ge-0 fish in Upernavik and Uummannaq regions in AugustSeptember 2020. Technical Report No. 120

1 Age-0 fish in Upernavik and Uummannaq regions in August-September 2020 Caroline Bouchard Technical Report no. 120 Greenland Institute of Natural Resources 17 December 2021 2 Title: Age-0 fish in Upernavik and Uummannaq regions in AugustSeptember 2020 Author: Caroline Bouchard Publisher: Greenland Institute of Natural Resources Date of publication: 2021 Financial support: Greenland Institute of Natural Resources Cover photo: A juvenile shorthorn sculpin (Myoxocephalus scorpius), a larval capelin (Mallotus villosus) and a larval American plaice (Hippoglossoides platessoides) collected during the survey. Copyright: Caroline Bouchard ISSN: 1397-3657 ISBN: 978-87-972977-3-5 EAN: 9788797297735 Web: http://www.natur.gl/publikationer/tekniske rapporter Citation: Bouchard C (2021) Age-0 fish in Upernavik and Uummannaq regions in August-September 2020. Technical report no. 120, Greenland Institute of Natural Resources, Greenland. ISBN 97887-972977-3-5, 15 pp. 3 English Summary An ichthyoplankton survey was conducted onboard R/V Sanna between 19 August and 8 September 2020 in the Upernavik and Uummannaq regions in coastal West Greenland. The objective of the present report is to document the abundance and diversity of larval and juvenile fish in the region in the late summer of 2020. The age-0 fish collected belong to seven species, predominantly capelin (Mallotus villosus). No polar cod (Boreogadus saida) were collected during the survey, suggesting the extremely warm sea surface temperatures observed in the study area in 2020 resulted in massive mortality among the eggs and larvae, leading to a complete recruitment failure. 4 Greenlandic Summary – Kalaallisut Naalisarneqarnera R/V Sanna ilaaffigalugu Upernaviup Uummannallu eqqaanni sinerissap qanittuani planton-inik aalisagaaranngortussanik misissuisoqarpoq ulluni 19. august – 8. september 2020-imi. Nalunaarusiornerullu uuma siunertaraa takussutissamik uppernarsaaserniassallugu 2020-imi aasap naajartornerani qanoq aalisagassanngortussanik qullugiaaqqanik aalisagaagaaqqanillu sumiiffinni taakkunani peqartigisimanersoq. Aalisagaagaaqqat suli ukioqanngitsut assigiinngitsut arfineq-marluupput, amerlanerpaajullutilli ammassaat (Mallotus villosus). Eqalukkanik (Boreogadus saida) katersat ilaqanngillat tamatumunngalu patsisaatinneqarpoq 2020-imi taamaasinerani immap qaava kissartorujussuusimammat suaaqqat qullugiaaqqallu eqaluganngortussat toqorarujussuarsimanerat, taamaalilluni pisarineqartussanngortussaagaluit piffissami tassanngaaneersuusut annaaneqarsimallutik. 5 Danish Summary - Dansk Oversigt Ombord på R/V Sanna blev der mellem d. 19. august og d. 8. september 2020 udført en undersøgelse af fiskeplankton i de kystnære områder i Upernavikog Uummannaq-regionerne i Vestgrønland. Formålet med denne rapport er at dokumentere, hvilke fiskearter der i sensommeren 2020 forekom som larverog ungfisk, og hvor mange der var af dem, i regionen. De indsamlede fisk, der er mindre end et år gamle, tilhører syv arter, men er overvejende lodde (Mallotus villosus). Der blev ikke fundet polartorsk (Boreogadus saida). Det tyder på, at de ekstremt høje temperaturer, der blev målt i overfladevandet, medførte massiv død af æg og larver, så der ikke er kommet nye polartorsk ind i bestanden i 2020. 6 Table of Contents English Summary ....................................................................................................................... 3 Danish Summary - Dansk Oversigt ........................................................................................... 5 List of Tables ............................................................................................................................. 7 List of Figures ............................................................................................................................ 8 1. Introduction ............................................................................................................................ 9 2. Materials and Methods ......................................................................................................... 10 2.1. Field sampling ............................................................................................................... 10 2.2. Data analysis ................................................................................................................. 10 3. Results .................................................................................................................................. 12 4. Discussion ............................................................................................................................ 14 5. References ............................................................................................................................ 15 7 List of Tables Table 1. Summary of ichthyoplankton caught in the regions of Upernavik and Uummannaq in West Greenland in August-September 2020. SL: standard length. SD: standard deviation .... 12 Table 2. Densities of age-0 fish in Upernavik (UPV) and Uummannaq (UMK) regions ....... 13 8 List of Figures Figure 1. Map of the study area with station location. Upernavik region: stations UPV1-7, Uummannaq region: stations UMK1-12. Stars: towns ............................................................ 11 Figure 2. Length frequency distribution of larval capelin in Uummannaq region. n=52 ....... 13 9 1. Introduction Coastal waters of West Greenland are rapidly warming, affecting fish population dynamics. Many marine fish species have pelagic larvae characterized by a narrow range of thermal tolerance, and are therefore highly sensitive to increases in sea surface temperatures. A recent study suggested partial recruitment failures of polar cod (Boreogadus saida) in the regions of Uummannaq and Disko Bay in warm years, following thermal stress and massive mortality among the eggs and larvae (Bouchard et al. 2020). In 2018-2019, a predominance of capelin (Mallotus villosus) was observed in Upernavik whereas the ichthyoplankton of Uummannaq was dominated by polar cod (Bouchard et al. 2020). The main objective of the present report is to document the late summer ichthyoplankton assemblages in Upernavik and Uummannaq regions in 2020. The objective of testing the glacial meltwater summer refuge hypothesis exposed in Bouchard et al. (2020) could not be tested as no polar cod larvae were found.