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Old 03-13-2000, 09:07 AM
Pete Pete is offline
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Join Date: Jan 2000
Location: Deerfield River, Upper Cape public access spots
Posts: 98
RE:Catch & Release Mortality

Sully & other Board members,

Well been away for a while. Trying to get the thesis in order and stop spending so much time on the web. Plus just built three flyrods and tying flies.

The figure that is used is from a paper from Paul Diodati and Anne Richards.

Diodati, P. and R. A. Richards. 1996. Mortality of striped bass hooked and released in salt water. Transactions of the American Fisheries Society 125: 300-307.

I feel that it was a very well done study and after I re-read it I'll post the highlights. They used some stripers as controls which is where some studies fail (because they don't use them). There was a more recent study by the Maryland DNR, but there is some debate over the study design (transferring fish from salt to the freshwater after hooking, lack of controls, mortality might have been associated with holding conditions - if I recall it correctly).

There appears to be a difference between freshwater and saltwater mortality figures, with the saltwater caught fish experiencing less mortality. Diodati and Richards estimated the mortality figure to be between 3-26%, with an overall figure of 9%. Other studies have estimated freshwater mortality to be 15.6% for artificials and 30.7% for natural baits (Harrell 1988), and mortality has been shown to be related to season, striper length and bait type (Hysmith et al. 1993). The fish (in Diodati and Richard's) were caught using only barbed hooks (if that makes a difference - another story) - using unbaited lures with 1-3 treble hooks, single-hook rubber jigs, or baited single hooks. Live seaworms or dead American sand lance were used for bait. Fish were caught by : casting from boats or shore (lures or jigs), trolling from boats (lures or jigs), or bait fishing from boats (single hooks). Hooks were always removed without regard to hooking location, or how deeply they were embedded. Playing time, handling time, depth of hook penetration in oral cavity, site of hooking, degree of bleeding and gear and individual tag number were recorded by a technician. The fish that had been hooked but survived showed a reduction in condition factor ([weight/length^3]*10,000) as compared to unhooked fish, as well as the "control" fish that were not susceptible to angling. The reduction in condition factor indicates that there is some negative effects (stress) from being angled. Angler skill level played a role in mortality, with more experienced anglers having lower mortality associated with their angling activities.

All of these fish were brought into the 2ha brackish pond (Cat Cove Marine Lab - Salem, MA) after being caught by a trap net operator in Newport, RI. The fish were allowed to acclimate for 50 days before angling began, and they assessed the mortality from netting, tagging, and transporting. 1015 fish were put into the pond. 2 weeks before angling began 20 fish were segregated and used as controls. The pond was closed to the public. The anglers used were volunteers, primarily from MA fishing clubs. Anglers were surveysed for level of experience and used their own gear.

Well I guess I summarized it and will not have to re-post.

I will say that I have witnessed some terrible handling of striped bass down at the mouth of the Merrimack. Fish don't breath too well in the air, and they certainly can't breath sand very well.

While I am on the subject of striped bass handling, I have sort of a pet peeve and that is the use of Boga Grips to lift the fish and hold it for weighing. I know many of you use it, but I think that there is the potential to damage the jaw musculature of the fish and potentially screw up it's ability to feed. I don't have any hard scientific data to back this up, just my own opinion (take it for what you will). The metal pinchers on the end do not spread out the weight of the fish, they are only 1/8th of an inch. I try to grab the fish by the caudal peduncle (base of the tail and by the jaw - that way all the weight is not concentrated on a small area. Well enough of the soap box.

Hey juro where do I send the money for the two-handed project?
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