Troutnut Forum > Fly Fishing Discussion > Spawning Fish
| Martinlf | December 16th, 2006, 11:29 am | |
| Palmyra PA Posts: 933 | I have always been a bit fearful about fishing when and where I thought it might be possible to disturb spawning fish. Steve of Flyfisher's Paradise in State College PA suggested the following (my paraphrases): 1: Avoid wading in general as much as possible. 2. Avoid wading in and fishing in gentle gravel filled riffles and tails of pools. 3. Fish to rising fish, which are not spawning. 4. Fish delayed harvest streams, most of which have fewer wild fish. These tips are helpful, but I'd be interested in others, and any information in general about ways to avoid disturbing spawners. I know browns and brookies spawn in fall, and redds can be disturbed by wading in them up to the time the eggs hatch in early spring. Most wild rainbows I understand are spring spawners, though fall spawning strains have been bred. When do the rainbows eggs hatch? Do they have similar spawning habits to browns and brookies--i.e. does rule 2 apply to them? I'd appreciate any information on this topic. | |
| Louis Is it not an art to deceive a trout with an artificial fly? A trout! that is more sharp-sighted than any hawk . . . and more watchful and timorous than your high-mettled merlin is bold! --Izaak Walton The Compleat Angler | ||
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| DMM | December 16th, 2006, 6:14 pm | |
| Posts: 141 | Hi Louis, I have some interesting(?) information for you. Generally speaking, Salmonidae spawn in streams (char can spawn in lakes). They use faster water for their redds to get oxygen to the eggs. The eggs are buried in gravel, and rely on diffusion to "breath." Just like stoneflies, the eggs need faster, cooler water to maximize oxygen intake. The redds are made of fairly large cobble. A steelhead or Pacific salmon uses gravel about the size of a baseball. Smaller fish use smaller cobble. Before building a nest, the fish clear away fines (gravel, sediment, sand, etc.). The exact location (eg. where within a riffle) the fish build redds depends on the preference of the particular species. This means, it is best not to wade at all. The time of year that the fish spawn depends on geographic location. They spawn earlier in cooler locations, typically. The following is an approximate time in days it takes eggs to hatch based on temperature. The first number is at 40oF, the second is at 50oF. This is about the optimal range for egg development. Rainbow: 80/31, Brown: 100/41, Brook: 103/44 Don't forget that other fish are spawning at this time as well, such as sculpins. So, again, the best advice is not to wade at all. Salmonidae stop eating for some time (usually several weeks before spawning--at about 40oF much of the feeding stops due to metabolism). After spawning, they are weak, and emaciated. The males are especially fragile. For rainbows, most males only spawn once (a lot of them die). So, my other suggestion would be to fish early in the spawning season, and not fish at all after spawning. Someone from your area will have to tell you exactly when spawning takes place, as it is different by me. I'm not telling you that you can't fish, but I generally don't fish anywhere (there are saltwater species spawning now, too) in winter, except stocked lakes. I hope this was useful, or at least new to you. | |
| David | ||
| Troutnut | December 17th, 2006, 11:30 am | |
| Fairbanks, AK Posts: 1122 | I've never been convinced that disturbing spawning fish actually harms the population. That seems to be one of those things about which some conservation-minded anglers worry themselves too much, and those worries are reinforced by the antiquated idea of closed seasons. I doubt that a fish disturbed while spawning (spooked or caught) will not eventually resume and finish its job. If it's fatally injured or kept, of course, it won't spawn, but the effect of that is no different from that of killing the same fish at any other time of the year. Half the fish disturbed will be males, anyway, and I'm pretty sure if one of them is taken out of action another will happily replace him. As far as egg survival goes, I'm pretty sure that the influence of angler foot traffic is dwarfed by routine fluctuations in factors like water level, water temperature, dissolved oxygen, substrate quality, sediment shifting, etc. It would be next to impossible to put a number on it, but if we did I bet it would be several digits past the decimal point. And I think in most cases the fluctuations in egg survival don't matter much, because the adult spawners produce more fry than can be supported as adults or even juveniles by the stream's habitat and food supply. I don't know what the typical number of eggs per mile would be exactly, but it seems like it would usually be in the tens of thousands to millions, whereas the number of adults the stream can support is usually in the hundreds or very low thousands per mile. It's like filling a jar with jelly beans: if the jar can only hold 500 beans, it doesn't matter if you start out with 20,000 beans or 20,100 beans: you're still only going to fit 500. If the population is very low, then egg production might indeed be a bottleneck, but if there are so few fish it's that much less likely that you'll accidentally step on the eggs. Unless you like dancing on gravel bars in a bull trout stream, I doubt this is a very common scenario. I'm not saying to be reckless -- it's just common sense to try not to stomp around in the redds. But almost anything we do in the stream can have some negative influence. For example, every step you take in the spring might squish several nymphs between the rocks, robbing the trout of how many eventual meals? And how much beneficial vegetation might you accidentally uproot when you have to wade through a patch of it? There are all kinds of small harms we might inflict, yet none of them keep us off the stream because their effects are so minor. I just don't see why this should be any different. Perhaps DMM can correct me if there are any studies showing that angler activity during spawning causes statistically significant damage to the population. I haven't heard of any. | |
| Jason Neuswanger The Troutnut | ||
| Martinlf | December 17th, 2006, 1:07 pm | |
