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Of all the steps to completion in gathering, holding, transportation and sale of aquatic livestock, the weak-link is the role of netting. Hand nets in particular exact a heavy, yet largely unacknowledged mortality toll in the handling of wild-caught marines.
Quizzically, much of this loss is avoidable through conscientious technique and using proper netting tools. Don't collect marines for a living? The same holds true for hobbyists and professionals dealing with larger, active aquatic livestock.
The Rationale: Ouch!:
Imagine what it's like to be caught in a net; in particular out on a reef. How about this for a comparison. Something BIG ripping off the roof of your house, swooping in with a LARGE net and lifting you and yours out. What size and how rough would the mesh of the net be relatively? How would it feel to have it scraped over your eyes and skin? Pretty frightening and painful. Small wonder aquatic livestock takes such a beating in the collecting process.
Reducing Capture Stress:
There are two obvious components in reducing the stress of capturing wild stock; proper tools and handling techniques. The latter involves knowing and acting in smooth, direct and non-rough ways to direct the livestock into the barrier/fence net (where used) and carefully handnettting and moving it to the collection buckets, through decompression... to preserve vitality.
Proper Tools: Netting
Includes adequate size, mesh and physical make-up of the netting material itself. If it's too coarse, you'll damage the catch. Too open a mesh, fins, snouts, spines et al. get hung up. On the other end of the scale, too fine a mesh and the nets are too visible and slow-dragging to be of use.
So what's a would-be fish catcher to utilize for net material anyway? There are suitable poly- and nylon, among other space-age substances that come ready-made of semi-assembly-requiring. In my opinion however (and I'm writing this article after all), the most appropriate, best available net material technology is fiberglass window screen fashioned over a frame. Allow me to elaborate.
Super Net Superstructure:
You could build your own frame and handle, but I don't. The store-bought wood handled variety (nope they don't float when underwater) heavy metal ring type (see photo) does just fine. I favor the six inch diameter ones for general practice, but home hobbyists may find larger/smaller rectangular ones more to their liking. No decent nets to start with in your neighborhood? Try fishing stores and mail order.
The Netting Itself:
Is acquired from a hardware store. It really is just standard black replacement fiberglass door/window screen material. To measure and cut I lay the screen out on a flat table, outline with a paint marker and ruler, & scissor-cut a rectangle to size (photo). How big? I do the bioassay and wrap the netting all the way around and snip a mark for measure.
Now get this; to make a squarish pocket (versus a less-desirable round bottom type) fold the rectangle material in half lengthwise and cut equal length corners (to be sewn up later with the rest of the margin).
You Sew & Sew:
Dear Reader, I've tried and tried to become a proficient on a sewing machine. Alas, I must admit I take any new nets (et alia sewing jobs) to a professional and have them sew up the seams with superstrong "upholstery thread". Real "salts" can hand sew their nets. Do it the easy way on a machine with appropriate thread.
Fitting the Netting:
To the frame is done by rolling it inward, over the metal frame and securing it with split tubing. This you may buy at a marine or regular hardware store; some folks cut their own from splitting stock polyethylene tubing.
One of the real advantages of this "screen technology" enters here. Imagine being underwater with your quarry at hand only to notice a fish-losing size tear/rip in your ordinary handnet. In all likelihood, your fish-collecting time is over. But with the new, improved screen net, you can simply remove or loosen the retaining tubing, pull up the screen-netting beyond the tear, and replace the retainer. Voila! You're back in biz! Sometime later back in the shop, I trim off the excess inside netting.
These high-tech nets are used to "pick off" fish livestock that has been driven into the pocket of a stationary fence net. The bunched up fishes are removed in an upsweeping net motion, while they tend to dive/fall into the nets bag.
Now here's the really neat part of using these nets. From this point the handnet containing the fishes is turned sideways, blocking escape, swam over to the catch/decompression bucket and 1,2,3 poured like so many "Pringles" out of a can. Without scratches, torn/torqued fins... You're done.
The contributing influences or sources of morbidity/mortality in wild collection of marine livestock are several; rough handling, inadequate decompression, crowding, pH/temperature/metabolite et al. stress, & net scraping and tangling.
The fiberglass screen nets described here virtually eliminate the ills of mucus loss and tearing associated with open-mesh netting use.
All livestock divers, distributors, wholesalers, institutions and hobbyists dealing with larger fishes are encouraged to adapt/adopt this technology to their benefit.
To Tami & Eric Rood of Ocean Pacific Tropicals on Kona, Hawaii for putting up with my many visits, and Mr. Fish (Hey Steve!) for the development and introduction of this technology.
Fenner, Bob & Cindy, D.V.M. 1986. The function of body slime in fishes. FAMA 6/86.
McDonnell, Bob. 1987. Simply net out the fish. FAMA 1/87.
Ostrow, Marshall E.. 1979. Handling fishes. TFH 9/79.
Pool, David. 1992. Catching and handling aquarium fish. AFM 11/92.
Quinn, John R. 1988. Gone fishin'; A hobbyist's guide to handling fishes. TFH 2/88.
Selznick, Steven. 1984. Preparing large cichlids for fish shows. FAMA 10/84.
Various steps to completion, in order.
1) Store bought "minnow" nets (these ones from Wal-Mart), with too visible, too coarse netting, too shallow for capture use. Featuring bendable metal frames and wooden handles.
2) Plain fiberglass screen door and window replacement material. Comes in a few widths/lengths, and colors.
3) Reworked frame and handle (original netting removed) and cut to size piece of new fiberglass netting. Note notching for squaring up open "bag" at net bottom.
4) Almost finished product. Edge attached with tubing; ready to be sewn up.