Inventory of Freshwater Fish Species Within Big Cypress National Preserve: the Basis for a Long-Term Sampling Program
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Inventory of Freshwater Fish Species within Big Cypress National Preserve: The Basis for a Long-Term Sampling Program Introduction habitats because fishes were concentrating, but had not yet experienced high mortality. We emphasized sampling during The Big Cypress ecosystem forms a largely undeveloped this period to record the maximum number of species living landscape in southwestern Florida. The ecosystem includes within each habitat. In addition, shallow wetlands were three major habitats: seasonally flooded marshes, forested sampled during the summer and fall high-water period. wetlands and upland pine habitats, all of which are intersected Because much of BCNP is inaccessible by road, helicopter, by manmade canals. Much of the landscape lies within the swamp buggy, and all-terrain vehicles were used to reach Federally protected Big Cypress National Preserve (BCNP), interior sites within the Preserve. which is managed by the National Park Service (fig. 1). To The diversity of habitats in BCNP presented challenges to understand this ecosystem, knowledge about the ecology of its the development of a comprehensive sampling regime. The fishes is especially important, because they are the most numer- effectiveness of any method varies by habitat, and each has ous vertebrates within the Preserve, and provide food for preda- inherent biases. To compensate, we used several techniques tors such as wading birds and alligators. The hydrologic change when taking a sample. Traps and nets provided a means of resulting from surface-water drainage and impoundment within the system has probably decreased fish biomass and numbers, Number of and altered the timing and the areas of fish availability to preda- Habitat samples tors (Duever and others, 1986). In addition, non-native fish Canals 155 species have colonized natural and disturbed habitats of the Big Cypress forest 49 Cypress ecosystem during the past three decades, because the Freshwater marsh 42 Table 1. Number of local climate and habitats are favorable for their colonization and Herbaceous prairie 33 samples per habitat type survival (Loftus and Kushlan, 1987). Sloughs/ponds/rivers 25 Only recent baseline data exist for fish communities in the Cypress prairie 15 Big Cypress system, and these data are relatively scarce. The first collections were made in the 1960s and 1970s during Mixed swamp forest 14 studies of the prey populations for wading birds (Kahl, 1964; Coastal marshes 10 Browder, 1976; Kushlan, 1974). The composition and distribu- 83° 82° 81° 80° tion of native and introduced fishes from the southern areas of ST. LUCIE SARASOTA DE SOTO HIGHLANDS the Preserve were reported on by Loftus and Kushlan (1987). EXPLANATION MARTIN 27° Big Cypress National Preserve Lake OKEECHOBEE Limited collections were made by W.F. Loftus (National Park Everglades National Park Okeechobee CHARLOTTE GLADES PALM BEACH Service, written commun., 1987), and by Dalrymple (1995). Direction of surface-water flow Road Small quantitative datasets on fish communities exist only for LEE HENDRY Canal HISTORIC Corkscrew Swamp (Carlson and Duever, 1977), and coastal S-190 Control Structure EVERGLADES habitats in the southern Big Cypress Swamp (Carter and others, COLLIER PALM BEACH COUNTY BROWARD COUNTY HENDRY COUNTY COLLIER COUNTY 1973). The present study, funded by the USGS Greater Ever- Gulf of Mexico BROWARD Naples glades Priority Ecosystems Science Program, in cooperation 26° BROWARD CO with BCNP, was conducted to produce a complete inventory of Atlantic Ocean MIAMI-DADE th MONR fishes for the Preserve, and to test methods for quantitatively e TAMIAMI CANAL Miami S-190 ve OE sampling those habitats. Le L28 Nor 75 S-140 r L28 Methods of Investigation 29 ve Interceptor Levee Road ner Ri Big Cypress fishes were inventoried throughout the period r Tu S-344 from October 2002 through June 2004 (Ellis and others, 2003). 25° Birdon Road Road L28 41 11 Mile We collected multiple samples in all major aquatic habitats in Levee Loop S-12A the Preserve. We also took samples during several seasons at Road S-343A 0 25 50 MILES many locations (table 1). Most data, however, were collected 0 10 MILES S-343B during the winter/spring dry season in canals and other deep- 0 10 KILOMETERS 0 25 50 KILOMETERS water habitats. The transition between the wet and dry seasons coincided with the time of highest species richness in many Figure 1. Map showing Big Cypress National Preserve. U.S. Department of the Interior Fact Sheet 2004-3131 U.S. Geological Survey Printed on recycled paper November 2004 sampling with a standardized unit of effort (soak time), Table 2. Distribution of fish species by