Environ Biol Fish https://doi.org/10.1007/s10641-019-0847-2
Left out in the cold: the understudied overwintering ecology of striped bass in Canada S. N. Andrews & C. F. Buhariwalla & B. Fleet-Pardy & M. J. Dadswell & T. Linnansaari & R. A. Curry
Received: 10 July 2018 / Accepted: 3 January 2019 # Springer Nature B.V. 2019
Abstract Striped Bass in Canadian waters occur at the most northern extent of the species range. At these latitudes, overwintering represents a significant portion of annual activities (Nov- May). During the winter period, Striped Bass generally occupy inland waterways, aggregate densely, feed little, and conduct minimal movements rendering them vulnerable to fisheries exploitation, pollution and habitat alterations. Despite the importance of winter survival to population viability, the winter period remains an understudied aspect of Striped Bass ecology throughout the species range. Here we review what is known as well as the knowledge gaps regarding the overwintering ecology for Striped Bass in Canadian waters. We discuss: all reported Canadian Striped Bass overwintering locations and their characteristics; environmental conditions that may be required S. N. Andrews (*) : B. Fleet-Pardy : T. Linnansaari : R. A. Curry Canadian Rivers Institute, Department of Biology, University of New Brunswick, P.O. Box 4400, Fredericton, NB E3B 5A3, Canada e-mail:
[email protected] C. F. Buhariwalla Inland Fisheries Division, Nova Scotia Department of Fisheries and Aquaculture, Pictou, Nova Scotia, Canada M. J. Dadswell Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada T. Linnansaari : R. A. Curry Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, Canada
for Striped Bass winter survival; environmental cues that may cause Striped Bass to enter overwintering habitats in late fall and depart in early spring; possible threats to overwintering habitat; and we propose numerous research questions necessary for improving Striped Bass conservation and management both within Canada and across the species range. Keywords Striped bass . Overwintering . Winter ecology . Winter habitat
Introduction The Striped Bass Morone saxatilis is an anadromous fish native to the Atlantic coast of North America and ranges from the St. Lawrence River, Quebec to the St. Johns River, Florida (Scott and Scott 1988). Throughout the warmer months, Striped Bass utilize numerous habitat types including freshwater rivers, estuaries, and marine coastlines (e.g., Scott and Scott 1988; Bjorgo et al. 2000; Grothues et al. 2009; Mather et al. 2009). The ecology of the Striped Bass in winter, by comparison, is poorly described. In general, it is thought that more northern Striped Bass populations in Canadian waters and Northern United States move inland to winter in presumably warmer coastal rivers, estuaries, and lakes (Scott and Scott 1988; Coutant 1990; Rulifson and Dadswell 1995). More recently, Striped Bass in these regions have been observed overwintering in locations with warm water discharge from power plants (Williams
Environ Biol Fish
and Waldman 2010; Buhariwalla et al. 2016) and even in marine habitats (Keyser et al. 2016). Striped Bass have been the focus of many intensive tagging and tracking studies from Gulf of St. Lawrence to Chesapeake Bay (Rulifson et al. 2008; Grothues et al. 2009; Pautzke et al. 2010; Wingate et al. 2011; Kneebone et al. 2014), but only a few studies have conducted winter tracking or report winter behaviour and movements (e.g., Bradford et al. 1998; Bednarski 2007). Most information regarding the winter habitat of Striped Bass in Canada result from directed winter surveys (Holland and Yelverton 1973), documentation of historic winter fisheries (Hogans and Melvin 1984; Scott and Scott 1988; Rulifson and Dadswell 1995), chance late season captures (Legendre et al. 1980) and, illegal harvesting operations (Douglas et al. 2003). As a result, there remain large knowledge gaps regarding the winter ecology of Striped Bass in Canadian waters. American Striped Bass populations which have received much study in recent decades display a diversity of movement patterns. United States origin Striped Bass have been observed to conduct large scale coastal migrations (Waldman et al. 1990), inhabit deep offshore water in both summer (Holland and Yelverton 1973) and winter (Waldman et al. 2012), occupy distant non-natal rivers over winter (Bednarski 2007), and even organize into distinct cohorts within rivers (Zlokovitz et al. 2003). Canadian populations on the other hand have been found to have different behaviours across seasons often staying close to natal rivers (Rulifson and Dadswell 1995; Rulifson et al. 2008) and have different physiological tolerances to environmental conditions (Bradford et al. 2001, 2014, 2015; Douglas et al. 2003); therefore, the ecology of Canadian populations many differ significantly from US counterparts. These differences suggest that US Striped Bass overwintering habits and habitats may not be synonymously applicable across the species range in both the US and Canada and is one of the reasons why knowledge gaps exist especially for Striped Bass overwintering in Canadian waters. Winter behaviour and habitats of Striped Bass are a critical management consideration (COSEWIC 2004, 2012). The long winter period for Striped Bass within Canada has been shown to affect juvenile survival and year class strength (Bernier 1996; Bradford and Chaput 1997; Bradford and Cook 2004). Winter aggregations of adults are subject to increased vulnerability to commercial fishing (Williams and Waldman 2010) as well as point source chemical and thermal pollution (Setzler
et al. 1980; Bradford et al. 1998; Dadswell 2006; Williams and Waldman 2010; Buhariwalla et al. 2016). Here we review the available information from peer-reviewed literature, academic and government reports, fisheries and historic accounts, and local/ traditional ecological knowledge to: discuss the general distribution of Striped Bass in Canadian waters during November through May; summarize the literature on Striped Bass ecology in documented overwintering locations in Canadian waters; and propose general characteristics of overwintering habitats and factors that may limit or control Striped Bass distribution. Defining winter Winter in the northern hemisphere is meteorologically defined as the period from 1 December to 28(29) February. It is characterised by days that are shorter (reduced photoperiods) and the coldest temperatures of the year (Halfpenny and Ozanne 1989). All north temperate fishes have adapted to this seasonality (e.g., Rulifson and Dadswell 1995; Harrison et al. 2016; Tommie et al. 2017). Managers of the historic Striped Bass fisheries in Canada considered the Bwinter harvest^ to be that which was taken through the ice and which closed when waters became Bnavigable^ in the spring (DMF 1871–1918). For this review, we define winter habitat as the locations where Striped Bass become torpid and aggregate, i.e., from November to early May. Canadian overwintering distribution The Atlantic Canadian provinces of Nova Scotia (NS), New Brunswick (NB) and Québec (QC) harbour distinct Striped Bass spawning populations in the most northern part of the species range (COSEWIC 2004; Fig. 1). These populations must survive the longest winter period (up to 7 months, i.e., November–May; C. Buhariwalla, unpubl. data) and the lowest marine (−2.0 °C; Bernier 1996) and freshwater (
