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The study is based on biological analyses of > 80,000 ind. of Pandalus hypsinotus collected in trawl surveys and trap fishery in the Tatar Strait in 2010–2022. Due to the lack of age-recording structures, the size-age structure of shrimp is usually determined by various statistical methods, each of which has some limitations and drawbacks. The modal analysis of size-sex composition dynamics is used in this study, including tracing the growth of strong year-classes. The analysis takes into account the dynamics of major seasonal events such as group molting, spawning, and larval hatching. The reproductive cycle of females is assumed to be 2 years. Based on results of the analysis, the life cycle of humpback shrimp in the Tatar Strait is as follows. After the larvae hatch from eggs in April-May, immature shrimp spend the first year of their life at the depths < 70 m, where they reach the carapace length of 9–15 mm, with a modal size of 11–12 mm. In the second year, they grow to the length of 20–22 mm, on average, then become males and migrate to deeper layer where join the adults. Further growth is described on the data for the strong year-class of 2010: the modal size of males reaches 26–27 mm at age 3 years, 29–30 mm — at age 4, 32–33 mm — at age 5, and 35–36 mm — at age 6. Gender transition of shrimp begins at age 5+, but most males become hermaphroditic at the age 6+. The modal size of intersex hermaphrodites ranges from 37 to 39 mm. At the age of 6 years and 9 months, the intersexes spawn en masse and transform into females. The first larval hatching of new females occurs after 15 months, i.e. at exactly 8 years of age. At least three cycles of spawning (larvae release) are assumed for females, taking into account their polymodal size composition and dynamics of their size increments per molt by age. In assumption of 2-year reproductive cycle, the female stage lasts 6 years. Thus, the total life span for the most of humpback shrimps is estimated to be 12 years (6 years before gender transition and 6 years after). Apparently, a small number of them live 14 years and spawn four times, and some can live up to 16 years and spawn five times.

Abstract Shrimps are the most consumed species among crustaceans and are well appreciated for their flavor and high nutritional value. This work investigated the antioxidative compounds of Northern shrimp (Pandalus borealis) and its processing discards (shells and heads) using various solvents and chromatographic techniques as well as mass spectrometry. Ethanol served as the best extraction medium, and the extracts obtained demonstrated strong antioxidant activity in a β-carotene-linoleate emulsion system. The antioxidative compounds of the extract were isolated using a silica gel column chromatography, followed by thin layer chromatography. This led to the identification of two highly polar and two low polarity compounds. These compounds, for the first time, were isolated and purified by using reversed-phase HPLC. Their structures were tentatively elucidated using electrospray mass spectrometry. These unique compounds were heterocyclic phenolic compounds and identified as 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tetrahydropyridin-2-yl) quinoline and 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tertahydropyridin-2-yl)-7,8-dihydroquinoline and their isomers. The proposed novel compounds in shrimp provide a reason for their oxidative stability and potential benefits, as well as possibly serving as substrates for the discoloration of shrimp. Graphical Abstract

The offshore Northern shrimp (Pandalus borealis) bottom trawl fishery in eastern Canada currently uses 22 and 28 mm bar spacing Nordmøre grids to limit bycatch from using small mesh codends. However, a recent rebound of juvenile redfish (Sebastes spp.), that can pass through the grids, has greatly increased bycatch. To address this concern, this study investigated the effectiveness of 17 and 15 mm bar spacing Nordmøre grids in a twin-trawl (paired) configuration against the traditional 22 mm bar spacing grid. Size selectivity analyses showed that the 17 and 15 mm grids resulted in no significant reduction in shrimp catch across all length classes. The 17 mm grid significantly reduced redfish bycatch for all length classes and the 15 mm grid significantly reduced redfish bycatch for individuals larger than 95 mm total length. Less redfish entered the codend with the experimental grids, however, the overlap in width between redfish and Northern shrimp limits the overall sorting efficiency of the grids, leaving some redfish still vulnerable to capture. [ABSTRACT FROM AUTHOR]

