Walleye Spawning evidence at Lake Erie
Signs of walleye spawning in Maumee Bay, Lake Erie
During the mid-1990s, anglers reported large quantities of walleye (Stizostedton vitreum) in spawning state concentrated on shallow points next to the Maumee River channel during spring. These fish had flowing eggs and semen and were supposed to be actively spawning in Maumee Bay. To investigate the capacity of walleye spawning, we used a benthic pump to sample for eggs at five sites next to the Maumee River channel and one site near Turtle Island in Maumee Bay on 5 April 1998, a time when walleye were actively spawning in rivers as well as on mid-lake reefs.
We located walleye eggs at every one of the six sites sampled.
Comparative wealth of eggs ranged from 17 to 2,105 per 2-minute sample, with a mean of 459 ([ or -] 232). Egg viability ranged from 33 to 54% across the sites and 10% of the feasible walleye eggs were found to be in late phases of embryonic growth suggesting that egg survival to hatching is likely. These results are the first documentation of walleye spawning in Maumee Bay, suggesting that Maumee Bay is a feasible spawning place for walleye, perhaps representing an important source of recruiting for the Lake Erie stock.
In the late 19th century, Wakeham and Rathbun (1897) referred to Maumee Bay as the most productive spawning grounds for a lot of important fish species in all of Lake Erie. By 1930, but the fish spawning habitat of Maumee Bay became highly degraded due to industrial pollution, eutrophication, siltation, and related low dissolved oxygen levels (Wright 1955). States in Maumee Bay reflected states in the other regions of the Lake Erie basin. The degraded habitat conditions, coupled with overexploitation, led to the dramatic decline of the walleye (Stizostedion vitreum) population in the lake by the late 1950s. Distinct stocks of walleye were virtually removed from formerly productive spawning regions including the Cuyahoga, Maumee, and Sandusky rivers and bays (Schneider and Leach 1977; Hatch and others 1987).
The passage of the Great Lakes Water Quality Agreement in 1972 eased habitat rehabilitation efforts and, coupled with the close of the walleye fishery from 1970 72, led to improved walleye recruiting and substantial increases in walleye amounts (Hatch and others 1987). The creation of numerous powerful walleye year-courses coupled with prohibitive direction plans helped raise the population to over 100 million harvestable age-2 and older fish by 1988. Present amounts (2001) are estimated at about 40 million fish (Turner and others 2001). Copying stocks of walleye were booming again in most historical spawning places in Lake Erie and its own tributaries.
Since the mid 1990s, anglers have found substantial concentrations of mature fish in spawning condition in the shallow regions next to the Maumee River channel each springtime, indicating that walleye were using these places to spawn. Anglers reported catching large quantities of female walleye with mature eggs and ejaculating males. These observations were similar to those made by commercial fishermen in Maumee Bay prior to 1957, but no confirmation of these early observations was ever made (Pinsak and Meyer 1976). In 1998, walleye anglers in Maumee Bay supplied research workers at the Ohio Department of Natural Resources, Division of Wildlife, and Michigan State University with particular places where they supposed walleye were spawning along the Maumee River channel in Maumee Bay. In this paper, we present the very first recorded evidence that confirms angler observations of walleye spawning in Maumee Bay.
To ascertain if walleye were spawning in Maumee Bay, the writers tried six possible spawning sites along the Maumee River channel during noon on 5 April 1998 using a benthic pump. We recorded depth (m), water temperature ([degrees]C), and substrate composition at every sample site to supply features of the habitat . Substrate composition was established in three ways: surface visual evaluation (Platts and others 1983); visual evaluation of substrate particles gathered with eggs; and surrogate estimate of particle kind (in other words, hard or soft base) by tactile probing with a post.
