SRAC Publication No. 394

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November 1992

SouthernRegionalAquacultureCenter

Harvesting Warmwater Fish

Gary L. Jensen1 and Martin W. Brunson2

Aquaculture is an established andviable commercial agriculturalpractice in many states. It includesa variety of native and exotic spe-cies grown for human consump-tion, fish bait, recreational fishingand hobby use. At some time inthe production cycle from broodfish to marketing different live pro-duct forms, one or more life stagesof fish must be harvested from theculture facility.

A successful fish farmer mustknow how to keep fish alive andhealthy when they are moved. Dif-ferent handling operations, likeharvesting, can trigger stress-re-lated conditions in fish. Stressfrom various handling practicesweakens fish and makes themmore susceptible to disease out-breaks and adverse physiologicalimbalances. The sensitivity of fishto stress associated with handlingvaries among species. Some arehardy, while others are extremelydelicate and sensitive to the small-est of stressors. Eggs and youngfish are more susceptible to sud-den changes in their environmentthan are older, larger fish.

More care and precautions are re-quired during harvesting if fishwill be restocked into other facili-ties for further growout ratherthan sent to a nearby processing1Louisiana Cooperative Extension Service2Cooperative Extension Service, Mississippi

State University

plant. However, recent problemsin the catfish industry with redspots and blotches in fillets, called“red spot syndrome,” are thoughtto be caused by stress incurredduring harvest and transport toprocessing facilities. Therefore, itis wise to take every stress preven-tion measure possible any timefish are handled or harvested,regardless of their destination.

cause of improper harvesting tech-niques, poor pond design or insuf-ficient planning. Consequently,harvesting logistics should alwaysbe considered in the design andconstruction of aquaculture ponds.The approximate number andweight ranges of fish in pondsshould also be known or projectedso both the pond owner and buy-ing customer are not disappointed

Several methods can be used to with a shortage of fish for delivery.harvest fish efficiently and safely,but careful planning is required Pre-harvesting guidelinesfor a successful harvesting opera- Plan easy removal. Before plan-tion. Too often, ponds are seined ning the harvest operation, makeand only a few fish are caught be- sure that fish can be removed eas-

Fish basket on boom truck for moving fish from pond to truck.

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ily from the production unit. If acage or raceway is used to grow-out fish, then harvesting is some-what simplified and fish numbersand weights should be known.However, when fish are in a largepond, several factors can delay orstop harvesting. Also, an inven-tory of fish stocks is more difficultto maintain when a pond has beenin continuous production for sev-eral years. In such systems, largerfish are “topped” and smaller fishhave been understocked, resultingin a wide diversity of sizes of fishin the pond.

Avoid debris and delays. First,check for debris on the pond bot-tom that will snag the seine or live-car. Aquatic plants may not bevisible at the water surface, butmay be growing at or near thepond bottom. These plants cancause the net to roll up at the bot-tom and may make seine draggingimpossible. Fish can be killed ifthey are entrapped in aquaticweeds during harvest. Nuisanceweeds should be controlled beforeharvesting is scheduled. During anunexpected delay in harvesting,fish prices may change, an off-fla-vor condition may develop, andthe crop may have to be held intothe next growing season, seriouslyimpacting cash flows. So, avoid un-necessary delays that may becostly.

Take samples. It is important toknow what’s in your pond beforeharvest. Sample fish with a shortseine, cast net, lift net or snaghooks, depending on species.Keep records of fish numbers andamounts of feed consumed. En-sure that the quantity of fish ex-pected to be harvested can bemarketed. Otherwise, you mayhave to release many fish after ex-pending considerable time andlabor. The harvesting operationmay severely stress fish after theyare trapped, crowded and held.Release of these fish back into thepond or culture facility can mark-edly affect their mortality risk.

Check fish health. It is essentialthat fish are healthy and in goodcondition before being harvested.

