Maintenance of the genetic structure of a wild fishery is a key component for responsible marine stock enhancement. The historic model of spawning for stock enhancement of red drum in Florida’s Central Gulf coast required five 12-feet-diameter (12-ft) tanks with three female and three male adult red drum in each to achieve a satisfactory effective spawning population size. A single 20-feet-diameter (20-ft) tank, five times the volume of a 12-ft tank, for spawning 30 adult red drum presents opportunities to improve efficiency through reduced logistical complexities, labor, and footprint, while maintaining or improving genetic diversity of hatchery offspring in Florida Stock Enhancement Hatcheries. A study is in progress at SERF to determine the effective population size of spawning red drum in a 20-ft tank to determine if this strategy is a more efficient alternative than the historic model.
A key consideration before implementing the study was to design and construct a prototype filtration and egg collection system that could be used with the 20-ft tank. Traditional filtration systems for spawning tank are not efficient for large tanks. The new spawning system designed and tested by SER team members reduced water use and labor, and improved water chemistry from the traditional design. These improvements were keys to effectively operate a large spawning tank. SER staff then adapted the prototype design for a 20-ft-tank. Construction and assembly of the spawning system was accomplished by SER staff and key functions tested and refined before stocking fish.
Adult red drum were stocked into the 20-ft tank and a 12-ft tank on November 4 and 6, 2014 to evaluate husbandry and maintenance of the 20-ft tank. Although not expected necessarily, spawning commenced soon afterward in both tanks as fish were stocked at the end of the natural spawning season. Beginning in late January, the red drum captive maturation cycle (a compressed seasonal cycle of 150 days) was initiated. Spawns began in July and are being collected for through October 2015. The spawning contribution of the individuals in the 12-ft and 20-ft tanks will be determined using genetic markers over the course of the four-month spawning period and replicated with new populations of red drum in subsequent years. This data is a key to the design and operation of stock enhancement facilities in Florida and other states that subscribe to approaches for maintaining the genetic structure of wild red drum populations.
Habitat loss and fire suppression are well known threats to the persistence of the threatened Florida scrub-jay. However, many populations are also becoming increasingly isolated by changes to the surrounding landscape. Connectivity within and among metapopulations has been greatly reduced by human development, especially in coastal counties. Translocation is one strategy that is being evaluated to boost the size of smaller populations and to better link these populations with each other.
Efforts to translocate Florida scrub-jays are still in their early stages and have been successful in only two regions of the state. During the past few years, I have participated in experimental translocations of isolated scrub-jay family groups to recently restored public lands which have populations below their potential carrying capacity. An ongoing partnership of staff from FWRI, the Brevard Zoo, and FWC’s Division of Habitat and Species Conservation conducts these targeted scrub-jay translocations in Brevard County and Volusia County.
In January, we trapped and banded a family of Florida scrub-jays in a heavily developed urban area in Brevard County and moved them to nearby Buck Lake Wildlife Management Area. Birds were captured from a utility right-of-way behind a car wash. Not only was this one of the coldest days I have ever banded birds but it was also my first ever experience bird banding in the parking lot of a car wash! A family of four individuals was moved to a hacking cage at Buck Lake and then released 24 hours later. A resident scrub-jay immediately joined the group and they began to set up a territory in the immediate area around the hacking cage. Continued monitoring efforts will be vital in determining the effectiveness of these efforts.
Obtaining estimates of density or abundance for large carnivores that are rare, elusive, and inhabit remote wildlands has been a long standing challenge for scientists. The FWC Panther Research Team, along with collaborators at the National Park Service and Conservancy of Southwest Florida, initiated a study in 2014 to estimate the density of Florida panthers in a 162 km2 section of the Big Cypress National Preserve north of I-75 (Alligator Alley). Fifty passive infrared motion detecting cameras were deployed within a standardized grid across the study area from April to September 2014 to capture photographs of both marked (radiocollared) and unmarked panthers. Cameras collected five photos in rapid succession when triggered by motion. During the study period, 88,534 photos of wildlife were recorded. The majority of photos were white-tailed deer and Osceola wild turkey. Other species documented included river otters, feral hogs, Florida black bears, bobcats, coyotes, alligators, several species of birds, insects, herps, and panthers. Individual panthers are not reliably identifiable by their fur, unlike spotted or striped felids, hence our reliance on having a portion of the population marked. In order to estimate density, photographs of marked and unmarked panthers will be analyzed within a spatial mark-resight (SMR) model that is based upon the framework of traditional mark-recapture analyses. The SMR model utilizes the spatial component of marked panther encounter histories at known locations (camera sites) across the study area, counts of unmarked panthers at camera sites, and radio telemetry data from marked panthers using the study area, to derive a density estimate. Results should help direct future research projects that utilize this study design to derive population densities across multiple study areas in order to obtain a range-wide population estimate for panthers with acceptable levels of precision. Such estimates play a critical role in determining progress towards achieving recovery criteria established for the endangered Florida panther.
The internal newsletter of the FWC Fish and Wildlife Research Institute