Otolith growth across two generations in Atlantic herring (Clupea harengus)

The Atlantic herring (Clupea harengus) has a wide distribution and a complex metapopulation structure with interactions between the sub-populations. The sub-populations show different adaptations, both genetic and non-genetic, to their environments, and clear differences are found between Atlantic and Baltic herring. Offspring (F1 generation) from Atlantic and Baltic parents (Atlantic purebreds and Atlantic-Baltic hybrids) were co-reared in a common garden experimental set-up. Initially there were three salinity regimes (6 psu, 16 psu and 35 psu), but the 6 psu regime was terminated at larval life stages. Repetitive samples were taken from each group throughout the whole experiment providing a unique collection of sibling samples from larval to adult life stages. Otoliths from all life stages were available for further otolith microstructure analysis and corresponding microstructure analysis was also available from the two parental populations. The Atlantic parental herring were larger than the Baltic parental herring, but the larval otolith increments indicated an opposite trend where the Baltic herring had better larval growth. The F1 larval somatic parameters indicated a trend where the 35 psu group was larger than the 16 psu group, indicating an impact from environmental factors. The adult purebreds were longer than the adult hybrids, which could indicate a genetic impact. An interaction effect including both salinity and genetics as factors was present for the adult weights and for the otolith larval increment widths of both larval and adult life stages. The results from the present study indicate that these traits were affected by both the environment (salinity) and the underlying genetics. These findings are of high importance in sustainable management when characterising herring stocks, but other environmental factors, like temperature,should also be given more attention and included in further research in addition to having a broader genetic baseline for analysis.Masteroppgåve i biologiMAMN-BIOBIO39

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

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.publishedVersio

Testing of trawl-acoustic stock estimation of spawning capelin 2021

This report describes the third in a series of trawl-acoustic monitoring surveys of the spawning stock of capelin during the migration to the coast. The survey is a response to a proposal from the industry to evaluate the possibility of using winter monitoring of maturing capelin as an input to the capelin assessment and advice. The timing and geographic coverage of the survey are such that they would be relevant to use for advice given that the output is reliable. Pre-defined areas off the Troms and Finnmark coast were covered using two vessels, Vendla surveying the western part and Eros the eastern part.Testing of trawl-acoustic stock estimation of spawning capelin 2021publishedVersio

Fangstprøvelotteriet 2022 - erfaringer og resultat

Etter at vi startet opp med fangstprøvelotteriet i 2018 har vi sett en gradvis og betydelig forbedring i prøvetakingen fra de kommersielle pelagiske fiskeriene, og i 2022 mottok vi totalt sett ca 70% av de bestilte prøvene. Selv om vi fremdeles er noe lavere enn vi burde ser det ut som fangstprøvelotteriet begynner å bli godt innarbeidet i alle ledd og at inngangsdataene til bestandsberegningene har blitt forbedret. Fangstprøvelotteriet gir de viktigste grunnlagsdataene fra de norske fiskeriene for kvoteanbefalingene for pelagisk fisk, og en forbedring av prøvetakingen fra fangstprøvelotteriet vil derfor først og fremst komme fiskerinæringen til gode, gjennom bedre kvoterådgivning inn mot forvaltningen av våre viktige pelagiske fiskebestander.Fangstprøvelotteriet 2022 - erfaringer og resultatpublishedVersio

Report of the 4th Workshop on Age Reading of horse mackerel, Mediterranean horse mackerel and blue jack mackerel (Trachurus trachurus, T. mediterraneus and T. picturatus) (WKARHOM)

