-catch reduction in 1998 was in the same order of magnitude of the one achievable by technical measures in net selection applied in that fishery and research. A combination of both could substantially reduce traditional by-catch levels in brown shrimp fisheries.

Entwicklung des Aufwandes in der deutschen Garnelenfischerei

The German brown shrimp fishery experienced considerable changes during the recent four decades. Contrarily to the decline in number of vessels the technical standard and size of the shrimping vessels improved and the fishing power as well as the effort of the single boats have strongly increased. As fishing effort by the whole fleet may be calculated different ways, trends in total effort may differ according to the relevant author´s approach. The present study tries to estimate the total trawled area by the fleet in the mid fifties as well as in 1996. The result is that there seems to be no change in the order of magnitude of the total trawled area for the German shrimping fleet itself, though shifts in geographical areas as within seasons were reported. However, the development of the Danish and Dutch shrimping fleets have contributed to an increase in terms of annually trawled area. Therefore pooled fishing effort must have increased considerably.

Bestandserfassung und -überwachung des atlanto-skandischen Herings. EU-Studie "Hydroacoustic Surveys of Atlanto-Scandian Herring in the Norwegian Sea, 1998-2000 (ASH-II)"

The atlanto-scandian herring consists of two major stocks, i.e. the Icelandic summer spawner and the Norwegian spring spawner. Both stocks have recovered well after complete collapse in the seventies and allow for a controlled fishery. The total allowable catch of the Norwegian spring spawner is currently 1.3 mill. t. The resumption of the fishery is accompanied by an annual and multi-national survey with Norwegian, Faeroe Islands, Icelandic and Russian contribution. In 1998 the EU will contribute to the survey with the Swedish vessel ”Argos” and in 1999 with the ”Walther Herwig III” under Dutch, Swedish and German participation. About half of the survey costs are covered by the EU by means of a funded study, the other half is contributed by the participating nations.

Reduzierung der Schädigung des Meeresbodens durch Baumkurren und Grundschleppnetze

An EU funded research project was started in 1998 by institutes from Ireland, Belgium, the Netherlands and Germany to reduce the adverse environmental impact of demersal trawls. In the frame of this project the Institute for Fishery Technique of the Federal Research Centre for Fisheries, Hamburg, is developing a jet beamtrawl replacing the heavy tickler chains of a traditional flatfish beam trawl by water jet nozzles placed at the lower side of the beam with the jets directed towards the sea bottom. First trials on the dutch research vessel “Tridens” were performed in March 1998. Catch and bycatch of a jet beamtrawl and a traditional beamtrawl were compared. The efficiency of the jet beamtrawl was not satisfactory and will have to be improved.

Deutsche und internationale Bestandsuntersuchungen an Heringen mit hydroakustischen Methoden

The international hydroacoustic herring survey in the North Sea is carried out since the early eighties with Dutch, Scottish, Danish und Norwegian contribution. Since 1994 Germany also participates in this survey on a regular basis and has taken over a sector in the easter part between the Dogger Bank and the Danish coast. This area is known for the abundance of chiefly juvenile herring and sprat. During the 1995 cruise some 420000 t of herring were found here, most of them being juveniles of age group I. Analyses of plankton hauls showed that planktonic echos were not caused by juvenile herring, instead the echos were apparently produced by small pelagic gastropodes of the genus Spiratella.

The Marine Stewardship Council: new hope for marine fisheries

To help reverse the downward trends for the world's marine fish stocks, the Worldwide Fund for Nature (WWF) and the Aglo-Dutch Unilever have jointly formed the Marine Stewardship Council (MSC), an independent, non-profit, non-governmental membership body. The rationale and strategies to achieve the goals of the joint effort are discussed.

The Great Albatross Philippine Expedition and Its Fishes

The Philippine Expedition of 1907-10 was the longest and most extensive assignment of the Albatross's 39-year career. It came about because the United States had acquired the Philippines following the Spanish-American War of 1898 and the bloody Philippine Insurection of 1899-1902. The purpose of the expedition was to surbey and assess the aquatic resources of the Philippine Islands. Dr. Hugh M. Smith, the Deputy Commissioner of the U.S. Bureau of Fisheries, was the Director of the Expedition. Other scientific participants were Frederick M. Chamberlain, Lewis Radcliffe, Paul Bartsch, Harry C. Fasset, Clarence Wells, Albert Burrows, Alvin Seale, and Roy Chapman Andrews. The expedition consisted of a series of cruises, each beginning and ending in Manila and exploring a different part of the island group. In addition to the Philippines proper, the ship also explored parts of the Dutch East Indies and areas around Hong Kong and Taiwan. The expedition returned great quantities of fish and invertebrate speciments as well as hydrographic and fisheries data; most of the material was eventually deposited in the Smithsonian Institution's National Museum of Natural History. The fisehs were formally accessioned into the museum in 1922 and fell under the car of Barton A. Bean, Assistant Curator of Fishes, who then recruited Henry W. Fowler to work up the material. Fowler completed his studies of the entire collection, but only part of it was ever published, due in part to the economic constraints caused by the Depression. The material from the Philippine Expedition constituted the largest single accession of fishes ever received by the museum. These speciments are in good condition today and are still being used in scientific research.

