Effects of marine conditions, fishing, and smolt traits on the survival of tagged, hatchery-reared sea trout (Salmo trutta trutta) in the Baltic Sea

2007 ◽  
Vol 64 (9) ◽  
pp. 1183-1198 ◽  
Author(s):  
Irma Kallio-Nyberg ◽  
Irma Saloniemi ◽  
Eero Jutila ◽  
Ari Saura
Keyword(s):  
Survival Rate ◽  
Baltic Sea ◽  
Salmo Trutta ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Survival Rates ◽  
Clupea Harengus ◽  
The Baltic Sea ◽  
Sea Trout ◽  
The Baltic

The marine survival of tagged sea trout (Salmo trutta trutta) smolt groups (n  =  236) stocked from 1970 to 2001 in the Baltic Sea was analysed using a linear mixed model. The response variable, survival rate, was associated with smolt size, release date, sea surface temperature in May, and prey fish abundance, and interactions among these factors. The effect of smolt size was in interaction with Baltic herring (Clupea harengus membras) abundance; smolt size had an optimum of about 22 cm in years when herring were abundant, but when herring were less abundant, the survival of larger smolts was higher. Early stocking in warm springs or late stocking in cold springs gave the best survival rates for trout. Changes in return activity or fishing methods have made tag returns a less reliable way of estimating survival during the last 30 years. The actual return rate of undersized fish (<40 cm) compared with their estimated proportion among captured fish decreased over time, which suggests that the survival rate for the later years was probably underestimated. It is likely that we were unable to include all the relevant explanatory variables in the model, as year effects remained significant, suggesting unknown annual variation affecting survival.

Salinity effects on egg production, hatching, and survival of Eurytemora affinis (Copepoda, Calanoida)

Crustaceana ◽  
2020 ◽  
Vol 93 (3-5) ◽  
pp. 429-445 ◽  
Author(s):  
Lauri Kuismanen ◽  
Louise Forsblom ◽  
Jonna Engström-Öst ◽  
Ulf Båmstedt ◽  
Olivier Glippa
Keyword(s):  
Body Size ◽  
Baltic Sea ◽  
Egg Production ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Salinity Range ◽  
The Baltic Sea ◽  
Eurytemora Affinis ◽  
Optimal Salinity ◽  
The Baltic

Abstract Salinity is an important biodiversity regulating factor in the Baltic Sea, forming a physiological dispersal barrier for species. The salinity in the Baltic Sea has been predicted to decline due to increased precipitation and fewer saline water inflows from the ocean. This causes stress to species already living on the edge of their tolerances and can alter species compositions and interactions in ecosystems. Calanoid copepod resting eggs, originating from a known egg bank on the seabed in the western Gulf of Finland, were incubated in the laboratory. We monitored the hatching of the calanoid copepods Acartia sp. and Eurytemora affinis, as well as the survival to maturity of hatched Eurytemora affinis nauplii in salinities ranging from 0 to 25. Further, we also investigated salinity-related effects on body size and egg production. Based on the results of our generalized linear mixed model, peak hatching occurred within the salinity range 5-20 (6.3 at the study site). Body size was not affected by salinity and most eggs were produced in salinities of 5, 7.5 and 15. The results suggest that E. affinis lives on the edge of an optimal salinity and that a decline of salinity could affect the fitness of the local populations of the species.

scholarly journals An ecosystem model of food web and fisheries interactions in the Baltic Sea

2003 ◽  
Vol 60 (5) ◽  
pp. 939-950 ◽  
Author(s):  
Chris J Harvey ◽  
Sean P Cox ◽  
Timothy E Essington ◽  
Sture Hansson ◽  
James F Kitchell
Keyword(s):  
Baltic Sea ◽  
Food Web ◽  
Species Interactions ◽  
Gadus Morhua ◽  
Population Analysis ◽  
Clupea Harengus ◽  
Trophic Relationships ◽  
The Baltic Sea ◽  
Management Actions ◽  
The Baltic

