scholarly journals Effects of Environmental Changes on Reproductive Process of Walleye Pollock in the Subarctic Ocean (Background of HUBEC Program around Funka Bay as a Modelling Area)

1994 ◽  
Vol 3 (4) ◽  
pp. 303-308_1 ◽  
Author(s):  
Yasunori Sakurai ◽  
Hideo Miyake
Keyword(s):  
Environmental Changes ◽  
Walleye Pollock ◽  
Reproductive Process ◽  
Funka Bay

Effect of environmental factors and prey species on daytime and nighttime vertical distribution of juvenile walleye pollock in and around Funka Bay

2014 ◽  
Vol 80 (2) ◽  
pp. 139-149 ◽  
Author(s):  
Yohei Kawauchi ◽  
Masayuki Chimura ◽  
Takashi Mutoh ◽  
Masamichi Watanobe ◽  
Hokuto Shirakawa ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Vertical Distribution ◽  
Prey Species ◽  
Walleye Pollock ◽  
Funka Bay

scholarly journals Annual variation in otolith increment widths of walleye pollock (Gadus chalcogrammus) larvae in Funka Bay, Hokkaido, Japan

2015 ◽  
Vol 24 (4) ◽  
pp. 325-334 ◽  
Author(s):  
Yota Kano ◽  
Tetsuya Takatsu ◽  
Yutaro Hashimoto ◽  
Yuta Inagaki ◽  
Toshikuni Nakatani
Keyword(s):  
Annual Variation ◽  
Walleye Pollock ◽  
Funka Bay ◽  
Otolith Increment

scholarly journals THE USE OF REMOTE SENSING, REGRESSION QUANTILES, AND GIS APPROACHES FOR MODELING OF SCALLOP LARVAE: A Case Study in Funka Bay, Hokkaido, Japan

2011 ◽  
Vol 6 (2) ◽  
pp. 191
Author(s):  
I Nyoman Radiarta
Keyword(s):  
Remote Sensing ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Environmental Changes ◽  
Monitoring Program ◽  
Environmental Parameters ◽  
Sea Surface ◽  
Remotely Sensed Data ◽  
Funka Bay ◽  
Scallop Larvae

In the development of scallop cultivation in Japan, larvae collection and propagation become an important factor. Although the monitoring program has been conducted, modeling of species distribution is becoming an important tool for understanding the effects of environmental changes and resources management. This study was conducted to construct a model for providing estimation of the scallop larvae distribution in Funka Bay, Hokkaido, Japan using the integration of remote sensing, Regression Quantile (RQ) and Geographic Information System (GIS)-based model. Data on scallop larvae were collected during one year spawning season from April to July 2003. Environmental parameters were extracted from multi sensor remotely sensed data (chlorophyll-a and sea surface temperature) and a hydrographic chart (water depth). These parameters together with larvae data were then analyzed using RQ. Finally, spatial models were constructed within a GIS by combining the RQ models with digital map of environmental parameters. The results show that the model was best explained by using only sea surface temperature. The highest larvae densities were predicted in a relatively broad distribution along with the shallow water regions (Toyoura and Sawara to Yakumo) and the deeper water areas (center of the bay). The spatial model built from the RQ provided robust estimation of the scallop larvae distributions in the study area, as confirmed by model validation using independent data. These findings could contribute on the monitoring program in this region in order to distinguish the potential areas for an effective spat collection.

scholarly journals VERTICAL DISTRIBUTION OF WALLEYE POLLOCK JUVENILES BEFORE AND AFTER THE PERIOD OF TRANSITION FOR FEEDING IN FUNKA BAY, HOKKAIDO, JAPAN

2011 ◽  
Vol 19 (3) ◽  
Author(s):  
Yohei Kawauchi ◽  
Osamu Shida ◽  
Hiroya Okumura ◽  
Naoki Tojo ◽  
Hiroki Yasuma ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Walleye Pollock ◽  
Funka Bay ◽  
Before And After

Evaluation of the reproductive parameters of female neotropical migratory fish from a lotic and lentic environment of a dammed river

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Luiza Mariz Amador De Souza ◽  
Gabriela Gonçalves Theobaldo ◽  
Elizete Rizzo ◽  
José Enemir Dos Santos ◽  
Nilo Bazzoli ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Reproductive Potential ◽  
Microscopic Analysis ◽  
Oocyte Diameter ◽  
Migratory Fish ◽  
Reproductive Parameters ◽  
Follicular Atresia ◽  
Biometric Data ◽  
Reproductive Process ◽  
Lotic Environment

