11-20-2014, 09:52 PM
[quote FSHRGLF]I can put each fish I catch into an age class based on size. Big fish reqire time/age. I don't think that the fast growth replacement theory fits. [/quote]
You're better than most biologists! Big fish require time, but not in the sense that most mammals do. An old fish does not = a big fish. Fish growth is indeterminate as opposed to mammals where growth is determinate. Large fish are the result of fast growth.
[quote FSHRGLF]In a related matter, how many pounds of fish does a pelcian eat per day? I have seen hundreds on the lake at one time in the spring with 40 or so in residency to the fall.[/quote]
Pelicans, as well as other pisciverous bird (ie: cormorants) can be a real problelm with fisheries. While I cannot tell you how many fish a pelican will eat in a day. But I CAN tell you that in 1989 (March - October) cormorants consumed an estimated 5069kg of fish (~12,000lbs!) at Minersville Reservoir in southern Utah. Trout made up 44% of that total! These numbers are based off of a daily consumption rate of 465 g per bird per day. That's a little over 1lb of fish per day per bird.
In 1988 the estimated consumption of catchable-size trout by loons and cormorants was greater than the estimated sportfish harvest by anglers!
See the attached document for all the information you could ever want concerning cormorants!
what did Utah do to correct this problem? They went to special regulations (artificial flies and lures only) with restrictive harvest regulations as well as changed stocking practices (spring vs fall) and stocking sizes (increased stocking size to get past bird predation size).
Is this an issue at Henry's? I don't know. If it is, then they have options.
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You're better than most biologists! Big fish require time, but not in the sense that most mammals do. An old fish does not = a big fish. Fish growth is indeterminate as opposed to mammals where growth is determinate. Large fish are the result of fast growth.
[quote FSHRGLF]In a related matter, how many pounds of fish does a pelcian eat per day? I have seen hundreds on the lake at one time in the spring with 40 or so in residency to the fall.[/quote]
Pelicans, as well as other pisciverous bird (ie: cormorants) can be a real problelm with fisheries. While I cannot tell you how many fish a pelican will eat in a day. But I CAN tell you that in 1989 (March - October) cormorants consumed an estimated 5069kg of fish (~12,000lbs!) at Minersville Reservoir in southern Utah. Trout made up 44% of that total! These numbers are based off of a daily consumption rate of 465 g per bird per day. That's a little over 1lb of fish per day per bird.
In 1988 the estimated consumption of catchable-size trout by loons and cormorants was greater than the estimated sportfish harvest by anglers!
See the attached document for all the information you could ever want concerning cormorants!
what did Utah do to correct this problem? They went to special regulations (artificial flies and lures only) with restrictive harvest regulations as well as changed stocking practices (spring vs fall) and stocking sizes (increased stocking size to get past bird predation size).
Is this an issue at Henry's? I don't know. If it is, then they have options.
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