1. Calcein as an Alternative Chemical Marker for Lake Herring
RESULTS:
We were able to successfully mark 145,000 Lake Herring using the Calcein immersion bath with very little behavioral discomfort or mortality. All fish returned to normal activity once the treatment was completed. All Lake Herring showed a strong brilliant green fluorescence on their outer body including scales, fin rays, and operculum (Figures 5-7). Internal examination of spinal column, vertebrate, and jaw bone also showed strong brilliant green glow under ultraviolet light (Figures 8 & 9). The otolith was the only hard structure that showed a green marking but was not as vibrant (Figure 10).
ABSTRACT:
Restoring native Lake Herring (Coregonus artedi) populations in Lake Ontario is a joint effort by the New York State Department of Environmental Conservation and the U.S. Geological Survey. Restoration efforts have given rise to new culture techniques and methods for marking fish prior to release. In order to evaluate the efficacy of using hatchery supplementation to restore wild fish populations, fish need to be marked prior to release. Juvenile Lake Herring are fragile, thus mass marking techniques that reduce the handling of individual fish are required. We evaluated the usefulness of Calcein (SE-MARK) as a marker on hard structures, in particular the otolith. Juvenile Lake Herring (100 days old) were immersed in 5,000 mg/L Calcein for 4 minutes to apply the chemical marker. Observations of the chemical marker were evaluated 8 days and 30 days following the treatment. All fish immersed in Calcein presented a valid mark, with strong brilliant markings on the bones, scales, and fin rays. The otolith was the only hard structure that did not show a brilliant marking due to the opaque nature of the structure. We suggest using Calcein to produce strong discernable marks on the hard structures of Lake Herring fingerlings.
G. E. MACKEY, M. A. CHALUPNICKI, J. H. JOHNSON
USGS Great Lakes Science Center,
Tunison Laboratory of Aquatic Science
Cortland, NY
And
T. KEHLER
USFWS Northeast Fishery Center
Lamar, PA 16848
N. H. RINGLER SUNY College of Environmental Science and Forestry Syracuse, NY 13210
METHODS:
Adult Lake Herring were captured in Chaumont Bay, Lake Ontario (Figure 1 & 2) in November 2013 then transported to the Tunison Lab of Aquatic Science (TLAS) in Cortland, N.Y. The males and females were spawned on station and the fertilized eggs were allowed to develop. Hatched larvae were transferred to larger rearing tanks and allowed to grow for 100 days (Figure 3). Calcein used in this study was obtained from Western Chemical (Ferndale, Washington) under the brand name SE-MARK. Calcein was diluted to 0.5% to give a treatment concentration of 5,000 mg/L. A 1.5% saline solution was also prepared as a preliminary treatment to remove water from fish to increase Calcein retention.
Figure 5: Calcein Marked Scale
Figure 6: Calcein Marked Fin Rays
Figure 1: Gravid Female Lake Herring
Figure 2: Trap Netting Site
Figure 3: Juvenile Lake Herring
Figure 7: Calcein Marked Operculum
Figure 8: Calcein Marked Vertebrate
INTRODUCTION:
Lake Herring (Coregonus artedi) were once abundant in Lake Ontario, but due to the invasive alewife (Alosa pseudoharengus) and commercial fishing, the population has been depressed. Alewife are currently found in all of the Great Lakes and are known to cause physiological problems in salmonid fry. Restoring the Lake Herring population will increase native diversity in the lake while providing an alternative food source that is low in thiaminase. Currently there is a binational effort to restore native deepwater coregonid populations into Lake Ontario by the NYDEC, USGS, U.S. Fish and Wildlife Service and the Ontario Ministry of Natural Resources along with a concurrent effort by the NYDEC and USGS to restore native Lake Herring. Interest in the restoration of Lake Herring has given rise to new culture techniques, and methods for marking them prior to release. Tetracycline compounds have been used to mark fish as it binds to the calcium in new bone growth, and fluoresces under ultraviolet light (Weber and Ridgeway 1962; Hendricks et al. 1991; Marking et.al 2011). However, the time needed to mark fish with these compounds may be detrimental to sensitive fish and cause added mortality. Calcein (SE-MARK) is an alternative chemical marker that is being evaluated for its usefulness to mark fish when traditional chemical markers are not available or unable to produce a visible mark. Numerous fish species have been noted to be marked with Calcein using injections, osmotic inductions, immersion baths, and as a dietary supplement (Gelsleichter et al 1997; Mohler 2003; Honeyfield et al. 2011). We evaluated the usefulness of Calcein as a chemical marker for Lake Herring as previous trials with OTC have been unsuccessful.
One liter cups were modified with a fine mesh bottom and perforations on the side to enhance rapid filling and draining of fluids during treatment (Figure 4). Approximately 300 fish were transferred to one of four modified cups and placed in the 1.5% saline bath for 4 minutes. Fish were then transferred to the 5000 mg/L Calcein for an additional 4 minutes. Oxygen was introduced through diffusers to achieve saturation and the temperature was maintained one degree Celsius below culture water with an ice bath. Following immersion the fish were gently rinsed in a water bath then returned to the outside raceways. To reduce stress caused from the treatments the raceways were covered with metal screen and a vinyl tarp. A subsample (n=10) of fish from each raceway was evaluated for exterior mark retention at eight days and thirty days post immersion. A handheld SE-MARK detector was used in a dark room to enhance fluorescence under ultraviolet light (Excitation nm, Emission 515nm). Internal hard structures were evaluated at the Northeast Fishery Center, Lamar Pennsylvania. Otoliths and spinal column vertebrate were removed and cleaned from a subsample of fish eight days post treatment. Hard parts were mounted and viewed under a dissecting microscope equipped with digital camera and an ultraviolet light to fluoresce Calcein.
Figure 9: Calcein Marked Jaw Bone
Figure 10: Calcein Marked Otolith
CONCLUSIONS:
Our results suggest that Calcein is a safe and effective chemical marker for Lake Herring at 5,000 mg/L for 4 minutes following a 1.5% saline bath for 4 minutes. Lake Herring showed very little behavioral discomfort or mortality as a result of the bath. This is a practical technique to mark large numbers of Lake Herring in a short amount of time unlike OTC that requires at least 6 hours for one treatment. Due to the different chemical composition of the herring otoliths, the intensity of its fluorescence is less compared to that of other hard structures. This may be acceptable as fish need to be killed in order to view the otolith while the fin rays, operculum, and scales can be easily viewed with a hand held SE-MARK detector unit without sacrificing the fish. This is a promising technique to mass mark fish that should be considered as an alternative to traditional chemical markers.
Figure 4: Immersion in Calcein
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