Benchmark Workshop on Baltic Cod stocks (WKBALTCOD2)

Orio, Alessandro; Karpushevskaia, Anastasiia; Nielsen, Anders; Sundelöf, Andreas; Berg, Casper Willestofte; Albertsen, Christoffer Moesgaard; Stralka, Conrad; Vitale, Francesca; Schade, Franziska; Köster, Fritz; Olesen, Hans Jakob; Strehlow, Harry Vincent; Sande, Hege; Mosegaard, Henrik; Horbowy, Jan; Behrens, Jane; Hjelm, Joakim; Lövgren, Johan; Tomkiewicz, Jonna; Hüssy, Karin; McQueen, Kate; Brander, Keith; Nielsen, Kåre Nolde; Weltersbach, Marc Simon; Ruciński, Marcin; Eero, Margit; Pierce, Maria E.; Ryberg, Marie Plambech; Storr-Paulsen, Marie; Plikshs, Maris; Cardinale, Massimiliano; Bryan, Meaghan D.; Andersen, Michael; Casini, Michèle; Bergenius, Mikaela; Mion, Monica; Höglund, Nils; Linke, Sebastian; Carlshamre, Sofia; Larsson, Staffan; Haase, Stefanie; Krumme, Uwe; Trenkel, Verena M.; Gertseva, Vladlena V.; Amosova, Viktoriia; Cormon, Xochitl; Heimbrand, Yvette

doi:10.17895/ices.pub.4984

Cited by 7 publications

(2 citation statements)

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“…The frequent occurrence of WBC and EBC in the same fishing hauls in collections for these studies indicate that the two stocks live in close association in SD 24. Although stock affiliation of Baltic cod is considered in current stock assessments and practical fisheries management in SD 24 [ 6 , 18 ], the ecological mechanisms underlying coexistence and the long-term dynamics of stock mixing in this area are still unknown.…”

Section: Introductionmentioning

confidence: 99%

Living apart together: Long-term coexistence of Baltic cod stocks associated with depth-specific habitat use

Schade¹,

Weist²,

Dierking

et al. 2022

PLoS ONE

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Coexistence of fish populations (= stocks) of the same species is a common phenomenon. In the Baltic Sea, two genetically divergent stocks of Atlantic cod (Gadus morhua), Western Baltic cod (WBC) and Eastern Baltic cod (EBC), coexist in the Arkona Sea. Although the relative proportions of WBC and EBC in this area are considered in the current stock assessments, the mixing dynamics and ecological mechanisms underlying coexistence are not well understood. In this study, a genetically validated otolith shape analysis was used to develop the most comprehensive time series of annual stock mixing data (1977–2019) for WBC and EBC. Spatio-temporal mixing analysis confirmed that the two stocks coexist in the Arkona Sea, albeit with fluctuating mixing proportions over the 43-year observation period. Depth-stratified analysis revealed a strong correlation between capture depth and stock mixing patterns, with high proportions of WBC in shallower waters (48–61% in <20m) and increasing proportions of EBC in deeper waters (50–86% in 40-70m). Consistent depth-specific mixing patterns indicate stable differences in depth distribution and habitat use of WBC and EBC that may thus underlie the long-term coexistence of the two stocks in the Arkona Sea. These differences were also reflected in significantly different proportions of WBC and EBC in fisheries applying passive gears in shallower waters (more WBC) and active gears in deeper waters (more EBC). This highlights the potential for fishing gear-specific exploitation of different stocks, and calls for stronger consideration of capture depth and gear type in stock assessments. This novel evidence provides the basis for improved approaches to research, monitoring and management of Baltic cod stocks.

