Intertidal Habitat Use, Population ... - Wiley Online Library

Transactions of the American Fisheries Society 137:23–32, 2008 Ó Copyright by the American Fisheries Society 2008 DOI: 10.1577/T06-174.1

[Article]

Intertidal Habitat Use, Population Characteristics, Movement, and Exploitation of Striped Bass in the Inner Bay of Fundy, Canada ROGER A. RULIFSON* Institute for Coastal and Marine Resources 1 and Department of Biology, East Carolina University, Greenville, North Carolina 27858, USA

SEAN A. MCKENNA North Carolina Division of Marine Fisheries, 943 Washington Square Mall, Washington, North Carolina 27889, USA

MICHAEL J. DADSWELL Department of Biology, Acadia University, Wolfville, Nova Scotia B4P 2R6, Canada Abstract.—Striped bass Morone saxatilis were sampled from intertidal weirs in Minas Basin and Cobequid Bay, Bay of Fundy, to determine tidal behavior, population characteristics, movements, and exploitation. During 1985 and 1986, 1,864 striped bass ranging from 69 to more than 600 mm in fork length were captured in three commercial weirs from May to December along the north shore of Minas Basin and Cobequid Bay. Catches were lowest during early summer and highest in late summer and fall. Catches were greatest when low tide occurred from dusk to midnight (1800–2400 hours), a second peak being observed when low tide occurred from dawn to late morning. Largest weir catches at a clear-water site (Minas Basin) were associated with spring tides (0.5–0.9 m above mean low water [MLW]), but at turbid water sites (Cobequid Bay) the best catches were during neap tides (1.0–1.7 m above MLW). The largest striped bass were captured from June to August (280–610 mm), but age-0 (69–94-mm) and age-1 (141–240-mm) fish dominated the catches in September and October. A total of 1,431 striped bass were marked: 1,163 in 1985 and 268 in 1986. The recapture rate was 21.3% for fish released in 1985 and 8.9% for those released in 1986; 55.8% were recreational recaptures, and 44.2% came from commercial fisheries. The mean day of recapture from all sources (recreational and commercial) in marine waters of the Bay of Fundy was September 3, but for striped bass recaptured in local, freshwater overwintering sites it was May 21. The average distance moved for striped bass recaptured in Minas Basin and local watersheds was 55 km, and for long-distance movement it was 780 km. Tags were returned from Nova Scotia, New Brunswick, Massachusetts, Rhode Island, Connecticut, New Jersey, and Virginia. All tag returns from outside Minas Basin were from fish larger than 390 mm at time of release. The fastest travel time was 17.8 km/d by a fish recaptured in Rhode Island 45 d after release. Our findings demonstrate that the striped bass frequenting Minas Basin and Cobequid Bay each summer consist of a portion that overwinters in freshwater around the Bay of Fundy and a portion that migrates southward along the eastern coast of the United States.

Striped bass Morone saxatilis support important commercial and recreational fisheries on the eastern seaboard of the United States and Canada. The Bay of Fundy is a region where the species has been exploited for centuries by fisheries of various types (Perley 1852; Dadswell et al. 1984a) and is known to contain mixed U.S. and Canadian stocks (Rulifson and Dadswell 1995; Wirgin et al. 1995). Striped bass tagged in the Bay of Fundy and its watersheds have been recaptured

along the East Coast of the USA, and fish tagged in spawning rivers of the USA have been recaptured in the Bay of Fundy (Nichols and Miller 1967; Clark 1968; Boreman and Lewis 1987; Harris 1988; Rulifson and Dadswell 1995). Typically, striped bass populations north of North Carolina migrate north during the summer and return southward to wintering areas prior to entering natal streams to spawn in the spring (Setzler et al. 1980; Waldman et al. 1990). The result of these movements is that unknown proportions of mixed U.S. and Canadian stocks occur throughout the migratory pathway and in the Bay of Fundy. Since striped bass stocks are known to undergo large, decades-long population size oscillations and these changes are often out of phase latitudinally (Merriman 1941; Van

* Corresponding author: [email protected] 1 Now the Institute for Interdisciplinary Coastal Science and Policy. Received July 24, 2006; accepted May 3, 2007 Published online January 3, 2008

