INTRODUCTION
Gunnels, family Pholidae, are small, elongate, laterally-compressed benthic fishes that inhabit shallow, marine coastal locations in the North Atlantic, Arctic and North Pacific Oceans (Mecklenburg, Reference Mecklenburg2003; Nelson, Reference Nelson2006). Gunnels have been observed primarily in rocky intertidal and shallow subtidal areas, especially among kelp and other macroalgae. Nine species, from four genera, are reported in the eastern North Pacific (Nelson et al., Reference Nelson, Crossman, Espinosa-Pérez, Findley, Gilbert, Lea and Williams2004). The most speciose genus is Pholis with five taxa recorded in the North Pacific: longfin gunnel (Pholis clemensi); banded gunnel (Pholis fasciata); crescent gunnel (Pholis laeta); saddleback gunnel (Pholis ornata); and red gunnel (Pholis schultzi).
The known distribution of Pholis clemensi (Rosenblatt, Reference Rosenblatt1964; ITIS, 2012) is reported by Mecklenburg et al. (Reference Mecklenburg, Mecklenburg and Thorsteinson2002) as ‘…southeastern Alaska off Fillmore Island to northern California at Arena Cove' (Mendocino County—latitude 38.908°). Though it is known to occur at depths between 7.3 and 64 m, individuals of the species are typically found in shallow (<18 m) mixed habitats of rock and sand with biogenic cover such as hydroids and bryozoans (Mecklenburg et al., 2002; Love, Reference Love2011). While much of the life history is unknown, one observation suggests the longfin gunnel may be a ‘cleaner' species after an individual was noted inside the mouth of a lingcod (Ophiodon elongates: Lamb & Edgell, Reference Lamb and Edgell2010).
A small, cryptic species, the longfin gunnel was not described until 1964 (Rosenblatt, Reference Rosenblatt1964). The genus Pholis is characterized by dark bands that extend halfway down the dorsal section of the body; a variety of colour morphs have been observed. The longfin gunnel is differentiated from other members of the genus by distinct black spots, typically one to three, that occur between the dorsal bands against a light background. It reaches a maximum length of 13 cm. The anal fin is described as exceeding half the length of the body; other external characters include large pectoral fins, very small pelvic fins, and the absence of the lateral line (Eschmeyer et al., Reference Eschmeyer, Herald and Hammann1983).
The only record of a longfin gunnel in California was included in an addendum in Miller & Lea (Reference Miller and Lea1976) as being collected off Point Arena, California (latitude 38.908°). It was collected by R.N. Lea and L.L. Laurent, on SCUBA by rotenone and hand-net at 70 feet (21.3 m) on 21 June 1973. The specimen is accessioned in the Department of Ichthyology at the California Academy of Sciences (CAS 28453). We document here a southern range extension of 304.5 km for the species to Point Lobos, California (latitude 36.524°N) as well as eighteen additional remotely operated vehicle (ROV) observations from north central California (Table 1).
Observations of Pholis clemensi from north central California.
MATERIALS AND METHODS
In late summer 2010, a research cruise was conducted off central California, ranging from east of Soquel Canyon in the north to Point Lobos in the south, aboard the 20 m sailing vessel RV ‘Derek M. Baylis'. Video transects were conducted along the seafloor using a Mariscope FO-II ROV. The ROV was equipped with two video cameras, one which provided real-time imagery to the surface via an umbilical for ROV piloting and data collection and the other was a high-definition camera mounted to the side of the ROV, which recorded the seafloor in 1080i high definition (HD) at 30 frames per second. The ROV was also equipped with four lights to illuminate the seafloor and was rated to operate at a maximum of 350 m.
RESULTS
A small, eel-like fish was observed while reviewing the HD video collected during the cruise. The observation came on a dive off Point Lobos, within Point Lobos State Marine Reserve. The ROV position on the seafloor was estimated based on the GPS location of the vessel. Beginning coordinates for the dive were latitude 36.524N, longitude 121.971W and depth 61 m (Figure 1).
Map of Point Lobos State Marine Reserve, California remotely operated vehicle dive site where a longfin gunnel was observed at 61 m depth (SMCA, State Marine Conservation Area; SMR, State Marine Reserve).
A sequence of video frame-grabs was collected to aid in identification. The specimen was confirmed by the authors to be a longfin gunnel (Figure 2). Video and frame-grab photographs showed a small elongate fish with a long, continuous dorsal fin and dark barring on the dorsum. The photograph clearly illustrates the characters typical of the species, black spots on white background between darker bars.
Frame grab from high definition video of the longfin gunnel captured from a remotely operated vehicle off of Point Lobos 31 August 2010 in 61 m (A), still images of individuals taken off (B) Bodega Bay 27 July 2011 in 45.1 m, (C) Pillar Point 14 July 2011 in 32.7 m and (D) Point Arena on 7 August 2011 in 42.5 m.
Subsequently, additional observations were recorded from ROV ‘Beagle' operating from FV ‘Donna Kathleen' while surveying the north central California coast Marine Protected Areas to establish baseline conditions. ‘Beagle' was equipped with a Kongsberg digital still camera and HMI lighting and photographs were taken manually from the surface support vessel. Photographs were geo-referenced with the vehicle position using a short baseline acoustic navigation system.
CONCLUSION
These videographic images represent the first records of the species south of Arena Cove. The southern range of the longfin gunnel (Pholis clemensi) was latitude 38.908N, located near Point Arena and was determined from a single captured specimen. The images captured from the ROV videos indicate that the range extends at least 304.5 km farther south than previously thought, as far as Point Lobos (latitude 36.51014N), and reinforces the notion that our understanding of species distributions at any moment in time is an artefact of the tools we have to sample the marine environment. As the collection of visual imagery continues to be more commonplace, we predict that similar range and depth extensions will become increasingly common.
ACKNOWLEDGEMENTS
Generous support for this research came from the California Ocean Protection Council, California Sea Grant (Project No. R/MPA-8; JBL Award No. 09-015), National Park Service (Project No. R/CESUMPA-20; JBL Grant Number: J8C07110002), Undergraduate Research Opportunities Center (UROC) at California State University Monterey Bay, California, MPA Monitoring Enterprise, Campbell Foundation, Firedoll Foundation, Dirk and Charlene Kabcenell Foundation, Larry L. Hillblom Foundation, Hobson Family Foundation, Springcreek Foundation, The Nature Conservancy, FV ‘Donna Kathleen' and the Maricich Family and the David and Lucile Packard Foundation. We thank Oceana's Board of Directors and staff, with special thanks to M. Gorny and Oceana's Pacific Team; IfAME students J. Watson, H. Kelley, J. Moye, C. Denney, B. Downey, J. Adelaars, A. Alfasso, C. Turner, C. Carpenter, E. Ramsay, A. Launer, S. Loiacono and M. Fredle; the MARE team D. Rosen, A. Lauermann, S. Holz, AJ Reiter, Y. Yokozawa, and P. Ang-Terry and Captain D. Robinson, Sealife Conservation and the crew of RV ‘Derek M. Baylis' for key support in the field and in the laboratory. N. Donlou was supported by Oceana as a graduate intern. Video analysis was conducted at the Institute for Applied Marine Ecology's Image Analysis Laboratory and Oceana's Monterey, California office.
