scholarly journals Stock assessment of the Baltic Sea fish in the ICES Working Groups

Trudy VNIRO ◽  
2018 ◽  
Vol 174 ◽  
pp. 58-71
Author(s):  
V. М. Amosov ◽  
◽  
А. S. Zezera ◽  
A. I. Karpushevskaia ◽  
T. G. Vasilijeva ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Stock Assessment ◽  
The Baltic Sea ◽  
Working Groups ◽  
The Baltic ◽  
Sea Fish

Impact of 21st century climate change on the Baltic Sea fish community and fisheries

2007 ◽  
Vol 13 (7) ◽  
pp. 1348-1367 ◽  
Author(s):  
BRIAN R. MACKENZIE ◽  
HENRIK GISLASON ◽  
CHRISTIAN MÖLLMANN ◽  
FRIEDRICH W. KÖSTER
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
21St Century ◽  
Fish Community ◽  
The Baltic Sea ◽  
The Baltic ◽  
Sea Fish

scholarly journals The influence of uncertainty in target strength on abundance indices based on acoustic surveys: examples of the Baltic Sea herring and sprat

2009 ◽  
Vol 66 (6) ◽  
pp. 1404-1409 ◽  
Author(s):  
Svetlana M. Kasatkina
Keyword(s):  
Baltic Sea ◽  
Size Structure ◽  
Stock Assessment ◽  
Clupea Harengus ◽  
Statistical Characteristics ◽  
Target Strength ◽  
The Baltic Sea ◽  
Abundance Indices ◽  
Acoustic Surveys ◽  
The Baltic

Abstract Kasatkina, S. M. 2009. The influence of uncertainty in target strength on abundance indices based on acoustic surveys: examples of the Baltic Sea herring and sprat. – ICES Journal of Marine Science, 66: 1404–1409. In situ, target-strength (TS) measurements at 38 kHz and an analysis of biometric fish characteristics are presented for the Baltic Sea herring (Clupea harengus membras) and sprat (Sprattus sprattus). It is demonstrated that the application of two TS–length functions for the Baltic Sea clupeids, the first for young herring and sprat and the second for adult herring, is reasonable, and the two functions can therefore replace the well-known equation used since 1983. Parameters of the proposed relationships, accompanied by their statistical characteristics, are included in a model to obtain uncertainty in acoustically derived abundance indices. Major components of survey uncertainty, such as spatial variability, species composition, and size structure, are also included in the simulation. The proposed TS functions should permit estimates of more realistic abundance dynamics of Baltic Sea clupeids, by years and age groups, thereby providing important information for stock assessment models.

Incorporating environmental variability in stock assessment: predicting recruitment, spawner biomass, and landings of sprat (Sprattus sprattus) in the Baltic Sea

2008 ◽  
Vol 65 (7) ◽  
pp. 1334-1341 ◽  
Author(s):  
Brian R. MacKenzie ◽  
Jan Horbowy ◽  
Fritz W. Köster
Keyword(s):  
Baltic Sea ◽  
Environmental Variability ◽  
Positive Impact ◽  
Stock Assessment ◽  
Assessment Procedure ◽  
The Baltic Sea ◽  
Sprattus Sprattus ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The Baltic

Temperature has a significant positive impact on recruitment of sprat, Sprattus sprattus, in the Baltic Sea. Here we evaluate whether an existing recruitment model for the year classes 1973–1999 can forecast recruitment for five new year classes. The coefficient of variation (CV) of predictions was 5%, and four of five new year classes were within 95% confidence limits of predictions made by the earlier model. We then assimilated climatic, oceanographic, and recruitment linkages and their uncertainty into the standard International Council for the Exploration of the Sea (ICES) assessment procedure to predict key advisory-related variables such as spawning stock biomass (SSB) and landings. These linkages enable a forecast of recruitment earlier than the annual assessment meeting. Forecasts made using the North Atlantic Oscillation to predict the 2006 year class showed that spawner biomass would be 15% lower than spawner biomass calculated using the ICES standard methodology. The difference in perception of future biomass does not affect the advice for the stock because the spawning stock biomass is greater than the critical biomass limit (SSB > BPA). However, when this is not the case or when it is desirable to broaden the ecosystem basis for fisheries management, incorporation of knowledge of recruitment processes may be beneficial.

scholarly journals Eastern Baltic cod in distress: biological changes and challenges for stock assessment

2015 ◽  
Vol 72 (8) ◽  
pp. 2180-2186 ◽  
Author(s):  
Margit Eero ◽  
Joakim Hjelm ◽  
Jane Behrens ◽  
Kurt Buchmann ◽  
Massimiliano Cardinale ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Gadus Morhua ◽  
Stock Assessment ◽  
The Baltic Sea ◽  
Stock Status ◽  
Management Measures ◽  
Stock Assessments ◽  
Management Advice ◽  
The Baltic ◽  
Eastern Baltic

Abstract The eastern Baltic (EB) cod (Gadus morhua) stock was depleted and overexploited for decades until the mid-2000s, when fishing mortality rapidly declined and biomass started to increase, as shown by stock assessments. These positive developments were partly assigned to effective management measures, and the EB cod was considered one of the most successful stock recoveries in recent times. In contrast to this optimistic view, the analytical stock assessment failed in 2014, leaving the present stock status unclear. Deteriorated quality of some basic input data for stock assessment in combination with changes in environmental and ecological conditions has led to an unusual situation for cod in the Baltic Sea, which poses new challenges for stock assessment and management advice. A number of adverse developments such as low nutritional condition and disappearance of larger individuals indicate that the stock is in distress. In this study, we (i) summarize the knowledge of recent changes in cod biology and ecosystem conditions, (ii) describe the subsequent challenges for stock assessment, and (iii) highlight the key questions where answers are urgently needed to understand the present stock status and provide scientifically solid support for cod management in the Baltic Sea.