Signs of good condition includegood feeding appetites, no mortali-ties and no obvious external prob-lems. A sample of fish can beexamined by a qualified fishhealth specialist to determine ifany obvious health-related prob-lems exist. This does not mean thatfish are certified to be disease free,but it does provide more informa-tion to determine the condition offish stocks. If sick fish are handled,the added stress can trigger a dis-ease outbreak that can cause highmortalities.

Try to pick favorable conditions.You should have adequate labor,equipment and supplies availablefor harvesting. Weather and waterquality conditions may also be im-portant. On many farms, food-sized fish for processors areharvested regardless of theweather. Only thick ice on pondsmay stop some harvesting opera-tions. Movement of large trucksand harvesting equipment can rutand damage levee tops that are ex-cessively wet and lack protectivecover such as gravel. In severecases, equipment may not even beable to reach ponds because of thepoor condition of access roads orlevee tops. Main levees shouldhave a gravel cover that providesan all-weather surface.

Stop feeding. Take fish off feed be-fore they are harvested. With-drawal varies from one to twodays during summer, to three ormore days during winter. This isespecially true if fish will be trans-ported long distances. Undigestedfood can be regurgitated in thetransport tank and foul the waterquality. Fish are also hardier andless stress occurs when their stom-achs are empty. If food fish havebeen fed medicated feed, be surethat the proper withdrawal timehas passed before they are har-vested for processing. A 21-daywithdrawal period is required forTerramycin® medicated feeds andthree days for feeds containing pre-scribed levels of Romet® for cat-fish. Water quality conditionsshould be good during harvest. Be-ware of possible low oxygen con-

centrations when fish are har-vested at or shortly after sunrise.

Check for hydrogen sulfide. Indeep water ponds, hydrogen sul-fide can accumulate in oxygen-de-ficient bottom muds and may bereleased upon disturbance of thepond bottom. This gas is highlytoxic to fish and can be detectedby a smell similiar to that of rotteneggs. If unsure about this condi-tion, stir up the mud around theproposed harvesting site to deter-mine if a potential problem exists.If a rotten egg smell is noticed,find another suitable site. Stir upthe site to release the gas beforeharvesting or treat with potassiumpermanganate to oxidize the gas.This condition is seldom a prob-lem in shallow, warmwater fishponds.

Check temperatures. Harvest sen-sitive species during the earlymorning when water tempera-tures are lower and sunlight is lessintense. Some fish, like goldenshiners, striped bass and thestriped bass hybrids, are harvestedmost successfully at water tem-perature less than 65°F to mini-mize stress and fish losses. Theyrequire special handling duringharvest at higher temperatures.Fish should be moved quicklyfrom ponds to buckets or transporttanks in freezing, windy weather.Exposure to sudden temperaturechanges can shock fish, especiallysmall ones.

Investigate custom harvesting. Insome areas, harvesting can be con-tracted. The custom harvester sup-plies the labor, equipment andexpertise. Cost is based on thetotal pounds of fish harvested andpossibly a distance factor. Produc-ers may also cooperate in a localarea by sharing labor and capitalfor harvesting purposes. Manyfarms have their own harvestingcapability when harvesting is fre-quent or self-sufficiency is neededbecause of the unavailability ofcustom services. Purchase of spe-cialized harvesting equipmentshould be cost beneficial, and ade-quate labor is essential.

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Basic equipmentThere is a variety of harvestingequipment used in the commercialfish farming industry. Variousnets are available for harvesting,in addition to specialized equip-ment that includes livecars, boomtrucks, loading baskets, fishpumps, boat with outboard motor,and other items. The choice ofequipment depends on the size ofthe operation, available labor, fre-quency of use, available capital,preferred harvest method, volumeand sizes of fish harvested, andspecies considerations.

Cast nets. These are inexpensiveand useful for sampling. Cast netsare made of monofilament nylon,and the mesh size should bematched to the species harvested.Fish with spines entangle easily.With practice and patience, any-body can throw a cast net properly.

