TrophyCatch Research

FWC freshwater researchers use photo analytics to assess TrophyCatch submissions.

• TrophyCatch made submissions easier in season two.
• While easier on fish and anglers, it left biologists with less data.
• Biologists developed a way to estimate fish size just from pictures.
• As the technique becomes more refined and accurate, biologists will use it more as a tool for the program.

TrophyCatch relies on photo documentation of a bass’s weight for program qualification. Originally, the program required participants to photo document both weight and length of entrant bass to qualify for Lunker and Trophy levels, and Hall of Fame level bass required on-site verification by a Florida Fish and Wildlife Conservation Commission (FWC) biologist. Season two of the program transitioned to requiring only a single weight-documentation photograph for all three tiers of recognition to simplify the process. This shift reduced handling of bass, reduced their time out of water, and made it easier for anglers to participate. However, by lifting the requirement of length-documentation photos it left TrophyCatch biologists with less information to help verify reported weights of entrant bass.

Researchers begin investigating alternative methods of verifying length of and weight of trophy bass. They developed a technique referred to as “trophy bass photo analytics” where biologists use an object of known size in the photo (e.g., measuring tape or digital scale) to scale dimensions within the focus of the photo, which can then be applied elsewhere in the shot. Similar to existing equations that use length and girth to estimate a bass’s weight, trophy bass photo analytics allows biologists to measure a bass’s length, body depth, or cross-sectional area in a photo, and these values can then be entered into equations that estimate a bass’s weight.

FWC’s trophy bass photo analytics equations are based on nearly 200 bass that were photographed, weighed, and measured by biologists during 2014–2015. To make sure that these methods were applicable to bass of nearly all sizes, they included bass from 2.2–13.1 lbs; however, 65% of the bass were ≥ 8 lbs, since the project’s focus was to help verify weights of trophy bass.

Although the core process of trophy bass photo analytics has been the same throughout development, researchers have continuously honed and diversified the technique. It can be applied to variety of bass orientations, such as vertically or horizontally held bass or bass lying on a flat surface. As testing and refinement of these techniques verify accuracy standards, TrophyCatch biologists expect to increasingly rely on trophy bass photo analytics as a tool for the program.

FWRI biologists try to crack the riddle of Kingsley Lake

• FWC has made trophy Largemouth Bass management a priority in FWC’s Black Bass Management Plan.
• The TrophyCatch program helps biologists collect data on hard to study trophy-size largemouth bass.
• Kingsley Lake is home to a disproportionate number of trophy bass documented in the program.
• Biologists theorize the deep cooler waters of Kingsley provide a summer refuge for bass, slowing metabolism and reducing stress.
• Researchers are currently conducting a study tracking these large bass while logging water temperatures and depth.

To find out what is going on biologists designed a temperature and depth selection study. They implanted 10 bass with acoustic telemetry tags equipped with depth and temperature sensors. The tags continuously emit ultra-sonic signals that contain the depth and temperature measurements for where the bass is located. Researchers hear and decode the tag signals with underwater receivers that temporarily store these data. They also made a detailed bathymetric map of Kingsley Lake and have temperature loggers deployed across a range of depths. Later biologists can compare the depths and water temperatures used by our tagged bass with the depths and water temperatures available to them in the lake. Researchers also designed the receiver array to provide 100% coverage of the lake, meaning they should continuously hear the fish for the duration of the project as long as they remain in the lake. Study bass were tagged during December 2015–January 2016, and the operational life of the tags is about 24 months. The study is expected to last at least those two years.

In the end biologists hope to better understand the conditions that drive exceptional trophy-bass fisheries, like Kingsley Lake. If they are able to identify critical depth or temperature preferences of bass at Kingsley Lake, they could use that knowledge to identify other lakes in Florida that have similar characteristics with the possibility of implementing fisheries management actions such as stocking, boat ramp access and construction, or fish attractor construction at these lakes.

FWRI biologists discuss the factors that contribute to the growth of trophy-sized Florida bass.

Anglers from around the world travel to Florida for the opportunity to catch a Florida bass (Micropterus salmoides). The state is known as the Fishing Capital of the World in part because of the trophy-size Florida bass that can be found in many different habitats, from one-acre ponds to large natural lakes, rivers and marshes. In general, trophy-size Florida bass grow faster than the general population. However, not all bass reach trophy status. Actually, chances are slim that any bass will grow to 8 pounds or larger. Trophy-size fish are typically the old and rare members of the bass population and many things must fall into place for them to reach this size. Decades of research on the Florida bass have revealed several about these sought-after sportfish.

Potential

The most important factor influencing the occurrence of trophy-size bass is natural growth potential.  Florida bass are genetically different and grow much larger than the northern largemouth bass. Scientists at the FWC’s Fish and Wildlife Research Institute (FWRI) have surveyed lakes and rivers across Florida to determine where genetically pure Florida bass populations occur. The FWC has established conservation programs to protect these populations.  

Growth to trophy size also differs between genders. Female Florida bass grow faster than male bass and typically only the females grow larger than 8 pounds. Florida’s warm climate and long growing season also enhance the growth rates of Florida bass.

