scholarly journals Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves

2004 ◽  
Vol 61 (10) ◽  
pp. 1900-1917 ◽  
Author(s):  
C Tara Marshall ◽  
Coby L Needle ◽  
Nathalia A Yaragina ◽  
Adnan M Ajiad ◽  
Evgeny Gusev
Keyword(s):  
Body Size ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Condition Index ◽  
Energy Reserves ◽  
Stored Energy ◽  
Stock Level ◽  
Length Relationship ◽  
Condition Indices

To evaluate interstock differences in condition, it would be advantageous to develop stock-level condition indices from standardized databases on weight and length. This study describes a method for estimating stock-level condition when individual-level observations on length and weight are not easily accessible. For each year in a 56-year time series (1946–2001) for Northeast Arctic cod (Gadus morhua), pseudo-observations of weight and length were generated by pairing the Norwegian and Russian values for weight-at-age provided annually to the assessment working group with estimates of length-at-age derived from the same databases. A weight–length relationship fit to each year was then used to predict weight-at-length, i.e., girth, for a range of standard lengths (30–120 cm). This index was uncorrelated with both the liver condition index and the abundance of Barents Sea capelin (Mallotus villosus), suggesting that at the stock level, the girth of cod is not necessarily indicative of the magnitude of stored energy reserves. Partitioning body size into length-at-age and girth revealed long-term trends in body size. In particular, large/old cod showed substantially higher values of both length-at-age and girth that could be the result of long-term increases in fishing mortality.

scholarly journals Barents Sea cod (Gadus morhua) diet composition: long-term interannual, seasonal, and ontogenetic patterns

2019 ◽  
Vol 76 (6) ◽  
pp. 1936-1936 ◽  
Author(s):  
Rebecca E Holt ◽  
Bjarte Bogstad ◽  
Joël M Durant ◽  
Andrey V Dolgov ◽  
Geir Ottersen
Keyword(s):  
Diet Composition ◽  
Gadus Morhua ◽  
Barents Sea

Comparing three body condition indices in amphibians: a case study of yellow-bellied toad Bombina variegata

2010 ◽  
Vol 31 (4) ◽  
pp. 558-562 ◽  
Author(s):  
Rodica Plăiaşu ◽  
Tibor Hartel ◽  
Raluca Ioana Băncilă ◽  
Dan Cogălniceanu ◽  
Joost Smets
Keyword(s):  
Body Size ◽  
Body Condition ◽  
Condition Index ◽  
Quality Parameters ◽  
Direct Measurements ◽  
Wide Range ◽  
Bombina Variegata ◽  
Condition Indices ◽  
Three Body

AbstractBody condition is important because it is correlated with population and habitat quality parameters. Since the direct measurements are either lethal or unreliable, a wide range of non-lethal body condition indices has been proposed. The aim of our study was to apply and compare three body condition indices (Fulton's index, relative body condition mass index and residual index) using body size indicator – body mass data for 24 populations of the yellow bellied toad (Bombina variegata). The condition index should be independent of body size indicator, in this case snout vent length (SVL). Therefore we tested all three indices for the statistical independence of SVL and for the normality of distribution. Fulton's index violated the independence assumption, whereas the relative body condition mass index did not have a normal distribution. Residual index was found both independent of SVL and normally distributed. Moreover, the residual index highlighted biological significant differences on the basis of altitude and season. Our results recommend the residual index as a useful tool in amphibian monitoring and conservation.

scholarly journals The code of the long-term biomass cycles in the Barents Sea

2003 ◽  
Vol 60 (6) ◽  
pp. 1251-1264 ◽  
Author(s):  
Harald Yndestad
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Temperature Cycle ◽  
Biomass Growth ◽  
Sea Temperature ◽  
Arctic Cod ◽  
Temperature Cycles ◽  
Large Fluctuations ◽  
Capelin Mallotus Villosus