Lift nets. Bait minnow and tropi-cal fish producers may use lift netsto capture small numbers of fish.These nets are made of soft, smallmesh that minimizes injury. Fishare lured into the trapping areawith feed, and the net is liftedquickly when fish are evident. Thelift net and its assembly are port-able.

Short seines. Short 10- to 20-footlong “Commonsense” minnowseines work well to harvest fry intight schools. Seines can be pulledmanually by two persons or canbe shortened and used like a dipnet from a boat. The water shouldbe clear. Once fry break out ofschools and scatter, a V-trap canbe used for harvest of small, deli-cate fry.Success depends upon knowingthe habits of fish and locating thetrap properly. The V-trap usuallyhas glass or fine mesh sides thatform a narrow vertical openingthat fish enter. A lead panel mayextend from one or both sides ofthe mouth to guide fish into theopening as they move along thepond bank. Set the trap so fryswim between it and the shore.The lead panel intercepts fry andleads them into the trap. Use a dip

net to harvest fish daily (or asoften as necessary dependingupon species) from the box-shaped trap.

Gill nets. These can be used inponds to harvest large fish selec-tively or a few at a time. They arenormally strung across a pond.They are made of clear, monofila-ment nylon that makes them diffi-cult for fish to detect. Floats areused to mark their location, andeach end is anchored. Nets can betotally submerged or extendedfrom the surface to the pond bot-tom. Fish can be driven into thenet by a boat to increase the catch.Gill nets work best at night whenless visible, and should be checkedfrequently because fish caught usu-ally die. They can also be eaten ordamaged by turtles or other preda-tors.

Large seines. The most commontype of harvesting equipment isthe seine or harvesting net. Seineswork well in large regular-shapedponds with relatively flat, unob-structed bottoms. Ponds that canbe harvested without draining arecalled seine-through ponds. Nowater is drained for seining typicallevee type ponds, but in some em-bankment ponds water levels arelowered to facilitate harvest.

Net featuresMesh size. Select the proper meshsize to harvest fish of the desiredsize. Fish shouldn’t go through, begilled or become entangled in thenet. Raschel nylon mesh is avail-able in various sizes and is recom-mended for fingerlings 4 inches orsmaller.

Small mesh seines are harder topull because of more resistance.Also, mud does not sift throughthem as readily. Seine lengthshould be one and one-half timesthe widest part of the pond. Thisassures enough length to keep theweighted line on the pond bottomand levee toe as the seine is pulled.The depth of the seine should alsobe one and one-half times themaximum water depth. For largecommercial catfish ponds, seinesmay be longer than 1,000 feet.

Because of such weight, tractorsare used to pull them.

Texture. Net texture is determinedby the material and how the meshis formed, either with knots orwoven. Nylon nets should becoated with a resin or asphalt-based net preservative to preventcatfish from getting caught bytheir spines. Polyethylene nets re-quire no coating treatment. Knot-ted net is suitable for catfish, butmost scaled fish require soft, un-coated knotless nets. These netslimit injuries from scale losscaused by abrasions. Carp or buf-falo fish, however, can be har-vested with knotted nets. Number42 nylon twine is recommendedfor catfish and other large fish toprovide adequate strength. Netmanufacturers can recommend theproper size, number and distanceinterval between floats.

Bottom line. The bottom line, ormudline, of the seine can have amany-ends sisal mudline, 2-inchdiameter mudline of knotlessmesh nylon netting or hard rubberrollers. The design affects howdeep the bottom line digs into thepond bottom and its ease of pull-ing. Evaluation studies of variousmudline designs indicate that rol-ler-mudline equipped seines arepreferred when harvesting food-sized channel catfish from pondswith irregular bottoms consistingof deep, soft muds. The mesh-mudline is recommended whenharvesting channel catfish fromponds with hard bottoms or har-vesting fingerlings because of itslighter weight and tendency toclear mud.

