Proceedings of the Second PICES Workshop on the Okhotsk Sea and Adjacent Areas [Nemuro, Japan, November 9-12, 1998]

Table of Contents [pdf, 0.01 Mb] Preface [pdf, 0.01 Mb] Masaaki Aota Long-term tendencies of sea ice concentration and air temperature in the Okhotsk Sea coast of Hokkaido [pdf, 0.05 Mb] Hajime Ito & Miki Yoshioka Geography of the seasonally ice covered seas [pdf, 0.5 Mb] George V. Shevchenko & Victor F. Putov On wind and tide induced sea-ice drift on the northeastern shelf of Sakhalin Island (analysis of radar data) [pdf, 0.96 Mb] Boris S. Dyakov, A.A. Nikitin, L. S. Muktepavel & T.A. Shatilina Variability of the Japan and Okhotsk Seas ice cover depending on geopotential field H500 over the Far-Eastern region [pdf, 0.10 Mb] Aleksandr G. Petrov & Nikolay A. Rykov Intermediate cold layer and ice cover in the Sea of Okhotsk [pdf, 0.37 Mb] Vladimir Ponomarev, Olga Trusenkova, Elena Ustinova & Dmitry Kaplunenko Interannual variations of oceanographic and meteorological characteristics in the Sea of Okhotsk [pdf, 0.16 Mb] George V. Shevchenko & Akie Kato Seasonal and interannual changes of atmospheric pressure, air and water temperature in the area of the Kuril Ridge [pdf, 0.13 Mb] George V. Shevchenko & Vladimir Yu. Saveliev Spatial variability of the wind field in the area of the Kuril Islands [pdf, 0.15 Mb] Alexander L. Figurkin & Igor A. Zhigalov Seasonal variability and specifity of the oceanological conditions in the northern Okhotsk Sea in 1997 [pdf, 1.04 Mb] Igor A. Zhabin Ventilation of the upper portion of the intermediate water in the Okhotsk Sea [pdf, 0.80 Mb] Vladimir A. Luchin & Alexander L. Figurkin Oceanographic conditions over the Kashevarov Bank [pdf, 0.61 Mb] Toshiyuki Awaji, Tomohiro Nakamura, Takaki Hatayama, Kazunori Akimoto & Takatoshi Takizawa Tidal exchange through the Kuril Straits [pdf, 2.01 Mb] Tomohiro Nakamura, Toshiyuki Awaji, Takaki Hatayama, Kazunori Akimoto, Takatoshi Takizawa & Masao Fukasawa Vertical mixing induced by tidally generated internal waves in the Kuril Straits [pdf, 0.83 Mb] Katsuro Katsumata & Ichiro Yasuda Water exchange between the Okhotsk Sea and the North Pacific Ocean estimated by simple models [pdf, 0.97 Mb] Konstantin A. Rogachev Oyashio west path culmination as the consequence of a rapid thermohaline transition in the Pacific Subarctic [pdf, 0.22 Mb] Yasuhiro Kawasaki On the year-to-year change in subarctic water characteristics around the Kuril Islands [pdf, 0.39 Mb] Alexander L. Figurkin & Evgeniy E. Ovsyannikov Influence of oceanological conditions of the West Kamchatka shelf waters on spawning grounds and on pollock egg distribution [pdf, 0.97 Mb] Igor E. Kochergin & Alexander A. Bogdanovsky Transport and turbulence characteristics for the northeastern Sakhalin shelf conditions [pdf, 0.08 Mb] Igor E. Kochergin, Alexander A. Bogdanovsky, Valentina D. Budaeva, Vyacheslav G. Makarov, Vasily F. Mishukov, S.N. Ovsienko, Victor F. Putov, L.A. Reitsema, J.W. Sciallabba, O.O. Sergucheva & P.V. Yarosh Modeling of oil spills for the shelf conditions of northeastern Sakhalin [pdf, 0.32 Mb] Valentina D. Budaeva & Vyacheslav G. Makarov A peculiar water regime of currents in the area of eastern Sakhalin shelf [pdf, 0.66 Mb] Nikolay A. Rykov The oceanographic databases on the Sakhalin shelf [pdf, 0.27 Mb] Akifumi Nakata, Iori Tanaka, Hiroki Yagi, Tomomi Watanabe, Gennady A. Kantakov & Andrew D. Samatov Formation of high-density water (over 26.8 sigma-t) near the La Perouse Strait (the Soya Strait) [pdf, 0.09 Mb] Minoru Odamaki & Kouji Iwamoto Currents and tidal observations by Hydrographic Department of Maritime Safety Agency, off the Okhotsk coast of Hokkaido [pdf, 0.16 Mb] Yasushi Fukamachi, Genta Mizuta, Kay I. Ohshima, Motoyo Itoh, Masaaki Wakatsuchi & Masaaki Aota Mooring measurements off Shiretoko Peninsula, Hokkaido in 1997-1998 [pdf, 0.19 Mb] Mikhail A. Danchenkov, David Aubrey & Stephen C. Riser Oceanographic features of the La Perouse Strait [pdf, 0.91 Mb] Iori Tanaka & Akifumi Nakata Results of direct current measurements in the La Perouse Strait (the Soya Strait), 1995-1998 [pdf, 0.06 Mb] Gennady A. Kantakov & George V. Shevchenko In situ observations of Tsushima and West-Sakhalin currents near La Perouse (Soya) Strait [pdf, 0.79 Mb] Irina Y. Bragina Geographical and biological characteristics of the net zooplankton in the southwestern part of the Sea of Okhotsk during 1987-1996 [pdf, 0.27 Mb] List of corresponding authors [pdf, 0.01 Mb] (Document pdf contains 193 pages)