scholarly journals Recovery of depleted Baltic Sea fish stocks: a review

2010 ◽  
Vol 67 (9) ◽  
pp. 1856-1860 ◽  
Author(s):  
Robert Aps ◽  
Hans Lassen
Keyword(s):  
Baltic Sea ◽  
Management Strategy ◽  
Action Plan ◽  
The Baltic Sea ◽  
Fish Stocks ◽  
Management Measures ◽  
The Baltic ◽  
Sea Fish ◽  
Term Management

Abstract Aps, R., and Lassen, H. 2010. Recovery of depleted Baltic Sea fish stocks: a review. – ICES Journal of Marine Science, 67: 1856–1860. Attempts to recover some depleted Baltic fish stocks between 1995 and 2008 are reviewed. Management measures aimed at recovery were adopted by competent authorities (until 2005 the International Baltic Fisheries Commission, IBSFC), including the Baltic Salmon Action Plan (1997), Long-Term Management Strategy for Cod Stocks in the Baltic Sea (1999), Long-Term Management Strategy for the Sprat Stock in the Baltic Sea (2000), Recovery Plan for Baltic Cod (2001), and the Long-Term Objectives and Strategies for the Management of Baltic Sea Herring (2000–2002). For all stocks, TACs have been set systematically more than the scientific advice based on sustainable exploitation. We interpret this as “decision overfishing”. There is also evidence of extensive underreporting of catches, which is interpreted as “implementation overfishing”. This means that a management body is knowingly maintaining a situation of overfishing. Nevertheless, measures have also been taken to combat the situation. Our analysis suggests that decision overfishing is related strongly to overcapacity of the fleets. The combination of decision overfishing and implementation overfishing, and not the management measures per se, could be the reason for the failure of depleted stocks to recover.

Modelling indices of abundance and size-based indicators of cod and flounder stocks in the Baltic Sea using newly standardized trawl survey data

2017 ◽  
Vol 74 (5) ◽  
pp. 1322-1333 ◽  
Author(s):  
Alessandro Orio ◽  
Ann-Britt Florin ◽  
Ulf Bergström ◽  
Ivo Šics ◽  
Tatjana Baranova ◽  
...  
Keyword(s):  
Time Series ◽  
Baltic Sea ◽  
Stock Assessment ◽  
Generalized Additive Models ◽  
Sustainable Use ◽  
Demersal Fish ◽  
Additive Models ◽  
Trawl Survey ◽  
The Baltic Sea ◽  
The Baltic

Standardized indices of abundance and size-based indicators are of extreme importance for monitoring fish population status. The main objectives of the current study were to (i) combine and standardize recently performed trawl survey with historical ones, (ii) explore and discuss the trends in abundance, and (iii) the trends in maximum length (Lmax) for cod (Gadus morhua) and flounder (Platichthys flesus) stocks in the Baltic Sea. Standardization of catch per unit of effort (CPUE) from trawl surveys from 1978 to 2014 to swept area per unit of time was conducted using information on trawling speed and horizontal opening of the trawls. CPUE data for cod and flounder stocks were modelled using generalized additive models (GAMs) in a delta modelling approach framework, while the Lmax data were modelled using ordinary GAMs. The CPUE time series of the Eastern Baltic cod stock closely resembles the spawning stock biomass trend from analytical stock assessment. The results obtained furnish evidence of the cod spill-over from Subdivisions (SD) 25–28 to SD 24. The decline of Lmax in recent years was evident for both species in all the stocks analysed indicating that the demersal fish community is becoming progressively dominated by small individuals. It is concluded that the standardization of long time series of fisheries-independent data constitutes a powerful tool that could help improve our knowledge on the dynamics of fished populations, thus promoting a long-term sustainable use of these marine resources.

Temporal and spatial sedimentation rate variabilities in the eastern Gotland Basin, the Baltic Sea

Boreas ◽  
2002 ◽  
Vol 31 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Christian Christiansen ◽  
Helmar Kunzendorf ◽  
Kay-Christian Emeis ◽  
Rudolf Endler ◽  
Ulrich Struck ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Sedimentation Rate ◽  
The Baltic Sea ◽  
Gotland Basin ◽  
Temporal And Spatial ◽  
The Baltic

Russian Oil: Production and Exports

2003 ◽  
pp. 136-146
Author(s):  
K. Liuhto
Keyword(s):  
Baltic Sea ◽  
Statistical Data ◽  
Oil Production ◽  
The Baltic Sea ◽  
North West ◽  
The North ◽  
Oil Transportation ◽  
Sea Ports ◽  
The Baltic

Statistical data on reserves, production and exports of Russian oil are provided in the article. The author pays special attention to the expansion of opportunities of sea oil transportation by construction of new oil terminals in the North-West of the country and first of all the largest terminal in Murmansk. In his opinion, one of the main problems in this sphere is prevention of ecological accidents in the process of oil transportation through the Baltic sea ports.

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