Abstract Barents Sea capelin (Mallotus villosus), Norwegian spring-spawning herring (Cluea harengus), and Northeast Arctic cod (Gadus morhua) have been associated with large fluctuations of biomass growth. The cause of these large fluctuations has been poorly understood and led to problems in biomass management. The identification of a deterministic cause would provide the possibility of forecasting future biomass fluctuations. In this investigation, the Kola Section sea temperature and the biomasses of capelin, herring, and cod have been analyzed by a wavelet transform to identify the source of the long-term cycles. The wavelet analysis shows that the Kola Section temperature has dominant cycles at the lunar-nodal tide cycles of 3×18.6=55.8, 18.5 and 18.6/3 = 6.2 years. The recruitment of Barents Sea capelin, Norwegian spring-spawning herring, and Northeast Arctic cod has adopted an optimal recruitment cycle close to the stationary 6.2 years Kola temperature cycle. Long-term biomass growth is correlated to the phase relation between the biomass eigen-frequency cycle and the Kola temperature cycles. The biomasses of capelin, herring and cod have long-term growth when the 6.2 and 18.6 years Kola temperature cycles are positive at the same time. There is a long-term biomass reduction when the temperature cycles are not positive at the same time, and a biomass collapse when the temperature cycles are negative at the same time. The deterministic property of the 18.6 years lunar-nodal tide provides a new way of long-term biomass forecasting over periods of 50–80 years or more.

Fuzzy set approach to condition assessments of novel sustainable pavements in the Canadian climate

2009 ◽  
Vol 36 (5) ◽  
pp. 754-764 ◽  
Author(s):  
Amir Golroo ◽  
Susan L. Tighe
Keyword(s):  
Fuzzy Set ◽  
Ad Hoc ◽  
Condition Index ◽  
Concrete Pavement ◽  
Pervious Concrete ◽  
Pavement Condition ◽  
Pavement Structures ◽  
Condition Indices ◽  
Condition Assessments

Since the use of pervious concrete pavement structures (PCPSs) is essentially still in the trial stage in Canada, long-term and quantitative pavement condition data are not available. The existing approaches applied to assess pervious concrete pavement structure (PCPS) conditions are ad hoc and suffer from methodological limitations. A fuzzy set technique is proposed herein as an efficient tool for dealing with qualitative and incomplete pavement condition data on distress types, severities, densities, and weighting factors. Using this method, a comprehensive fuzzy condition index was developed based on Ministry of Transportation of Ontario (MTO) methodology and using fuzzy pavement condition data. This fuzzy condition index was converted to a single value that allowed for comparisons of pavement conditions using several ranking techniques. A case study of 24 PCPS sites was utilized to demonstrate how the fuzzy representations of the condition index compared with associated single values. It is shown that this approach can effectively provide extensive condition indices for PCPSs and rank them accordingly, using only limited and imprecise pavement condition data.

scholarly journals Effect of a fish stock's demographic structure on offspring survival and sensitivity to climate

2017 ◽  
Vol 114 (6) ◽  
pp. 1347-1352 ◽  
Author(s):  
Leif Christian Stige ◽  
Natalia A. Yaragina ◽  
Øystein Langangen ◽  
Bjarte Bogstad ◽  
Nils Chr. Stenseth ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Condition Index ◽  
Wide Distribution ◽  
Commercial Fishing ◽  
Demographic Structure ◽  
Data Set ◽  
Spawning Period ◽  
Spawning Stock ◽  
Eggs And Larvae

Commercial fishing generally removes large and old individuals from fish stocks, reducing mean age and age diversity among spawners. It is feared that these demographic changes lead to lower and more variable recruitment to the stocks. A key proposed pathway is that juvenation and reduced size distribution causes reduced ranges in spawning period, spawning location, and egg buoyancy; this is proposed to lead to reduced spatial distribution of fish eggs and larvae, more homogeneous ambient environmental conditions within each year-class, and reduced buffering against negative environmental influences. However, few, if any, studies have confirmed a causal link from spawning stock demographic structure through egg and larval distribution to year class strength at recruitment. We here show that high mean age and size in the spawning stock of Barents Sea cod (Gadus morhua) is positively associated with high abundance and wide spatiotemporal distribution of cod eggs. We find, however, no support for the hypothesis that a wide egg distribution leads to higher recruitment or a weaker recruitment–temperature correlation. These results are based on statistical analyses of a spatially resolved data set on cod eggs covering a period (1959−1993) with large changes in biomass and demographic structure of spawners. The analyses also account for significant effects of spawning stock biomass and a liver condition index on egg abundance and distribution. Our results suggest that the buffering effect of a geographically wide distribution of eggs and larvae on fish recruitment may be insignificant compared with other impacts.

