scholarly journals Mitigation of seal-induced damage in salmon and whitefish trapnet fisheries by modification of the fish bag

2004 ◽  
Vol 61 (7) ◽  
pp. 1195-1200 ◽  
Author(s):  
Esa Lehtonen ◽  
Petri Suuronen
Keyword(s):  
Halichoerus Grypus ◽  
Coregonus Lavaretus ◽  
Wire Grid ◽  
The Past ◽  
Steel Wires ◽  
Bag Experiments ◽  
The Wire ◽  
The Difference ◽  
The Baltic ◽  
The Gulf Of Finland

Abstract During the past decade, seal-induced gear and catch damage has increased dramatically in the Baltic Sea. The problems are most severe in the coastal trapnet fisheries for salmon (Salmo salar) and whitefish (Coregonus lavaretus), where grey seals (Halichoerus grypus) in particular frequently visit the traps. There is an acute need for gear modifications and other solutions that can prevent seals from entering the fish bag of the traps. Modifications that have been tested in Finland include a wire grid installed in the funnel of the trap and a fish bag made of extra-strong netting material. In comparative fishing experiments conducted in 2001 in the Gulf of Finland the grid was made of 2-mm steel wires with 175-mm spacing. The average undamaged salmon catch per haul in the fish bag of modified trapnets was significantly higher (70%) than that of traditional traps (Mann–Whitney, p < 0.01). In the whitefish experiments, the average undamaged catch of whitefish per haul was 16% higher in modified trapnets than in traditional traps, but the difference was not significant (Mann–Whitney, p > 0.05). These results indicate that the wire grid did not prevent fish from swimming into the fish bag. Experiments also suggest that the wire grid and the extra-strong netting prevented seals from entering the bag. However, on some occasions seals were able to tear the fish through the netting. Underwater observations confirmed that the wire grid kept adult seals outside the bag while salmon and whitefish could be seen entering through the grid into the bag.

Whitefish (Coregonus lavaretus (L.)) landings in the Baltic Sea during the past 100 years: combining official datasets and grey literature

2013 ◽  
Vol 64 ◽  
pp. 133-152 ◽  
Author(s):  
Aare Verliin ◽  
Lauri Saks ◽  
Roland Svirgsden ◽  
Markus Vetemaa ◽  
Mehis Rohtla ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Grey Literature ◽  
Coregonus Lavaretus ◽  
The Baltic Sea ◽  
The Past ◽  
The Baltic

scholarly journals Estimation of grey seal (Halichoerus grypus) diet composition in the Baltic Sea

2007 ◽  
Vol 6 ◽  
pp. 177 ◽  
Author(s):  
Karl Lundström ◽  
Olle Hjerne ◽  
Karin Alexandersson ◽  
Olle Karlsson
Keyword(s):  
Baltic Sea ◽  
Diet Composition ◽  
Estimation Method ◽  
Clupea Harengus ◽  
Halichoerus Grypus ◽  
Coregonus Lavaretus ◽  
Correction Factors ◽  
The Baltic Sea ◽  
Hard Part ◽  
The Baltic

We examined the digestive tract contents from 145 grey seals (Halichoerus grypus) collected between 2001 and 2004 in the Baltic Sea. We compensated for biases introduced by erosion of otoliths, both by using additional hard-part structures other than otoliths, and species-specific size and numerical correction factors. In the absence of numerical correction factors based on feeding experiments for some species, we used correction factors based on a relationship between otolith recoveryrate and otolith width. A total of 24 prey taxa were identified but only a few species contributed substantially to the diet. The estimated diet composition was, independently of the prey number estimation method and diet composition estimation model used, dominated by herring (Clupea harengus), both by numbers and biomass. In addition to herring, common whitefish (Coregonus lavaretus) and sprat (Sprattus sprattus) were important prey, but cyprinids (Cyprinidae), eelpout (Zoarces viviparus), flounder (Platichtys flesus) and salmon (Salmo salar) also contributed significantly. Our results indicated dietary differences between grey seals of different age as well as between seals from the northern (Gulf of Bothnia) and the southern (Baltic Proper) Baltic Sea.

Smart Estimation Ver-H.1.0

2018 ◽  
Author(s):  
Sigit Haryadi
Keyword(s):  
Sample Size ◽  
Confidence Level ◽  
Time Span ◽  
Regression Equation ◽  
Weight Factor ◽  
The Past ◽  
Level Of Confidence ◽  
The Future ◽  
Future Value ◽  
The Difference

We cannot be sure exactly what will happen, we can only estimate by using a particular method, where each method must have the formula to create a regression equation and a formula to calculate the confidence level of the estimated value. This paper conveys a method of estimating the future values, in which the formula for creating a regression equation is based on the assumption that the future value will depend on the difference of the past values divided by a weight factor which corresponding to the time span to the present, and the formula for calculating the level of confidence is to use "the Haryadi Index". The advantage of this method is to remain accurate regardless of the sample size and may ignore the past value that is considered irrelevant.