habitat and were suitable for most habitats. We used Gee-type minnow traps, box traps, collapsible mesh traps, and Breder traps. Soak times were generally 24 hours, although 1-hour sets were also performed. Small-fish Species traps were fished unbaited and relied on encounter by the fish to generate captures. Hoop nets were normally Canals Sloughs, ponds, rivers Mixed swamp forest Freshwater marsh Cypress forest Cypress prairie Herbaceous prairie Coastal marshes All wetlands Freshwater wetlands Deep-water habitats fished unbaited, but were baited for 24-hour periods American eel x x - - - - - - - - x in deep-water areas to sample larger fishes. We used Atlantic needlefish x - - - - - - - - - x experimental gill nets to sample canal fishes by deploy- black acara x x x x x x x x x x - ing two nets in tandem, each with four 2.4-meter deep black crappie x - - - - - - - - - x x 1.8-meter wide panels. The first net had panels with blue tilapia x x - x x x - x x x - bar-mesh sizes of 1.2, 2.5, 3.7, and 5 centimeters, and bluefin killifish x x x x x x x x x x - the second had meshes of 6.2, 7.6, 8.8, and 11 centime- bluegill x x x x x - - x x x - ters. Nets were typically set from 1 to 4 hours. bluespotted sunfish x x x x x - x x x x - We employed two electrofishing rigs to sample bowfin x x - - x - - - x x - fishes. The first was a boat-mounted Smith-Root type brook silverside x x - x x x x - x x - 6A electrofisher with a maximum current output of brown bullhead x - - - - - - - - - x 1,008 volts dc at 120 pulses per second. It performed brown hoplo x - - - - - - - - - x well in sampling canals, but was too large for use in clown goby x - - - - - - x x - - vegetated habitats. In forested habitats and marshes, coastal shiner x - - - - - - - - - x crested goby x - - - - - - - - - x we sampled with a small barge carrying a Smith-Root crevalle jack x - - - - - - - - - x model 2.5 Gas-powered Pulsator (GPP) electrofisher dollar sunfish x x x x x x x x x x - having a maximum current of 1,000 volts dc at Everglades pygmy x x x x x - x - x x - 120 pulses per second. Samples were standardized to sunfish 300 seconds of total shock time. flagfish x x x x x x x x x x - We also maintained sight records for species Florida gar x x x x x x x - x x - observed but not captured, which we were able to frillfin goby x - - - - - - - - - x gizzard shad x - - - - - - - - - x positively identify. Extensive collections of voucher golden shiner x x x x - - - - x x - specimens were saved to document the identities of golden topminnow x x x x x x x x x x - BCNP fishes, and they are stored at the South Florida gray snapper x - - - - - - - - - x Collection Management Center repository at Everglades gulf killifish x - - - - - - x x - - National Park. hardhead catfish x - - - - - - - - - x Habitat Classification hogchoker x x - - - - - x x - - inland silverside x - - - - - - x x - - Sampling was planned using a stratified design based jewel cichlid x - - x - - x - x x - on habitat category. The habitat-classification scheme ladyfish x - - - - - - - - - x was based on the seasonally inundated habitats identi- lake chubsucker x x - - x - - - x x - fied by Duever and others (1986). Eight broad habitat largemouth bass x x x x x x x x x x - categories were used, based on dominant vegetation least killifish x x x x x x x - x x - marsh killifish x x x x x x x x x x - and hydroperiod (National Park Service, 1991); six of Mayan cichlid x x x x x x x x x x - these are subject to seasonal dry-down. The habitats are mosquitofish, eastern x x x x x x x x x x - ranked by hydroperiod from longest to shortest: oscar x x - - - - x - x x - • Cypress forest — includes bald cypresscypress Taxodium pike killifish x x x x x x x x x x - distichum and pond cypress Taxodium ascendens. pinfish x - - - - - - - - - x • Mixed swamp forest — forested wetlands domi- rainwater killifish x x - - - - - x x - - nated by hardwoods (Duever and others, 1986). red drum x - - - - - - - - - x redear x x x x x x - x x x - • Freshwater marshes — wetlands dominated by a redfin needlefish x - - - - - - - - - x variety of grasses and sedges. redfin pickerel - - - - x - - - x x - • Coastal marshes — herbaceous wetlands that sea- sailfin molly x x x x x x x x x x - sonally vary between fresh and brackish salinities Seminole killifish x x - x - - - - x x - sharksucker x - - - - - - - - - x (National Park Service, 1991). sheepshead x - - - - - - - - - x • Cypress prairie — wetland with an open canopy of sheepshead minnow x - - x - - x x x x - sparse dwarf pond cypress (National Park Service, snook x x - - - - - - - - x 1991). spotted sunfish x x x x x x x - x x - • Herbaceous prairie — short-hydroperiod wetlands spotted tilapia x x x x x x x x x x - characterized by a variety of grasses (Duever and striped mojarra x x - - - - - - - - x others, 1986).