Canadian Journal of Fisheries and Aquatic Sciences Preference for near -shore and estuarine habitats in anadromous Arctic char (Salvelinus alpinus) from the Canadian high Arctic (Victoria Island, NU) revealed by acoustic telemetry Journal: Canadian Journal of Fisheries and Aquatic Sciences Manuscript ID cjfas-2015-0436.R2 Manuscript Type: Article Date Submitted by the Author: 14-Jan-2016 Complete List of Authors: Moore, JeanDraft Sebastien; Université Laval, Institut de Biologie Intégrative et des Systèmes Harris, Les; Fisheries and Oceans Canada, Kessel, Steven; University of Windsor, Great Lakes Institue of Environmental Research Bernatchez, Louis; Universite Laval Tallman, Ross; Fisheries and Oceans Canada, Fisk, Aaron; University of Windsor, Great Lakes Institute for Environmental Research BEHAVIOR < General, COMMERCIAL FISHERIES < General, MIGRATION < Keyword: General, STOCK DISCRIMINATION < General, ANADROMOUS SPECIES < Organisms https://mc06.manuscriptcentral.com/cjfas-pubs Page 1 of 37 Canadian Journal of Fisheries and Aquatic Sciences 1 Preference for near-shore and estuarine habitats in anadromous Arctic char 2 (Salvelinus alpinus ) from the Canadian high Arctic (Victoria Island, NU) revealed 3 by acoustic telemetry 4 5 Jean-Sébastien Moore 1*, Les N. Harris 2, Steven T. Kessel 3, Louis Bernatchez 1, Ross F. 6 Tallman 2, Aaron T. Fisk 3 7 8 1 Institut de Biologie Intégrative et des Systèmes and Département de Biologie, 9 Université Laval, Québec, QC, Canada 10 2 Fisheries and Oceans Canada, Central and Arctic Region, Arctic Aquatic Research 11 Division, Winnipeg, MB, Canada Draft 12 3 Great Lakes Institute of Environmental Research, University of Windsor, Windsor, ON, 13 Canada 14 15 [email protected] 16 [email protected] 17 [email protected] 18 [email protected] 19 [email protected] 20 [email protected] 21 *Corresponding author 22 1030 Avenue de la Médecine, Québec, QC, Canada, G1V 0A6 23 Phone: 418-656-3402; Fax: 418-656-7176 https://mc06.manuscriptcentral.com/cjfas-pubs Canadian Journal of Fisheries and Aquatic Sciences Page 2 of 37 24 Abstract (173 words – 175 max) 25 We used an array of fixed acoustic receivers (N = 42) to track the summer marine 26 movements of 121 anadromous Arctic char equipped with acoustic transmitters at three 27 locations in the Cambridge Bay region, where commercial and subsistence fisheries 28 target the species. The timing of transitions between salt and fresh water was influenced 29 by the putative river of origin of tagged individuals, but not by their size or sex. Females, 30 however, were more likely to remain proximate to rivers where they were tagged 31 throughout the summer. A majority of fish migrated west from their rivers of origin, 32 primarily moving between estuarine environments. Individuals occupied estuaries for 33 several days between bouts of marine movement, and these periods of residency 34 coincided with spring tides in someDraft estuaries. We also recorded increased numbers of 35 detections on receivers located less than 1.5 km from the coast, indicating a preference 36 for near-shore habitats. Finally, we report evidence of extensive stock mixing throughout 37 the summer, including at known fishing locations and periods, a finding with implications 38 for fisheries management. 39 40 41 42 Keywords: Arctic fisheries, habitat use, migration ecology, mixed stocks, salmonids, 43 tracking 2 https://mc06.manuscriptcentral.com/cjfas-pubs Page 3 of 37 Canadian Journal of Fisheries and Aquatic Sciences 44 Introduction 45 Arctic fish species are facing multiple threats associated with climate change, 46 increased harvests, and growing pressures from non-renewable resource 47 exploration/extraction and shipping industries (Reist et al. 2006; Arctic Council 2009; 48 Christiansen and Reist 2013). Managing these threats to ensure that conservation goals 49 are met and that subsistence and commercial fisheries remain sustainable will require the 50 identification of critical habitats, a key knowledge gap for many Arctic species 51 (Christiansen and Reist 2013). Indeed, the spatial ecology of many Arctic fishes remains 52 poorly understood, especially in Canadian waters, and characterizing habitat use in both 53 space and time during relevant life-stages is essential for effective management and 54 conservation (Rosenfeld and HatfieldDraft 2006; Costello et al. 2010; Walther et al. 2015). 55 Passive acoustic telemetry offers a powerful tool for the study of habitat use and for the 56 long-term monitoring of fish movement (Heupel and Webber 2012; Hussey et al. 2015). 57 Studies tracking the marine migrations of adult salmonids, however, remain rare (e.g., 58 Drenner et al. 2012; Klimley et al. 2013), and this is particularly true in the Arctic. 59 The Arctic char ( Salvelinus alpinus (L.)) is a facultatively anadromous salmonid 60 with a circumpolar distribution (Johnson 1980; Nordeng 1983; Reist et al. 2013). 