The fragmentation of watercourses caused by dams is considered to be one of the main threats to aquatic biodiversity worldwide, especially for ichthyofauna. Several studies have shown that the environmental modifications caused by dammed water bodies can change the various reproductive parameters of freshwater fish. Therefore, the present study aims to comparatively analyze the reproductive potential of female Megaleporinus reinhardti, a migratory species, sampled in the lentic environment of the Três Marias Reservoir and the lotic environment of the São Francisco River. Biometric data were obtained from 79 females and the biological indices were subsequently calculated. Additionally, the microscopic analysis of the gonads was performed, and the follicular atresia index was compared. The results of the study show that fish from the lotic environment presented higher gonadal volume, fecundity, and oocyte diameter, and a lower follicular atresia index when compared to fish from the lentic environment. In summary, the data suggest that environmental changes, i.e. from a lotic to lentic environment, caused by river damming, may negatively affect the reproductive process of migratory fish, such as M. reinhardti, and impair the maintenance of the population of this species in lentic environments

A probabilistic cellular automata approach for predator–prey interactions of arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) in the eastern Bering Sea

2012 ◽  
Vol 69 (2) ◽  
pp. 259-272
Author(s):  
Kun Chen ◽  
Kung-Sik Chan ◽  
Kevin M. Bailey ◽  
Kerim Aydin ◽  
Lorenzo Ciannelli
Keyword(s):  
Cellular Automata ◽  
Bering Sea ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Predator Prey ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma ◽  
Arrowtooth Flounder

We developed a hybrid cellular automata (CA) modelling approach to explore the dynamics of a key predator–prey interaction in a marine system; our study is motivated by the quest for better understanding of the scale and heterogeneity-related effects on the arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) dynamics during the summer feeding season in the eastern Bering Sea (EBS), but can be readily extended to other systems. The spatially explicit and probabilistic CA model incorporates individual behaviours and strategies and local interactions among species, as well as spatial and temporal heterogeneity due to geographical and (or) environmental changes in the physical environment. The model is hybridized, with an individual-based model (IBM) approach for increasing its capacity and continuum and for balancing between computational efficiency and model validity, which makes it suitable for simulating predator–prey dynamics in a large, complex ecological environment. We focus on the functional and aggregative responses of predators to prey density at different spatial scales, the effects of individual behaviours, and the impacts of systematic heterogeneity. Simulations from the model with suitable parameter values share qualitatively similar features found in field observations, e.g., local aggregations around hydrographical features. Spatial heterogeneity is an important aspect of whether local-scale functional and aggregative responses reflect those operating over large, or global, scales.

scholarly journals Methodological approaches to the analysis of the functioning of agricultural ecosystems in the context of anthropogenic environmental changes

2021 ◽  
Vol 262 ◽  
pp. 03019
Author(s):  
Laura Khalishkhova ◽  
Anzhela Temrokova ◽  
Inga Guchapsheva ◽  
Oksana Bagova ◽  
Madina Marzhokhova
Keyword(s):  
Environmental Changes ◽  
Natural Capital ◽  
Agricultural Ecosystem ◽  
Reproductive Process ◽  
Agricultural Ecosystems ◽  
Social Ecological ◽  
Economic Parameters ◽  
Methodological Approaches ◽  
Methodological Principles ◽  
Main Components

The study provides methodological approaches to the analysis of the functioning of agricultural ecosystems in the context of anthropogenic environmental changes, based on the assessment of rationalization and efficient use of natural capital through energy consumption for the production of final products, and describes the agricultural ecosystem operating on the principles of market economy. A set of general methodological principles for analyzing the functioning of an agricultural ecosystem has been proposed. An algorithm for achieving optimal ecological and economic parameters of the functioning of the components of the agricultural ecosystem is presented, including a set of step-by-step actions, as well as multi-functional dependences of the reproductive capabilities of the main components of the agricultural ecosystem. A complex of ecological and economic parameters of the reproductive process of the agricultural ecosystem, used for its optimization, has been developed. The interpretation of terms and concepts, generalized in the course of the research within the framework of the presented approach, is carried out. A new principle of agricultural ecosystem organization is highlighted, considering it as a social, ecological and economic system.

scholarly journals Acoustic Observation of Spawning Walleye Pollock Theragra chalcogramma and Hydrographic Condition in Funka Bay.

1995 ◽  
Vol 61 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Kohji Iida ◽  
Tohru Mukai ◽  
DooJin Hwang ◽  
Tomoko Hayakawa ◽  
Yukihiro Matsuyama
Keyword(s):  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Funka Bay ◽  
Walleye Pollock Theragra Chalcogramma ◽  
Hydrographic Condition ◽  
Acoustic Observation
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