Separating two herring stocks from growth data: long-term changes in survey indices for Western Baltic Spring Spawning Herring (<i>Clupea harengus</i>
) after application of a stock separation function

Gröhsler, Tomas; Schaber, Matthias; Larson, Niklas; Oeberst, Rainer

doi:10.1111/jai.12924

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…In addition to the effects of visibility, reduced water oxygen content (Pauly and Cheung, 2018), salinity (Berg et al, 2018), limited availability of suitably sized plankton for the larger herring may reduce the growth and maximum size of Baltic herring (Möllmann et al, 2005). Further, there is a tendency that adult Baltic populations migrate into habitats with higher salinities for feeding, e.g., from the western Baltic into the Skagerrak (Clausen et al, 2015) or from the central Baltic into the western Baltic (Gröhsler et al, 2015). Whether this migration is due to direct salinity effect on herring or is due to better feeding conditions needs to be investigated.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Otolith Microstructure of Herring Larvae and Sibling Adults Reared Under Identical Early Life Conditions

et al. 2020

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Atlantic herring (Clupea harengus) is a euryhaline species, occupying fully marine habitats (35 psu) in the North Atlantic, as well as brackish waters (<20 psu) such as in the adjacent Baltic Sea. We co-reared Atlantic purebreds and Atlantic/Baltic F1 hybrids in two salinity regimes (16 and 35 psu) in a common garden experiment for 3 years until their first maturity. This setup enabled for the first time a direct comparison between adults and their larval siblings at respective salinity regimes in terms of larval growth indicated by otolith microstructure. We validated that otolith microstructure analysis of adult otoliths is reflecting the experienced otolith growth during the larval stage. No major selection in terms of otolith growth had taken place during the juvenile stage, except for one experimental group. Surviving adult Atlantic purebreds reared at 16 psu had higher otolith growth compared to their larval stages. The validation that otolith microstructure analyses of adult herring can reliably be extracted and used to examine larval growth even after several years adds strong support for further use of such analyses. Among the parental generation, Baltic herring had a faster initial otolith growth than Atlantic herring. The growth of their laboratory-reared F1 progeny was intermediate compared to their parents. In general, larval growth of both Atlantic purebreds and Atlantic/Baltic hybrids reared in 16 psu was significantly larger than for those herring reared at 35 psu. There was no significant difference in larval growth between Atlantic purebreds and Atlantic/Baltic hybrids reared at 35 psu, but hybrid larval growth was significantly higher compared to larval growth of Atlantic purebreds at 16 psu. This was not reflected at the adult stage where purebreds were ultimately larger than hybrids (Berg et al., 2018). This indicates the influence and importance of environmental and genetic factors throughout the life of Atlantic herring, along with genetic contributions to phenotypic variability.

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Section: Discussionmentioning

confidence: 99%

Comparison of Otolith Microstructure of Herring Larvae and Sibling Adults Reared Under Identical Early Life Conditions

et al. 2020

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“…It is therefore assumed that herring in this area were fish managed as WBSS. However, in recent years, an increasing fraction of herring from the central Baltic has migrated further westwards into the western Baltic [ 48 , 49 ]. Herring from the central Baltic have an even lower VS [ 50 ].…”

Section: Discussionmentioning

confidence: 99%

Comparative biology and population mixing among local, coastal and offshore Atlantic herring (Clupea harengus) in the North Sea, Skagerrak, Kattegat and western Baltic

et al. 2017

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The population structure of Atlantic herring (Clupea harengus) from 13 local, coastal and offshore areas of the North Sea, Skagerrak, Kattegat and western Baltic (northeast Atlantic) was studied using biological and environmental data from 1970–2015. The objective was to identify distinct populations by comparing variability in the temporal and spatial phenotypic characteristics and evaluate the potential for mixing of populations in time and space. The populations varied in biological characteristics such as mean vertebral counts (VS), growth and maturity ogives. Generalized additive models indicated temporally stable VS in the North Sea and western Baltic, whereas intra-annual temporal variation of VS occurred in other areas. High variability of VS within a population was not affected by environmental factors such as temperature and salinity. Consequently, seasonal VS variability can be explained by the presence or absence of herring populations as they migrate between areas. The three main populations identified in this paper correspond to the three managed stocks in this area: Norwegian spring spawners (NSS), western Baltic spring spawners (WBSS) and North Sea autumn spawners (NSAS). In addition, several local populations were identified in fjords or lakes along the coast, but our analyses could not detect direct mixing of local populations with the three main populations. Our results highlight the importance of recognizing herring dynamics and understanding the mixing of populations as a challenge for management of herring.

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Multi-fleet state-space assessment model strengthens confidence in single-fleet SAM and provides fleet-specific forecast options

Nielsen¹,

Hintzen

Mosegaard³

et al. 2021

ICES Journal of Marine Science

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The state-space assessment model (SAM) is increasingly used to assess fish stocks in International Council for the Exploration of the Sea. One unique feature of the SAM class is that it allows the fishing selectivity to vary over time, and the degree to which it varies is not subjectively assigned, but estimated within the model. Selection may vary over time due to changes in the spatial pattern of the fish stock or fishing fleet, but a direct cause of selectivity change can be changed in fishing technology or other measures that target specific segments of the fish stocks. If the relative catches from fishing fleets which target different age or size classes of a species are changing over time, then the overall selectivity will also change—even if the selectivity within each fleet is fairly constant. A recent extension of the SAM model allows multiple fleets to be defined. It has been applied to two herring stocks to allow more detailed and fleet-specific management options in forecasts. For both stocks, the assessment from the multi-fleet models was consistent with the results from the single-fleet models, which strengthens confidence in the estimated time-varying selectivity for these and other stocks.

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Separating two herring stocks from growth data: long-term changes in survey indices for Western Baltic Spring Spawning Herring (Clupea harengus ) after application of a stock separation function

Cited by 3 publications

References 8 publications

Comparison of Otolith Microstructure of Herring Larvae and Sibling Adults Reared Under Identical Early Life Conditions

Comparison of Otolith Microstructure of Herring Larvae and Sibling Adults Reared Under Identical Early Life Conditions

Comparative biology and population mixing among local, coastal and offshore Atlantic herring (Clupea harengus) in the North Sea, Skagerrak, Kattegat and western Baltic

Multi-fleet state-space assessment model strengthens confidence in single-fleet SAM and provides fleet-specific forecast options

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