Seine reelsA hydraulically operated seinereel is often used to transport,store and beach the seine. Thereare various models and sizes. Mostare single reels, but some havetwo. The smaller second reel haulsin the loose end of the seine whenfish are funneled into a sock orlivecar. With the single reel, theloose end is landed manually. Astandard 5-foot reel can storeseines as long as 1,200 feet. The

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Hydraulic seine reel used in seining large ponds.

reel is mounted on a trailer. Some concentrate fish in one to twohave hydraulic controls that pivot hours.the reel into various positions toline up with the seine as it is

Seining technique. The shape of

landed.the pond determines how itshould be seined. Usually the

Basic harvesting operation proper length of seine is stretchedacross the narrow end of the pond

Seine crew. Five to seven personsform a seining crew for largeponds. Two to four persons insidethe pond keep the weighted lineon the bottom near each levee toe,two drive the tractors, and one op-erates a boat to dump mud fromthe bottom line. An experiencedcrew can seine a large pond and

in front of the drain structure: Abracket on the bow of the boat, orthe float line laid over the bow,helps push the seine as it collectsmud. Watch the float line for indi-cations that the net is “muddingup.” The floats will be pulled un-derwater if this occurs. The seineboat should quickly move to roll

or dump the mud from the seineso that fish do not escape. A 14-foot boat with a 25-horsepoweroutboard motor is adequate. Achemical boat also works well andhas ample space for carrying a live-car. Pull the seine slowly with azig-zag motion at about 25 to 45feet per minute to prevent theseine from lifting off the bottom.Seines will have to be pulled overor pushed under aerators, depend-ing on how they are anchored.

Seines can be pulled manually orwith small tractors, trucks or four-wheelers in small ponds less thanseveral acres. A seine longer thanseveral hundred feet, however, isdifficult to pull manually in pondswith soft, muddy bottoms. A bagthat is woven into the seine is anice feature for small seines. Itprovides a good area to capture,hold and harvest fish.

Land the seine near a water sup-ply or aerator where fresh, oxygen-ated water can be provided ifneeded. When fish are crowded,they can rapidly deplete the dis-solved oxygen in a localized area,especially in warm weather.

Holding fish. A device called alivecar, or sock, is used to crowdand hold fish. Attach it to the seineafter fish are crowded with the har-

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Seining boat for working large seines. Boom truck used for loading fish from pond onto haulingtruck

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Livecar (sock) used for holding fish after seining.

vesting seine. This lessens thechance of the livecar hanging upon snags and decreases the pullingdrag. A short piece of rope ties offthe funnel end of the harvestingseine until the livecar is attached.

The livecar has a metal loadingframe which attaches to the seinewith drawstrings. The metal load-ing frame sets up a narrow chuteto funnel fish into the livecar asthe seine is beached. Without thechute, many fish can remain in theseine as it is landed. They will thenbe much harder to move into thelivecar.

Water should beat least 2 ½ to 3feet deep for easy fish transfer. Ifwater temperatures are below60°F, fish can be held many hoursand overnight. However, if tem-peratures are in the low 80s orhigher, fish should beheld onlyfor a short time and carefullymonitored. Water temperatures af-fect fish activity and ease of grad-ing in socks before harvesting. Useone mesh size larger than normal,and allow overnight grading be-fore harvesting fish in winter. Thiswill avoid harvesting many off-sized, unmarketable fish. The sockneeds to be in good condition orfish will escape overnight. Haul-ing trucks can be scheduled withassurance when fish are held inlivecars.

Minimize stress. When holdingfish, move the sock to deeperwater to provide more room and

clearer water. In warm or hotweather, it is helpful to cool fishbefore harvest by moving the socknear a flowing well but not underit or directly in the high currentarea. Fish in socks are usually socrowded that little water move-ment takes place within the sock,and the increased current prob-ably stresses the fish on the exte-rior of the sock as they constantlyswim against the current. Harvest-ing stakes can be used to securethe lead line into the pond bottomand hold the float line about 1 footabove the water surface. If thesock if not properly anchored, cur-rents from a well or an aerator canroll up the livecar and kill fish.Also, beware of the possibility oftheft when fish are held overnight.Livecars are more secure for hold-ing catfish than seines becausethey have a solid mesh bottomand double float line that preventfish from jumping out. Fish aregood escape artists. Several live-cars may be required if many fishare harvested. About 5,000 poundsof fish can be held in each 10-footlength of a standard-sized sock attemperatures below 80°F. The in-creasing frequency of “red filletsyndrome” in catfish is thought tobe directly related to harvest andholding stressors.

