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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Freckled Blenny

Synonyms and Other Names: Isesthes scrutator. Original combination: Isesthes ionthas.

Taxonomy: available through www.itis.gov

Identification: A key to the four species of Hypsoblennius from the western Atlantic is given in Smith-Vaniz (1980), from which the following is taken:

Dorsal fin XII (14).  Anal fin II (15-16).  The species is similar in appearance to Hypsoblennius hentzi (feather blenny).  Unlike the feather blenny, the freckled blenny has an upper lip with a free dorsal margin extending around the snout.  Additionally, the bony interorbital width is narrower in the freckled blenny than in the feather blenny.  The feather blenny has a dark spot that is usually present on the dorsal fin, and centered on the second dorsal spine.  In the freckled blenny, a dark spot on the dorsal fin is generally absent; however, if present it is centered on the third dorsal spine.

The feather-like cirri above the eyes are generally much longer in males.  Colour patterns also differ between the genders.  Females have small dark melanophores (freckles) covering the snout, lips, bottom (ventral) half of the head and sometimes on their trunk.  In males, the freckles are either weakly developed or absent.

See Smith-Vaniz (1980) for a detailed description of morphology.  Ditty et al. (2005) described and illustrated the larvae.  A key to the Blenniidae of the western central Atlantic is given in Williams (2002); this key was modified for the Gulf of Mexico by McEachran and Fechhelm (2005).

Size: to 10 cm (Hoese and Moore 1998)

Native Range: The species has a disjunct distribution, including the western Atlantic (from North Carolina to Florida near Matanzas inlet) and the northern Gulf of Mexico (from Cedar Keys, Florida to Aransas Bay, Texas; Smith-Vaniz 1980, McEachran and Fechhelm 2005).

Interactive maps: Point Distribution Maps

Ecology: The freckled blenny prefers hard-bottomed habitat (e.g., oyster), and lower salinities (Hoese and Moore 1998).  Spawning occurs from May to September in South Carolina (Crabtree and Middaugh 1982).  Empty oyster shells are used as spawning sites, and the males continuously guard the eggs from predation (Crabtree and Middaugh 1982).

Larvae settle at the size of 11.3 to 12.1 mm standard length (SL), and sexual maturity occurs at a length of about 20 to 21 mm SL (Ditty et al. 2005).  Larval development is described in detail in Ditty et al. (2005).

Means of Introduction: Uncertain.  Possibly from ballast water.  Alternately, a waif specimen.

Geoghegan et al. (1992) was the first to report the capture of a 54 mm freckled blenny in November of 1985 from an impingement sample at the Indian Point Nuclear Generating Station, approximately 68 km north of the mouth of the Hudson River.  Although the authors were unable to rule out a natural range extension at that time, they suspected the introduction was from ballast water.  More recent reports relegate the introduction to ballast water (e.g., Wonham et al. 2000).

Status: Reported from New York.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: A testament to the sexual dimorphism apparent in this species, males were originally described as Isesthes ionthas and females were described separately as Isesthes scrutator (Smith-Vaniz 1980).

References: (click for full references)

Crabtree, R. E. and D. P. Middaugh.  1982.  Oyster shell size and the selection of spawning sites by Chasmodes bosquianus, Hypleurochilus geminatus, Hypsoblennius ionthas (Pisces, Blenniidae) and Gobiosoma bosci (Pisces, Gobiidae) in two South Carolina estuaries.  Estuaries.  5:150-155.

Ditty, J. G., R. F. Shaw and L. A. Fuiman.  2005.  Larval development of five species of blenny (Teleostei: Blenniidae) from the western central North Atlantic, with a synopsis of blennioid family characters.  Journal of Fish Biology 66: 1261-1284.

Geoghegan, P., M. T. Mattson, J. J. Reichle and R. G. Keppel.  1992.  Influence of salt front position on the occurrence of uncommon marine fishes in the Hudson River estuary.  Estuaries 15: 251-254.

Hoese, H. D. and R. H. Moore.  1988.  Fishes of the Gulf of Mexico.  Second Ed.  Texas A & M University Press.  College Station, TX.

Smith-Vaniz, W. F.  1980.  Revision of western Atlantic species of the blenniid fish genus Hypsoblennius.  Proceedings of the Academy of Natural Sciences of Philadelphia 132: 285-305.

Williams, J. T.  2002.  Blenniidae.  Pages 1768 – 1772 in: Carpenter, Kent E., (Ed.).  The Living Marine Resources of the Western Central Atlantic.  Volume 3.  Bony fishes part 2 (Opistognathidae to Molidae), sea turtles and marine mammals.  FAO Species Identification Guide for Fishery Purposes.  Food and Agriculture Organization of the United Nation, Rome.

Wonham, M.J., J.T. Carlton, G.M. Ruiz, and L.D. Smith. 2000. Fish and ships: relating dispersal frequency to success in biological invasions. Marine Biology. 136:1111-1121

Other Resources:

Author: Schofield, P.J.

Peer Review Date: 9/19/2011

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.