Category: Fish

Posted on

Hydrilla and Carp Control Update 11/21

November 1, 2021

Hydrilla and Carp Control Update 11/21

Rick Stuebing

Florida Fish and Wildlife (FWC) is planning to add four hundred (400) carp to Johns Lake in the near future. They typically put carp in the lake every few years. The primary purpose of the carp is to assist with controlling Hydrilla. There is a delicate balance to maintain with the number of carp in the lake. If the population grows too large, they will eat not only the Hydrilla but the important native plants as well, which could negatively impact the eco-system of the lake. FWC monitors the growth of the hydrilla to determine how many carp to add and what frequency to put them in Johns Lake.

There is no way to accurately say exactly how many of the carp stocked in the past are alive because we don’t have accurate numbers for stocking mortality (predation by largemouth bass when they are young, etc.). We are working to get better numbers on the natural grass carp mortality curve. From what some have observed, you start to lose 10-20% per year after age 6 or so. Most do not live past the age 10-12 years old. The maximum length of a grass carp is 4.6 ft (1.4 m), and the maximum weight is 97 pounds (44 kg). Adults look identical to juveniles, and they are not able to reproduce.

Plants Preferred by the Grass Carp

  • Hydrilla
  • Coontail
  • Muskgrass
  • Naiad
  • Slender and jointed spikerush

Plants Preferred by the Grass Carp

  • Water hyacinth
  • Water lettuce
  • Water lilies
  • Torpedo grass
  • Hygrophila
  • Cattail

Posted on

Fishing Update March 2021-Spawning

March 7, 2021

Fishing Update March 2021-Spawning

John Schmidt

Guest Author: Jim Sweatman

In case you are wondering about the health of the fish and the impact of fishing during the spawning season, here is a response from our Fisheries Management Project Leader:

Bass in this area of Florida spawn between December – April the weeks before the full and new moons, versus a distinct narrow spawning window like they have “up north”. Furthermore, fish have a mechanism called “compensational mortality” which means if one nest fails for some reason then another has a higher survival.

Because of these 2 factors, our research has shown no impact of bed fishing or tournament fishing on the spawning or recruitment success of largemouth bass in Florida. Factors that do affect spawning/recruitment are: (1) food available to the young when they hatch and (2) cover available to hide from predators. Reducing nutrients from yard run-off via swales, getting houses along the shorelines hooked up to sewage rather than on septic, allowing for natural fluctuations in a lake based on hydrology rather than flood control, and proper aquatic plant management, are all factors that do impact spawning and recruitment success.

Our latest surveys show the bass population in Johns Lake is doing very well. Our annual report from last year is on our web page if you are interested.

We have not analyzed the data for this year, as we are still collecting it, but the bass fishery looks very good based on what we have so far. See pictures attached taken on January 21st and the 24th.

Sincerely,

Jim Sweatman
Fish Orlando Project Leader/TrophyCatch Assistance
Division of Freshwater Fisheries Management (NE Region)
Florida Fish & Wildlife Conservation Commission
321-231-9593 (m)
jim.sweatman@myfwc.com
myfwc.com/fishorlando

Posted on

Triploid Grass Carp

June 6, 2019

Triploid Grass Carp

Rick Stuebing

Introduction

The use of Triploid Grass Carp is one of several methods to control the hydrilla in Johns Lake. Triploid grass carp are unique, olive-green, cigar-shaped fish often observed basking in the sunshine in shallow water as they soak up warm surface temperatures. What sets these fish apart from others is their intense appetite for a wide variety of underwater plant life. Often, plant problems in ponds and lakes are due to invasive, exotic species such as hydrilla, which have no natural enemies in Florida. It is in everyone’s best interest to prevent these plants from spreading and taking over our waterways.

Grass carp come from Asia and also have no natural enemies in Florida. The triploid “grass carp” is a sterile version of the white amur. It has been used in private and public Florida waters for the control of noxious aquatic plant species since 1972. Triploid grass carp are considered a natural method for controlling aquatic vegetation and macro-algae. They can live for many years (20 plus years in some cases). Their ability to live long typically makes them significantly more cost effective than herbicides.

Grass carp usually take six months to a year to be effective in reducing problem vegetation, although they provide much longer term control than other methods, often up to five years before restocking is necessary. When used in conjunction with herbicide treatments, control of problem vegetation can be achieved quickly, and fewer carp are required to maintain the desired level of vegetation.

