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|Various Techniques for Mudpuppies and Waterdogs|
Necturus alabamensis, Blackwarrior Waterdog; Necturus beyeri, Gulf Coast Waterdog; Necturus lewisi, Neuse River Waterdog; Necturus maculosus, Mudpuppy; Necturus punctatus, Dwarf Waterdog
Mudpuppies and waterdogs live in large aquatic systems such as streams, rivers, and impoundments in the eastern half of the United States. During the day they remain hidden under rocks and debris and in furrows or under bank overhangs. They become active at night as they forage for food. Mudpuppies and waterdogs breed in the fall and females deposit eggs in late spring or early summer depending on localities (Petranka 1998). Their secretive behavior renders them difficult to observe or collect by sight searches.
Surveys for mudpuppies and waterdogs can be conducted during day and night searches, but night searches are generally more productive. Because mudpuppies and waterdogs occur in a variety of lentic habitats, it may be necessary to try several searching methods. Here we describe 10 methods reported in the literature for capturing mudpuppiesand waterdogs. Methods include hook and line, dip nets, seines, trawls, capturing by hand, electro-shocking, snorkeling and scuba diving, traps, spotlighting, and spearing. Effective methods vary depending on habitats, densities, or purposes of the research. For example, Cagle (1954) found that bank lines and trotlines in Louisiana indicated that mudpuppies and waterdogs inhabit shallow or deep water where they find cover such as roots of trees, piles of rocks, submerged logs, and cavities in banks. Gunter and Brode (1964) reported that deep pools where water was still and the bank undercut or overhanging with stumps or tree trunks, provided the most suitable habitat for Necturus in southern Mississippi.
Habitat types dictate appropriate methods to survey for mudpuppies and waterdogs. For example, deeper water requires trawls and surveys in shallow water should include turning rocks and electro-shocking. Inaccessible hiding spots may influence the success of some techniques. Best methods for observing and capturing larvae are snorkeling and searching in leaf litter and silt with dip nets.
Hook and line involves “fishing” for mudpuppies and waterdogs with baited fishing hooks (Eycleshymer 1906; Brimley 1920; Pearse 1921, Bishop 1926; Viosca 1937; Lagler and Goellner. 1939; Cagle 1954; Neill 1963; Gunter and Brode 1964; Schoop 1965; Shoop and Gunning 1967; Vogt 1981; Pfingsten and White 1989; Mount, 1975; Bart and Holzenthal 1985).
Hooks may be on trotlines, which consist of a line stretched across a stream with multiple hooks at various depths (Cagle, 1954; Pfingsten and White, 1989) or single lines such as hand lines (Cagle, 1954) and lines tied to trees, etc. on banks.
A variety of baits have been used to attract mudpuppies and waterdogs. The effectiveness of different baits have not been determined but studies have shown that successful baits consist of rotting meat (Pfingsten and White, 1989), earthworms (Bishop, 1941; Gunter and Brode, 1964; Bart and Holzenthal, 1985), crayfish and liver (Cagle, 1954). Gunter and Brode (1964) recommend that lines be checked at 30-minute intervals.
Although ages of mudpuppies and waterdogs are indeterminate, Shoop and Gunning (1967) succeeded in capturing adults and juveniles. They reported that capturing patterns of N. maculosus and N. beyeri with baited setlines were female-biased during the colder months, which might be due to energy requirements of females depositing yolk in eggs. Shoop (1965) found that sex ratios of juveniles and adults collected by electro-shocking were equal.