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Winkle et al. 1979; Ulanowicz and Polgar 1980; Hurst and Conover 1998), the portion of migratory stocks at any coastal location may vary widely from year to year (Fabrizio 1987; Wirgin et al. 1993). United States striped bass stocks declined to low population levels during the 1980s but have since rebounded to almost record numbers, perhaps due to the various U.S. fishing moratoria declared during the 1980s and 1990s (Richards and Rago 1999) or environmental oscillations leading to enhanced reproduction (Field 1997). Angler catches of striped bass in the inner Bay of Fundy during summer and abundance of spawners in the Shubenacadie watershed during spring were very high during the late 1990s (Rulifson and Tull 1998), but it is unknown if these were fish from local stocks or migrants from U.S. stocks. During the last few years, largely as a response to the apparent lack of spawning success of striped bass in some Bay of Fundy watersheds, there has been a movement to declare Fundy stocks threatened and to restrict fishing (Douglas et al. 2002). Striped bass adults ascend rivers in the spring to spawn in fresh or brackish waters and often remain for extended periods before returning to the sea. In Atlantic Canada, some proportion of many populations overwinter in freshwater (Jessop 1980; Hogans 1984; Rulifson and Dadswell 1995) and migrate from fresh to brackish water in spring to spawn (Rulifson and Tull 1998; Gemperline et al. 2002; Paramore and Rulifson 2001). Whether this behavior among Canadian populations has a genetic component is unknown, but it is in response to this possibility and the apparent poor spawning success for some populations that a fishing moratorium in Canada is now being considered (R. Bradford, Fisheries and Oceans Canada, Halifax, personal communication). Although our study was conducted 20 years ago, we believe it remains pertinent because limited information is available on the behavior, population characteristics, and movements of striped bass in marine waters of Atlantic Canada. In addition, little information exists on exploitation rates of striped bass in the Bay of Fundy and how exploitation is partitioned between recreational and commercial fishers. Tidal power generating projects have been proposed or constructed in the Bay of Fundy (Douma and Stewart 1981; Dadswell and Rulifson 1994) and new ones are presently in planning stages; to understand the environmental impacts of these projects, we need to know which fish species and stocks may be affected and for what periods they utilize Bay of Fundy marine habitats. The presence of migrant striped bass in the inner Bay of Fundy is important in understanding striped bass long-term stock dynamics because devel-

opment of tidal power in this region has the potential of impacting both U.S. and Canadian striped bass stocks (Dadswell and Rulifson 1994). It was in these contexts that our study was conducted in Minas Basin and Cobequid Bay. Study Site The Bay of Fundy is an embayment of the Atlantic Ocean positioned between the state of Maine and the provinces of New Brunswick to the west and Nova Scotia to the east. The inner Bay of Fundy consists of two large embayments: Minas Basin, the eastern portion, and Chignecto Bay, the western portion that also contains Cumberland Basin (Figure 1). These embayments have extreme tidal amplitudes (up to 16 m) and swift tidal currents (1–4 m/s) during tidal exchange (Greenberg 1984). Tides are semidiurnal and asymmetrical, having a periodicity of 12.4 h. Extensive intertidal flats, 1–2 km wide, dominate the shoreline at low tide. The strong tidal currents resuspend bottom sediments during each tidal cycle resulting in high levels of suspended silt (10–1,000 mg/L) and low water transparency (Amos and Alfoldi 1979). Surface temperatures in the inner Bay of Fundy are similar to those in the northern Gulf of Maine during summer (Sutcliffe et al. 1976) but salinities are lower, varying between 22% and 30% (Bousfield and Leim 1958). The study was conducted in Minas Basin and Cobequid Bay of the inner Bay of Fundy, Nova Scotia, because of its active recreational and commercial fisheries for striped bass and its planned location for future tidal power development. The embayment is 1,125 km2 and is divided into two parts by a large point of land, Economy Point (Figure 1). The seaward portion is known as Minas Basin, and the landward portion, Cobequid Bay. Minas Basin is the deeper of the two parts and is dominated by cool, clear seawater from the Bay of Fundy (Bousfield and Leim 1958; Amos and Alfordi 1979). Tidal currents in Minas Channel are 4.0 m/s in the narrows at Cape Split, and then decrease to 1.5 m/s in Minas Basin (Greenberg 1984). The residual current is driven by tidal flow in two clockwise gyres: a stronger gyre in the Southern Bight, and a second gyre offshore from Five Islands (Greenberg 1984). At low tide, extensive intertidal flats up to 2 km wide appear along the shoreline off Five Islands to the north and in the Southern Bight to the south, lesser flats appearing around the periphery at various locations. Cobequid Bay is a large (45-km 3 10-km) and shallow (,20-m) eastern extension of Minas Basin formed by two landmasses extending into Minas Basin, between Economy Point and Tennycape (Figure 1), which channel the movement of ocean waters into

STRIPED BASS IN THE INNER BAY OF FUNDY

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FIGURE 1.—Map of the Minas Basin and Cobequid Bay of the inner Bay of Fundy, Nova Scotia, indicating the sites of collection weirs, extent of the intertidal zone, and the geographical locations referred to in the text.