The benthic pump consisted of a 39 kg iron sled which was attached to a diaphragm pump in the surface by a flexible 5.0 cm diameter hose (Stauffer 1981; Roseman and others 1996). This collection procedure was successful for sampling demersal walleye eggs on mid-lake reefs in western Lake Erie and caused no damage or mortality to walleye eggs (Roseman and others 1996, 2001). Because walleye are understood to spawn over the shallowest points on mid-lake reefs (Roseman and others 1996, 2001), we directed our sampling effort on the shallowest points at the places indicated by angler observations. We gathered three replicate samples at every site by towing the sled for 2.0 minutes at about 0.5 m/sec.
Eggs and benthic debris (Dreissenid mussels and shells, sand, benthic organisms) were deposited into a 0.5 [m.sup.3] basket lined with 0.5 [mm.sup.2] net netting. The net lining comprising the sample was subsequently removed and put in a labeled plastic bag. Samples were refrigerated at 5[degrees]C until they may be sorted in the lab, which happened about three hours after set. In the lab, samples were rinsed through a galvanized steel wire screen (6.0 mm bar mesh) to separate big debris from finer particles and eggs.
The staying little particulate matter was subsequently examined for walleye eggs. Identification of eggs was based on egg diameter (millimeters), egg colour, and following hatching of eggs (Roseman and others 1996). Hatched larvae were identified according to Auer (1982). Accumulated eggs were examined with 10x magnification to evaluate egg viability. All eggs that were ruptured or revealed hints of opaqueness or fungal development were classified as dead eggs. All clear or eyed eggs were classified as feasible eggs. We computed the average amount of eggs collected per tow and standard deviation of the mean at every sample site (Snedecor and Cochran 1989).
To evaluate possible egg survival in Maumee Bay, workable walleye eggs were classified by developmental period (Nelson 1968; Hurley 1972; McElman and Balon 1979) using a compound microscope with variable magnification. Phase 1 eggs were pre-organogenesis period, while phase 3 eggs were late embryonic period with developed eyes, pectoral fin buds, and caudal mesenchyme rays in addition to chromatophores along the ventral line and yolk sac. Phase 2 eggs revealed intermediate growth with undeveloped eyes and lacked fin buds and mesenchyme rays.
Large quantities of walleye eggs
Large quantities of feasible walleye eggs were gathered, confirming that walleye spawned in Maumee Bay in 1998. Walleye egg amounts ranged from 17 to 2,105 per 2-rain tow with a mean of 459 ([ or -] 232) per tow . The largest amount of eggs was gathered from site MB-2 situated on the periphery of Turtle Island , where a mean of 1,009 ([ or -] 179) walleye eggs was accumulated per tow .
The larger substrate particles at this site might have retained eggs a lot better in relation to the sandy substrates common to other sampling sites in Maumee Bay. The fewest eggs were collected from sites MB-1 and MB-4 along the border of the Maumee River channel, which averaged just 130 ([ or -] 94) eggs per tow (Table 2). These catch rates were somewhat lower than those on mid-lake reefs during this same time period where egg amounts ranged from 540 on Cone reef to 2,582 on Toussaint reef (Roseman 2000; Roseman and others 2001).
Egg viability in Maumee Bay ranged from 33 to 54% across the sites (Table 2) and was within the scope of viability approximations (18 to 63%) watched on mid-lake reefs in western Lake Erie during an identical time period (Roseman 2000). About 10% of the viable walleye eggs gathered in Maumee Bay were found to be phase 3 of embryonic growth. Based on reported temperature dependent development rates (Allbaugh and Manz 1964; McElman and Balon 1979), we estimated that these late embryonic period eggs would hatch within 3 days at the present water temperature in Maumee Bay (8.3 to 10.2[degrees]C; .
Thus, survival of eggs from deposit to hatching was likely in Maumee Bay. Eggs gathered at the exact same time from mid-lake reefs were in first periods of growth (phase 1 and 2; Roseman 2000), indicating the eggs in Maumee Bay were spawned before than those on offshore reefs. Also, water temperatures in Maumee Bay ranged from 8.3 to 10.2[degrees]C, and temperatures on the reefs ranged from 6.9 to 7.9[degrees]C (Roseman 2000).