Long-handled dip nets can be useful for collecting all stages of mudpuppies and waterdogs (Gibbons and Nelson, 1968) but several researchers have found them to be particularly effective in capturing immature specimens (Guttman, et al, 1990; Shoop and Gunning, 1967) and larvae (Ashton and Braswell, 1979; Cagle, 1954). Cagle collected N. louisianensis larvae in all months that searches were conducted (January, February, June, July, and August). Pearse (1921) provides a detailed description of how to capture mudpuppies and waterdogs with dip nets in Lake Monona, Wisconsin. He suggested that just before the lake freezes that investigators, at night, search the bottom in shallow water (about 2 ft. deep) and slowly place a dip net from a boat in front of a salamander and tickle the tail with a stick causing it to quickly move into the net. Pearse reports large numbers of specimens are captured by this method. A “D” frame dip net is recommended because it can be placed more flush to the substratum than a rounded frame.
Moving rocks may be required to expose mudpuppies and waterdogs. Turning cover objects involves carefully moving rocks, logs, and other objects such as non-natural items (viz. large pieces of trash) and capturing mudpuppies and waterdogs with dip nets, or seines (Sajdak 1982). Turning cover objects facing upstream in a current helps researchers see salamanders more quickly because flowing water washes away suspended silt; otherwise, cloudy water conditions may stay for an extended time hindering visibility. In shallow clear water, mudpuppies and waterdogs are usually visible when cover objects are moved and can be easily guided by hand into nets (Sajdak, personal communication). Cover objects can be moved with the aid of potato hoes (herp rakes) log peaveys, log cant hooks, or by hand. Rocks should be placed back in original positions to reduce the build up of silt around rocks. For details on methods to turn rocks, see Survey Techniques for Hellbenders (Cryptobranchus alleganiensis) by Pauley, et al. (2003).
Successful use of seines to capture mudpuppies and waterdogs has been reported by, Bart and Holzenthal (1985), Bartlett (1988), and Matson (1998).
Bart and Holzenthal (1985) found depositional zones (litter) to be the
most productive habitats for N. beyeri. They used a 3.3 m seine
with a 6mm mesh to dredge up large amounts of leaf litter from deposits
along banks of creeks to estimate the catch per effort. Matson (1998)
used a 1.8-meter seine to capture specimens beneath overturned siltstone
Trawling can be an effective method to capture mudpuppies and waterdogs in deep water. Reigle (1967) reported using a trawl at depths between 24 and 120 ft in Green Bay and captured 2 Necturus at 60 ft and one at 90 ft. Other captures in deep water (10 to 35 ft) have been reported in Lake Erie and Lake Michigan (described in Reigle 1967).
Capturing active mudpuppies and waterdogs by hand can be difficult because of their slippery integument and few researchers have reported this method. Smith (1911) reported capturing all stages with this method and Gibbons and Nelson (1968) reported capturing specimens by hand and a dip net with 2 or 3 collectors wading abreast in water approximately 1 m deep. If mudpuppies and waterdogs are known to be present, counting nests is an effective survey or monitoring method. This can be a particularly good method to monitor populations if executed every year with the same effort, i.e., same number of cover objects, hours of effort, and number of people. Mudpuppies and waterdogs attach their eggs on the underside of objects that are about 2 to 4 feet deep (Harris 1961). Although Pearse (1921) and Smith (1911) reported large flat stones 1.5 to 2 ft in diameter are preferred, almost any convenient cover object may be used for nesting (Harris 1961). In Lake Michigan, the Michigan State Department of Conservation placed several hundred large, shallow wooden boxes filled with gravel in water about 2 to 4 ft deep to serve as spawning sites for largemouth bass. In later years of this study, boxes attracted spawning Necturus and about one-fourth of these boxes were used as nesting sites (Fitch 1959). As far as we know, further studies on the effectiveness of nesting boxes have not been conducted. Use of boxes could be an excellent method to conduct a monitoring program for mudpuppies and waterdogs.
Electro-shocking requires at least 2 people, one person works the electro-shocker and the other captures stunned mudpuppies and waterdogs with an insulated dip net or seine. Electro-shocking as a method to collect mudpuppies and waterdogs has been reported by Fitch (1959), Shoop (1965), Shoop and Gunning (1967), and Meffe and Sheldon (1987). Meffe and Sheldon (1987) used block seines (0.6 mm mesh) to capture stunned mudpuppies and waterdogs. Their collection sites consisted primarily of large deeper, muddy areas of streams with leafy, undercut sections, although specimens were taken in sandier, open areas. Shallow water where investigators can wade is more conducive to use of electro-shocking equipment and to retrieve stunned mudpuppies and waterdogs since they do not have swim bladders.
