Harvest Control for Schooling Fish Stocks under Cyclic Oceanographic Regimes: A Case for Precaution and Gathering Auxiliary Information

1998 ◽  
pp. 853-872 ◽  
Author(s):  
M Vasconcellos ◽  
T Pitcher
Keyword(s):  
Auxiliary Information ◽  
Fish Stocks ◽  
Schooling Fish

scholarly journals A Comparison between Two Sonic Measuring Systems for Demersal Fish

1970 ◽  
Vol 27 (4) ◽  
pp. 737-742 ◽  
Author(s):  
R. G. Dowd ◽  
E. Bakken ◽  
O. Nakken
Keyword(s):  
Linear Relation ◽  
Demersal Fish ◽  
High Density ◽  
Measuring Systems ◽  
Fish Stocks ◽  
Digital Counter ◽  
Schooling Fish ◽  
Wide Range ◽  
Two Systems

Two sonic methods for estimation of abundance of fish stocks, the echo integrator and the digital counter methods, were compared on single and schooling fish in the Lofoten area of Norway during March 1969. Good correlation was obtained between the two systems for both situations, but the slopes of the regressions of integrated values on the digital counter differed significantly between low and high density fish concentrations. This suggests that the two systems treated the echo information differently, but nevertheless maintained a linear relation between themselves over a wide range of counts.

Prey harvest of the Australasian gannet (Sula serrator) in Tasmania

1993 ◽  
Vol 20 (6) ◽  
pp. 777 ◽  
Author(s):  
N Brothers ◽  
R Gales ◽  
D Pemberton
Keyword(s):  
Prey Species ◽  
Fork Length ◽  
Commercial Fishery ◽  
Target Species ◽  
Jack Mackerel ◽  
Fish Stocks ◽  
Schooling Fish ◽  
Mean Size ◽  
The Mean ◽  
Prey Items

This study investigated the diet of the Australasian gannet (Sula serrator) at Pedra Branca, an island off the south coast of Tasmania. A total of 109 regurgitations representing 394 prey items was collected from the gannets between 1986 and 1991. Pelagic schooling fish, with fork length less than 200 mm, were the most common prey items. Redbait (Emmelichthys nitidus) and jack mackerel (Trachurus declivis) were the dominant prey species, with redbait being the most numerous, contributing 72% by number and 56% by mass. The diet of the Australasian gannet was compared with the fish taken by the commercial purse seine fishery in which jack mackerel was the target species and redbait a bycatch. The mean size of commercially caught fish of both species was greater than that taken by the gannets. We suggest that there is a threshold (in the size of the fish) above which the birds cannot capture and handle the prey, effectively limiting the resource available to them. It appears that the commercial fishery and the gannets, while harvesting the same species, exploit schools of different-size fish. The potential of Australasian gannets as indicators of fish stocks is discussed.

The Impact of Missing and Error-Prone Auxiliary Information on Sparse-Matrix Sub-Population Parameter Estimates

Methodology ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 89-99 ◽  
Author(s):  
Leslie Rutkowski ◽  
Yan Zhou
Keyword(s):  
Sparse Matrix ◽  
Small Body ◽  
Auxiliary Information ◽  
Poor Quality ◽  
Quality Data ◽  
Estimation Methods ◽  
Parameter Estimates ◽  
Population Parameter ◽  
Conditioning Model ◽  
The Impact

Abstract. Given a consistent interest in comparing achievement across sub-populations in international assessments such as TIMSS, PIRLS, and PISA, it is critical that sub-population achievement is estimated reliably and with sufficient precision. As such, we systematically examine the limitations to current estimation methods used by these programs. Using a simulation study along with empirical results from the 2007 cycle of TIMSS, we show that a combination of missing and misclassified data in the conditioning model induces biases in sub-population achievement estimates, the magnitude and degree to which can be readily explained by data quality. Importantly, estimated biases in sub-population achievement are limited to the conditioning variable with poor-quality data while other sub-population achievement estimates are unaffected. Findings are generally in line with theory on missing and error-prone covariates. The current research adds to a small body of literature that has noted some of the limitations to sub-population estimation.

Relationships between temperature and Pacific hake distribution vary across latitude and life-history stage

2020 ◽  
Vol 639 ◽  
pp. 185-197 ◽  
Author(s):  
MJ Malick ◽  
ME Hunsicker ◽  
MA Haltuch ◽  
SL Parker-Stetter ◽  
AM Berger ◽  
...  
Keyword(s):  
Life History ◽  
Environmental Effects ◽  
Environmental Conditions ◽  
Vancouver Island ◽  
Additive Models ◽  
Life History Stage ◽  
Fish Stocks ◽  
Merluccius Productus ◽  
Multiple Dimensions ◽  
Effects Of Temperature

Environmental conditions can have spatially complex effects on the dynamics of marine fish stocks that change across life-history stages. Yet the potential for non-stationary environmental effects across multiple dimensions, e.g. space and ontogeny, are rarely considered. In this study, we examined the evidence for spatial and ontogenetic non-stationary temperature effects on Pacific hake Merluccius productus biomass along the west coast of North America. Specifically, we used Bayesian additive models to estimate the effects of temperature on Pacific hake biomass distribution and whether the effects change across space or life-history stage. We found latitudinal differences in the effects of temperature on mature Pacific hake distribution (i.e. age 3 and older); warmer than average subsurface temperatures were associated with higher biomass north of Vancouver Island, but lower biomass offshore of Washington and southern Vancouver Island. In contrast, immature Pacific hake distribution (i.e. age 2) was better explained by a nonlinear temperature effect; cooler than average temperatures were associated with higher biomass coastwide. Together, our results suggest that Pacific hake distribution is driven by interactions between age composition and environmental conditions and highlight the importance of accounting for varying environmental effects across multiple dimensions.