| Palmyra PA Posts: 933 | I find both David and Jason's observations interesting, and again we are in the realm of needing some controlled studies which may not be forthcoming. Several shop owners I know of have counseled caution in regard to fishing when fish are spawning, while a Pennsylvania Fish Commission biologist I once talked with about this took the same position Jason did in his post. Recently I fished a rainbow stream, assuming that the fish were probably spring spawners, and, along with my more knowledgeable fishing partner, checking the bottom to be sure we didn't step into any redds. I have no fear that we caused any problems, and I'm sometimes willing to carefully fish wild brown trout streams in the winter following the first three guidelines listed in my first post recommended by Steve Sywensky. I've always wished to err on the side of caution, but I sometimes do wonder if I am being overly cautious--or not cautious enough. I look forward to David's reply, and others' well-reasoned information on this topic. | |
| Louis Is it not an art to deceive a trout with an artificial fly? A trout! that is more sharp-sighted than any hawk . . . and more watchful and timorous than your high-mettled merlin is bold! --Izaak Walton The Compleat Angler | ||
| DMM | December 20th, 2006, 1:06 am | |
| Posts: 141 | Coho salmon, leopard sharks, and ling cod are all fish that can be decimated by fishing them while they are spawning. There are different reasons for this, but I will stick with a salmonid example. While I could write a book on the topic, I will keep it brief. Conditions (fishing, oceanic conditions, fecundity, etc.) being what they are, coho recruitment is at a one to one ratio. That is to say, for every coho that spawns, one will return the next generation to spawn. I'd have to show you models, articles, etc., but it is a major problem in coho recovery plans. In general, fisheries models from which regulations come (in part) only worry about recruitment versus removal from a population. That is to say, as long as 500 fish are added to the population a year, when 500 are removed, the models are satisfied. One of the problems with quantitative fisheries has been a historical neglect of the biology of the organism modeled. They also tend to neglect major environmental changes (flood years, etc.). Since most fisheries (inland sport) are given regulations that don't change for years, the regulations can often be terrible (not able to cope with change). Also, to keep sport fishermen happy, regulatory agencies try to maximize the allowable take. My point, is that many regulations are not meant to deal with loss at a given time. Spawning populations are more susceptible to capture because the fish are concentrated in a smaller area. Also, stepping on a redd can destroy all the eggs from a single female. This is like killing 5 fish (I chose this number arbitrarily for demonstrative purposes). Also, none of the eggs will mature to spawn themselves. Therefore, you are also killing the fish that are never spawned due to their potential parents being stepped on (since fish live for several years after reaching sexual maturity, and in theory have several chances to spawn). Also, fisheries models estimate certain mortality levels for catch and release fishing. During spawning, mortalities sky rocket past estimates (often). If a fishery is modeled to have fishing during spawning, then fishing should not have an effect on the population abundance (directly). I just thought of another example. A summer steelhead fishery was shut down over here for years after a study showed catch and release mortalities at 90%. This was directly linked to a crash in the population. This was due to warm water/hooking stress. Anyway, it is an example of the decimation of a stock due to fishing pressure during spawning. Several anglers can have a huge effect on redds. A careless wader can crush 1000's of eggs. Studies show that populations subject to random selection as opposed to natural selection can have a lowered fitness. Wading through redds is like random selection. You destroy entire genomes by wiping out family groups. A lot of papers posit that whole genomes are necessary for eveolution as opposed to single alleles. A few tidbits... On average, only 16% of eggs are fertilized during natural spawning. A number of these wont be viable. So there isn't all that much excess. In response to too many fish to be supported by the system, they play a role in the ecology. They feed adults, insects, and birds, which in turn contribute to the ecosystem. Again, I'd rather natural selection choose which of these fish survive (careful angling of healthy adults has a relatively low mortality impact). I hope you are able to follow some of my thoughts. I'm in a hurry as I'm busy. I just couldn't let Jason thought he had won... :) Seriously, if Jason's arguments are examined in detail, many fall apart. It is true that more studies need to be done, but I personally have always been one to err on the side of caution. It's better to limit your fishing now for a few months than to later face a moritorium or other disaster situation. If studies show that there is no effect from these fishing practices (spawning), the most you lose is a few days on the water. Ultimately, I am not telling anyone what to do. You all have to make your own choices. I'm am just trying to offer some information to help you to make informed decisions. If this was all unclear, let me know. I'll write another reply in a few weeks. | |
| David | ||
| Shawnny3 | December 20th, 2006, 6:08 pm | |
| Pleasant Gap, PA Posts: 573 | Wow. You guys are amazing. Again: Wow. -Shawn | |
| Jewelry-Quality Artistic Salmon Flies, by Shawn Davis www.davisflydesigns.com | ||
| Troutnut | December 20th, 2006, 7:39 pm | |
| Fairbanks, AK Posts: 1122 | Lots of good points David, and a few I would take issue with too. Unfortunately I'm frantically packing for the holidays so I won't have time to coherently organize my rebuttal for a while! | |
| Jason Neuswanger The Troutnut | ||
| Upnorth2 | December 21st, 2006, 12:48 am | |
| Wisconsin Posts: 62 | DMM I lived on the West Coast for awhile and wondered by the coho seemed to decline over a period of time. Was unaware of the studies you referred to so thanks for clearing some things up in your post. I always thought that the Seattle hoards had to have some kind of affect. | |
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