61 Migratory individuals leave the fresh water at ice-breakup and spend the summer in the 62 marine environment where they feed until they migrate back to fresh water before rivers 63 freeze (Johnson 1980; Bégout Anras et al. 1999). While many other anadromous 64 salmonids return to freshwater only to spawn (Fleming 1998, Quinn 2005; but see 65 exceptions documented from Dolly Varden ( S. malma ; Armstrong 1974), brown trout 66 (Salmo trutta ; Jonsson 1985), and cutthroat trout ( Oncorhynchus clarkii clarkii ; Wenburg 3 https://mc06.manuscriptcentral.com/cjfas-pubs Canadian Journal of Fisheries and Aquatic Sciences Page 4 of 37 67 and Bentzen 2001)), anadromous Arctic char must return to fresh water every winter even 68 as juveniles or non-spawning adults, presumably to avoid high salinity and sub-zero 69 water (Johnson 1980; Klementsen et al. 2003; but see Jensen and Rikardsen 2012). Arctic 70 char are iteroparous and repeat spawning is common with up to 50% of adults spawning 71 at least twice in some populations (Fleming 1998). Arctic char, however, do not usually 72 spawn in consecutive years because the short ice-free period limits feeding opportunities 73 in the marine environment, thus delaying gonadal development (Dutil 1986). In some 74 populations, Arctic char forego marine migrations in the year before spawning 75 (Gyselman 1994). Arctic char generally home to their natal system to spawn, but straying 76 and stock mixing can be common (e.g., Dempson and Kristofferson 1987; Jensen et al. 77 2015), especially in years when individualsDraft do not spawn (Moore et al. 2013; Moore et al. 78 2014). In some systems, spawning and overwintering sites are located in different areas, 79 requiring a post-spawning migration within freshwater (Johnson 1980; Beddow et al. 80 1998). 81 Relatively few studies have examined the spatial ecology of anadromous Arctic 82 char during the marine phase of its life cycle (Moore et al. 2014). Existing data suggest 83 that the migration from fresh water to the marine environment occurs after the river ice 84 breaks, but before the sea ice is entirely melted (Bégout Anras et al. 1999). A period of 85 estuarine residency follows marine entry, and can last several days, at least until the sea 86 ice is melted (Bégout Anras et al. 1999), and others have found that Arctic char may 87 reside close to estuaries for the entire duration of the summer marine phase (Spares et al. 88 2015). Catches of Arctic char in fisheries in near-shore habitats tend to exceed off-shore 89 catches (Dempson and Kristofferson 1987; Finstad and Heggberget 1993), and some 4 https://mc06.manuscriptcentral.com/cjfas-pubs Page 5 of 37 Canadian Journal of Fisheries and Aquatic Sciences 90 telemetry data also suggest a preference for near-shore habitats (Spares et al. 2012; 91 Jensen et al. 2014). Preference for warmer and less saline waters has also been suggested 92 (Bégout Anras et al. 1999; Spares et al. 2012). Mark-recapture studies suggest that 93 distances travelled by Arctic char at sea are typically short, with the majority of 94 recaptures occurring less than 100 km from the tagging location (Dempson and 95 Kristofferson 1987; Berg and Jonsson 1989; Finstad and Heggberget 1993), although 96 some occasional long-distance migration events of more than 300 km have been 97 documented (Jensen and Berg 1977; Dempson and Kristofferson 1987). 98 We used acoustic telemetry to describe the marine migratory behaviour and 99 habitat use of anadromous Arctic char from the Cambridge Bay region of Nunavut. To 100 address this overall objective, we examinedDraft three different spatio-temporal aspects of 101 anadromous Arctic char habitat preference. First, we examined the timing of fresh- 102 /saltwater transitions in relation to different biological variables (mainly size and sex). 103 Second, we examined whether individuals from rivers distributed around Wellington Bay 104 (Fig. 1) predominantly remained in or migrated out of Wellington Bay, and if they left, 105 the timing of their departure and the direction they take once leaving the area. Third, we 106 tested the hypothesis that tagged Arctic char preferred near-shore and estuarine habitats 107 as opposed to off-shore habitats, as suggested by previous studies (Dempson and 108 Kristofferson 1987; Spares et al. 2012; Spares et al. 2015; Jensen et al. 2014). 109 Furthermore, the largest commercial fishery for wild anadromous Arctic char in Canada 110 operates in this region and targets several different stocks defined on a river-by-river 111 basis (the word ‘stock’ is used throughout to refer to the management units that receive 112 distinct quotas in the region and we note that their biological validity remains to be 5 https://mc06.manuscriptcentral.com/cjfas-pubs Canadian Journal of Fisheries and Aquatic Sciences Page 6 of 37 113 tested). This fishery has been operating since 1960 with average landings of 41,290 kg 114 per year (Day and Harris 2013). Our last objective was therefore to test the hypothesis 115 that currently recognized stocks mix at sea, with a particular emphasis on whether they 116 mixed at the main fishing sites during the fishing periods.