If fish must be landed in shallowwater, or a large number must beharvested, consider another har-vest method. Harvest fish as be-fore, but stake out the harvesting

seine. Do not use a livecar. Pull ashort cutting seine of the desiredmesh through the fish to roughlygrade and concentrate them forloading. If fish require overnightholding, leave them in the largerarea of the staked harvesting seine.

Watershed ponds. Harvesting ismore difficult in watershed pondsbecause pond depths are usuallymore than 10 feet. Obstacles arecommon in bottoms and on banks.Fresh water is usually absent atthe harvesting site. Watershedponds usually have to be drainedto a smaller area with a maximumdepth of 6 to 8 feet. The heightfrom the harvesting area to thelevee top makes loading a trans-port truck difficult and time con-suming without the use ofmechanized equipment. Ideally,fish are harvested in coldermonths so stress on fish is less andponds can refill with runoff waterduring late winter and earlyspring.

Most baitfish are harvested byseining because it is faster thanusing lift nets. Fish are crowdedinto the bag portion of the seine,then the bag is staked. Minnowsare dip netted into floating hold-ing boxes with nylon walls. Sum-mer harvests are stressful becauseof warm surface waters. Pumpingcool well water near the harvest-ing operation helps reduce stressand losses. Minnows are harvestedfrequently to keep up with cus-tomer orders.

When manually beaching a seine,pull it slowly and carefully to keepthe lead line on the pond bottom.Too often there is an unnecessaryrush to land the seine, and manyfish escape under the lead linewhen it is accidentally lifted offthe bottom. Four persons canbeach a seine. Two pull in each ofthe loose ends. One keeps the leadline on the bottom, and the otherhelps pull and piles the seine onthe bank. When the lead line is onshore, raise it and close off bothends by slipping your arm underthe seine and lifting it out of thewater. This forms a hammockshape that traps fish. Concentrate

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fish into the middle, and move theseine to deeper water to stake it ifdesired. Harvesting stakes free uplabor to move fish rather than justhold the seine.

Fish pumpsA fish pump can be used for har-vesting. There are various models.They move fish rapidly and safelyfrom tanks or ponds to haulingtrucks. Crowding is required, thenthe pump intake is placed where itcan move fish and water to a de-watering tower or box. The waterreturns to the ponds, and fish areloaded into the transport tank.Pumps can be portable unitsmounted on trailers or fixed unitsmounted on a transport truck.They are commonly used in thetrout industry and are being evalu-ated for use with warmwater spe-cies.

The use of fish pumps often meansfish weights are determined bywater displacement rather thanwith scales. This weighing methodis less stressful on fish than scaleweighing and can be accom-plished quickly. One pound ofwater is displaced by 1.02 poundsof fish, and 1 gallon of waterweighs 8.35 pounds. To determinefish weights by water displace-ment, just determine the change inwater volume in gallons in thetransport tank after fish are loadedand use a simple formula.

For example, if loaded fish in-crease (displace) the water volumein a tank by 50 gallons, then theweight of fish is equal to 50 gal-lons x 8.35 pounds/gallon x 1.02or 425.8 pounds. A water displace-ment tube on the outside of thetank, or a clear viewing plate inthe tank wall, can be used to calcu-late the amount of water dis-placed. This is a new technique formost warmwater fish farmers butoffers some real advantages andpromise.

Harvesting eggs and fryBesides food-sized and fingerlingfish, there are situations wheneggs and fry require harvesting.Catfish egg masses are usually re-

moved from spawning boxes andtransported to hatcheries for incu-bation. To remove the eggs, use awide blade scraper or putty knifeto loosen the adhesive egg massfrom the bottom of the spawningcontainer. Gently raise the box to-ward the shallowest water alongthe bank so the eggs can be moreeasily retrieved if they fall out ofthe box.