Snorkeling can be used to find all life stages but requires a dip net to capture specimens. Cochran (1995) and Cochran and Lyons (1985) reported using this method. Snorkeling can work in most habitats with the possible exception of deeper water where divers may not be able to remain emerged for an extended time. In such situations, scuba gear may be more appropriate. Vogt (1981) reported scuba divers frequently observed mudpuppies and waterdogs in lakes in Wisconsin.
A variety of traps have been used to capture all life stages of mudpuppies and waterdogs. Funnel traps or commercial minnow traps are effective in capturing adults (Ashton and Braswell, 1979; Gendron, n.d.). These authors recommend them for larvae as well. Sever and Bart (1996) used modified Thiel-Turkey traps as described by Manning (1986) baited with earthworms. Pfingsten and White (1989) reported that commercial collectors use fyke nets baited with partially rotted fish and canned dog food. Hacker (1956) used traps but did not describe the type of trap. As far as we know, studies using crayfish traps have not been reported in the literature. Because of the small size of these traps they may be more effective for larvae and juveniles.
Fred Schueler of the Eastern Ontario Biodiversity Museum conducts annual winter surveys for mudpuppies and waterdogs in areas where specimens congregate. Specimens are captured with dip nets. On their webpage (address provided below), they encourage others to establish similar studies but caution that other areas may not be as productive as their site at Oxford Mills.
Lagler and Goellner (1941) reported spearing mudpuppies and waterdogs with “ordinary fish spears” in Michigan by the Department of Conservation in an attempt to control “noxious fish”. Since this method kills mudpuppies and waterdogs, it is not recommended.
Things that could bias your counts
Although researchers apply the same methods with the same efforts for monitoring, differences in water quality might bias results depending on methods applied. Shoop and Gunning (1967) pointed out the importance of electrolyte content, turbidity, and depth of water for the success of collecting salamanders by electro-shocking and discussed that the low success of collecting mudpuppies by this method in their study was undoubtedly influenced by these factors. Also, any methods relying on human vision can result in different counts under varied conditions of water transparency.
The presence of permanent external gills and four toes on the hind feet easily identify adults. Identification of larvae can be more difficult but four toes on the hind feet combined with the dorsal fin terminating on the tail, i.e., not extending onto the body (Petranka1998) should assist in separating mudpuppy and waterdog larvae from other salamander larvae.
Mudpuppies and waterdogs are active in cold water and muddy water during and after rain events. Muddy water may impair one’s ability to see them. They become less active in warm water during late summer and early fall in the southern states. Raindrops can disarrange water surfaces and reduce the ability to see and capture animals thus biasing results.
Time of year
Seasonal activity patterns may vary by region (Harris 1959a) and in different lakes and streams depending on the fluctuation of water temperatures (Eycleshymer 1906). Adult mudpuppies and waterdogs in the southern states are probably more active during the cooler months of October through March (Viosca 1937; Cagle 1954; Gunter and Brode 1964; Schoop 1965; Bart and Holzenthal 1985; Meffe and Sheldon 1987; Sever and Bart 1996). Shoop and Gunning (1967) found adults in almost equal numbers in autumn and spring in Louisiana, Brimley (1920) reported finding most adults in March and April in North Carolina, and Ashton (1985) found them most active during spring (March to May) and autumn. Cagle (1954) reported finding larvae in all months (January, February, June, July, and August) that searches were conducted in Louisiana and Ashton and Braswell (1979) reported larvae in July in North Carolina.