ABSTRACT The Gulf of Maine (GOM) northern shrimp, Pandalus borealis, once supported a significant winter fishery, but a moratorium has been placed on the fishery since 2014 because of a population collapse and recruitment failures that have been attributed to unfavorably warm water temperatures. The GOM is at the southernmost end of the northern shrimp's range, suggesting its population dynamics and distribution may be vulnerable to warming water temperatures. In this study, we used survey data to estimate spatial indicators for GOM northern shrimp at four life history stages to identify possible temporal trends and examine relationships between the indicators and northern shrimp abundance and bottom temperature. We observed patchier distributions over time, which were related to declining population abundance, and a distributional shift northward that was associated with warming bottom water temperatures. Northern shrimp habitat distribution was strongly associated with bottom temperature. Shrimp of all life stages were found in bottom waters cooler than the station's average bottom temperature. [ABSTRACT FROM AUTHOR]

This study investigated the use of alternative ingredients obtained from Pandalus borealis by-products on flesh pigmentation and growth in post-smolt Salmo salar (initial weight of ~ 300 g). Four experimental diets were fed to fish in triplicate tanks for 16 weeks: a control diet and three other diets containing either synthetic astaxanthin, shrimp hydrolyzate, or shrimp oil. Fish that were fed the shrimp hydrolyzate diet exhibited higher red hue (based on L*a*b* data) when compared to fish fed the two other pigmented diets and had higher final weight. In addition, shrimp oil was found to be as efficient as artificial astaxanthin to increase the intensity of flesh pigmentation in Atlantic salmon. The shrimp hydrolyzate tested in our study provides an excellent source of astaxanthin and protein for Atlantic salmon. Likewise, shrimp oil could also constitute a natural source of astaxanthin and oil to this species. [ABSTRACT FROM AUTHOR]

The offshore Northern shrimp (Pandalus borealis) bottom trawl fishery in eastern Canada currently uses 22 and 28 mm bar spacing Nordmøre grids to limit bycatch from using small mesh codends. However, a recent rebound of juvenile redfish (Sebastes spp.), that can pass through the grids, has greatly increased bycatch. To address this concern, this study investigated the effectiveness of 17 and 15 mm bar spacing Nordmøre grids in a twin-trawl (paired) configuration against the traditional 22 mm bar spacing grid. Size selectivity analyses showed that the 17 and 15 mm grids resulted in no significant reduction in shrimp catch across all length classes. The 17 mm grid significantly reduced redfish bycatch for all length classes and the 15 mm grid significantly reduced redfish bycatch for individuals larger than 95 mm total length. Less redfish entered the codend with the experimental grids, however, the overlap in width between redfish and Northern shrimp limits the overall sorting efficiency of the grids, leaving some redfish still vulnerable to capture.

Shrimp shells are a key source of chitin, commonly extracted through chemical methods, which may cause minor molecular damage. Nowadays, there is great interest in achieving close to zero protein content in crude chitin in order to use it for high-end markets. Therefore, this study optimized the enzymatic deproteination using two commercial proteases (SEB Pro FL100 and Sea-B Zyme L200) for effective and fast removal of residual protein from Northern shrimp (Pandalus borealis) shell chitin for the first time. The protein content was determined using both the Kjeldahl method and amino acid analysis using gas chromatography–mass spectrometry (GC-MS). The performance of papain (Sea B Zyme L200) was superior to fungal protease (SEB Pro FL100) for this application, and it achieved residual protein content of 2.01%, while the calculated optimum for the latter enzyme was 6.18%. A model was developed using 24 factorial design, and it was predicted that the lowest residual protein content using fungal protease and papain could be achieved at the following conditions: a pH of 4.2 and 7, and an enzyme concentration of 4 and 1.5%, respectively. Thus, the low-protein content obtained using enzymatic deproteination could be an alternative approach to the traditional methods, indicating their potential to produce premium-quality chitin.