Remove the eggs with your hand,and put them into a plastic fishbasket that has mesh openings.The basket can be placed inside aninner tube for flotation. The open-ings allow water to pass freelythrough the basket as it is pulledfrom box to box. Tie a rope be-tween the egg collection containerand your belt or pants’ belt loop topull the container as you walk tocheck spawning boxes, and keepyour hands free.

Tubs or ice chests can also be used,but they are less suitable. Watercan warm more quickly and waterquality can deteriorate faster un-less eggs are emptied frequentlyand the water is replenished. Donot hold eggs in stagnant waterduring collection for more than 15minutes without aeration or ad-ding fresh, clean water. Make sureall pieces of the egg mass are re-moved from the spawning box sothe male catfish can service an-other female, rather than care for asmall fragment of eggs.

Yolk-sac fry can be harvested fromincubation troughs by siphoningwith a 1/2 inch-diameter clearplastic hose. Siphon fry into a dipnet or strainer that is submergedin a bucket of clean water. The frycan now be quickly stocked into arearing trough. To harvest olderswim-up fry, use a fine meshaquarium dip net to transfer themfrom the rearing trough to abucket of clean water for stockinginto a transport tank. Alwaysmove small fish in a cushion ofwater, and minimize their time outof water.

Harvesting situations andoptionsThere are three harvesting situa-tions to consider:

■ Partial harvesting exists whereonly part of the fish are re-moved.

■ The pond may also be toppedwhere larger market-size fishare selectively harvested fromponds with mixed fish sizes.

■ Finally, the pond maybe cleancropped, where all fish are har-vested.

The only reliable way to harvestall fish from a pond is to drain itcompletely. This involves a combi-nation of draining and seining.Avoid using a seine in very shal-low water because it stirs up themud and causes low dissolvedoxygen and high toxic gas condi-tions which can be extremelystressful to fish. Shallow water canalso warm quickly in hot weather.

Seine trapping relies on feed to at-tract fish into a trapping area. Aseine at least 200 feet long workswell. Locate the seine parallel tothe pond bank or across a cornerabout 50 feet from shore. A pullrope attached to each end is stakedon the bank for easy retrieval. Thetrapping area should have a firmbottom, be free of any debris andbe less than 5 feet deep. Catfishand other species may be shy ini-tially, but can be lured into thetrapping area by feeding outsidethe open end of the corral seineand drawing them in with a trailof feed. Use floating feed to ob-serve feeding activity. Feed rou-tinely at the time you intend toharvest. Do not alter your feedingactivity on harvest day, except forusing less feed.

To harvest, simply pull the coiledseine ends to shore. Drag the seinecarefully to shore to concentratefish. Have enough labor availableto keep the bottom line on thepond bottom while dragging theseine to shore. Trapping success inthe same area requires a 7-to 14-day recovery time before fish losetheir shyness and the operation

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can be repeated. Because of the im-portance of baiting with feeds, thismethod is more effective duringwarm weather when fish are feed-ing actively.

Many catfish producers prefer totop their ponds by harvestinglarger market-sized fish in a popu-lation of mixed fish sizes. Thismethod works best in seine-through ponds that require nodraining. The same pond mayhave fish harvested three or moretimes yearly. Fish are harvestedwhen sufficient numbers reachmarket size. This may be 1,500 ormore pounds per acre in large 10-to 20-acre commercial ponds. Har-vesting efficiency in seine-throughponds should be about 70 percentto 90 percent of the harvestablesized fish, depending on species,size, experience of harvesters, andthe condition of the pond and har-vesting equipment. Catfish can cre-ate large craters in pond bottomsthat can become extensive aftercontinuous production of 4 ormore years. These depressionsprobably reduce harvest rates.However, there is considerablecontroversy over how often apond should be clean cropped andrenovated to restore fish invento-ries and repair pond bottoms andlevees,

Other trapping methods includelarge lift nets and drop nets, butthey are usually not as effective.The lift net covers too small anarea, and repeated use can reducefish production. Catches with thedrop net decrease considerablyafter the initial catch.