In northern states, most studies reported finding adult mudpuppies and waterdogsacross the seasons but with most catches in the spring and autumn. Pfingsten and White (1989) reported that mudpuppies and waterdogs do not hibernate and feed during the winter in northern states. Pearse (1921) reports that they are active throughout the winter in Wisconsin with the largest numbers caught in January and February. Bishop (1926) found evidence of seasonal movement in New York. In autumn, adults migrated to shallow tributaries for breeding, whereas sexually immature individuals remained in deeper water of larger streams.
Months of greatest activity by states are October or early November in Wisconsin (Vogt 1981), October and December in Wisconsin (Reigle 1967), autumn in Wisconsin (Hacker 1956), November through February with January and February being the best months in Wisconsin (Pearse 1921), (Pearse also reports catching females on nests in May and July), April in Michigan (Lagler and Goellner 1939 and 1941; Fitch 1959; Gibbons and Nelson 1968), and spring and autumn in the Great Lakes area (Eycleshymer 1906). Through a mark-recapture study, Sajdak (1982) found that seasonal capture patterns increased rapidly in early September, continued through early spring and gradually decreased from April to June when captures became rare and continued at low levels through the summer. Smith (1911) reported the best times to collect larvae in Pennsylvania to be July, August, and September. Time of year may also bias the sex ratio of this salamander. In the spring, males are seldom seen when females are spawning (Pearse 1921; Bishop 1926).
Time of day
Mudpuppies and waterdogs are mainly nocturnal (Eycleshymer 1906; Bishop 1926; Viosca 1937; Lagler and Goellner 1939; Lagler and Goellner 1941; Cagle 1954; Harris 1959a; Harris 1959b; Neill 1963; Gunter and Brode 1964; Shoop and Gunning 1967; Ashton 1985; Bart and Holzenthal 1985; Pfingsten and White 1989). During the day they take refuge under cover objects such as large rocks, logs, litter, trash and in banks that are undercut or with overhanging trees and stumps (Eycleshymer 1906; Gunter and Brode 1964). They tend to be more active during the day in muddy or weed-choked water (Bishop 1926; Viosca 1937; Harris 1959a; Pfingsten and White 1989).
Water conditions do not seem to restrict the presence or activities of mudpuppies and waterdogs. They are found in diverse, permanent ecological water systems and conditions. They occur in lakes, ponds, and streams that vary from deep and sluggish to swift-moving as well as muddy, weed-choked streams and even polluted waters (Bishop 1941). When establishing a monitoring program one should measure water visibility. Changes in water quality as a result of timbering activities, road construction, etc., could alter habitats over time due to silt loads. While population numbers could remain constant, detecability could change. For example, if one started counting salamanders when a stream was clear and then over the years that stream became cloudy, counts of salamanders could go down, not because of real declines, but because the ability to capture or count them has decreased.
Experienced collectors may be more successful in spotting and catching mudpuppies and waterdogs. Agility in water and quickness with dip nets are critical to successful capture. Surveys are physically demanding especially when turning large rocks and carrying an electro-shocker. Sizes of rocks one investigator may be capable of turning may exceed the size of another person’s capability. To assure that future data are consistent and eliminate bias, sizes of rocks turned should be measured and recorded in any monitoring program. For safety reasons such as back strain, it might be prudent to establish a limit on the size of rocks that will be moved.
Some methods, viz. dip nets, seines, and electro-shocking, may require searching and capturing specimens simultaneously while wading.
Advantages of search methods:
Advantages of capture methods
Disadvantages of search methods:
Disadvantages of capture methods:
Searches by methods described above may be by either time or area constraints x number of investigators. This could provide some data on relative abundance in very general ways as detectibly and ability to capture specimens are likely to vary from place to place.
Estimating densities requires some method of mark and recapture technique such as passive integrated transponders (PIT) tags. Gender determination, body-size measurements (total length and snout-to-vent length) and weight could provide data to determine reproductive status and possible success of the survival of populations.
To our knowledge, there are no published techniques for count variations for mudpuppies and waterdogs.
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