Physical Characteristics

Grass carp are actually members of the minnow family. Grass carp grow to an average of 15-20 pounds and 20-35 inches in length. In larger lakes with large numbers of plants, they can grow up to 50-60 pounds and exceed 50 inches in length. In Florida, the largest reported grass carp weighed 75 pounds.

Grass carp sometimes appear silver in color, but often display an olive green or dark gray hue on top with light gold or pale yellow sides. Their belly is silvery or bluish-white and fins are light green or gray. Unusually large fish scales are another distinguishing characteristic.

Grass Carp Sterility

When grass carp are able to reproduce, they are called “diploid”. Florida law dictates that grass carp used for weed control must be sterile, or “triploid.” “Triploid” grass carp are hatchery-raised fish that have been sterilized by “shocking” fertilized eggs. This leaves the fish unable to produce viable eggs. This technique is used to eliminate reproduction in Florida waters.

Permitting

In Florida, only triploid grass carp are allowed and a permit is always required, even when stocking privately owned waters. Permits may be obtained by contacting the Florida Fish and Wildlife Conservation Commission (FWC).

What They Eat

They are normally readily available for purchase year round in several sizes but require a permit. The smaller ones are cheaper but have a higher chance of being eaten by bass. Most grass carp are shipped at about 11 inches. If stocked at a proper rate, at correct sizes, targeting proper plant species, and the right time, you will achieve significant vegetation control the first year, depending on the severity of the problem.

They prefer softer, pliable aquatic vegetation such as hydrilla and milfoil.  Fortunately, hydrilla is their favorite food. This desire for delicate vegetation reduces tendencies to eat most desirable emergent and floating aquatic vegetation species. Grass carp’s selective diet is perfect because it allows floating plants such as watermeal, and emergent species as pickerelweed, lilies and duck potato, to coexist with the fish. This allows these floating and emergent species to both serve as refuge for fish and wildlife, while also helping to manage influxes of nutrients that occur over the growing season.

Plants Preferred by the Grass Carp

  • Hydrilla
  • Coontail
  • Muskgrass
  • Naiad
  • Slender and jointed spikerush

Plants Preferred by the Grass Carp

  • Water hyacinth
  • Water lettuce
  • Water lilies
  • Torpedo grass
  • Hygrophila
  • Cattail

Conclusion

In May of 2019 FWC added approximately 1,000 sterile grass carp to Johns Lake. 500 were released near the public boat ramp and 500 near the Deer Island Cove.  There were also 1,000 stocked in April/May 2015 and 750 in Feb 2016. There is no way to accurately say how many of those carp are alive because we don’t have perfect numbers for stocking mortality (predation by largemouth bass when they are young, etc.). From what some have observed, you start to lose 10-20% per year after age 6 or so. Most do not live past age 10-12. 

FWC agreed to stock the additional 1,000 carp because of the way the hydrilla expanded so quickly in September 2018. When you get the right balance of carp, you shouldn’t have to treat with as much herbicide.  All lakes are different and the stocking of carp should always be in conjunction with small, sometimes frequent, herbicide treatments.

From an FWC perspective Johns Lake looks great. We have good coverage of submersed vegetation and the water clarity is good. We are seeing an upward trend in our largemouth bass population and noticing more ducks as well.

Posted on

Johns Lake 2019 Angler Survey (Creel)

October 1, 2018

Johns Lake 2019 Angler Survey (Creel)

John Schmidt

     Johns Lake is a Fish Orlando BIG WATER BODY that is managed by FWC to keep good fish habitat. The creel is just one way they evaluate their work, along with electrofishing, guide reports, Wednesday night tournament results, hook and line samples, TrophyCatch submissions and angler diaries. FWC creels are set up the same every time they run them, so they can be compared with one another. FWC used to conduct them every five years, but they recently shortened it to every 3 years, in order to evaluate the new bass regulation implemented in July 2016 (5 bass limit of fish < 16 inches of which one may be > 16 inches).

      In 2019 the creel will run from January 6, 2019 to April 19, 2019. The creel is broken into four periods (Jan 1 – Jan 28th; Jan 29th – Feb 25th; Feb 26th – Mar 25th; Mar 26th – April
22nd). The computer randomly picks 6-week days and 4 weekend days from each period. It also randomly picks whether they will be out there in the morning, mid-day or evening. 

     The Wednesday night tournament shuts down when we “fall back” from daylight savings time and then starts again when we “spring forward” into daylight savings. There are two randomly selected creel week days that will fall during the Wednesday night tournament time. However, as mentioned above, they track the information on the Wed night tournaments aside from the creel.

