1. Winter Flounder Spawning Areas in New Haven Harbor
Jose J. Pereira 1,2, Ronald Goldberg 1, Paul Clark 1 , Craig Obergfell 2, Chris Miller National Marine Fisheries Service, Milford Laboratory, 212 Rogers Ave., Milford, CT Department of Ecology and Evolutionary Biology, University of Connecticut, 3 University of Pennsylvania
Abstract
As part of a previous study in 1994, 24 gravid female winter flounder were fitted with acoustic transmitters and released in New Haven Harbor, CT prior to the spawning season. The transmitters sent out a unique numerical signal so that individual fish could be identified. We visited the harbor weekly during spawning season and systematically searched the harbor for tagged fish using a directional hydrophone. Areas where fish were found were thought to be potential spawning areas. Fish were frequently located in Morris Cove on the eastern side of the harbor and around the east breakwater. Using a benthic sled, we then sampled these areas in an effort to collect fertilized winter flounder eggs and to confirm the presence of spawning activity at the site.
Since only a few winter flounder eggs were collected in 1994, the same six sampling sites were sampled more intensively in Triplicate tows were conducted at each site approximately biweekly from February to the beginning of April. In 1999, four sites in the shallower areas of Morris Cove were sampled using the same protocol as for the six sites sampled in In total, over 1400 eggs were collected, 115 of which were winter flounder eggs. The greatest number of winter flounder eggs were collected in mid-March in both years. The observed distribution of winter flounder eggs indicates that the northern end of Morris Cove and the area adjacent to it and east of the main channel are spawning areas for winter flounder.
Sampling stations in New Haven Harbor. Sites C1 – C20 (circles with the red center markers) are listening stations used during the acoustic tagging study in Circles are 800 meters in radius and represent a conservative estimate of the range of the tag. The boat would be positioned at the red marker and tagged fish in the area would be located. Circles in which tagged winter flounder spent time during spawning season were sampled with a benthic sled in 1994 but very few eggs were obtained. These same sites were sampled more intensively in Some shallower areas of Morris Cove (orange markers 1 - 5) were sampled in Triplicate five minute tows were conducted at each site. Each tow covered about 600 meters.
Winter flounder eggs at various stages of development. Notice the small size and the lack of an oil globule in the yolk.
Typical Bottom Types
(Stills captured from video tape filmed by divers in late August and early September of 1998)
Heavy shell over sand or silty-sand typically found near the center of C5. This type of cover was also found at the #1 shallow water station in Morris Cove (orange marker # 1) where most of the winter flounder larvae were caught in 1999.
Hydrophone used to track winter flounder
Benthic sled used to collect eggs and larvae
Hard sand with a light layer of vegetation found in shallow water site #2. Vegetative cover would be reduced in the winter.
Hard sand with a heavy layer of vegetation found in shallow water sites 4 and 5 where most of the winter flounder eggs were collected in Vegetative cover would be reduced in the winter, especially the ulva.
Recently hatched winter flounder larvae approximately 3 mm in length. Notice diagnostic pigment band in the middle of the tail.
Mean sizes of winter flounder eggs and larva. Error bars represent the standard deviation, numbers in parentheses represent numbers collected.
Acknowledgement: Thanks to Ron Goldberg and Joe Choromanski of the Milford Laboratory for filming the underwater footage.