scholarly journals The use of historical catch data to trace the influence of climate on fish populations: examples from the White and Barents Sea fisheries in the 17th and 18th centuries

2005 ◽  
Vol 62 (7) ◽  
pp. 1426-1435 ◽  
Author(s):  
Dmitry L. Lajus ◽  
Julia A. Lajus ◽  
Zoya V. Dmitrieva ◽  
Alexei V. Kraikovski ◽  
Daniel A. Alexandrov
Keyword(s):  
Atlantic Salmon ◽  
Gadus Morhua ◽  
Statistical Data ◽  
Barents Sea ◽  
Fishing Effort ◽  
Temperature Data ◽  
Average Weight ◽  
Historical Records ◽  
Formal Statistical Analysis

Abstract We analysed catch records of Atlantic salmon (Salmo salar), cod (Gadus morhua), and halibut (Hippoglossus hippoglossus and Reinhardtius hippoglossoides) from the 17th and 18th centuries from several locations of the Barents and White Seas areas. Historical records, found in Russian archives, allow analysis of long-term series of catches, and sometimes of the average weight of the fish. In total, we obtained data on catches of salmon for 51 years (for the period from 1615 to 1772) and of cod and halibut for 33 years (for the period from 1710 to 1793). These data are comparable with respect to fishing effort within the series. The data on Atlantic salmon are also comparable with statistical data for the period 1875–1915. We found notable fluctuations in catches and sometimes in the average weight of salmon. There was also fluctuation in catches of cod and halibut. Both observational comparison of catch series and temperature data and formal statistical analysis showed that catches tended to decrease during relatively colder periods.

scholarly journals Economic impacts of changes in the population dynamics of fish on the fisheries of the Barents Sea

2006 ◽  
Vol 63 (4) ◽  
pp. 611-625 ◽  
Author(s):  
P. Michael Link ◽  
Richard S.J. Tol
Keyword(s):  
Population Dynamics ◽  
Fish Species ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Short Term ◽  
Fishing Activity ◽  
The Barents Sea ◽  
Capelin Mallotus Villosus ◽  
Long Term Impact

Abstract A bioeconomic simulation model of the two interacting fish species cod (Gadus morhua) and capelin (Mallotus villosus) and their fisheries is presented and applied to assess the consequences of changes in the population dynamics of these important fish stocks in the Barents Sea. In each scenario, the population dynamics of the fish species are changed by reducing the reproduction-induced productivities and/or the carrying capacities. Stock sizes and landings of fish are calculated for each fishing period, and the net present values of profits from fishing are determined for time periods prior to and after the change in population dynamics. Results show that reduced growth rates or carrying capacities lead to lower stock levels and consequently to smaller catches. There is only a small short-term economic impact on the fisheries, but the long-term consequences are pronounced. In some cases, greater fishing activity in the first few years after the change in population dynamics causes harvests to remain stable despite diminishing stock sizes. This stabilizes the returns from fishing in the short term, but veils the apparent negative long-term impact on the fisheries resulting from adversely affected stock dynamics.

Analysis Of Condition and Swimming Performance in Juveniles of White Sea Bream, Diplodus Vulgaris

1997 ◽  
Vol 77 (3) ◽  
pp. 913-916 ◽  
Author(s):  
S. Planes ◽  
O. Hertel ◽  
J.-Y. Jouvenel
Keyword(s):  
White Sea ◽  
Swimming Performance ◽  
Condition Index ◽  
Initial Result ◽  
Sea Bream ◽  
Maximum Speed ◽  
Length Relationship ◽  
Three Samples ◽  
Condition Indices ◽  
Bad Weather

A pilot study was conducted to follow condition and swimming performances over two months using three samples of 50 juveniles of white sea bream, Diplodus vulgaris. The initial result indicated that the weight-length relationship followed the model; W=5.2xl0-3L349. According to this relationship, condition indices were estimated for each individual as the observed weight related to the computed weight. Measures of swimming velocities realized in an artificial flume show variations through time with an increase and decrease directly correlated to condition indices. Maximum speed of an individual was measured at 12.3 cm s1. Analysis of environmental conditions indicated that the decrease of condition index and swimming performances was related to bad weather which induced turbid water in juvenile habitats.