     During similarly constructed creels conducted on Johns Lake in 2011 and 2016, they had largemouth bass catch rates that were around 1 bass/man-hr. For example, if two average bass fishers on Johns lake fished from 6 am – 12 pm, that would be 12 man-hrs (6 hrs fished x 2 fishers). Accordingly based on the last two creels, they would catch an average of 12 bass during their trip. 

     There are very few waters in Florida that can brag of catch rates of one bass/man-hr or higher. In the last two decades, bass catch rates this high have only been recorded in this area on West Lake Tohopekaliga, the Stick Marsh/Farm 13 Reservoir in Palm Bay, Turkey Lake (A Fish Orlando FAB FIVE) in Orlando and the Winter Park Chain (A Fish Orlando BIG WATER BODY) in Winter Park.

     One of the main reasons Johns Lake’s bass fishery is good is because the water levels fluctuate. The low’s allow for growth of terrestrial and transitional wetland plants, that when flooded, provide energy for the system via epiphytic algae (the green algae slime that is on the stems of plants). The aquatic insects and small fishes eat the algae, which are in turn are eaten by bigger predators. The highs allow for flooding and control nuisance plants (cattails, etc.), and flood associated wetlands, which after the waters subside, bring the baitfish produced in these wetlands, back into the lake to provide food and energy. While you may not believe this after the last two years of high water on your docks, the highs don’t get as high for as long as they historically used to before canals and structures were built, which is part of the reason they must spend some time treating cattails, floating mats, etc. on Johns Lake. However, it is nothing compared to the mess that would result if water levels were strictly stabilized!

     An extreme low occurred in 2001, when most of Johns Lake dried up. It stayed down until 2003, and in the process, large stemmed woody plants, etc. grew on the lake bottom. When the lake re-flooded, FWC stocked it with 250,000 fingerling bass. Stocking of bass only works on new waters and those that have dried up and re-flooded. Only a small percentage of the bass stocked survive after the first year, but these become the brood stock (spawners) that repopulate the lake. 

     With all the energy produced from the flooding of the terrestrial vegetation came amazing action for big bass in 2006 – 2012. This was documented in our 2011 creel. Approximately 400 – 600 trophy bass were caught Jan – Apr in the 2011 creel! In the first year of TrophyCatch (2012), Johns Lake was second in the state for submissions.

     All good things do come to an end, and by 2013, most of the woody stemmed vegetation produced from the 2001 drought was gone. While the catch rates for bass were still good in the 2016 creel, accordingly, with this energy source reduced, we saw a drastic reduction in memorable (> 20 inch) and trophy (> 24″) bass. 

     One trophy bass FWC shocked and tagged ($100 prize) on Johns Lake last spring was caught by an angler within one week of tagging. All the fishery biologists in the state insert $100 trophy tags in bass that they electrofish in order for the research division to get a “handle” on how many are kept and how many are released. In the past few years on Johns Lake they have tagged approximately 11 trophy bass and 9 of the 11 tags have been returned. Fortunately, the anglers released all their tagged Johns Lake trophy bass.

     FWC’s Fish Orlando annual report can be found each year on their website. You can also check out FWC’s web page. They also have a Fish Orlando app available for apple phones, but it only covers the FAB FIVE, URBAN PONDS and fish ID. It is currently being updated to IOS12. Good luck fishing!
 
Posted on

Grass Carp

November 1, 2017

Grass Carp

Mary Louise Grable

Ctenopharyngodron

      Grass carp are nonnative fish imported from Asia for the control of higher invasive aquatic plant species such as hydrilla. They are a more cost effective method of control than using herbicides
or the use of mechanical means. A combination of the methods is the most effective in trying to control hydrilla. Estimates for using grass carp to control hydrilla are $15 per acre as opposed to $100 – $500 per acre using herbicides. Mechanical harvesting is even more expensive. 

      Grass carp are one of the largest members of the minnow family. Their life span is approximately 15 years. It takes about 6 months to a year for the fish to become effective in controlling vegetation. One of the few species of fish that eats plants, the grass carp does not eat all varieties of plants. It is important that overstocking does not occur. The grass carp found in Florida lakes have three sets of chromosomes (triploid) and are certified to be sterile. The largest triploid found in Florida was 15 years old, measured 56 inches in length and weighed 75 pounds. 

     These fish have large scales with a silvery to dark gray back, lighter golden sides and white belly. The body is round with a broad head. The fish are stocked in Johns Lake. Sometimes they are caught while fishing for tilapia or catfish. If a grass carp is caught, it is required that it be released

Proudly powered by WordPress