scholarly journals The Burden of the Nondiversifiable Risk of Entrepreneurship

2010 ◽  
Vol 100 (3) ◽  
pp. 1163-1194 ◽  
Author(s):  
Robert E Hall ◽  
Susan E Woodward
Keyword(s):  
Relative Risk ◽  
Risk Aversion ◽  
Venture Capital ◽  
Dynamic Program ◽  
Certainty Equivalent ◽  
Important Class ◽  
Relative Risk Aversion ◽  
The Past ◽  
Equity Value ◽  
The Difference

Entrepreneurship is risky. We study the risk facing a well-documented and important class of entrepreneurs, those backed by venture capital. Using a dynamic program, we calculate the certainty-equivalent of the difference between the cash rewards that entrepreneurs actually received over the past 20 years and the cash that entrepreneurs would have received from a risk-free salaried job. The payoff to a venture-backed entrepreneur comprises a below-market salary and a share of the equity value of the company when it goes public or is acquired. We find that the typical venture-backed entrepreneur received an average of $5.8 million in exit cash. Almost three-quarters of entrepreneurs receive nothing at exit and a few receive over a billion dollars. Because of the extreme dispersion of payoffs, an entrepreneur with a coefficient of relative risk aversion of two places a certainty equivalent value only slightly greater than zero on the distribution of outcomes she faces at the time of her company's launch. (JEL G24, G32, L26, M13)

Contacts between the Late Roman Empire and North-Central Europe

1996 ◽  
Vol 76 ◽  
pp. 31-50 ◽  
Author(s):  
Aleksander Bursche
Keyword(s):  
Roman Empire ◽  
Central Europe ◽  
The Baltic Sea ◽  
European Continent ◽  
North Central ◽  
The Past ◽  
Vistula River ◽  
English Speaking ◽  
English Speaking World ◽  
The Baltic

The concept of Central Europe is understood here to cover the geographical centre of the European continent (i.e. the territory between the Elbe, Bug and Neman rivers, that is, eastern Germany, Poland, Bohemia, Slovakia and Lithuania), formerly treated in much of the English-speaking world as ‘Eastern Europe’. In the past six years, however, this area has been moving closer to the West. This paper shall concentrate on the region north of the Carpathian mountains, particularly the Vistula river-basin and Scandinavia (without Norway), in other words the territory round the Baltic Sea.

Predation by Sharks on the Grey Seal (Halichoerus grypus) in Eastern Canada

1983 ◽  
Vol 40 (3) ◽  
pp. 267-271 ◽  
Author(s):  
Paul Brodie ◽  
Brian Beck
Keyword(s):  
Key Words ◽  
Population Size ◽  
Halichoerus Grypus ◽  
Longline Fishery ◽  
Grey Seal ◽  
Eastern Canada ◽  
The Past ◽  
Harbour Seals ◽  
Commercially Important ◽  
Important Fish

The increase in population size of the grey seal (Halichoerus grypus) off eastern Canada over the past 20 yr may be attributed to a decrease in shark stocks, their supposed predators. Reduction of the shark population is presumed to have resulted from a directed longline fishery and, of greater significance, from a change in the fishery for swordfish (Xiphias gladius) from selective harpooning to pelagic longlining, which has produced a large bycatch of sharks. The resulting enhanced survival of grey seals is reflected in greater infestation of commercially important fish species by the codworm (Phocanema decipiens).Key words: grey seals, harbour seals, sharks, swordfish, codworm, predation, fisheries

The Flynn Effect

2018 ◽  
Author(s):  
Angela Duckworth ◽  
Keyword(s):  
Graduate School ◽  
The United States ◽  
Delay Of Gratification ◽  
Average Score ◽  
Past Century ◽  
Political Scientist ◽  
Abstract Reasoning ◽  
Flynn Effect ◽  
The Past ◽  
The Difference

In tandem with increases in delay of gratification, the human capacity for abstract reasoning has increased enormously over the past century. This phenomenon is called the Flynn Effect, after the political scientist who discovered it. I first learned about the Flynn Effect in graduate school. I remember thinking it was impossible. How could it be that as a species, we're getting smarter? And not just a little bit smarter. The size of the Flynn Effect is staggering: more than 30 IQ points—the difference between getting an average score on a standard intelligence test versus qualifying as mentally gifted. Gains are comparable in all areas of the United States and, indeed, around the world.

Avoiding Psychiatric Disability Overdiagnosis, Part 1: General Disability and Occupational Disability—Going Beyond Medical Impairment Assessments

2021 ◽  
Vol 26 (4) ◽  
pp. 3-7
Author(s):  
Fabien Gagnon ◽  
Les Kertay
Keyword(s):  
Mental Health ◽  
Work Disability ◽  
Well Being ◽  
Psychiatric Disability ◽  
Disability Assessment ◽  
Health Work ◽  
Occupational Disability ◽  
The Past ◽  
The Difference ◽  
Mental Health Work

Abstract Claims of occupational psychiatric disability have increased considerably over the past 20 years. To avoid psychiatric disability overdiagnosis, it is important to improve the clinical assessment of mental health work disability. This article discusses general disability issues and their impact on individual well-being, social participation, and frequently associated poverty. It defines the difference between impairment assessment and disability assessment, explores three common disability models, and raises issues about psychiatric disability and its potential overdiagnosis.