History of Whaling and Estimated Kill of Right Whales, Balaena glacialis, in the Northeastern United States, 1620–1924

This study, part of a broader investigation of the history of exploitation of right whales, Balaena glacialis, in the western North Atlantic, emphasizes U.S. shore whaling from Maine to Delaware (from lat. 45°N to 38°30'N) in the period 1620–1924. Our broader study of the entire catch history is intended to provide an empirical basis for assessing past distribution and abundance of this whale population. Shore whaling may have begun at Cape Cod, Mass., in the 1620’s or 1630’s; it was certainly underway there by 1668. Right whale catches in New England waters peaked before 1725, and shore whaling at Cape Cod, Martha’s Vineyard, and Nantucket continued to decline through the rest of the 18th century. Right whales continued to be taken opportunistically in Massachusetts, however, until the early 20th century. They were hunted in Narragansett Bay, R.I., as early as 1662, and desultory whaling continued in Rhode Island until at least 1828. Shore whaling in Connecticut may have begun in the middle 1600’s, continuing there until at least 1718. Long Island shore whaling spanned the period 1650–1924. From its Dutch origins in the 1630’s, a persistent shore whaling enterprise developed in Delaware Bay and along the New Jersey shore. Although this activity was most profi table in New Jersey in the early 1700’s, it continued there until at least the 1820’s. Whaling in all areas of the northeastern United States was seasonal, with most catches in the winter and spring. Historically, right whales appear to have been essentially absent from coastal waters south of Maine during the summer and autumn. Based on documented references to specific whale kills, about 750–950 right whales were taken between Maine and Delaware, from 1620 to 1924. Using production statistics in British customs records, the estimated total secured catch of right whales in New England, New York, and Pennsylvania between 1696 and 1734 was 3,839 whales based on oil and 2,049 based on baleen. After adjusting these totals for hunting loss (loss-rate correction factor = 1.2), we estimate that 4,607 (oil) or 2,459 (baleen) right whales were removed from the stock in this region during the 38-year period 1696–1734. A cumulative catch estimate of the stock’s size in 1724 is 1,100–1,200. Although recent evidence of occurrence and movements suggests that right whales continue to use their traditional migratory corridor along the U.S. east coast, the catch history indicates that this stock was much larger in the 1600’s and early 1700’s than it is today. Right whale hunting in the eastern United States ended by the early 1900’s, and the species has been protected throughout the North Atlantic since the mid 1930’s. Among the possible reasons for the relatively slow stock recovery are: the very small number of whales that survived the whaling era to become founders, a decline in environmental carrying capacity, and, especially in recent decades, mortality from ship strikes and entanglement in fishing gear.

Studies on the seasonal cycle of sea surface temperatures, salinities, oxygen and phytoplankton in Koddiyar Bay, Trincomalee in relation to the shore seine fishery

In Sri Lanka waters, Durairatnam (1963, 1969) had reported on the seasonal variation of plankton at Puttalam lagoon, Dutch Bay, Portugal Bay and in the inshore and off shore waters off Colombo. Similar investigations were carried out at Koddiyar Bay especially in the estuarine waters where the three tributaries of the river Mahaveli empty their waters into the bay. The estuary is perennial. The fishes constituting the estuarine fisheries are mostly shallow water marine species which can tolerate considerable variations of salinities. Prawns and crabs also constitute a very valuable fishery in estuarine waters.

Salt and water balance in the Mundel Lake: a strongly choked coastal lagoon

The Mundel Lake is an extremely shallow lagoon on the west coast of Sri Lanka. It is connected to the Puttalam Lagoon through 15 km long Dutch Canal. Salinity measurements and daily sea level data were obtained fortnightly from January 1993 to March 1994 and they were used to quantify the salt and water budget along with precipitation, evaporation and freshwater runoff. Extreme fluctuations of salinity and sea level are striking features of the system. Salinity of the Mundel Lake and Dutch Canal varied from 5-46.5 and 6 61 ppt respectively while the sea level ranged from -0.25 to +1.2 m. Tidal variations were not seen in the lagoon due to its long narrow canal system. Salt budget showed that the deposition of salt on the lagoon bottom during periods of decreasing water level. During increasing water level, salt is dissolved again. Flow of water through the Dutch Canal between the Puttalam Lagoon and Mundel Lake is driven by the changes in sea level. These changes are mainly due to seasonal changes of net freshwater supply and, to a lesser degree, to seasonal changes in sea surface height. As the flow rates are small due to the long and narrow canal, the residence time ranges between two months and several months in the Mundel Lake, except during season of high freshwater supply. As the water exchange is weak, the Mundel Lake becomes hyper saline with strong fluctuations in salinity. This implies a stress to all lagoon dwelling aquatic organisms and also to aquaculture practices in the area.