Fig 1.
A) The location of northern shrimp (Pandalus borealis) and zooplankton sampling sites respective to shrimp fishing areas (SFAs; gray polygons). The Eastern Assessment Zone (EAZ) and Western Assessment Zone (WAZ) correspond to SFA2 and SFA3, respectively. The main bathymetric features, shown in color, have been extracted from GEBCO Compilation Group (2023). Schematic surface flow patterns (arrows), together with the main currents and topographic features, are indicated in black. Orange points represent sites where P. borealis was sampled between 2022 and 2023 across five shrimp fishing areas (SFAs 4-6, WAZ and EAZ). Blue points represent sites where zooplankton was sampled in 2023 across eight stations (from north to south: Hatton, Killinek Main, Isecold-3, Hatton Basin, SagBank, Isecold-2, Isecold-1, and Sentinel). The annual mean surface (B) and bottom (C) temperatures averaged over the sampling years (i.e., 2022-2023) have been extracted from the Global Ocean Physics Analysis and Forecast (GLORYS). D) Annual mean sea ice concentration (2022-2023) extracted from the MASAM2 dataset for the region of interest [43].
Fig 2.
Carbon and nitrogen isotopic composition of northern shrimp (Pandalus borealis) and zooplankton.
Stable isotope biplots illustrate the isotopic composition of Pandalus borealis across the shrimp fishing areas SFA2 (yellow), SFA3 (purple), SFA4 (red), SFA5 (green), and SFA6 (blue). The isotopic composition is represented by solid symbols: squares for P. borealis females, dots for males, and a triangle for zooplankton. Each shrimp data point is the mean for the group with error bars representing ± SD. Sample sizes are presented in S2 and S7 Tables.
Fig 3.
The estimated trophic levels of female and male northern shrimp (Pandalus borealis) in five shrimp fishing areas in Canada’s sub-Arctic.
Horizontal lines represent the trophic levels occupied by different shrimp individuals (mean trophic level values given above the boxes; black numbers). The middle part of the boxes represents the interquartile range, i.e., the middle quartiles (or the 75th minus the 25th percentile). The whiskers represent the variability outside the 75th and 25th percentile. Estimates were made using the ‘tRophicPosition’ model.
Fig 4.
Stable isotope biplots illustrating seasonal and spatial changes in the isotopic niche structure of the northern shrimp (Pandalus borealis) population in Canada’s sub-Arctic.
The positions occupied by females and males of shrimp in the isotopic space are represented by dots in each δ13C − δ15N biplot. Standard ellipses (solid lines) enclose the size-corrected standard ellipse area (SEAc, fits 40% of the data) of shrimp along the shrimp fishing areas (A): SFA2 (yellow), SFA3 (purple), SFA4 (red), SFA5 (dark green), and SFA6 (dark blue); and seasons (B): winter (light green), spring (dark grey), summer (orange), and autumn (light blue). Variation in the sizes of the standard ellipse areas (Figs C and D; with mean SEAc values given above the boxes) was calculated using SIBER.
Table 1.
Summary of individual lipids as a percentage of total FAs (mean ± SD) in Pandalus borealis tissues (muscle and eggs) collected across shrimp fishing areas (SFAs) in Canada’s sub-Arctic.
Table 2.
Summary of individual lipids as a percentage of total FAs (mean ± SD) in Pandalus borealis tissues (muscle and eggs) collected across shrimp fishing areas in Canada’s sub-Arctic.
Fig 5.
Principal component analysis (PCA) biplot illustrating the relative correlations between fatty acids found in northern shrimp (Pandalus borealis) and the fishing areas.
Each point represents a shrimp sample from the following shrimp fishing areas: SFA2 (yellow), SFA3 (purple), SFA4 (red), SFA5 (dark green), and SFA6 (dark blue). The coloured ellipses represent 95% confidence intervals around the means of the sampled sites. Only fatty acids contributing ≥1% are included in Fig 5A. The correlation between the saturated fatty acids (SAFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) and the fishing areas is shown in Fig 5B. The essential fatty acids (EFAs) are represented by omega-3 (ω3), omega-6 (ω6), and the sum of the EFAs 20:4ω6, 20:5ω3, and 22:6ω3.
Fig 6.
Bar plots illustrating the seasonal contributions of fatty acids in Pandalus borealis tissues.
The bar plots represented the relative proportions of saturated FAs (SAFAs), monounsaturated FAs (MUFAs), and polyunsaturated FAs (PUFAs) found in shrimp tissues. The total contributions of omega-3, omega-6, and essential fatty acids (EFAs), as well as the contributions of FAs derived from bacterial and zooplankton sources, are also illustrated by the bars. EFAs are the sum of the fatty acids: 20:4ω6, 20:5ω3, and 22:6ω3.
Table 3.
The relative concentration of lipid classes in northern shrimp (Pandalus borealis) throughout Canada’s sub-Arctic. The average lipid class contents (as mg/g WW) are measured in milligrams per gram of wet weight. The maximum values obtained are shown in bold.
Fig 7.
Seasonal and spatial variations in lipid classes and total lipid content in northern shrimp (Pandalus borealis).
Triacylglycerol, phospholipid, and total lipid contents are measured in mg per g of wet weight (mg/g WW). The middle part of the box, or the “interquartile range,” represents the middle quartiles (or the 75th minus the 25th percentile). The black line in the box represents the median. The minimum and maximum values of the data are indicated by the upper and lower lines of the box, respectively. Points beyond the lines represent outliers in the data set.