Lauren Bliss '03

Marine Mote Laboratories, Summer 2002

The depletion of wild fish populations around the world due to overexploitation,         habitat destruction, disease, environmental changes, and other factors         has ignited an interest in fisheries stock enhancement. Several commercially         important species in the U.S., such as the salmonid species of the Pacific         Northwest, the striped mullet of Hawaiian waters, and the red drum of         the Gulf of Mexico are being raised in hatcheries by the thousands and         have been shown to augment wild fish stocks. Many other declining wild         fish stocks are potential candidates for enhancement, but research indicates         that not all populations automatically rebound upon the addition of hatchery-raised         juveniles. One candidate on the west coast of Florida is the common snook,         Centropomus undecimalis. The population around Sarasota, Florida         has been suppressed in the past 30 years due to overfishing, increased         housing and seawall developments along the creeks, and environmental extremes         such as bouts of red tide and cold snaps. The closure of the commercial         industry in 1957, sportfishing size restrictions, the promotion of recreational         catch-and-release, and education through the Snook Foundation have helped,         and stock enhancement is the next to join this suite of conservation tactics.         Dr. Kenneth Leber and Senior Biologist Nathan Brennan of Mote Marine Laboratory         in Sarasota are researching the efficacy of snook stock enhancement, and         I was fortunate to work as an intern in Mote’s Center for Fisheries Enhancement         for three months.

   In May 2002, over 2000 juvenile snook were released into the Sarasota creek   systems. Bowlees Creek and Whitakers Bayou received a 50% increase in snook   (original abundance was determined in an April pre-release study), while the   control sites, North Creek and South Creek, received only a 10% increase. Hatchery   fish were tagged using two cutting-edge methods: coded wire tags (CWT) and visible   implant elastomers (VIE), both developed by Northwest Marine Technologies. Two   months later, I was able to assist in the first round of sampling and tagging   to determine post-release snook density estimates in the four creeks. The most   favorable scenario would be a two-fold increase with an equal ratio of wild   to hatchery fish in Bowlees Creek and Whitakers Bayou, but little change in   the juvenile population structure of North and South Creeks (other than natural   mortality trends). To analyze the population, we pulled seine nets at low tide   at every 200 feet of each creek and sorted through the catch. I learned how   to handle the target species, prepare and insert CWTs and VIEs, and record data   on fish measurements and water quality at the site. The work was physically   demanding and exciting as this study is the first of its kind to use such extensive   tagging techniques in the field. The researchers question whether the creek   systems can support more than 2 snook per 100 feet of suitable shoreline habitat.   Data from the following sampling trips will help to sort through these questions.

   During our time back at the lab I entered the data from our sampling trips,   compiled bibliographic information on pertinent stock enhancement articles,   and cared for hatchery-raised snook and red snapper in the department’s tank   systems. The fish maintained in the “wet lab” are currently identified by a   number of tags in different tissues and are kept as part of an ongoing tag retention   study. I was able to assist in a periodic check on the tags, which required   anesthetizing the fish with a cocaine derivative. I was also fortunate to assist   Mr. Brennan and Research Biologist John Ransier of the Port Manatee state hatchery   in a red drum tag retention study. Over 2,000 one-month-olds were anesthetized   and tagged with CWTs using Mark-4 machines fitted with “headmolds” for precise   insertion into the tissue behind the eye. CWTs are typically not used in such   small fish because it is time consuming and can result in high mortality. However,   if tag retention remains high over the next year, the headmold method may be   an efficient, industrial-scale way to tag red drum prior to release. Florida   hatcheries are taking a more scientific approach to red drum enhancement compared   to hatcheries in Texas, and Ransier hopes his results will help biologists in   Texas understand how released drums are affecting wild populations.

   My internship at Mote introduced me to many facets of fisheries stock enhancement,   and more importantly, the inner workings of long-term field studies at a large-scale   marine laboratory. Mote is a business as much as it is a research institution,   and budgeting, scheduling, and managing require as much time as the actual science.   I was also shocked at how such extensive fieldwork was needed for a handful   of data points. It is no wonder our knowledge of marine systems lags behind   that of terrestrial environments. During my time in the field I recognized the   importance of maintaining good relationships with local anglers and residents   along the creeks, understanding the region’s natural history, and conducting   numerous pilot studies before starting the long-term research. Solid methodology   is critical to obtaining accurate results, as I became well aware of within   my first week. This summer was an eye-opening learning experience that would   not have been possible without your support. I thank the ES Mellon Grant for   its generosity in enabling me to take advantage of such an opportunity.