Status of Prey Fish
continued from page 2
days nearshore water is <4º C (39º F) during
the first winter after hatch. Year class size is also influenced by the
abundance of spawners in a curvilinear manner ― weak year classes are
produced by large and small spawning stocks whereas strong year classes are
produced by intermediate spawning stocks. In spring 2003, the size of the
spawning stock was intermediate. May-July water temperatures, however, were
cooler than average indicating unfavorable conditions for reproduction and
the duration of winter, although currently uncertain, is apparently going to
be longer than average indicating low survival of juvenile alewives.
Prognosis for the Lake
Ontario alewife population returning to previous abundance levels is poor.
The population apparently was unable to return to the moderate abundance
levels of the early 1990s despite the fact that reproductive success was
better than average in 2001 and 2002. The process of food web disruption,
mediated by exotic species, may well have eroded lower trophic level support
for the Lake Ontario alewife population to below that of the early 1990s.
With the carrying capacity of the lake reduced, the alewife population at a
low level, and environmental conditions unfavorable for production of age-1
alewives, we expect the index of adult alewife abundance to be at, or below,
the record low of 1998-1999 through 2005.
Rainbow Smelt
The 2003 population estimate of YAO rainbow
smelt was 90 million fish or 602 metric tons. This is also the lowest
abundance observed since the start of the series in 1997, and represents
approximately 23% of the average biomass observed during the recent
low-abundance period starting in 1999. The condition of smelt was not
assessed in 2003 because only a few fish were caught in the trawls, although
visual examination suggested that the condition in 2003 was not obviously
different from that in 2001.
The record low hydroacoustic
abundance estimate of YAO smelt is consistent with the bottom trawl estimate
made earlier in the year, which was the lowest since the start of the bottom
trawling program in 1978.
Number and biomass indices
of age-1 and older rainbow smelt were lower than in 2000-2002, setting new
record lows (numbers=92/tow). Abundance of rainbow smelt has been at or near
26-year lows for four consecutive years with biomass at 10-20% of the
long-term average of 4.58 kg (10.1 lb)/tow.
Rainbow smelt year classes
generally alternate between strong and weak in Lake Ontario apparently due
to cannibalism, primarily by yearling smelt on young-of-year. The catch of
yearling rainbow smelt in 2003 was lower than in 2002, thus breaking the
alternating pattern in year class strength that had been intact since 1983.
Because abundance of yearling rainbow smelt was low in 2003, we would expect
to see an increase in yearling abundance in 2004. However, during our
trawling survey in autumn 2003, few young-of-year rainbow smelt were
observed indicating that should an increase in yearling abundance occur in
2004, it will not be large.
The mean weight of rainbow
smelt caught during the June 2003 survey increased to 3.9 g (0.14 oz.) from
3.0 g (0.11 oz.) in June 2002, because yearling rainbow smelt (the youngest
age group in the catch) were less abundant in 2003 than in 2002. The
heaviest mean weight for rainbow smelt was 13.8 g (0.49 oz.) in 1979.
Abundance of large smelt remained low in 2003. Large smelt made up less than
3% of the population during 1989-2002 and in 2003 they made up <1% of the
population. The stratified mean catch per tow of large rainbow smelt ranged
from 1 to 14 during 1989-2002 and was only 1 in 2003. In contrast, during
1978-1983, large rainbow smelt were 10 to 26% of the population and mean
catch per tow ranged from 55 to 205.
Slimy Sculpin
Along the south shore of Lake Ontario, from
Olcott to Oswego, slimy sculpin numbers at depths >70 m (230 ft.) decreased
slightly from 1338 per tow in 2002 to 1277 per tow in 2003. In southeastern
Lake Ontario near Oswego, abundance of slimy sculpin showed some evidence of
recovering from the 65% drop that occurred between 1991 and 1992. Indeed,
catches at a few depths exceeded 4,000 fish, the largest catches of slimy
sculpins since 1991.
In 1996, we lost our ability
to index the sculpin populations at depths <70 m (230 ft.). In the future,
unless we encounter a notable dieoff of Dreissena, we will no longer
be able to index slimy sculpins at depths >70 m (230 ft.) with our
traditional trawling gear due to the steady expansion of the dreissenid
population into deeper water.
