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In this study, halibut bone, a byproduct of Greenland halibut processing, was prepared into a thick soup through a non-frying process. The formation of colloidal micro-nano particles and flavor characteristics in halibut bone soup was explored. The results showed that the nutrients in halibut bones migrated to the soup continuously with the cooking process and reached the highest concentration (total sugars, 38.16 mg/100 ml; water-soluble proteins, 25.71 mg/ml; fatty acids, 2.15 g/100 ml; solids, 1.14 g/100 ml) at 150 min. Taste substances such as organic acids, 5'-nucleotides and total free amino acids (TFAAs) content in halibut bone soup also reached maximum at 150 min. At this time, results for particle size showed that MNPs with uniform size (725.62 nm) were formed, which made the bone soup milky white, stable, and had good tasting. Headspace-gas chromatography-ion mobility spectrometry results showed that a total of 59 volatile substances were detected from the halibut bone soup. The content of volatile flavor substances in the 150 min group was lower than that in the 90-120 min group. Meanwhile, aldehydes and ketones gradually became esters. PRACTICAL APPLICATION: Soup is an indispensable part of the world food culture. In order to increase the added value of Greenland halibut, halibut bone soup was studied in this paper. This study found that halibut bone soup that had not been fried, formed the MNPs and has a more harmonious and pleasant flavor. Thus, non-fried halibut bone soup is a good processing method and can improve economic efficiency.

The North Atlantic Fisheries Organization (NAFO) has continuously lowered their advice regarding the Total Allowed Catch (TAC) for the coastal Greenland halibut fisheries in Western Greenland. This is due to concerns of overexploitation of the fishery. This paper investigates how the fishing intensity in the fishery for Greenland halibut (Reinhardtius hippoglossoides) in the Disko Bay, Greenland, affects the current and future income opportunities of coastal fishers. Through bio-economic modelling, I find presence of economic overexploitation of the Greenland halibut fish stock in the Disko Bay. Specifically, the actual Greenland halibut stock in 2019 is found to constitute only 56 pct. of the economic optimal stock size in the baseline scenario. The actual profit is almost 40 million DKK lower than the optimal profit due to higher costs of harvesting, which arise because the actual stock size is lower than the optimal and because of a suboptimal split of the TAC between vessels (above 6 m in length) and boats (6 m or below in length) in the fishery. The results presented in this article show that there is significant scope for economic optimization of the coastal Greenland halibut fishery through a temporary reduction in harvest of Greenland halibut to regenerate the stock to its optimal size and a transfer of TAC from the boat segment to the vessel segment. Notably, this article does not find that the stock of Greenland halibut in the Disko Bay is further decreasing at current (2019) harvest levels, however, this finding is contingent on the length of the data series used for the estimation of the growth model.

Despite the commercial importance of Greenland Halibut (Reinhardtius hippoglossoides), important gaps still persist in our knowledge of this species, including its reproductive biology and sex determination mechanism. Here, we combined single-molecule sequencing of long reads (Pacific Sciences) with chromatin conformation capture sequencing (Hi-C) data to assemble the first chromosome-level reference genome for this species. The high-quality assembly encompassed more than 598 Megabases (Mb) assigned to 1594 scaffolds (scaffold N50 = 25 Mb) with 96% of its total length distributed among 24 chromosomes. Investigation of the syntenic relationship with other economically important flatfish species revealed a high conservation of synteny blocks among members of this phylogenetic clade. Sex determination analysis revealed that similar to other teleost fishes, flatfishes also exhibit a high level of plasticity and turnover in sex determination mechanisms. A low-coverage whole-genome sequence analysis of 198 individuals revealed that Greenland Halibut possesses a male heterogametic XY system and several putative candidate genes implied in the sex determination of this species. Our study also suggests for the first time in flatfishes that a putative Y-autosomal fusion could be associated with a reduction of recombination typical of the early steps of sex chromosome evolution.

Control of appetite and feed intake in fish larvae are still largely unexplored. Two of the key players in controlling vertebrate's feed intake are cholecystokinin (CCK) and peptide YY (PYY). Here we investigated the mRNA expression of pyy, cck and cck receptors (cckr) in the brain (head) and gut of Atlantic halibut larvae in response to three consecutive meals. We used Artemia nauplii cysts that are commonly ingested by halibut larvae when present as inert feed, and three water-soluble extracts as attractants to stimulate appetite. Cyst intake was not affected by the use of attractants and overall ingestion rate was low. Differences in mRNA expression of cck and pyy were observed between the halibut larvae that had eaten and those that had not despite readily available feed (cysts), supporting that mechanisms for control of feed intake are at least partly functional. All genes analysed were present in the brain and gut, however the different expression profiles between paralogues suggest potential divergent functions. In the gut, cck2 and pyyb mRNA expression was significantly higher in the larvae that ate cysts compared to larvae that decided to not eat, indicating that these genes play a satiety function in the halibut larvae similar to the general vertebrate scheme. However, cck2, cck2r1, and pyy mRNA expression in the brain were lower in the fed-filled larvae group compared to larvae before eating, which contrasts with the presumable anorectic function of these genes. Further research is required to fully evaluate how PYY and CCK affect the feeding biology in halibut larvae, contributing to formulate inert diets that can stimulate appetite and feed intake.

Identifying the nursery origins of individual Pacific halibut (Hippoglossus stenolepis) is critical to a refined understanding of regional productivity, the effects of environmental forcing on population dynamics, and the spatial impacts of mortality and bycatch. Otolith microchemistry may provide a tool for identifying fish origins, but a precursor to using microchemistry-based assignment models is to evaluate the extent to which there exists detectable spatial structure in these natural tags. Here, we examined assignment accuracy as a function of spatial scale using canonical discriminant function analyses (DFA) applied to microchemical data from age-2 Pacific halibut in the western Gulf of Alaska (GOA) and southeastern Bering Sea (SEBS). Element:calcium ratios were assayed for fourteen trace elements using inductively coupled plasma mass spectrometry; δ13C and δ18O were determined via isotope ratio mass spectrometry. Substantial assignment success (∼75–90 %) was observed at spatial scales that are consistent with stock management. Elemental signatures were defined primarily by δ18O, δ13C, and 88Sr:48Ca, with a minor contribution from 55Mn:48Ca. Individuals were most commonly mis-assigned to adjacent locations. However, discontinuities were observed within the western GOA that suggest that elemental signatures do not vary along strictly longitudinal and latitudinal clines. These results highlight the need to exercise caution when attempting to use otolith microchemistry to assign fish to their origins when the baseline elemental data are unable to resolve missing nursery sources from the locations that are included in the discrimination models.