Cobequid Bay. High-velocity currents, combined with shallow water, cause extensive vertical mixing of the water column and resuspension of silt (Amos and Alfoldi 1979). Slack water during tide change is limited to 15–30 min, allowing little time for surface waters to clear. Easternmost Cobequid Bay receives the outflow of the Shubenacadie–Stewiacke watershed, which supports a self-sustaining population of striped bass (Rulifson and Dadswell 1995; Rulifson and Tull 1998). Salinities in Cobequid Bay are lower than those in Minas Basin, and water temperatures are warmer due to solar heating of the extensive intertidal flats at low tide (Bousfield and Leim 1958). Water column temperatures are similar from top to bottom in both regions because of vertical mixing caused by the large tides (Amos and Alfoldi 1979). The residual current pattern includes a small, counterclockwise gyre in the westward end of Cobequid Bay between Economy Point and Tennycape (Greenberg 1984).

Cobequid Bay near Economy Point (45823 0 N, 63850 0 W), and one weir was located in Minas Basin (45823 0 N, 6485 0 W) on the intertidal flats of Five Islands, approximately 22 km away (Figure 1). These weirs were V-shaped, between 500 and 800 m in length, and were positioned 0.8–1.3 km from the high (spring) tide mark (Gordon 1993). At high tide, weirs were covered by approximately 5–7 m of water. During spring tides, the weirs were about 1 km landward from the low watermark; during neap tides portions of the weirs remained flooded and inaccessible. All three

Methods Striped bass were examined in commercial weirs at low tide from May to December during 1985 and 1986 (Figure 2) and were tagged from June 1 to October 18, 1985, and from June 9 to October 5, 1986. Seven commercial weirs were in this region, but only three were used for data collection. Two of the weirs were in

FIGURE 2.—Monthly catch per tide of individual striped bass captured in weirs in Minas Basin and Cobequid Bay (May–December 1985).

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RULIFSON ET AL.

weirs were visited every low tide they were accessible during the 1985 tagging season (June through October), but only intermittently during May, November, and December. During 1986, a single weir was visited each day during the tagging period and intermittently until December. Weirs are positioned with wing tips facing shore and the heart centered in the portion furthest from shore. Brush (usually spruce) is woven between 2- and 3-mlong wooden stakes to form the wings, and small-mesh net, brush, and boulders are used in fabricating the weir heart, which retains a small pond at low tide (Gordon 1993). The weirs are operated only during the period from May to December. They must be rebuilt each spring because they are destroyed in winter by the buildup of mobile pack ice in the inner Bay of Fundy (Gordon and Desplanque 1983). Weirs were visited with the fisher at low tide. Sampling periods ranged from 0 to 90 min depending on phase of the tides and prevailing winds. Weirs were sampled as soon as receding waters moved seaward of the wing tips, trapping the catch within the weir. Fish were recovered by seining with small-mesh nets and by dip net. All striped bass were checked for tags and enumerated; those not kept by the fisher were measured for fork length (fork length [FL]; mm), weighed (g), had a scale sample taken from between the dorsal fin and the lateral line, were marked with a Floy FT-1 single barb dart tag (international orange), and were then released either back into the weir pond or into the receding waters. Tags were individually numbered and had a return address to the North Carolina Division of Marine Fisheries in Morehead City. Scales were aged using two readers, and annuli distances were measured using a dissecting microscope with an ocular micrometer. Distance moved was measured as the length of coastline between the tagging site and the recapture location. Exploitation (l) was calculated as a direct estimate based on striped bass tagged (m) versus tags (r) returned (Ricker 1975). Results Catch Patterns A total of 1,864 striped bass were captured in the three weirs during 1985 and 1986. Striped bass catches were influenced by season, time of day, and tidal characteristics. Catches were lowest during spring and early summer and highest in late summer and fall (Figure 2). Catches were largest when low tide occurred between 1800 and 2400 hours, a second peak taking place when low tide occurred between 0400 and 1000 hours (Figure 3). Few striped bass were captured from midnight to about 0300 hours, during the period when high tides occurred from just after dark to 2300