Deepwater
Sculpin
We did not capture any deepwater sculpin in
2003 and we did not conduct additional trawling to attempt to capture
deepwater sculpin. During 1998-2000, we caught five deepwater sculpin at
depths of 110-150 m (361-492 ft.), two while conducting long-term assessment
trawling, and three while conducting short-term assessment trawling that
targeted deepwater prey fishes in mid lake, along the international
boundary. Prior to 1998, the last documented record of a deepwater sculpin
being captured in U.S. waters of Lake Ontario was over 50 years ago.
²
2003 NYSDEC Lake
Ontario Report
General
In 1996, anglers fishing Lake Ontario and
its tributaries contributed over $75 million to the New York State economy.
In recent years, the Lake
Ontario ecosystem has undergone dramatic changes resulting primarily from
the introduction of exotic zebra and quagga mussels (Dreissena polymorpha
and D. bugensis, respectively). In addition, improve-ents in
wastewater treatment have reduced excessive nutrient concen-rations to
historic, more natural levels, thereby lowering the productive capacity of
the Lake Ontario ecosystem. Surveys conducted by the USGS in 2002 and 2003
documented further deterior-tion in abundance and distribution of the
deepwater amphipod, Diporeia. This phenomenon is thought to be
directly linked to the continued range expansion of quagga mussels into
deeper waters, as is the recent concern regarding potential shifts in the
abundance and distribution of the opossum shrimp, Mysis.
The exotic round goby (Neogobius
melanostomus) was first documented in the New York waters of Lake
Ontario in 2001, and numerous reports now confirm the presence of this
species from the Lower Niagara River in the west to the Thousand Islands
region of the St. Lawrence River in the east. The first gobies documented in
a U.S. fisheries assessment program were collected by the Research Vessel
Kaho at 55 m depth off Olcott. Round gobies were documented for the
first time in the diets of cormorants from Pigeon and Snake Islands in 2002,
and became the dominant prey of Snake Island cormorants in 2003.
Based on spring 2003 bottom
trawling, adult alewife abundance was somewhat more abundant than in 2002,
however, fish condition was low. A summer 2003 hydroacoustic preyfish
survey, however, indicated that alewife numbers had declined dramatically,
and alewife condition deteriorated further. While a relatively thin and not
fully developed thermocline during the July survey may have biased survey
results, a number of independent observations support the hypothesis that
alewife numbers declined between spring and summer. First, mean length and
weight of age-3 Chinook salmon declined to record low levels in 2003, while
Chinook fishing success (catch per hour) reached record high levels.
These observations suggest
that the primary prey of Chinook salmon (alewife) was in limited abundance.
Alewife condition between spring and fall 2003 improved at a record high
rate, indicating fewer alewives competing for food or an abundance of
available food. The presence of the exotic zooplankter Bythotrephes
(spiny water flea) in alewife stomachs during the fall of 2003 suggests that
the former is more likely, as Bythotrephes abundance is typically
suppressed through alewife predation.
Coldwater Fisheries Management
·
Fish stocking included 1.62
million Chinook salmon, 256,000 coho salmon, 681,000 rainbow trout, 500,000
lake trout, 452,000 brown trout, and 82,000 Atlantic salmon .
·
In 2003, 420,000 lake trout
and 181,050 brown trout were stocked offshore by military landing craft in a
continuing effort to reduce predation on newly stocked fish by cormorants
and predatory fish.
·
Initial results evaluating the
performance of shore-stocked vs. barge-stocked brown trout at Sodus Bay
(Salmon River hatchery reared) and Oak Orchard (Caledonia hatchery reared)
in 2001 and 2002 suggested that shore-stocked brown trout outperformed
barge-stocked fish in both open lake and tributary fisheries, and that
nearly nine times more fish returned to the creek from the Oak Orchard
stockings,. Due to the larger size of Caledonia Hatchery brown trout
relative to Salmon River Hatchery, stocking locations by hatchery were
reversed in 2003 to evaluate the influence of size at stocking on
post-stocking survival, and this experimental stocking will continue in
2004. Evaluations will continue through 2006.
·
Mean lengths of age-1 and
age-2 Chinook salmon sampled in the open lake fishery were below average,
although the differences in lengths between many years were not
statistically significant. Reductions in Chinook salmon growth in 2003 were
most evident in age-3 fish. Mean lengths of age-3 fish in 2003 were record
lows, and were significantly different from all other years compared (e.g.,
mean length of age-3 Chinook in August 2003 was 35.57 inches, 1.64 inches
and approximately 3.9 lbs less than August 2002).