Research and commercial trawl catches of humpback shrimp Pandalus hypsinotus from the Tatar Strait (Japan Sea) in 2004–2020 were investigated, with bioanalysis of about 45 thousand specimens. Average timing of group molting, spawning, and eggs laying are determined, terms of gonads and eggs development are estimated. Prespawning and molting of the females occur between January-April, with the peaks in early February and middle February, respectively. All oviparous females have 30–40 days to lay eggs, and molt during 50–55 days; the peak of the eggs laying occurs in late June. The males molt in July-August, afterwards the largest individuals change gender and new intersexes are formed. The males have the second molting in October-December, with the peak in late November. In January, after finish of the males molting, a new annual reproduction cycle starts from the prespawning molting of females. Both vitellogenesis and embryogenesis are observed through the year, though females with developing gonads prevail from August to January (because of a long time span between winter and summer moltings while the egg carrying continued 15 months) but oviparous females — from February to July. The individual reproductive cycle of Pandalus hypsinotus in the Tatar Strait lasts 24 months, with 9 months of vitellogenesis (quick growth of gonads) and 15 months of embryogenesis. During the 2-year reproductive cycle, most of females pass through the following stages: i) gonads development (just after eggs laying) when almost all oviparous females (up to 95 % in May) have green gonads under carapace that corresponds to the stage of development «eggs laid — gonads weakly developed»; ii) summer molting from August when females lose hairs on pleopods and the gonads growth accelerates; iii) respawning in January-March (together with the firstly spawning intersexes, with slight delay of the latter); iv) initial developing of eggs during summer; v) stage of «eyed eggs» from December to March; and vi) eggs laying and molting from late March to late May; then the 2-year reproductive cycle repeats.

Shrimp shells are a key source of chitin, commonly extracted through chemical methods, which may cause minor molecular damage. Nowadays, there is great interest in achieving close to zero protein content in crude chitin in order to use it for high-end markets. Therefore, this study optimized the enzymatic deproteination using two commercial proteases (SEB Pro FL100 and Sea-B Zyme L200) for effective and fast removal of residual protein from Northern shrimp ( Pandalus borealis ) shell chitin for the first time. The protein content was determined using both the Kjeldahl method and amino acid analysis using gas chromatography-mass spectrometry (GC-MS). The performance of papain (Sea B Zyme L200) was superior to fungal protease (SEB Pro FL100) for this application, and it achieved residual protein content of 2.01%, while the calculated optimum for the latter enzyme was 6.18%. A model was developed using 2 4 factorial design, and it was predicted that the lowest residual protein content using fungal protease and papain could be achieved at the following conditions: a pH of 4.2 and 7, and an enzyme concentration of 4 and 1.5%, respectively. Thus, the low-protein content obtained using enzymatic deproteination could be an alternative approach to the traditional methods, indicating their potential to produce premium-quality chitin.

The size selectivity and usability of three codends were quantified and compared for the first time in the inshore Northern shrimp (Pandalus borealis) trawl fishery of Iceland using the covered codend method: a conventional diamond-mesh codend (T0), conventional square-mesh codend (T45), and a 90° turned mesh codend (T90) constructed of four panels and with shortened lastridge ropes. Fishers, wanting to increase the average-individual size of captured shrimp, had requested the T90 codend to be compared with conventional codends for consideration in the fishery. Results showed that, on average, the T45 and T90 codends had better size selectivity than the T0 codend in terms of releasing individuals smaller than 13 mm carapace length (Minimum References Size; MRS). The T90 codend retained significantly less Northern shrimps between 9 and 19 mm than the T0 codend and between 15 and 19 mm than the T45 codend. No significant difference of size selectivity between T45 and T0 codends was observed. All three codends presented high retention ratios of Northern shrimps above MRS (>63%) for the population encountered. However, the T0 codend was not effective at sorting out small Northern shrimps; at least 86% of Northern shrimps smaller than 13 mm were retained in the T0 codend if encountered. Catches from T45 and T90 codends had a lower proportion of shrimp below MRS. Since discarding of undersized Northern shrimps is prohibited in Iceland and fishers wanted to catch on average larger shrimp, using the novel T90 codend would enable fishers to use their quotas more efficiently.

In retail, whole, cooked Northern shrimp (Pandalus borealis) is commonly stored in illuminated display freezers for an extended time period. The aim of the present study was to understand how and when light-induced lipid oxidation occurs. Two sizes of cooked shrimp were packed in air and stored frozen with and without artificial light for 84 days. Samples were investigated for oxidative stability (peroxide value (PV), volatile compounds, and tocopherol consumption) and color changes and free astaxanthin.PV only increased significantly for shrimp stored with light (up to 20 meq/kg). α-tocopherol content remained unchanged during the storage period irrespective of the storage condition. Shrimp stored with light showed an increased L*-value and decreased a* and b*-values, whereas these color values did not change significantly in shrimp stored in darkness. The color changes could not be explained by changes in the free astaxanthin content as no significant changes occurred in free astaxanthin content during storage. The formation of volatile compounds depended on the shrimp size and light exposure, but the concentration of e.g. 2-methylbutanal, 3-methylbutanal and 1-penten-3-ol increased significantly more in shrimp stored in light than when they were stored without light. In conclusion, illuminated storage increased lipid oxidation in Northern shrimp.

