Population structure, reproduction and laboratory behavior of the introduced Belonesox belizanus (Poeciliidae) in Florida

Abstract

SynopsisThe pike killifish, Belonesox belizanus, is native to Mexico and Central America and was introduced into Dade County, Florida in 1957. This study reports on the structure and reproduction of the Florida population and compares the species with other members of the family Poecihidae. The mean standard length (SL) of mature females was about 103 mm. Most females larger than 75 mm SL contained yolked ova, fertilized eggs, or embryos. Mature males averaged about 72 mm SL, and most males larger than 55 mm SL were mature. The sex ratio was significantly skewed in favor of females among adults, but it did not differ significantly from I : 1 among immature fish. Average brood size was about 99, and there was a significant positive correlation of brood size with size of the parent female. There was no evidence of superfetation. Sizes and weights of embryos and neonates were the largest reported for the family. There was a significant decrease in mean embryo weight as development proceeded, indicating that developing embryos received little or no nutrient input from the maternal system after fertilization, The average interbrood interval of aquarium-held females was 42 days, and females stored viable sperm at least 47 days. Reproduction continued year round in the field. Laboratory-born neonates were immediately piscivorous and exhibited distinctive behavior associated with filling the swimbladder and with avoiding detection by predators.

Distribution and Abundance of Introduced Fishes in Florida's Charlotte Harbor Estuary

“…The blackchin tilapia has been successful in colonizing the highersalinity areas of Tampa Bay (Courtenay et al 1974). Turner and Snelson (1984) found reproducing populations of the pike killifish at salinities ranging from 0 to 50 in southeast Florida, and Florida populations of the Asian swamp eel also tolerate brackish conditions (Schofield and Nico 2009). …”

Distribution, Spread, and Habitat Predictability of a Small, Invasive, Piscivorous Fish in an Important Estuarine Fish Nursery

“…Julian day was included to represent seasonality [37]. Waterbody type was included to test for the potential importance of mesohabitat, given previous qualitative observations of habitat preference (Miller [30]: "swamps and the eddies of streams"; Turner and Snelson [20]: " . .…”

“…Waterbodies were classified as creek (natural tributaries of larger rivers), canal (dredged inlets of larger rivers), bayou (large open embayment of a river), and river (mainstems of the two main rivers within the B. belizanus range, Alafia and Little Manatee). Dominant shoreline type at each sampling site was included because of qualitative observations of differences in B. belizanus presence between vegetation type [20], and was characterized as emergent marsh (primarily black rush, Juncus roemarianus), mangrove (red mangrove, Rhizophora mangle, or black mangrove, Avicennia germinans), small terrestrial vegetation (primarily leather fern, Acrostichum danaefolium), shrubs/trees, or artificially hardened (e.g., sea wall or rip rap). Associated with shoreline type were qualitative variables for whether or not the shoreline was inundated during sampling and whether or not the shoreline vegetation was overhanging the sampling site; these variables could influence the probability of presence along shoreline habitat, as shown for other fishes [47,48].…”

“…The shallow-water piscivore niche of B. belizanus has other members [28], although the fact that the species is immediately piscivorous after birth [20] and is resident year-round in such systems generally differentiates it from other piscivores. The niche (described as "piscivorous in open water habitat in the middle and high water column, principally using pectoral fins for motility") is recognized as being quite distinct from other fishes in the native range [60].…”

“…Data are lacking to determine when the species first occurred in western Tampa Bay, but potential mechanisms facilitating occurrence include aquarium release [74], bait bucket release [65,75], or bird carry-off [11,76]. A single inseminated female B. belizanus released into a water body may be sufficient to establish a population because of large potential brood sizes (>300; [20]) and no evidence for deleterious phenotypic effects in poeciliid populations founded by a single individual [63].…”