·
Mean weights of age-3 male and
female Chinook salmon returning to the Salmon River hatchery in 2003 were at
record low levels, as was mean weight of age-1 males (jacks). The predicted
weight of a 900 mm (34.5 in.) total length Chinook (15.5 lbs.) increased
slightly from the record low observed in 2002. Mean weights of age-2 coho
were also low in 2003. Growth of steelhead was intermediate among years
sampled, however, they are surveyed in the spring of the year and therefore
do not reflect growth during 2003.
·
Since the institution of
seasonal base flows in the Salmon River, a dramatic increase in natural
reproduction of Chinook salmon has been documented. Densities of
young-of-year Chinook salmon were markedly lower in 2003, likely due to
reduced baseflows resulting from prolonged drought conditions in the fall of
2002.
·
A three-year tagging study was
initiated in 1999 to address the effects of stocking method on the recent,
relatively poor survival of Salmon River stocked Washington steelhead.
Considerable differences exist in numbers returned between fish stocked in
different years and among fish stocked in a given year returning in
different years, and evaluations will continue in 2004.
·
225,000 pre-smolt Chinook
salmon and 65,720 rainbow trout were reared by cooperating sportsmen in net
pens within Lake Ontario tributaries.
·
Evaluations of the performance
of steelhead pen-reared at Oswego Harbor are very favorable. To date, 80
coded wire-tagged steelhead have been collected from the Oswego River,
Salmon River, and the open-lake fishery. Sixty-eight of the 80 returns were
pen-reared fish. Also, there was no significant difference between stocking
method (pen-reared vs. direct stocked) and return location (open lake,
Salmon River, Oswego River).
·
Separate lots of marked
Chinook salmon from the Salmon River and Caledonia Hatcheries (40,000 each)
were stocked into the Lower Niagara River (2000 and 2002) and Oak Orchard
Creek (1999 and 2001) to assess differential effects of hatchery origin and
pen rearing vs. traditional stocking on performance in the fishery.
Returns of the 1999 year
class stocked at Oak Orchard in 2001 and 2002 suggest that pen-reared Salmon
River Hatchery origin Chinook returned the greatest yield to Oak Orchard
Creek. Direct-stocked Caledonia fish returned at an intermediate level, and
direct-stocked Salmon River fish returned the poorest. Returns of the 2000
and 2002 year classes stocked at the Niagara River are in contrast with the
Oak Orchard study. Returns to the stocking site from the 2000 stocking
slightly favor the Salmon River direct stocked fish over the pen reared
fish. The Caledonia direct stocked fish returned the poorest.
With only age-1 returns from
the 2002 stocking available, the pattern of pen reared fish and direct
stocked Salmon River fish returning better than the direct stocked Caledonia
fish is similar to that observed with the 2000 year class. Evaluations will
continue through 2005.
Lake Trout
Restoration
Catch of age-2 lake trout in 2003 declined,
and was the third lowest on record. Trends in numbers of age-2 lake trout
caught in trawls and age-3 fish caught in gill nets for the 1975 to 1995
year classes suggested that recruitment of hatchery fish to the population
was governed by survival during their first year after stocking. Subsequent
to the 1995 year class, this relationship has deteriorated, suggesting
increased mortality of stocked lake trout during their second year in the
lake.
·
A total of 702 adult lake
trout were captured in the September 2003 gill net survey. Catch rates for
mature lake trout remained remarkably stable from 1986 to 1998. The catch
per unit of effort (CPUE) of mature fish, however, declined by 30% between
1998 and 1999. Poor survival of hatchery fish was likely responsible for
declining abundance of immature lake trout since 1989 and current declines
in adult numbers. The CPUE for mature lake trout in 2003 increased, but was
34% below the 1986-1998 average.