CRITICAL FACTORS OF WATER CONTENT FOR FISH STOCKS IN THE WATER RESERVOIRS OF KAZAKHSTAN

2017 ◽  
pp. 9-18
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Evgeniy Vyacheslavovich Kulikov
Keyword(s):  
Water Content ◽  
Water Level ◽  
Water Availability ◽  
Hydrological Regime ◽  
Fishing Effort ◽  
Water Reservoirs ◽  
The Caspian Sea ◽  
Annual Fish ◽  
Commercial Fish ◽  
Fish Stocks

The hydrological regime of water reservoirs in different years has a decisive impact on the abundance of commercial fish stocks and the quality of ichthyocenoses. In this connection in 2015-2016 there was conducted a retrospective analysis and ranking of hydrological regime impact on these factors. The paper gives evaluation of catches and fish stocks under different scenarios of water availability in the main fishing ponds of the Republic of Kazakhstan that give about 80% of the annual fish catch of the country (except the Caspian Sea). There were analyzed 2000 factors of hydrological regime (water level, annual discharge) and 1845 factors of fishing stocks (catches, abundance, fish biomass). The paper determines the critical characteristics of water availability for fish stocks. There have been proposed a number of administrative decisions and actions in case if water content would approach to the critical level. Among them: limitation of fish catches in the following year; widening zones restricted for fishing; intensification of safety measures of the fish young in residual ponds during arid periods; introduction of catch standards for a unit of fishing effort in low-water years, high-water years and years with normal water level in rivers.

Pescadores migrantes: análisis de su dinámica e integración Social

2019 ◽  
Vol 37 (3) ◽  
pp. 18
Author(s):  
Fernando González Laxe
Keyword(s):  
Renewable Resources ◽  
Sustainable Management ◽  
Social Groups ◽  
Technological Innovations ◽  
Social Competition ◽  
Factors Affecting ◽  
Fish Stocks ◽  
Fishery Resources ◽  
Migration Dynamics ◽  
The Many

The globalization of the economy encourages massive population displacements and inevitably generates a cosmopolitization of societies. This leads to concern, misunderstanding and rejection. The most vulnerable social groups in society can perceive the population as intruders and enemies in social competition. Undoubtedly, the extreme spatial instability of fishery resources is among the many factors affecting migration dynamics. Various reasons for the mobility of fishermen are relevant around this concept. These include aspect related to traditions, to the capitalisation of activity, to technological innovations, and to innovation exchanges concerning the location of fish stocks. This article reflects on spatial increase of fishermen’s. The analyse are part of the paradigm of the sustainable management of common renewable resources, in particular fishery resources. It presents three lines of analysis: the reason for mobility; the choice of destination; and are the integration into host units.

RECLAMATION AND CULVERT CROSSINGS MADE OF CORRUGATED PIPES ON SPAWNING STREAMS

2020 ◽  
pp. 68-77
Author(s):  
O.N. CHERNYKH ◽  
◽  
A.V. RBURLACHENKO
Keyword(s):  
Single Point ◽  
Experimental Studies ◽  
Fish Passage ◽  
Future Research ◽  
Fish Stocks ◽  
Metal Structures ◽  
Natural Reproduction ◽  
Spiral Shape ◽  
Corrugated Metal ◽  
Spawning Streams

Recommendations are presented for solving issues that arise in the design and operation of tubular transport crossings of corrugated metal structures through spawning streams while ensuring the safety and natural reproduction of fish stocks. There are discussed the results of experimental studies of culverts made of metal corrugated pipes with a normal and spiral shape of corrugation the bottom of which is buried and filled with suitable granular material to the level of the natural channel of a small watercourse. It is established that when 10% of the area of the corrugated pipe is occupied by stone filling, its throughput is reduced by about 10-12%. Based on the review of the existing literature and the results of laboratory experiments, data is provided to estimate the values of the roughness coefficients of the composite cross-section of a single-point junction and directions for future research on culvert reclamation are outlined. Studying of the structure of the velocity distribution in culverts can lead to the improved conditions for fish passage without installing special structural elements in the transit path of the fish passage structure.

Privacy-preserving Collaborative Training for Medical Image Analysis Based on Multi-Blockchain

2020 ◽  
Vol 23 ◽  
Author(s):  
Wanlu Zhang ◽  
Qigang Wang ◽  
Mei Li
Keyword(s):  
Medical Image ◽  
Data Privacy ◽  
Medical Image Analysis ◽  
Auxiliary Information ◽  
Training Process ◽  
Private Data ◽  
Medical Institutions ◽  
Model Training ◽  
Collaborative Training ◽  
Similar Task

Background: As artificial intelligence and big data analysis develop rapidly, data privacy, especially patient medical data privacy, is getting more and more attention. Objective: To strengthen the protection of private data while ensuring the model training process, this article introduces a multi-Blockchain-based decentralized collaborative machine learning training method for medical image analysis. In this way, researchers from different medical institutions are able to collaborate to train models without exchanging sensitive patient data. Method: Partial parameter update method is applied to prevent indirect privacy leakage during model propagation. With the peer-to-peer communication in the multi-Blockchain system, a machine learning task can leverage auxiliary information from another similar task in another Blockchain. In addition, after the collaborative training process, personalized models of different medical institutions will be trained. Results: The experimental results show that our method achieves similar performance with the centralized model-training method by collecting data sets of all participants and prevents private data leakage at the same time. Transferring auxiliary information from similar task on another Blockchain has also been proven to effectively accelerate model convergence and improve model accuracy, especially in the scenario of absence of data. Personalization training process further improves model performance. Conclusion: Our approach can effectively help researchers from different organizations to achieve collaborative training without disclosing their private data.

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