hours. Catches also were related to tidal amplitude. The best catches in Minas Basin were associated with predicted spring low tides of 0.5–1.2 m above mean low water (MLW; Figure 4; Fisheries and Oceans Canada 1985. In contrast, Cobequid Bay catches were best during neap tides (0.9–1.7 m above MLW) when receding waters were clearer and the low tide mark was closer to the beach. Cobequid Bay weirs could not be sampled when predicted neap tides were 1.8 m or more above MLW unless winds influenced the tidal oscillation. The striped bass caught in 1985 represented four distinct length frequency classes and a wide range of large, older fish (Figure 5). Age-0 striped bass measured 69–94 mm FL and were caught only in Cobequid Bay weirs during September and October. Age-1 fish (141–240 mm FL) were the most abundant size-class and were caught in the greatest numbers in Cobequid Bay but also in the Minas Basin weir. Fish of larger size-classes dominated Minas Basin weir catches (Figure 5). Several striped bass over 600 mm FL were caught in the Minas Basin weir during 1986. We observed that FLs often differed by up to 100 mm among striped bass of similar age. Scale annuli measurements revealed two distinct groups. For age-1 and age-2 fish, one group had a narrow first annulus (1.49 6 0.25 mm [mean 6 SD]) compared with that of a second group, which had a significantly wider first annulus (3.02 6 0.34 mm; t-test: P 0.01). Among older striped bass there was a wide range of first annulus widths, ranging from 1.0 to 3.5 mm (mean ¼ 2.65 mm). Based on the same-year recapture of marked fish, the summer growth of age-1 and older striped bass in the inner Bay of Fundy was 0.375 6 0.118 mm/d. Fish measured before release during 1985 and recaptured more than 5 d after release but before October 31, 1985, were remeasured on the same measuring board by the same individual. Those recaptured in Minas Basin averaged a slightly faster growth rate of 0.382 6 0.127 mm/d (n ¼ 13) compared with that for fish recaptured in Cobequid Bay (0.348 6 0.079 mm/d; n ¼ 3; t-test: P , 0.05). Movement A total of 1,431 striped bass were tagged and released in Minas Basin and Cobequid Bay during the 2-year study: 1,163 in 1985 and 268 in 1986. About 32% (n ¼ 464) of the tagged fish were released in Minas Basin, and the remainder were released along the north shore of Cobequid Bay. The overall recapture rate was 19.0% (272). For striped bass released in 1985, the recapture rate was 21.3% (248) and for those released in 1986, it was


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FIGURE 3.—Catch of striped bass in Minas Basin and Cobequid Bay weirs in relation to time of low-tide collections during August and September 1985.

8.9% (24). Six recaptures were missing critical information and so could not be quantified. Tags were returned from 42 locations in Nova Scotia, New Brunswick, Massachusetts, Rhode Island, Connecticut, New Jersey, and Virginia. All tag returns from outside Minas Basin were striped bass larger than 390 mm FL at time of release. Nearly half of the tags (132, or 48.5%) were returned from locations along the north shore of Minas Basin and Cobequid Bay (Table 1). Recapture sites, in order of returns, were: Bass River (30), Cobequid Bay weirs (30), the Minas Basin weir (26), Economy River (19), Parrsboro Harbour (14), Sand Point (6), Portapique and Five Houses (6), Lower Five Islands (5), Upper Economy (4), Spencer’s Point and Great Village (4), Carr’s Brook weir (2), and Harrington River (1). Recaptured fish measured 200–535 mm FL at time of release and were at large between 0.5 and 1,458 d before recapture. Average distance traveled between release and recapture was 55 km. The mean date of recapture for north shore-caught fish was September 4, but striped bass were caught from June 1 to November 24. Thirty-two recaptures (11.7%) were reported for locations along the south shore of Cobequid Bay and Minas Basin (Table 1). Recapture sites included

Walton (9), Burntcoat (4), Noel Shore (3), Tennycape (3), Avon River (3), Avonport Beach (3), Bramber (2), and one recapture each from Noel, Pembroke, Cambridge, Cheverie, and Kempt Shore. Recaptured bass were 203–550 mm FL at release and were at large 7– 1,463 d before capture 9–68 km from the release sites. The mean date of capture for south shore striped bass was September 2, but they were caught from May 19 through October 22. The Shubenacadie–Stewiacke River watershed had the second largest number of recaptures, 103 striped bass or 37.8% of the total (Table 1). Recapture sites included the Shubenacadie–Stewiacke River forks (40), the Stewiacke River (37), Grand Lake (11), and Gays River (6). Those sites with two tag returns included the mouth of the Shubenacadie River, St. Andrew’s River, Enfield, and Grand Lake at Wellington; one tag was recovered in Grand Lake at Waverly. Fish lengths were 200–508 mm FL at release and were at large 16–2,776 d before recapture 14–128 km from the release sites. The mean date of recapture was May 21, but ranged from April 18 through September 18. One striped bass was recaptured from the Annapolis River in the outer Bay of Fundy and one from the Cumberland Basin in Chignecto on May 19, 1986, 242 d

