Here's some historic info on the Seneca Lake fishery for those of you interested. I got this information from DEC Historical Documents:
1.) Between 1902 and 1910, the annual commercial harvest of lake trout was estimated at 8,400lbs.
2.) Muskellunge fry were stocked in the lake in 1895. Walleyes were stocked in 1910 and 1914. Whitefish fry in 1913 and 1914. The only introduced stocked fish that have prospered in the lake have been rainbow trout, landlocked salmon and brown trout. All other stocked non-native species collapsed. (Keep in mind that I am talking about recent i.e. the last 120 years of fisheries records kept by NYSDEC. In the mid-1800s it's very likely that fish like pickerel and largemouth bass were introduced into many of the Fingerlakes and they have prospered.)
3.) Rainbow trout were stocked in Seneca Lake 1910 to 1913 and steelhead were stocked from 1917 to 1927. The rainbow trout people catch today in Seneca Lake are likely descendants from these steelhead stocks.
4.) Lake Trout were stocked as far back as 1927 at a rate of 175,000 fish per year. First plantings may have been in 1894.
5.) Natural reproduction of lake trout on Seneca Lake was as low as 15% in the late 1970s. The population was verging on collapsing.
6.) Smelt were stocked in 1909. The population was fairly insignificant until around 1973, when the population expanded considerably. This was around the same time as the lake trout decline and reproductive failures. A dip netting season was opened in 1974 with an 8 quart limit.
7.) Keuka Outlet was surveyed in 1960 and only two lamprey larvae (ammocoetes) were collected. At this point in time, the outlet was considered quite polluted. By 1976, after the Outlet cleaned up considerably, large numbers of lampreys were using the stream and delta area for spawning.
8.) Northern Pike really expanded their population in Seneca Lake around 1965. Numbers were excellent until around 1978, when their population started to taper off. The population increase corresponded with an increase of milfoil in the lake.
9.) Nutrient loading, including phosphorus and nitrogen loading via agricultural runoff and development resulted in higher "productivity" of Seneca Lake throughout the 1960s and 70s. Fish production increased at this time.
10.) American eels were common in Seneca Lake until the early 1900s.
11.) In 1979, lake trout were the most commonly targeted fish in Seneca Lake, followed by smallmouth bass. Then rainbow trout, yellow perch and northern pike, followed by largemouth bass and lastly smelt and bullhead.
12.) Brown trout were first stocked in Seneca Lake in 1979, in order to give anglers another salmonid to fish for while waiting for the lake trout population to rebound.
Anytime I read historical accounts on fishing the Finger Lakes a few things become apparent. Fishing success and fisheries are cyclical in nature. People have selective memories. The "good old days" for smelt dipping in Seneca Lake didn't last for long. Probably around 18 years at best. I remember great dip netting in 1980, but progressively worse dipnetting in the late 1980s.
Lake trout fishing was horrible on Seneca Lake in the 1970s. But perch and smallmouth bass populations were much higher back then than they are now, likely due to excessive nutrient loading. The pike fishing didn't become great until the 1960s and has been off and on ever since the late 1970s. There was never a terrific rainbow fishery in the lake. It was fair to good at best. Water quality in many area watersheds was much worse decades ago. Imagine Keuka Outlet being too polluted for lampreys to spawn in! Tough to believe, but it was true. Bottom line is to enjoy the great fishing we have in the present. Right now is a superb time in history for fishing Seneca Lake's lake trout and salmon populations. The brown trout and rainbow trout fishing is good and pike populations appear to be going up. I'd say perch and smallmouth are down. But history shows that some fishery is usually always doing well when others are down!