The very first experience of biological analysis of water in Saint-Petersburg

2021 ◽  
pp. 124-130
Author(s):  
Nataliya B. Balashova ◽  
Grigorii A. Kiselev
Keyword(s):  
Quality Analysis ◽  
Northern Coast ◽  
Original Source ◽  
Saint Petersburg ◽  
Neva River ◽  
The Baltic ◽  
First Time ◽  
Heavily Polluted Area ◽  
The Gulf Of Finland ◽  
Neva Bay

The biological method of water quality analysis, for the first time, was applied in Russia during the examination of Neva Bay of the Gulf of Finland in the Baltic Sea by Wislouch S.M. Neva River was a source of drinking water in St. Petersburg and, at the same time, a discharge for all city drains. As a result, it became hazardous to health, being a source of various diseases, especially cholera. From August 1911 to September 1912 pollution studies of the Bay were made to solve the question - where to send the treated waste water of the future sewage system of St. Petersburg. In total, 37 trips were made during this time, 510 samples were taken, including 375 plankton samples and 35 benthic samples. Wysłouch S. M. gave an overview of objects collected at 265 stations located in the area of Neva Bay - from estuary of Bolshaya Neva to Kronstadt, along the southern coast of the Bay and partially along the Northern coast. He brought a list of algae, including 97 species: Algae Cyanophyceae (writing all taxa retained on original source) – 17 species, Flagellata – 19 species, Peridineae – 1, One – 30, Conjugatae – 2, Diatomaceae – 28 species, Fungi (1), Bacteria (17), Protozoa (28), Rotatoria (17). Taking into account the algae and other organisms saprobity indices, areas with different degrees of contamination were identified. All the data was put on map of the Gulf. The most heavily polluted area was the Sea channel, and the area between the Lisij Nos and Kronstadt was the cleanest.

scholarly journals Frequency of deep convective clouds in the tropical zone from 10 years of AIRS data

2013 ◽  
Vol 13 (21) ◽  
pp. 10795-10806 ◽  
Author(s):  
H. H. Aumann ◽  
A. Ruzmaikin
Keyword(s):  
Brightness Temperature ◽  
Frequency Of Occurrence ◽  
Tropical Zone ◽  
Convective Clouds ◽  
The Past ◽  
Atmospheric Window ◽  
Deep Convective Clouds ◽  
Sst Anomaly ◽  
The Difference ◽  
Global Precipitation

Abstract. Deep convective clouds (DCCs) have been widely studied because of their association with heavy precipitation and severe weather events. Changes in the properties of DCCs are likely in a changing climate. Ten years of data collected by Atmospheric Infrared Sounder (AIRS) allow us to identify decadal trends in frequency of occurrence of DCCs over land and ocean. In the past, DCCs have been identified in the thermal infrared by three methods: (1) thresholds based on the absolute value of an atmospheric window channel brightness temperature; (2) thresholds based on the difference between the brightness temperature in an atmospheric window channel and the brightness temperature centered on a strong water vapor absorption line; and (3) a threshold using the difference between the window channel brightness temperature and the tropopause temperature based on climatology. Simultaneous observations of these infrared identified DCCs with the Advanced Microwave Sounding Unit–Humidity Sounder for Brazil (AMSU-HSB) using 183 GHz water channels provide a statistical correlation with microwave deep convection and overshooting convection. In the past 10 years, the frequency of occurrence of DCCs has decreased for the tropical ocean, while it has increased for tropical land. The area of the tropical zone associated with DCCs is typically much less than 1%. We find that the least frequent, more extreme DCCs show the largest trend in frequency of occurrence, increasing over land and decreasing over ocean. The trends for land and ocean closely balance, such that the DCC frequency changed at an insignificant rate for the entire tropical zone. This pattern of essentially zero trend for the tropical zone, but opposite land/ocean trends, is consistent with measurements of global precipitation. The changes in frequency of occurrence of the DCCs are correlated with the Niño34 index, which defines the sea surface temperature (SST) anomaly in the east-central Pacific. This is also consistent with patterns seen in global precipitation. This suggests that the observed changes in the frequency are part of a decadal variability characterized by shifts in the main tropical circulation patterns, which does not fully balance in the 10-year AIRS data record. The regional correlations and anti-correlations of the DCC frequency anomaly with the Multivariate ENSO Index (MEI) provide a new perspective for the regional analysis of past events, since the SST anomaly in the Nino34 region is available in the form of the extended MEI from 1871.

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