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TABLE 1.—Location, mode, and season of capture of striped bass tagged in weirs on the north shore of Minas Basin and Cobequid Bay during 1985 and 1986 and recaptured by recreational and commercial fishers along the Atlantic coast of North America. Season Fishery

FIGURE 4.—Catch of striped bass in Minas Basin and Cobequid Bay weirs in relation to predicted low-tide height during 1985. Spring tides were classified as those with predicted depths of less than 1 m at mean low water.

after release and at a distance of 125 km from the release site in Minas Basin. The Cumberland Basin recapture was 561 mm FL at release (Figure 6). Seven tag returns came from the U.S. East Coast and represented 2.5% of the recoveries (Figure 6). A striped

FIGURE 5.—Length-classes of striped bass captured in Minas Basin and Cobequid Bay weirs during 1985.

Spring

Summer

Fall

Recreational recaptures (n ¼ 154) Minas Basin North shore 2 23 South shore 2 8 Shubenacadie watershed 70 4 Annapolis River 1 0 Cumberland Basin 1 0 East Coast USA 2 0

24 14 2 0 0 1

Commercial recaptures (n ¼ 94) Minas Basin North shore, weir 2 4 North shore, gillnet 5 6 South shore, weir 2 0 South shore, gillnet 0 1 Shubenacadie, weir 2 0 Shubenacadie, gillnet 12 0 East Coast USA, trap 0 0 East Coast USA, gillnet 2 0

49 7 0 0 0 0 1 1

bass, 520 mm at tagging, was captured in Herring Cove, Massachusetts, 720 km from the Minas Basin, on June 22, 1986, 248 d after release. A 494-mm fish was recovered in Rhode Island 800 km from Minas Basin on November 3, 1985, only 45 d after release, for an average movement rate of 17.8 km/d, the fastest observed during the study. Two striped bass were recaptured in the Thames River at Norwich, Connecticut. These two fish were released 2 d apart in Minas Basin during 1985 and were recaptured from the Thames River within 4 d of each other by two different anglers. In addition, one fish was captured by gill net during spring and one in the fall by rod from New Jersey beaches, and one fish was captured by gill net during spring from a Virginia beach. Two distinct movement patterns emerged from the tag recapture data. One group of striped bass remained in Minas Basin and its watershed and demonstrated distinct seasonal movement patterns from marine to freshwaters and back (Table 2). A second group migrated southward in fall along the Atlantic coast and was recaptured at more northern locations in the spring (Table 1). Local movement in Minas Basin exhibited three distinct seasonal elements (Table 2). In spring, larger striped bass were recaptured moving upstream and downstream in the Shubenacadie River and concentrating at the Shubenacadie–Stewiacke forks. In summer, all year-classes of striped bass moved out of the Shubenacadie and were recaptured, often more than

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TABLE 2.—Seasonal recapture locations of striped bass tagged in weirs along the north shore of Minas Basin and Cobequid Bay during 1985 and 1986 and returned from local marine and freshwater sites. Season

FIGURE 6.—Distance to recapture location in relation to length at tagging of striped bass captured in Minas Basin and Cobequid Bay weirs. Specific recapture locations shown in the figure are as follows: New Jersey (NJ), Connecticut (CT), Virginia (VA), Rhode Island (RI), Massachusetts (MA), and the Cumberland Basin. Unmarked dots are local recaptures as in Tables 1 and 2.