A comparison of seafloor habitats and associated benthic fauna in areas open and closed to bottom trawling along the central California Continental Shelf

Executive Summary: A number of studies have shown that mobile, bottom-contact fishing gear (such as otter trawls) can alter seafloor habitats and associated biota. Considerably less is known about the recovery of these resources following such disturbances, though this information is critical for successful management. In part, this paucity of information can be attributed to the lack of access to adequate control sites – areas of the seafloor that are closed to fishing activity. Recent closures along the coast of central California provide an excellent opportunity to track the recovery of historically trawled areas and to compare recovery rates to adjacent areas that continue to be trawled. In June 2006 we initiated a multi-year study of the recovery of seafloor microhabitats and associated benthic fauna inside and outside two new Essential Fish Habitat (EFH) closures within the Cordell Bank and Gulf of the Farallones National Marine Sanctuaries. Study sites inside the EFH closure at Cordell Bank were located in historically active areas of fishing effort, which had not been trawled since 2003. Sites outside the EFH closure in the Gulf of Farallones were located in an area that continues to be actively trawled. All sites were located in unconsolidated sands at equivalent water depths. Video and still photographic data collected via a remotely operated vehicle (ROV) were used to quantify the abundance, richness, and diversity of microhabitats and epifaunal macro-invertebrates at recovering and actively trawled sites, while bottom grabs and conductivity/temperature/depth (CTD) casts were used to quantify infaunal diversity and to characterize local environmental conditions. Analysis of still photos found differences in common seafloor microhabitats between the recovering and actively trawled areas, while analysis of videographic data indicated that biogenic mound and biogenic depression microhabitats were significantly less abundant at trawled sites. Each of these features provides structure with which demersal fishes, across a wide range of size classes, have been observed to associate. Epifaunal macro-invertebrates were sparsely distributed and occurred in low numbers in both treatments. However, their total abundance was significantly different between treatments, which was attributable to lower densities at trawled sites. In addition, the dominant taxa were different between the two sites. Patchily-distributed buried brittle stars dominated the recovering site, and sea whips (Halipteris cf. willemoesi) were most numerous at the trawled site though they occurred in only five of ten transects. Numerical classification (cluster analysis) of the infaunal samples also revealed a clear difference between benthic assemblages in the recovering vs. trawled areas due to differences in the relative abundances of component species. There were no major differences in infaunal species richness, H′ diversity, or J′ evenness between recovering vs. trawled site groups. However, total infaunal abundance showed a significant difference attributable to much lower densities at trawled sites. This pattern was driven largely by the small oweniid polychaete Myriochele gracilis, which was the most abundant species in the overall study region though significantly less abundant at trawled sites. Other taxa that were significantly less abundant at trawled sites included the polychaete M. olgae and the polychaete family Terebellidae. In contrast, the thyasirid bivalve Axinopsida serricata and the polychaetes Spiophanes spp. (mostly S. duplex), Prionospio spp., and Scoloplos armiger all had significantly to near significantly higher abundances at trawled sites. As a result of such contrasting species patterns, there also was a significant difference in the overall dominance structure of infaunal assemblages between the two treatments. It is suggested that the observed biological patterns were the result of trawling impacts and varying levels of recovery due to the difference in trawling status between the two areas. The EFH closure was established in June 2006, within a month of when sampling was conducted for the present study, however, the stations within this closure area are at sites that actually have experienced little trawling since 2003, based on National Marine Fishery Service trawl records. Thus, the three-year period would be sufficient time for some post-trawling changes to have occurred. Other results from this study (e.g., similarly moderate numbers of infaunal species in both areas that are lower than values recorded elsewhere in comparable habitats along the California continental shelf) also indicate that recovery within the closure area is not yet complete. Additional sampling is needed to evaluate subsequent recovery trends and persistence of effects. Furthermore, to date, the study has been limited to unconsolidated substrates. Ultimately, the goal of this project is to characterize the recovery trajectories of a wide spectrum of seafloor habitats and communities and to link that recovery to the dynamics of exploited marine fishes. (PDF has 48 pages.)

