scholarly journals Oxygen depletion in coastal seas and the effective spawning stock biomass of an exploited fish species

2016 ◽  
Vol 3 (1) ◽  
pp. 150338 ◽  
Author(s):  
H.-H. Hinrichsen ◽  
B. von Dewitz ◽  
J. Dierking ◽  
H. Haslob ◽  
A. Makarchouk ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Environmental Conditions ◽  
Size Structure ◽  
Oxygen Depletion ◽  
The Baltic Sea ◽  
Egg Survival ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The Baltic ◽  
Baltic Cod

Environmental conditions may have previously underappreciated effects on the reproductive processes of commercially exploited fish populations, for example eastern Baltic cod, that are living at the physiological limits of their distribution. In the Baltic Sea, salinity affects neutral egg buoyancy, which is positively correlated with egg survival, as only water layers away from the oxygen consumption-dominated sea bottom contain sufficient oxygen. Egg buoyancy is positively correlated to female spawner age/size. From observations in the Baltic Sea, a field-based relationship between egg diameter and buoyancy (floating depth) could be established. Hence, based on the age structure of the spawning stock, we quantify the number of effective spawners, which are able to reproduce under ambient hydrographic conditions. For the time period 1993–2010, our results revealed large variations in the horizontal extent of spawning habitat (1000–20 000 km 2 ) and oxygen-dependent egg survival (10–80%). The novel concept of an effective spawning stock biomass takes into account offspring that survive depending on the spawning stock age/size structure, if reproductive success is related to egg buoyancy and the extent of hypoxic areas. Effective spawning stock biomass reflected the role of environmental conditions for Baltic cod recruitment better than the spawning stock biomass alone, highlighting the importance of including environmental information in ecosystem-based management approaches.

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 Deoxygenation impacts on Baltic Sea cod: Dramatic declines in ecosystem services of an iconic keystone predator

AMBIO ◽  
2021 ◽  
Author(s):  
Alessandro Orio ◽  
Yvette Heimbrand ◽  
Karin Limburg
Keyword(s):  
Ecosystem Services ◽  
Baltic Sea ◽  
Gadus Morhua ◽  
Generalized Additive Model ◽  
Additive Model ◽  
Maximum Length ◽  
The Baltic Sea ◽  
Hypoxic Zone ◽  
The Baltic ◽  
Baltic Cod

AbstractThe intensified expansion of the Baltic Sea’s hypoxic zone has been proposed as one reason for the current poor status of cod (Gadus morhua) in the Baltic Sea, with repercussions throughout the food web and on ecosystem services. We examined the links between increased hypoxic areas and the decline in maximum length of Baltic cod, a demographic proxy for services generation. We analysed the effect of different predictors on maximum length of Baltic cod during 1978–2014 using a generalized additive model. The extent of minimally suitable areas for cod (oxygen concentration ≥ 1 ml l−1) is the most important predictor of decreased cod maximum length. We also show, with simulations, the potential for Baltic cod to increase its maximum length if hypoxic areal extent is reduced to levels comparable to the beginning of the 1990s. We discuss our findings in relation to ecosystem services affected by the decrease of cod maximum length.

scholarly journals A three-dimensional view on biodiversity changes: spatial, temporal, and functional perspectives on fish communities in the Baltic Sea

2018 ◽  
Vol 75 (7) ◽  
pp. 2463-2475 ◽  
Author(s):  
Romain Frelat ◽  
Alessandro Orio ◽  
Michele Casini ◽  
Andreas Lehmann ◽  
Bastien Mérigot ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Temporal Dynamics ◽  
Marine Ecosystem ◽  
Fish Communities ◽  
The Baltic Sea ◽  
Functional Richness ◽  
Holistic Understanding ◽  
The Baltic

Abstract Fisheries and marine ecosystem-based management requires a holistic understanding of the dynamics of fish communities and their responses to changes in environmental conditions. Environmental conditions can simultaneously shape the spatial distribution and the temporal dynamics of a population, which together can trigger changes in the functional structure of communities. Here, we developed a comprehensive framework based on complementary multivariate statistical methodologies to simultaneously investigate the effects of environmental conditions on the spatial, temporal and functional dynamics of species assemblages. The framework is tested using survey data collected during more than 4000 fisheries hauls over the Baltic Sea between 2001 and 2016. The approach revealed the Baltic fish community to be structured into three sub-assemblages along a strong and temporally stable salinity gradient decreasing from West to the East. Additionally, we highlight a mismatch between species and functional richness associated with a lower functional redundancy in the Baltic Proper compared with other sub-areas, suggesting an ecosystem more susceptible to external pressures. Based on a large dataset of community data analysed in an innovative and comprehensive way, we could disentangle the effects of environmental changes on the structure of biotic communities—key information for the management and conservation of ecosystems.

Impact of Spawning Substrate Complexity on Egg Survival of Atlantic Herring (Clupea harengus, L.) in the Baltic Sea

2017 ◽  
Vol 41 (2) ◽  
pp. 549-559 ◽  
Author(s):  
Lena von Nordheim ◽  
Paul Kotterba ◽  
Dorothee Moll ◽  
Patrick Polte
Keyword(s):  
Baltic Sea ◽  
Clupea Harengus ◽  
Atlantic Herring ◽  
The Baltic Sea ◽  
Egg Survival ◽  
Spawning Substrate ◽  
The Baltic

scholarly journals The role of climate and fisheries on the temporal changes in the Bothnian Bay foodweb

2016 ◽  
Vol 73 (7) ◽  
pp. 1739-1749 ◽  
Author(s):  
Zeynep Pekcan-Hekim ◽  
Anna Gårdmark ◽  
Agnes M. L. Karlson ◽  
Pirkko Kauppila ◽  
Mikaela Bergenius ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Trophic Levels ◽  
Strong Increase ◽  
The Baltic Sea ◽  
Key Species ◽  
Long Term Changes ◽  
Spawning Stock ◽  
The Baltic ◽  
Bothnian Bay

Abstract Climate change, eutrophication, and fishing are main pressures associated with changes in the abiotic and biotic environment in several sub-basins of the Baltic Sea. Identifying the nature of such changes is of relative importance for fisheries and environmental management. The Bothnian Bay is the northernmost sub-basin in the Baltic Sea and the responses of the foodweb to long-term changes in combined pressures have not been investigated. In this study, we explore long-term changes in the Bothnian Bay foodweb, represented by key species across all trophic levels over the past 34 years, and identify potential environmental and anthropogenic drivers. The results indicate that salinity is the most important driver to explain changes in the composition of the offshore biota in the Bothnian Bay. These changes are probably driven by indirect effects of salinity rather than bottom-up effects. A decline in the herring spawning-stock biomass was most plausibly attributed to an increased competition for food due to a parallel increase in vendace, which uses the same food resources (zooplankton and zoobenthos) and may benefit from declining salinity due to its limnic origin. A strong increase in the abundance of grey seal and ringed seal populations was seen in the late 2000s but was not related to any of the pressure variables analysed. Temperature and nutrients were not identified as important drivers of changes in the overall biota. Our study explores correlative relationships between variables and identifies potential interactions in the foodweb to generate hypotheses for further studies.

Sign in / Sign up

Export Citation Format

Share Document