Humus state of chernozem at different ways of tillage in the agrosystems of the left-bank forest steppe of Ukraine

2015 ◽  
Vol 2 (3) ◽  
pp. 61-77
Author(s):  
O. Demydenko ◽  
V. Velychko
Keyword(s):  
Soil Cover ◽  
Forest Steppe ◽  
Left Bank ◽  
Energy Reserves ◽  
Soil Resources ◽  
Global Soil ◽  
Humus Accumulation ◽  
By Products ◽  
The Way

The contemporary condition of soil cover in Ukraine is characterized. The attention is focused onto widespread degradation processes in soils. The causes that determine the development of these negative processes are considered. The contemporary informational support for the condition of soil cover in Ukraine is estimated. In general, the current available information is of narrow-departmental nature, obtained by different methods and non-correlated monitoring programs. As a rule, it is stored in under-structured databases, incompatible with other information systems; mainly recorded on paper media unusable with modern technologies, whereby such information resources are diffi cult to be compiled together. These disadvantages are strong constraints against consistent usage of materials for evaluation, forecast and management of changes in the soil cover. The Soil Observation program should thereby be combined with Agrochemical Passportization and ecology-ameliora- tive monitoring; in other words, the application of innovative soil-agrochemical methodology is considered. Each individual type of surveys shall complement the others, and taken altogether, they shall constitute a con- sistent Information System, capable of solving the problems of assessing the condition, forecasting, manage- ment, usage and protection of soil resources. The monitoring procedures should be conducted on the basis of a new soil concept in line with unifi ed programs and methods, so as to meet European approaches to the maxi- mum extent. Such a technical composition enables getting information on present-day processes in soils, and is the only combination that actually helps us to “ecologize” our knowledge of soils, which is the leading trend in the scope of global soil-science. Thus obtained results will serve as a State-owned tool which would subse- quently facilitate the use and protection of soil resources all over the country, to be involved in a united global soil-information scope. The attention is focused onto social signifi cance of the information on soils and their fertility in terms of land resources optimization, as well as the formation of sustainable land use in Ukraine. Aim. To demonstrate the long-term effect of different ways of tillage of typical low-humus chernozem on the change in humus content and composition and the direction of transformation processes of organic fertili- zers. To study the changes in the structure of energy reserves in group and fractional composition of humus in typical low-humus light-loamy chernozem of the Forest-Steppe of Ukraine. Methods. Field, laboratory, microbiological, computational, mathematical and statistical. Results. It was determined that in conditions of long-term subsurface tillage the most effi cient humus accumulation occurs in the 0–20 cm layer of chernozem with simultaneous increase in its content in the lower part of the processed layer without any accumulation differentiation. Surface tillage leads to expressed differentiation in humus accumulation in the 0–20 cm layer of soil (0.005 % per year). When 6 t/ha of humus are replaced by 7 t/ha of by-products the intensity of humus accumulation is decreasing regardless of the way of tillage, but humus accumulation was found to be the most effi cient for subsurface tillage. The application of subsurface tillage leads to the increase in the ratio of C HA : C FA , which is conditioned by the increase in the humifi cation of plant remains of by-products in the 0−20 cm layer of soil by 110–112 % – for subsurface tillage, and by 105 % – for surface tillage. Conclusions. It was established that systematic subsurface tillage of typical chernozem of the Left-Bank Forest-Steppe of Ukraine leads to the structuring both of the total reserves of energy С org , and its quality content, aimed at the increase in the intensity of the processes of humifi cation and accumulation of organic carbon, and the decrease in miner- alization. The ratio of energy reserves С org of humic acids to fulvic acids in the 0−30 cm layer of chernozem is 1.85−1.87 regardless of the way of tillage, which testifi es to the repeatability of humus accumulation, but the total reserves of energy С org was higher for subsurface tillage (+ 31 Teracalorie/ha) compared to deep plough- ing. As for the surface tillage, the energy enrichment was at the level of deep ploughing.

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