Lake Kainji water hyacinth infestation and the control strategies

The paper documents the aquatic vascular plants situation of Lake Kainji, particularly with the invasion of water hyacinth (Eichhormia crassipes) hitherto alien to the lake system. The frequency of occurrence of some aquatic plants on Lake Kainji have increased whilst a few decreased over the period between 1984 and 1995. More than 53.6% of the lake surface has now been covered by aquatic vascular plants of which water hyacinth alone covered 30.6% (16.4% of the system). Apart from the characteristic rapid multiplication and biomass build-up of the plant, more than 9.1 clumps with a diameter range between 0.8-4cm enter the lake per minute. Thus more than 16.4ha per day or annually 6000ha of water hyacinth are added as drifts. Because of the peculiar hydrological cycle of the lake and the plant aggressiveness and invasiveness, NIFFR (with the support of the GTZ) had developed an approach of control which combines manual, biological, natural, boom construction and chemical measures. These are discussed

A survey of fisherfolk involved in artisanal fisheries in some selected areas of Ikorodu in Lagos State

The study focused on men and women involved in artisanal fisheries in some selected areas of Ikorodu Local government in Lagos State. The random sampling technique was used to select 50 fishermen each at Ibeshe and Baiyeku sites. The results revealed that majority of the fishermen were male, christian, semi-illiterate, and married. Data were collected on capital sources, labour used, income, gear techniques and type of fish caught. Analysis showed that the highest sources of capital were from personal savings (50%). Majority of labour used were hired labour, 44% at Ibeshe and 50% at Baiyeku. Highest monthly income ranged between N10, 000 - N25, 000 at both sites. Planks were mostly used at both sites for fishing boats as well as means of transport (Ibeshe 68%, Baiyeku 72%). Common fishing gear was the gill net, The fishes caught were found to be of various tyupes. Ethalmalosa fimbriata constituted the highest fish species caught by weight and number at both sites (50%). However, the problems of capital source were most peculiar coupled with high cost of fishing materials and labour scarcity

Contribution to the biology and geographical distribution of Aegagropila sauteri (Nees) Kutz. [Translation of: Gidrobiologicheskie Zhurnal, Kiev 4(3), 68-69, 1967]

Aegagropila sauteri is a peculiar green algae, the branched thalli of which, according to the amount of growth, forms velvety spheres of a diameter of 3-4, sometimes to 5-6 cm. and bigger. Investigators attribute it to a special genus of green algae. The authors examine Aegagropila sauteri in Lake Markakol (Kazakhstan).

Selective plankton feeding by the coregonid ”bondella” (Coregonus sp.) of Lake Maggiore [Translation from: Translation from: Memorie dell'Istituto Italiano di Idrobiologia Dott.Marco de Marchi 31 181-203, 1974]

In recent times, some specialists have begun to study the subject of food selection of fish in an organized way, thus highlighting its importance. In the present work, the author intends to evaluate the impact of predation on the eupelagic zooplanktonic biocenosis of Lake Maggiore, producing, in this way, as far as possible, a basis for a better understanding of the population dynamics of the species of zooplankton directly involved. Another aspect which has been studied is that related to the mechanism of selective capture set in action by the predator. To this end the study tries to bear in mind that the subject should be interpreted as a function of numerous factors acting contemporaneously, that is as the interaction of characters peculiar to the predator and to the prey. The species studied, locally called ”bondella”, belongs to the family Salmonidae, subfamily Coregoninae and was introduced into Lake Maggiore in 1950.

Individual growth and seasonal cycle of Daphnia middendorffiana in an Alpine lake [Translation from: Memorie dell'Istituto Italiano di Idrobiologia Dott.Marco de Marchi 26 41-83, 1970]

The problem of the peculiar reproductive biology of the cladoceran Daphnia middendorffiana is investigated from a cytological viewpoint, and by direct observation the meiotic phenomena of the eggs both subitaneous and resting is studied. and during maturation, the true mechanism of the succession of reproductive phases of different ecological significance. Samples were collected in the Italian Alpine Lake of Campo 4°.

