***Reconstructing the diet, trophic level, and migration pattern of Mysticete whales based on baleen isotopic composition.

Philip M. Riekenberg1*, Jaime Camalich1, Elisabeth Svensson1, Lonneke L. IJsseldijk2, Sophie M.J.M. Brasseur3, Rob Witbaard4, Mardik F. Leopold3, Elisa Bravo Rebolledo3,6, Jack J. Middelburg5, Marcel T.J. van der Meer1,  Jaap S. Sinninghe Damsté1,5, Stefan Schouten1,5
(1) Department of Marine Microbiology & Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, Den Hoorn, 1790AB, The Netherlands
(2) Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3854 CL, Utrecht, The Netherlands
(3) Wageningen Marine Research, Wageningen University and Research, PO Box 57, 1780 AB, Den Helder, The Netherlands 
(4) Department of Estuarine and Delta Systems, NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University, PO Box 140, 4400 AC, Yerseke, The Netherlands
(5) Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8a, 3584 CB, Utrecht, The Netherlands
(6) Current: Bureau Waardenburg, Department of Bird Ecology, 4101 CK Culemborg, The Netherlands

*Corresponding Author: PMR, phrieken@gmail.com

***General Introduction***
This data set contains the  nitrogen stable isotope values from amino acids contained in the baleen from whales stranded or bowcaught in the North Sea as described in the manuscript

The data in this manuscript was produced in the Stable Isotope Laboratory in the Marine Microbiology and Biogeochemistry Department at NIOZ. 

***Test Equipment***
For compound specific isotope analysis of amino acid nitrogen, dried and homogenized tissue (2-5 mg) was lipid extracted, acid hydrolyzed, derivatized to pivaloyl- isopropyl esters and analysed for δ15N of AAs via gas 
chromatography-combustion isotope mass spectrometry using a Thermo Trace 1310 GC attached to Delta V Advantage isotope ratio mass spectrometer via an Isolink 2 following the method presented in Riekenberg, et al. (2020). 
δ15N values for 14 AAs are reported: alanine (Ala), aspartic acid (Asp), glutamic acid (Glu), glycine (Gly), leucine (Leu), lysine (Lys), isoleucine (Ile), methionine (Met), phenylalanine (Phe), serine (Ser), 
threonine (Thr), tyrosine (Tyr), and valine (Val). Precision of amino acid δ15N values were <0.5‰ in standards run 10× per sequence for 14 AAs throughout the analytical runs supporting this study and within run SD are presented
in Supplemental Table 3 with the manuscript. Normalization using two standard reference mixtures along with a reference spike of norleucine (Nle) added to all samples and standards which served as an internal reference calibration 
following the method from Yarnes and Herszage (2017).  

***Description of data***
lab; laboratory that analyzed the sample
lab_sample_id; lab sample ID
user_sample_id; User sample ID
length_from_gum; sample distance from gum along baleen  
collected_sample_mass; sample weight
instrumentation; Elemental analyzer
analysis_type; Bulk analysis of solid material
analysis_date; date and month of analysis
client_id; Who owns the sample
analytical_matrix; all tissues in this data set
primary_reference_material; Primary isotope reference material
preparation_step; sample preparations
preparation_step; sample preparations
material_type; generalized categories for sample ID of tissues
material_sample_id; Exact sample ID for tissue types
collection_source; All field samples
investigator_name; Philip Riekenberg
investigator_orcid; 0000-0002-6275-5762
investigator_email; phrieken@gmail.com
collection_locality; Wadden or North Sea
taxon_rank; ID is to species level
scientific_name; Genus species
amino acid_d15N; delta 15 N value for each amino acid
amino acid_error; standard deviation for the sample replicates of each amino acid
d15N_measurement_scale; against atmospheric N2
d15N_measurement_unit; per mille
d15N_error; standard deviation of the sample replicates for each amino acid analysis