Based on the previous work from WKARHOM3 (ICES, 2018), the Working Group on Biological Parameters (ICES, 2020) identified the need for a new otolith exchange followed by an age read-ing Workshop. The Workshop on Age reading of Horse Mackerel, Mediterranean Horse Macke-rel and Blue Jack Mackerel (Trachurus trachurus, T. mediterraneus and T. picturatus) (WKAR-HOM4) had several main objectives; to review the current protocols of ageing Trachurus species, to update the advances in the validation of the ageing criteria (i.e. the annual deposition of one annulus, coherency of the interpretation), to evaluate the new precision of ageing data of Tra-churus species and to update guidelines, common ageing criteria and reference collections of otoliths. An online otolith exchange was performed using SmartDots during 2021 and 2022, and results including the three Trachurus species were published in advance of the meeting, showing a low Percentage of Agreement (PA) both when considering all the readers (44-55%) and the advanced readers only (52-54%) (Massaro and Jurado-Ruzafa, 2022). For T. trachurus the Coef-ficient of Variation (CV) was lower for the sliced samples (22-18%) than for whole otoliths sam-ples (44-38%). Readers participating in the exchange, following discussion during the WKAR-HOM4 meeting, agreed that the main cause of age determination error for T. trachurus was due to the different otolith preparation techniques (whole/sliced). These differences reflect the stunted growth and compactness of the annuli in older specimens (from the 4th-5th annuli on-wards). Anyway, for the three Trachurus species, there are several difficulties in age determina-tion: identification of the first growth annulus, presence of many false rings (mainly in the first and second annuli) and the interpretation and identification of the edge characteristics (opaque/translucent). The second reading exercise was performed during the workshop orga-nized in four different events (i.e. Trachurus trachurus whole otoliths -135 images-, T. trachurus sliced otoliths -95 images- T. mediterraneus whole otoliths -150 images- and T. picturatus whole otoliths –121 images). For T. trachurus no enhancement among readers’ precision was observed in all cases, in terms of PA and CV. Conversely, for T. mediterraneus and T. picturatus a notice-able improvement in terms of PA and decrease of CV occurred compared to the pre-workshop exchange. Finally, this group updated the ageing guidelines and a reference collection of images for all the species, with the aim to employ these tools for all laboratories.ICESN

Otolith growth across two generations in Atlantic herring (Clupea harengus)

The Atlantic herring (Clupea harengus) has a wide distribution and a complex metapopulation structure with interactions between the sub-populations. The sub-populations show different adaptations, both genetic and non-genetic, to their environments, and clear differences are found between Atlantic and Baltic herring. Offspring (F1 generation) from Atlantic and Baltic parents (Atlantic purebreds and Atlantic-Baltic hybrids) were co-reared in a common garden experimental set-up. Initially there were three salinity regimes (6 psu, 16 psu and 35 psu), but the 6 psu regime was terminated at larval life stages. Repetitive samples were taken from each group throughout the whole experiment providing a unique collection of sibling samples from larval to adult life stages. Otoliths from all life stages were available for further otolith microstructure analysis and corresponding microstructure analysis was also available from the two parental populations. The Atlantic parental herring were larger than the Baltic parental herring, but the larval otolith increments indicated an opposite trend where the Baltic herring had better larval growth. The F1 larval somatic parameters indicated a trend where the 35 psu group was larger than the 16 psu group, indicating an impact from environmental factors. The adult purebreds were longer than the adult hybrids, which could indicate a genetic impact. An interaction effect including both salinity and genetics as factors was present for the adult weights and for the otolith larval increment widths of both larval and adult life stages. The results from the present study indicate that these traits were affected by both the environment (salinity) and the underlying genetics. These findings are of high importance in sustainable management when characterising herring stocks, but other environmental factors, like temperature,should also be given more attention and included in further research in addition to having a broader genetic baseline for analysis

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

Atlantic herring (Clupea harengus) is a euryhaline species, occupying fully marine habitats (35 psu) in the North Atlantic, as well as brackish waters (&lt;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

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

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

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

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

Testing of trawl-acoustic stock estimation of spawning capelin 2021

This report describes the third in a series of trawl-acoustic monitoring surveys of the spawning stock of capelin during the migration to the coast. The survey is a response to a proposal from the industry to evaluate the possibility of using winter monitoring of maturing capelin as an input to the capelin assessment and advice. The timing and geographic coverage of the survey are such that they would be relevant to use for advice given that the output is reliable. Pre-defined areas off the Troms and Finnmark coast were covered using two vessels, Vendla surveying the western part and Eros the eastern part