Abstract Because fisheries operate within a complex array of species interactions, scientists increasingly recommend multispecies approaches to fisheries management. We created a food web model for the Baltic Sea proper, using the Ecopath with Ecosim software, to evaluate interactions between fisheries and the food web from 1974 to 2000. The model was based largely on values generated by multispecies virtual population analysis (MSVPA). Ecosim outputs closely reproduced MSVPA biomass estimates and catch data for sprat (Sprattus sprattus), herring (Clupea harengus), and cod (Gadus morhua), but only after making adjustments to cod recruitment, to vulnerability to predation of specific species, and to foraging times. Among the necessary adjustments were divergent trophic relationships between cod and clupeids: cod exhibited top-down control on sprat biomass, but had little influence on herring. Fishing, the chief source of mortality for cod and herring, and cod reproduction, as driven by oceanographic conditions as well as unexplained variability, were also key structuring forces. The model generated many hypotheses about relationships between key biota in the Baltic Sea food web and may ultimately provide a basis for estimating community responses to management actions.

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

Environmental genotoxicity and cytotoxicity levels in herring (Clupea harengus), flounder (Platichthys flesus) and cod (Gadus morhua) inhabiting the Gdansk Basin of the Baltic Sea

2018 ◽  
Vol 133 ◽  
pp. 65-76 ◽  
Author(s):  
Roberta Valskienė ◽  
Janina Baršienė ◽  
Laura Butrimavičienė ◽  
Wlodzimierz Grygiel ◽  
Virmantas Stunžėnas ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Gadus Morhua ◽  
Clupea Harengus ◽  
The Baltic Sea ◽  
Platichthys Flesus ◽  
The Baltic ◽  
Environmental Genotoxicity

scholarly journals Relationships between fish stock changes in the Baltic Sea and the M74 syndrome, a reproductive disorder of Atlantic salmon (Salmo salar)

2011 ◽  
Vol 68 (10) ◽  
pp. 2134-2144 ◽  
Author(s):  
Jaakko Mikkonen ◽  
Marja Keinänen ◽  
Michele Casini ◽  
Jukka Pönni ◽  
Pekka J. Vuorinen
Keyword(s):  
Atlantic Salmon ◽  
Baltic Sea ◽  
Salmo Salar ◽  
Gadus Morhua ◽  
Clupea Harengus ◽  
Fish Stock ◽  
The Baltic Sea ◽  
Atlantic Salmon Salmo Salar ◽  
Reproductive Disorder ◽  
The Baltic

Abstract Mikkonen, J., Keinänen, M., Casini, M., Pönni, J., and Vuorinen, P. J. 2011. Relationships between fish stock changes in the Baltic Sea and the M74 syndrome, a reproductive disorder of Atlantic salmon (Salmo salar). – ICES Journal of Marine Science, 68: 2134–2144. The M74 syndrome of Baltic salmon (Salmo salar), which appears as increased yolk-sac fry mortality (YSFM), impairs the reproduction of salmon stocks. Changes in the prey stocks of Baltic salmon in its two feeding areas, the southern Baltic Proper (BPr), where sprat (Sprattus sprattus) was the main prey species during the high incidence of M74, and the Bothnian Sea, where herring (Clupea harengus) is the dominant species, were analysed in relation to salmon growth and size and in relation to the incidence of M74. The high condition factor (CF > 1.05) of prespawning salmon predicted high YSFM. From the various stock factors of sprat and herring in the southern BPr, the biomass of sprat had the strongest positive relationships with the CF of prespawning salmon, and the total prey biomass with YSFM. It is concluded that the ample but unbalanced food resources for salmon in the BPr, primarily sprat, induce M74. By reducing the fishing pressure on cod (Gadus morhua) and by more effectively managing the sprat fishery in years when the cod stock is weak, the incidence of the M74 syndrome could be reduced and even prevented.

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