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Section: Introductionmentioning

confidence: 99%

Living apart together: Long-term coexistence of Baltic cod stocks associated with depth-specific habitat use

Schade¹,

Weist²,

Dierking

et al. 2022

PLoS ONE

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“…EBC plays a major role not only ecologically as a key predator species in the food web, particularly notable in the Baltic’s uniquely low biodiversity (Ojaveer et al 2010), but also economically as it has been fished recreationally and was the largest target species for commercial fisheries with an annual catch of up to 400,000 tons in the mid-1980s (ICES 2022). However, overfishing and size-selective fishing continued with excessively high total allowable catch resulting in fishing mortality typically 2-3 times higher than the maximum sustainable yield (MSY) (Birgersson 2022; ICES 2019; Eero et al 2011; Zeller et al 2011). Since the mid-1990s, multiple aspects of the EBC population have been deteriorating and have recently reached the unprecedented lowest point in their state since the 1950s (Birgersson 2022; Eero et al 2023).…”

Section: Introductionmentioning

confidence: 99%

Genomic Evidence of Fisheries Induced Evolution in Eastern Baltic cod

Han,

Brennan,

Monk

et al. 2024

Preprint

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Humans have become one of the greatest evolutionary forces, and their perturbations are expected to elicit strong evolutionary responses. Accordingly, during (size) selective overharvesting of wild populations, marked phenotypic changes have been documented, while the evolutionary basis is often unresolved. Time-series collections combined with genomic tools present unique opportunities to study how evolutionary changes are manifested at the genome-wide level. Here, we take advantage of a unique temporal dataset from the overexploited Eastern Baltic cod (Gadus morhua) population that exhibited a 48% decrease in asymptotic body length over the last 25 years. A genome-wide association study revealed pronounced peaks of outliers linked to growth performance. The contributing loci showed signals of directional selection with significantly high autocovariance in the allele frequency and excessive intersections with regions of high Fst as well as genes relevant to growth and reproduction. Moreover, pattern of directional selection for ancestral haplotype of the well-known chromosomal inversions in Atlantic cod (on linkage group 12) was observed, while the double crossover (~1Mb) enharbouring the vitellogenin genes within this region showed signs of drift or balancing selection. Our results demonstrate evident response of the genome over a relatively short time frame and further underscore implications for fisheries management and conservation policy regarding the adaptive potential of marine populations.

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SNP genotyping reveals substructuring in weakly differentiated populations of Atlantic cod (Gadus morhua) from diverse environments in the Baltic Sea

Wenne

Bernaś

Kijewska

et al. 2020

Sci Rep

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Atlantic cod (Gadus morhua) is one of the most important fish species in northern Europe for several reasons including its predator status in marine ecosystems, its historical role in fisheries, its potential in aquaculture and its strong public profile. However, due to over-exploitation in the North Atlantic and changes in the ecosystem, many cod populations have been reduced in size and genetic diversity. Cod populations in the Baltic Proper, Kattegat and North Sea have been analyzed using a species specific single nucleotide polymorphism (SNP) array. Using a subset of 8,706 SNPs, moderate genetic differences were found between subdivisions in three traditionally delineated cod management stocks: Kattegat, western and eastern Baltic. However, an F St measure of population differentiation based on allele frequencies from 588 outlier loci for 2 population groups, one including 5 western and the other 4 eastern Baltic populations, indicated high genetic differentiation. In this paper, differentiation has been demonstrated not only between, but also within western and eastern Baltic cod stocks for the first time, with salinity appearing to be the most important environmental factor influencing the maintenance of cod population divergence between the western and eastern Baltic Sea. Sustainable exploitation of living marine resources by fishery, aquaculture and biotechnology, and monitoring and predicting the effects of climate changes require an understanding of taxonomy and population biology. Populations are sustainably exploited if the removal of individuals does not reduce the ability of a population to reproduce and maintain its phenotypic and genetic diversity. Such populations have been defined for conservation purposes as "evolutionary significant units" 1 , and traditionally have been defined using genetic methods such as analyses of allozymes, nuclear DNA loci, microsatellites and mitochondrial DNA 2 and knowledge of fish biology and morphology 3. The management units are defined for reporting on stock assessment and catches by different countries. The issue of inconsistency between existing management units and population biology and

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Benchmark Workshop on Baltic Cod stocks (WKBALTCOD2)

Cited by 7 publications

References 0 publications

Living apart together: Long-term coexistence of Baltic cod stocks associated with depth-specific habitat use

Living apart together: Long-term coexistence of Baltic cod stocks associated with depth-specific habitat use

Genomic Evidence of Fisheries Induced Evolution in Eastern Baltic cod

SNP genotyping reveals substructuring in weakly differentiated populations of Atlantic cod (Gadus morhua) from diverse environments in the Baltic Sea

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