Aspects of the biology of coarse fish in the Dorset Stour

Some of the results from an investigation of five species of coarse fish, in the Stour River, carried out from 1968-1978 are presented in this article. The species involved were: Rutilus rutilis, Leuciscus leuciscus, L. cephalus, Esox lucius and Perca fluviatilis : which are of particular interest to anglers. Although these species show some similarities, as in the shape of the annual and seasonal growth curves, in most other respects each species occupies a distinct niche in the ecosystem and has a life-history strategy peculiar to itself. In this study only 5 species were investigated. When all the species present are considered the relationships or diversities suggested here will therefore be made far more complex.

Variabilité, circulation et chlorophylle dans la région du Dôme d'Angola en février-mars 1971

In February-March 1971 the hydrological conditions off Angola did not display the thermal dome mapped by Mazeika's averages (1967). Cold water cells observed are connected at the surface to a sinuous boundary between low-salinity coastal waters and high-salinity tropical oceanic waters. That boundary coincides rather regularly with an area where trades and SW winds alternate; photosynthesis growths rapidly in a thermoclinal layer that rises until 10 m of the surface but never outcrops. Below a poor and permanent homogeneous surface layer, chlorophyll concentrations show a distribution which is typical of divergence areas. Geostrophical and measured currents show off a transient process in horizontal and vertical movements, however the general curvature of the circulation is propitious to upwelling. Oxygen oversaturations of about 110%, suggest a moderate potential primary production which confirms slowness and alternation of movements. Also, the regular range of the various chemical and biological levels and moderate chlorophyll concentrations suggest an ecosystem where nutrients supply rapidly equilibrate phytoplankton consumption and not at all a 'phytoplankton bloom' area as that which exists in coastal upwelling. Values of Richardson's number show that instability becomes visible at the bottom of the euphotic layer. An evaluation of the vertical motion is inferred by the peculiar distribution and diurnal alternance of the winds shows that 'doming' structures may be sustained by local meteorological events.

Tarpon atlanticus in Colombia: a big fish in trouble

The natural history of Tarpon atlanticus (Valenciennes 1846) is reconstructed based on published information. Tarpon is a remarkable fish because of its peculiar larvae, large adult size, migration patterns and its capability to breathe atmospheric air. Destructive fisheries - some using dynamite - have much reduced the population of tarpon along the Caribbean coast of Colombia, and some catch data are presented which document this.

Fisheries survey of the River Otter 1978

This is the Fisheries survey of the River Otter report produced by South West Water Authority in 1979. This report focuses on the trout fishery in the River Otter and the possible effects of abstraction and/or pollution. A survey was carried out to describe the fish stocks. Trout and eels were the dominant species. The population structure of trout was peculiar, there being relatively few juveniles. Growth was good and there were numerous trout of take able size in the river at the end of the fishing season. Variations in the parameters measured are explained and nothing can be attributed to abstraction or pollution.

Deep coral and associated species taxonomy and ecology: (DeepCAST) II Expedition Report, Roatan, Honduras, May 21-28, 2011

NOAA has a mandate to explore and understand deep-sea coral ecology under Magnuson-Stevens Sustainable Fisheries Conservation Act Reauthorization of 2009. Deep-sea corals are increasingly considered a proxy for marine biodiversity in the deep-sea because corals create complex structure, and this structure forms important habitat for associated species of shrimp, crabs, sea stars, brittle stars, and fishes. Yet, our understanding of the nature of the relationships between deep-corals and their associated species is incomplete. One of the primary challenges of conducting any type of deep-sea coral (DSC) research is access to the deep-sea. The deep-sea is a remote environment that often requires long surface transits and sophisticated research vehicles like submersibles and remotely operated vehicles (ROVs). The research vehicles often require substantial crew, and the vehicles are typically launched from large research vessels costing many thousands of dollars a day. To overcome the problem of access to the deep-sea, the Deep Coral and Associated Species Taxonomy and Ecology (DeepCAST) Expeditions are pioneering the use of shore-based submersibles equipped to do scientific research. Shore-based subs alleviate the need for expensive ships because they launch and return under their own power. One disadvantage to the approach is that shore-based subs are restricted to nearby sites. The disadvantage is outweighed, however, by the benefit of repeated observations, and the opportunity to reduce the costs of exploration while expanding knowledge of deep-sea coral ecology.