once, along the northern and southern shores of Minas Basin and Cobequid Bay. In fall, one group moved seaward toward the Bay of Fundy and one group moved upstream in the Shubenacadie River to overwinter in Grand Lake (Table 2). Exploitation Recreational anglers recaptured 55.8% of the fish with returned tags. The remainder was harvested by commercial weirs (Canada), trap nets (USA), and by both commercial and sport gill nets (Canada and USA; Table 1). The majority of both recreational and commercial exploitation took place in Minas Basin and its watersheds (Table 1). Discussion The movement of striped bass over intertidal flats was influenced primarily by tides and light. Striped bass were captured in the weirs during ebbing tide when incoming tides were at dusk and again near dawn. Few were captured in weirs during tides that ebbed in full daylight or during full darkness. Lack of striped bass catches during full daylight ebbing tides may have been the result of active avoidance by bass of the intertidal zone during these high tides. Absence of striped bass from full darkness ebbing tides may be due to them moving seaward from the flats higher in the water column than during day and avoiding capture. Selection of swimming depth in the water column may also explain why they were captured to a lesser or greater degree during the spring neap cycle in the inner Bay of Fundy. Both observations were similar for catches of American shad Alosa sapidissima in Cobequid Bay weirs (Dadswell et al. 1984b). Shad catches were greatest during neap tide periods and when low tide occurred between 1800 and 2400 hours. The water column in Minas Basin is relatively clear,

Recapture location

May–Jun

Jul–Aug

Sep–Nov

North shore South shore Shubenacadie watershed Mouth Shubenacadie–Stewiacke forks Upriver Grand Lake

11 3

36 9

82 20

2 71 10 12

0 5 0 1

0 1 0 1

which means striped bass possibly moved over intertidal flats only when water depths were greatest (at high tide) and light levels were lowest resulting in capture on the ebb tide. In Cobequid Bay, the water is much more turbid (Amos and Alfoldi 1979). Striped bass may have utilized the intertidal flats to a greater degree but were captured primarily during neap tide ebbs. During spring tides in the turbid Cobequid Bay light penetration would have been minimal (Dadswell et al. 1983), and they likely swam higher in a deeper water column while high tide was ebbing, thereby avoiding the weir. Age-0 striped bass were collected only from Cobequid Bay weirs, suggesting that this region serves as late summer–fall nursery for the local stock that originates from the Shubenacadie watershed (Rulifson and Dadswell 1995). The extensive, intertidal zones of Cobequid Bay are a warm, low-salinity habitat that supplies age-0 striped bass with an abundance of benthic prey, especially sand shrimp Crangon septemspinosa (Rulifson and McKenna 1987). The age-0 fish averaged 80 mm FL when captured in September and October, which corresponded in size to age-0 fish captured inside the Shubenacadie estuary during late August 1919 (Dadswell et al. 1984a). Assuming they are Shubenacadie stock spawned in early June (Rulifson and Tull 1998), the growth rate for age-0 striped bass in the inner Bay of Fundy region is approximately 1.7 mm/d, which is similar to growth rates in the Hudson River (Hurst and Conover 1998). Whether these age-0 fish venture into Minas Basin before winter was undetermined, but none were recaptured in that region before 1986 as age-1 striped bass. Weirs were active and monitored until December 1985, and many tagged, age-0 striped bass were available after September. Striped bass in the inner Bay of Fundy apparently follow the flooding tide onto the intertidal flats and eventually into the tidal creeks to feed during high tide

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(Rulifson and McKenna 1987). Consequently, striped bass moved from deep water of relatively high visibility (Secchi visibility ¼ 200 cm or more) to turbid, shallow water (Secchi visibility ¼ 35–41 cm) at the head of tide (Amos and Alfoldi 1979). Striped bass occur within the macrotidal portions of the inner Bay of Fundy from late May to early June through December, which coincides with the fishing effort of commercial and recreational fishers. Whether striped bass are present in this area after December and throughout the winter was undetermined. A portion of Minas Basin bass use the Shubenacadie watershed as overwintering grounds, migrating upstream in the fall (Alexander 1975). The primary overwintering site is Shubenacadie Grand Lake, a deep, freshwater lake at the head of the Shubenacadie River near the city of Halifax (Rulifson and Dadswell 1995). An undetermined portion are native to the watershed and spawn downstream near the confluence of the Shubenacadie and Stewiacke rivers in late May and June (Rulifson and Tull 1998). However, not all overwintering striped bass may be native to this watershed. Two striped bass marked and released in the Annapolis River in May 1982 were recaptured near the Shubenacadie River spawning grounds in May 1983 (Dadswell et al. 1984a). Additionally, Wirgin et al. (1995) using mitochondrial DNA analysis determined that 2–7% of the striped bass collected on the Shubenacadie spawning grounds in 1992 and 1993 were not of Canadian origin, and recreational anglers we interviewed reported catching large striped bass in Grand Lake bearing tags with U.S. return addresses. Although some overwintering fish may be Shubenacadie stock that had migrated south in other years and were tagged along the U.S. coast, there is ample evidence that U.S. striped bass overwinter at Canadian locations in some years (Hogans 1984; Wirgin et al. 1995). After overwintering in Grand Lake, striped bass migrate downstream to spawn at the confluence of the Shubenacadie and Stewiacke rivers; at the same time, another group from the ocean migrates upstream to meet downstream migrants at the spawning grounds (Paramore and Rulifson 2001; Morris et al. 2003). Both groups return to marine waters of the inner Bay of Fundy in late June. Striped bass frequent both the north and south shores of Cobequid Bay throughout the summer. Age-0 fish appear to remain in Cobequid Bay. Larger fish may move seaward to Minas Basin and beyond. Some larger striped bass (those .390 mm FL) leave the Bay of Fundy for other coastal areas of the western Atlantic. Movement southward can be rapid, striped bass moving from the Bay of Fundy to south of Cape Cod within a month (Dadswell 1976; this study). However,