Time

Even with faster growth rates, it takes a while for a Florida bass to reach its full potential, so survival is always a factor in becoming a trophy bass. The recorded ages of trophy-size bass have ranged from 4-16 years old, with an average of 10 years of age in Florida. But only a small percentage of Florida bass live longer than 5 or 6 years, so reaching 10 years of age and trophy size is not the norm. Many factors can affect a bass’s odds of surviving long enough to reach trophy-size.

• Year One: During its first year of life, bass must not only find enough to eat, but also avoid being eaten by predators. Most fish do not make it through the first year.
• Anglers: Bass that survive the juvenile stages then have to avoid being caught and harvested by anglers. High rates of harvest, particularly for larger bass, lower the probability that fish will grow to trophy sizes. Slot size limits tend to allow more Florida bass to reach trophy sizes.
• Stress: For bass fortunate enough to find enough to eat, avoid predators and not be harvested, there are still threats to their survival. Stressors, such as low dissolved oxygen, can weaken their resistances to disease and infection leading to natural deaths. All things considered, it is pretty difficult for a bass to survive long enough to reach trophy size.

Food

When it comes to how food is related to bass growth, there is more to it than just the amount of prey available. The size and location of the prey affect a bass’s ability to capture them. Also, the energy required to catch prey, caloric content of the prey, digestion rates, and the rate the fish burns the energy all influence bass growth rates. Diet studies demonstrate that big bass eat large prey items, so availability of prey such as large-sized chubsuckers, shads, sunfish, and tilapia may have an effect on the size a bass can attain.

Environment

Habitat conditions also play a significant role in the production of trophy-size bass. Like plants, bass thrive in nutrient-rich environments. Water bodies that are naturally high in nutrients or have been enriched by human activities (e.g. agricultural runoff or phosphate strip mining) are more likely to produce trophy bass.

Clear lakes with good water quality and abundant aquatic plants also produce good numbers of trophy-size bass. For small bass, an abundance of aquatic vegetation provides cover from predators and supports a wide variety of prey like insects, crayfish and small fishes. In fact, the majority of bass reported to the FWC’s Big Catch Program the last 20 years were caught in lakes with heavy growth of aquatic plants. 

Extreme water fluctuations also create habitats that produces trophy bass fisheries. Sometimes this happens naturally during cycles of droughts and other times it results from lake water levels (lake drawdowns). The flooding or reflooding of a reservoir produces the same results. 

The journey to trophy size is an arduous one. As research continues, biologists will learn more about trophy-size bass and the factors that contribute to their growth. Science-based conservation will aid the preservation of Florida’s bass populations, helping ensure anglers continue to have opportunities to catch this prized sport fish.

Biologists study the trophy-bass fishery in Florida

• Researchers have tagged bass ≥ 8 lbs with high-reward ($100) tags across the state since 2011.
• Information from each tag return is used to measure annual state-wide catch, exploitation, and release rates of trophy-size bass as well as measure awareness and participation rates of TrophyCatch.
• Through five years of the tagging study, FWC researchers have tagged 836 trophy-size bass (136–195 per year) from 115 public waterbodies (42–56 per year) within Florida.

Since 2011, biologists from multiple divisions of FWC have worked to tag every bass 8 pounds or heavier that they sample during annual electrofishing surveys, which allows live-release of the bass. Each year, they have tagged between 136–195 trophy bass, and to date, the project has reached more than 115 public water bodies across Florida. The tags bear a unique ID code, a FWC telephone number, and a $100 reward for reporting catch of a tagged bass.

Trophy Bass Statistics

Catch Rates

• About one in eight to one in four trophy bass were caught by anglers in the state each year. This range of catch rates for trophy bass is quite similar to catch rates for smaller or average-size bass in Florida, suggesting that trophy bass are no more elusive to being caught than smaller bass.
• Just two to five percent of the trophy bass population are harvested each year. The tagging study confirmed the low harvest numbers by revealing 77 to 91 percent of tagged bass that were caught were released. These results reiterate that in Florida the catch-and-release ethic among bass fishermen is strong, especially when it comes to trophy bass.

Angler Data

• Anglers consistently caught more tagged bass via artificial lures (74–92%) than on live bait (8–26%). Interestingly, that pattern was mirrored by TrophyCatch data.
  • This doesn’t necessarily mean that artificial lures are better than live bait at catching big bass. To identify which is more effective, researchers would also need to know how frequently lures (or live bait) are used across all bass fishing trips, regardless of whether a trophy bass was caught. Future angler surveys may help look into this.
  • More tagged bass were caught by anglers during general recreational fishing trips (75–85%), whereas 15 to 25 percent of the tagged bass were caught during tournaments each year. As most tournament anglers would argue, they are probably not less effective at catching trophy bass. Rather, tournament fishing trips represent a small fraction of overall bass fishing at the state-wide level.

Since the trophy bass tagging study was designed to measure aspects of TrophyCatch performance and effects, researchers hope to operate the study in tandem with TrophyCatch, together monitoring Florida’s trophy bass fisheries over the long term. To register and get familiar with the submission procedures for TrophyCatch, please check out the website today. It’s a great way to get involved in science and conservation for trophy bass in Florida. If you happen to catch a tagged bass, clip the tag close to the bass’s body and retain the external end for record keeping. It has a unique identification code and telephone number (850-363-6037) for reporting your catch and collecting the tag-return reward.