This capstone project addresses the feasibility of farming the shrimp Pandalus platyceros, by investigating two essential issues: (1) whether the biology of P. platyceros is conducive to farm production and (2) consumer demand for this species. Chapter I examines the biological development of larval spot prawns to assess their survival in captive settings. This study monitors the development of newly hatched P. platyceros larvae until they reach post-larval stage, beyond the critical period. Chapter II consists of a discrete choice experiment based on surveying patrons of specialty seafood markets. Discrete choice experiments are a popular technique for documenting consumer preferences for different product characteristics. Through regression analysis one can estimate the part-worth utilities of each attribute level of a product, assigning a value to different characteristics. Arranging these characteristics in new ways can predict the cumulative willingness to pay (WTP) for a previously un-marketed product (ie a locally farmed, native shrimp). Through assessing the response of P. platyceros in culturing environments and determining a WTP for such a product, this study strives to determine if farming this species can be biologically and economically feasible. This methodology can be used as a framework for future research, including surveying broader market bases, exploring different product attributes, and investigating more detailed biological parameters for growing a new species for market.

In most trawl fisheries, drag forces tend to close the meshes in large areas of diamond mesh codends, negatively affecting their selective potential. In the Barents Sea deep-water shrimp (Pandalus borealis) trawl fishery, selectivity is based on a sorting grid followed by a diamond mesh codend. However, the retention of juvenile fish as well as undersized shrimp is still a problem. In this study, we estimated the effect of applying different codend modifications, each aimed at affecting codend mesh openness and thereby selectivity. Changing from a 4-panel to a 2-panel construction of the codend did not affect size selectivity. Shortening the lastridge ropes of a 4-panel codend by 20% resulted in minor reductions for juvenile fish bycatch, but a 45% reduction of undersized shrimp was observed. Target-size catches of shrimp were nearly unaffected. When the codend mesh circumference was reduced while simultaneously shortening the lastridge ropes, the effect on catch efficiency for shrimp or juvenile fish bycatch was marginal compared to a 4-panel codend design with shortened lastridge ropes. Dans la plupart des peches au chalut, les forces de trainee ont tendance a refermer les mailles de grands pans des culs de chalut a maille losange, ce qui a une incidence negative sur leur potentiel de selection. Dans la peche a la crevette nordique (Pandalus borealis) au chalut de la mer de Barents, la selectivite est basee sur une grille de tri suivie d'un cul a maille losange. La retention de poissons juveniles ainsi que de crevettes trop petites constitue toutefois un probleme persistant. Dans la presente etude, nous estimons l'effet d'appliquer differentes modifications aux culs de chalut qui ont toutes pour but de modifier l'ouverture des mailles et, ainsi, la selectivite du cul. L'utilisation d'un cul a deux panneaux plutot qu'a quatre panneaux n'a pas d'incidence sur la selectivite selon la taille. L'utilisation de cordes de couture d'un cul a quatre panneaux de 20 % plus courtes se traduit par des reductions mineures des prises accessoires de poissons juveniles, mais une reduction de 45 % des crevettes trop petites est observee. Les prises de crevettes de dimensions recherchees ne sont presque pas touchees. Quand la circonference de la maille du cul est abaissee tout en reduisant simultanement la longueur des cordes de couture, l'effet sur les prises de crevettes ou les prises accessoires de poissons juveniles est marginal comparativement a une conception de cul de chalut a quatre panneaux avec des cordes de couture plus courtes. [Traduit par la Redaction], 1. Introduction Various bycatch reduction measures are implemented in shrimp trawl fisheries globally, to restrict the bycatch of non-target species as well as undersized target species (Broadhurst and Kennelly 1995, [...]