Because initiation of spawning and embryonic growth are temperature dependent (Allbaugh and Manz 1964), the warmer water temperatures in the bay led to before spawning or more rapid growth than that incurred by eggs on the reefs. Rapid growth and hatching should minimize susceptibility to egg predators and offer a competitive advantage over other fish still in the egg period (Wolfert and others 1975).
In Lake Erie, walleye usually spawn on rugged midlake reefs and in gravel expanses of tributary rivers (Baker and Manz 1971; Hatch and others 1987; Roseman and others 1996; Roseman and others 2001). Predicated on our observations, bottom substrates at all sampling sites in Maumee Bay, except MB2, seemed to consist of sand and Dreissenid mussels and shell fragments. Website MB2 is found along the periphery of Turtle Island and has varying substrate makeup consisting of bigger and tougher substrate parts (estimated to be cobbles and small boulders) than the other websites, in addition to Dreissenid mussels and shell fragments . Based on present bathymetric maps (NOAA 1991) as well as the substantial quantity of sand accumulated during sampling, we surmised the knolls in Maumee Bay where we seen walleye eggs were composed mainly of sand and soft sediment overlain with Dreissenid mussels and shells .
Walleye in other systems are understood to make use of soft substrates and vegetated zones as spawning sites with successful recruiting. For instance, Priegel (1970) reported that walleye spawned on mats of plant life and around areas of open mud in marshes next to Lake Winnebago, WI. Likewise, Johnson (1961) found that eggs spawned on soft muck-detritus substrates lived in Lake Winnibigoshish, MN. Like the spawning places we seen in Maumee Bay, these spawning places had running water with nominal sedimentation and supplied sufficient dissolved oxygen for incubating walleye eggs.
Mean catch per effort of walleye eggs in Maumee Bay was somewhat lower than catches from western Lake Erie reefs during an identical period of time. Catches of walleye eggs from reefs on 6 April 1998 ranged from 540 to 2,582 per 2-minute tow and averaged 939 ([ or -] 419) eggs per tow (Roseman 2000; Roseman and others 2001). The larger variety of eggs collected from reefs may suggest that more fish spawn on the reefs. Also, the reefs may provide better incubation substrate in relation to the knolls in Maumee Bay.
The surfaces of the reefs have numerous crevices and cavities along with a diverse substrate composition that range from silt to boulders and exposed bedrock (Herdendorf and Braidech 1972; Roseman and others 1996), whereas the knolls in Maumee Bay seemed to be largely composed of sand. Substrate composition in the Turtle Island site was tougher and rougher than near the river channel and much more similar to that on mid-lake reefs (Roseman and others 1996). The rough substrate particle sizes on the reefs and at Turtle Island may keep eggs better in relation to the sandy substrate on knolls close to the river channel and describe why we found higher egg numbers at the Turtle Island site as well as on the reefs.
Walleye spawning divisions
In the Maumee River can be found about 70 kilometers upstream from Maumee Bay, with no known spawning places between both places (Trautman 1981; Mion and others 1998). Because walleye eggs are demersal and incubate on and within bottom substrates (McMahon and others 1984), and given the dilution possibility because of the tremendous volume of river discharge and long passage time from the upstream spawning places to Maumee Bay (Mion and others 1998), we believe it’s exceptionally improbable that eggs gathered in this study originated at upstream spawning places and truly signify signs of distinct spawning groups Of walleye in Maumee Bay.
Fish stocks signify exceptional breeding groups, frequently possessing new types of genetic, physiological, and environmental variation that preserve diversity in a species (Allendorf and others 1987). So, walleye spawning in Maumee Bay could signify an important evolutionary and environmental connection in the Lake Erie walleye population distinct from stores identified in the Maumee and Sandusky rivers (Stepien and Faber 1998). Farther, Maumee Bay supplies exceptional fishing opportunities to anglers when compared with other places in western Lake Erie.