In ponds used for fingerling pro-duction, especially when raisingdelicate fish species, harvestingkettles or basins are common fea-tures. They are made of pouredconcrete and have several open-ings with vertical grooves forplacement of wood tongue andgroove boards to adjust water lev-els inside the basin. These areasare located in front of the drainstructure, and their bottom is thesame elevation as the bottom ofthe drainpipe. A water supplypipe is often located near the basin

to furnish fresh, oxygenated wateras needed. Concrete steps from thebasin to the levee top make it eas-ier to carry tubs or buckets of fishand water. Before fish are concen-trated, the basin should be cleanedwith a broom or other devicewhile the drain is open to removeany mud or sediment that can ac-cumulate in the area. The harvestbasin is usually found inside thepond, but outside kettles alsoexist. Fish are usually dip nettedfrom the basin and placed in buck-ets of fresh water. These structuresare common in government hatch-ery ponds that frequently harvestsmall fingerlings of game fish spe-cies.

Removal from pondsWhen fish are moved from ponds,they are commonly lifted with aloading basket attached to a hy-draulic boom. The fish are firstcrowded in a livecar or cuttingseine. The boom can be mountedon a special truck. A front-endloader or backhoe will also workwell with a few modifications, in-cluding an extension pipe. Theloading basket is designed so fishdrop through a trap door with aneasy, safe release. The basket canmove 500 pounds or more perload. Weights are determined within-line, spring-loaded or electronicscales. The loading basket netshould be treated with a coating ifused for catfish. Do not overloadthe basket if fish will be restockedor hauled on a long trip. Makesure people are clear of the swing-ing basket as it moves and nobodyis underneath it.

Another method of harvesting fishinvolves dip netting fish into buck-ets or tubs filled with clean water.Fish should be moved quickly andshould not be overloaded. Waterquality deteriorates rapidly whenfish are concentrated, especially inwarm weather. A bucket-brigadehelps reduce the strain and workof heavy lifting. Remember, onegallon of water weighs 8.35pounds! This method works wellfor small, delicate fish where spe-cial harvesting precautions are re-

quired, but it can be time consum-ing if many fish are harvested.

Seine maintenanceSeine storage and care are impor-tant to prolong the life of equip-ment. Uncoated nylon seines aredamaged by direct sunlight. Re-move dead fish that can attractrats, which damage seines. Shortseines should be hung in a cov-ered site and air-dried. Never storea damp and unclean seine in aheap. Some aquatic weeds, para-sites and infectious diseases maybe transferred from pond to pondby harvesting equipment. For thisreason, remove any fish or nui-sance aquatic weed fragments. Air-drying the seine can kill mostparasites. Diseases such as bacte-rial ESC may remain alive in moistmud balls not cleaned from seines.Repair any holes in the seine assoon as they are detected in orderto maintain the equipment inworkable condition and ready foruse.

SummaryFish harvesting is an importantstep in getting fish out of produc-tion facilities in good condition sotheir survival and quality for otheruses are assured. Experience andcommon sense will be valuable fac-tors to assure success. Take time toplan properly before putting netsinto the water. Do not forget thatfish are sensitive to handling, andthat harvesting is the first stress ofmore to come if fish will begraded, held, transported and re-stocked. It takes a higher qualityfish to live after harvesting com-pared to one that will shortly beprocessed.

Additional informationFor information on sorting andgrading warmwater fish refer toSRAC Publication No. 391. De-tailed information on transportingwarmwater fish can be found inSRAC Publications 390, 392 and393. For additional information orassistance on this subject, contactyour local office of the Coopera-tive Extension Service.

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The work reported in this publication was supported in part by the Southern Regional Aquaculture Center through Grant No. 89-38500-4516 from the UnitedStates Department of Agriculture.