time at large for tagged striped bass is often considerable. Tagged fish from our study were at large for up to 9 years, which is comparable to information from Boreman and Lewis (1987) who recorded one striped bass that was recaptured 12 years after tagging. Our results and those of previous tagging studies (Rulifson and Dadswell 1995), parasite studies (Hogans 1985), and mitochondrial DNA studies (Wirgin et al. 1995) all indicate that the striped bass present in the Bay of Fundy are probably a mixture of stocks. Up to the mid-1980s, previous tagging studies released over 78,000 striped bass along the U.S. coast, but few recaptures were reported from Canadian waters (Boreman and Lewis 1987). There were, however, some exceptions: fish tagged on the spawning grounds in the Potomac River, Maryland (Nichols and Miller 1967), in Long Island Sound (Clark 1968), and in the Hudson River, New York (Harris 1988; Waldman et al. 1990), were recaptured in the Bay of Fundy. Striped bass tagged in Nova Scotia and New Brunswick portions of the Bay of Fundy watershed have been recaptured in Rhode Island, Massachusetts, Connecticut, New York, New Jersey, Delaware, Virginia, and North Carolina (Moss 1971; Dadswell 1976; Harris 1988). Hogans (1985) reported Ergasilus labracis from striped bass in Minas Basin, a parasite previously known only from U.S. waters. Wirgin and coworkers (1995) using mitochondrial DNA analysis suggested that 63% of striped bass captured during 1992 and 97% captured during 1993 in the Saint John River estuary, New Brunswick, were of U.S. origin. Based on the returns from our study, the recaptures of striped bass tagged in Minas Basin were similar to those for other Atlantic coast regions. The average return rate from striped bass tagging studies is about 21% (range ¼ 4.1–42.0%, 20 studies; Boreman and Lewis 1987) compared with 19.0% overall from our study. In our study exploitation by anglers was high, representing 55.8% of tag returns. Although some angled bass were probably released alive, angling pressure represents a substantial take of the species and the recent restrictive angling management in Canada appears to be justified (Douglas et al. 2002). Tag returns from commercial fishers in our study was comparable to those in other studies (Mansueti 1961; Boreman and Austin 1981), and it is well known that directed and bycatch fisheries take an appreciable portion of the striped bass population (Bradford et al. 1995). Striped bass in Atlantic Canada are now conservatively managed with restrictive take, including no commercial fishing and recreational size and bag limits (Douglas et al. 2002). Two spawning populations—the Shubenacadie River in the Bay of Fundy (Rulifson and


Tull 1998) and the Miramichi River in the Gulf of St. Lawrence (Robichaud-Leblanc et al. 1996)—produced large year-classes during the 1990s, and it is hoped that restricted take will now maintain population levels (R. Bradford, personal communication). It is unknown at this time whether the abundance of striped bass in the Shubenacadie watershed during spring spawning runs in the 1990s are all native fish and the result of highly successful recruitment to this population, or a function of influx from recent, historically high U.S. populations (Wirgin et al. 1995; Richards and Rago 1999). The status of other Bay of Fundy stocks in the Annapolis and Saint John rivers is unknown at this time. Acknowledgments Many people contributed to the success of this project. Commercial fishers H. Hill, G. Lewis, and J. Webb provided technical advice, field assistance, and companionship throughout our study. Many graduate and undergraduate students from Acadia University, Mount Allison University, the University of New Brunswick, and Unity College assisted in the field, including D. Themelis, H. Stone, J. Williams, M. Kellock, S. Burbine, P. Crawford, K. Stokesbury, R. Bradford, R. Nelson, P. Butryn, O. Kephart, C. Docktor, and C. Hoffman. Other contributors to field work included P. McCurdy, L. Langille, S. McLeod, and J. Cooper. The study was funded, in part, by the National Oceanic and Atmospheric Administration, National Marine Fisheries Service, under the Anadromous Fish Conservation Act (Public Law 89-304). Additional support was provided by the State of North Carolina, Fisheries and Oceans Canada, East Carolina University, Unity College in Maine, the Fundy Weir Fisherman’s Association, and the Hudson River Foundation. References Alexander, D. R. 1975. Sport fisheries potential on twenty lakes in the headwaters of the Shubenacadie River system, Nova Scotia. Department of the Environment, MAR/T-75-10, Ottawa. Amos, C. L., and T. T. Alfoldi. 1979. The determination of the suspended sediment concentration in a macrotidal system using Landsat data. Journal of Sedimentology and Petrology 4:159–174. Boreman, J., and H. M. Austin. 1981. Production and harvest of anadromous striped bass stocks along the Atlantic coast. Transactions of the American Fisheries Society 90:13–20. Boreman, J., and R. R. Lewis. 1987. Atlantic coastal migration of striped bass. Pages 331–339 in M. J. Dadswell, R. J. Klauda, C. M. Moffitt, R. L. Saunders, R. A. Rulifson, and J. E. Cooper, editors. Common strategies of anadromous and catadromous fishes.