Intribution to the developing year-course in certain years. This recruiting possibility provided by spawning habitat in Maumee Bay adds added resilience to the Lake Erie residents.
Although anecdotal evidence indicated that walleye spawned in Maumee Bay in the early portion of the 20th century when habitat conditions were more immaculate, no direct evidence was ever gathered to substantiate these claims. Reports describing habitat quality during the early portion of the century suggested Maumee Bay definitely had sufficient gravel substrates and water quality (high dissolved oxygen, low turbidity) to support successful walleye spawning (Wakeham and Rathbun 1897; Pinsak and Meyer 1976). Nevertheless, habitat conditions in Maumee Bay were visibly deteriorated by 1930 (Wright 1955) and became seriously degraded between 1950 and 1970, coinciding with the decline in abundance of walleye in Lake Erie (Schneider and Leach 1977; Hatch and others 1987).
Walleye spawning habitat
In the lake and tributaries were significantly degraded in this time period as a result of siltation, eutrophication, and related low dissolved oxygen levels (Schneider and Leach 1977), and any spawning places in Maumee Bay would also have been vitiated. Favorable changes in land use practices in the watershed since the 1970s have led to improvements in water quality and habitat conditions for walleye spawning and nursery places (Hatch and others 1987; Knight 1997). Large quantities of walleye again spawn in Lake Erie tributaries in addition to on mid-lake reefs (Roseman and others 1996; Turner and others 2001), as well as our signs of walleye spawning in Maumee Bay is additional indicator of successful direction leading to improved habitat conditions as well as the rehabilitation of the Lake Erie walleye population.
Coordinates of egg collection sites in Maumee Bay, depth, and underside substrate kind for every site sampled on 5 April 1998.
# Latitude Longitude (m) Substrate
MB-1 N 41[degrees]44.000′ W 83[degrees]24.050′ 2.0-3.0 Sand/Dreis *
MB-2 N 41[degrees]45.090′ W 83[degrees]23.300′ 2.5-4.0 Sand/Stone/
MB-3 N 41[degrees]44.786′ W 83[degrees]22.359′ 2.0-3.0 Sand/Dreis
MB-4 N 41[degrees]44.575′ W 83[degrees]21.012′ 2.5-4.0 Sand/Dreis
MB-5 N 41[degrees]44.127′ W 83[degrees]21.920′ 2.5-4.0 Sand/Dreis
MB-6 N 41[degrees]43.040′ W 83[degrees]24.325′ 2.0-3.0 Sand/Dreis
Amount of walleye eggs gathered from sites in Maumee Bay on 5 April 1998.
Bottom Amount of
Temperature Eggs ([double Viability
Website (#) * Depth (m) ** ([dagger]) dagger]) (%) ([section])
MB1 2.0-3.0 9.9 130 (94) 47
MB-2 2.0-3.0 8.3 1,009 (179) 54
MB-3 2.0-3.0 8.5 300 (142) 33
MB4 2.5-4.0 8.6 130 (67) 33
MB-5 2.5-4.0 10.2 400 (214) 43
MB-6 2.0-3.0 9.9 506 (234) 37
* Corresponds to sites identified in Number 1.
** Depth tried.
([dagger]) Water temperature ([degrees]C) on underside.
([double dagger]) Mean amount of walleye eggs gathered for all
tows at each site (standard deviation).
Percentage of eggs living at time examined.
This research was financed by the Michigan Sea Grant College System (Job R/GLF 43), the Michigan Department of Natural Resources, as well as the Ohio Division of Wildlife. The writers recognize Jennifer Burton, Robert Haas, Bill Hill, Tracy Maynard, Edward O. Roseman, Randy Szwast, Bradley E. Thompson, Christine Tomichek, and Bill Wellenkamp for help with various stages of this study. The standard of the manuscript was improved by the comments of two anonymous reviewers. We also thank the anglers of Maumee Bay and Lake Erie for their patience and understanding while enabling us to examine their precious fishery.