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American Fisheries Society, Symposium 1, Bethesda, Maryland. Bousfield, E. L., and A. H. Leim. 1958. The fauna of Minas Basin and Minas Channel. National Museum of Canada Bulletin 166. Bradford, R. G., K. A. Robichaud, and S. C. Courtenay. 1995. Bycatch in commercial fisheries as an indicator and regulator of striped bass (Morone saxatilis) in the Miramichi estuary. Canadian Special Publication of Fisheries and Aquatic Sciences 123:249–259. Clark, J. R. 1968. Seasonal movements of striped bass contingents of Long Island Sound and the New York Bight. Transactions of the American Fisheries Society 97:320–343. Dadswell, M. J. 1976. Notes on the biology and research potential of striped bass in the Saint John estuary. Pages 76–95 in M. J. Dadswell and A. F. Needler, editors. Baseline survey and living resource potential study of the Saint John River estuary, volume III. Fish and fisheries. Huntsman Marine Laboratory, St. Andrews, New Brunswick. Dadswell, M. J., R. Bradford, A. H. Leim, D. J. Scarratt, G. D. Melvin, and R. G. Appy. 1984a. A review of research on fishes and fisheries in the Bay of Fundy between 1976 and 1983 with particular reference to its upper reaches. Canadian Technical Report of Fisheries and Aquatic Sciences 1256:163–294. Dadswell, M. J., G. D. Melvin, and P. J. Williams. 1983. Effect of turbidity on the temporal and spatial utilization of the inner Bay of Fundy by American shad (Picses: Clupeidae) and its relationship to local fisheries. Canadian Journal of Fisheries and Aquatic Sciences 40(Supplement 1):322–330. Dadswell, M. J., G. D. Melvin, P. J. Williams, and G. S Brown. 1984b. Possible impact of large-scale tidal power developments in the Bay of Fundy on certain migratory fish stocks of the northwest Atlantic. Canadian Technical Report of Fisheries and Aquatic Sciences 1256:577–599. Dadswell, M. J., and R. A. Rulifson. 1994. Macrotidal estuaries: a region of collision between migratory marine animals and tidal power development. Biological Journal of the Linnaean Society 51:93–113. Douglas, S. G., R. G. Bradford, and G. Chaput. 2002. Assessment of striped bass (Morone saxatilis) in the Maritime Provinces in the context of species at risk. Canadian Science Advisory Secretariat, Research Document 2003/008, Ottawa. Douma, A., and G. D. Stewart. 1981. Annapolis STRAFLO turbine will demonstrate Bay of Fundy tidal power concept. Hydro Power 1:1–8. Fabrizio, M. C. 1987. Growth-invariant discrimination and classification of striped bass stocks by morphometric and electrophoretic methods. Transactions of the American Fisheries Society 116:728–736. Field, J. D. 1997. Atlantic striped bass management: where did we go right? Fisheries 22(7):6–9. Fisheries and Oceans Canada. 1985. Canadian tide and current tables, volume 1. Atlantic coast and Bay of Fundy. Fisheries and Oceans Canada, Ottawa. Gemperline, P. J., R. A. Rulifson, and L. Paramore. 2002. Multiway analysis of trace elements in fish otoliths to track migratory patterns. Chemometrics and Intelligent Laboratory Systems 60:135–146.

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