·
Accurate calculation of the
average age of mature, female lake trout is no longer possible due to a lack
of funding for coded-wire tags. Average age of mature female lake trout has
been increasing steadily since the mid 1980s. The average age of 9.55 years
in 2001 reflects a population comprised of the oldest group of mature
females since the rehabilitation program was initiated.
·
In 2003, a total of 6
naturally produced lake trout (108 to 404 mm or 4.25 to 16 in. total length)
were caught with bottom trawls. Survival of naturally produced lake trout to
the fingerling stage in summer and fall occurred each year during 1993-2002.
Further, survival to older ages has also been apparent. The distribution of
catches of wild fish suggests that lake trout are reproducing throughout New
York waters.
·
The estimated annual harvest
of lake trout since the slot limit (635 – 762 mm or 25 to 30 in.) was
reinstated in 1992 has been more than 4 times lower than previous years when
no size limits were in effect. Harvest reached its lowest recorded level in
2003 with an estimated 4,711 lake trout harvested. The percentage of lake
trout harvested by anglers that were of trophy size (>762 mm or >30 in.)
reached a record high 48.5% in 2003.
·
A study evaluating the effect
of location (onshore vs. offshore) and timing (May vs. June) of stocking on
the survival of lake trout is being conducted at Olcott and Sodus, New York.
Preliminary results suggest that offshore stocking substantially enhances
catches of stocked, age-1 lake trout in bottom trawl surveys, however,
catches at older ages indicate that stocking method affects distribution of
fish as well as survival. Although early catches of experimental fish were
encouraging, the returns at age-2 and older remain insufficient to discern
with certainty which, if any, stocking method conveys the best survivorship.
Warmwater
Fisheries
·
211,480 fingerling walleye
were stocked into Lake Ontario embayments and the Lower Niagara River.
·
Total catch of warmwater fish
in the 2003 Eastern Basin gill netting program increased slightly for the
second year since the record low levels observed in 2001, as did smallmouth
bass abundance. Three year moving average catches for walleye, yellow perch,
and pumpkinseed are increasing, whereas the same for smallmouth bass is
relatively stable. Growth of smallmouth bass has increased in recent years.
Lake sturgeon have been collected in seven of the last nine years,
suggesting improvement in population status.
·
Index gill netting in the
Thousand Islands region of the St. Lawrence River revealed continued low
abundance of smallmouth bass and northern pike.
·
Yellow perch abundance in Lake
St. Lawrence index gill netting remained fairly stable in 2003. Smallmouth
bass abundance fell below the long-term average. Walleye abundance decreased
27% from 2003, but remains above the long-term average.
Sport Fishery
Assessment
·
Total trout and salmon fishing
success (catch rate per hour) reached record high levels in 2003 for both
charter and non-charter boats.
·
Total fishing boat trips, and
trips targeting trout and salmon, have declined significantly since the 1990
peak. Largest declines in effort occurred between the 1990-91 seasons and
the 1991-92 seasons, before reductions in the Lake Ontario stocking program
were discussed.
·
In 2003, total effort was
estimated at 79,958 fishing boat trips, a record low among the 19 years
surveyed. Total fishing boat effort in 2003 was down 15.8% compared to the
1998-2002 boat trip average, and down 63.3% compared to the 1990 peak.
·
An estimated 47,874 boat trips
targeted trout and salmon in 2003, a record low effort estimate for trout
and salmon anglers among the years censused. Trout and salmon fishing effort
in 2003 was down 22.6% compared to its 1998-2002 average, and down 74.0%
compared to the 1990 peak year.
·
The number of lampreys
observed per 1,000 trout and salmon caught was estimated at 23.98 in 2003, a
96.8% increase compared to the 1998-2002 average, and the highest value
observed among the 18 years that sea lamprey observations have been
specifically asked for.
·
Trips targeting smallmouth
bass during the open season show a variable but statistically significant
upward trend over the years censused, averaging 3.4% per year. An estimated
27,754 boat trips targeted smallmouth bass abundance in the Eastern Basin as
measured in index gill nets remains low. In addition, harvest rates of
smallmouth bass in the Eastern Basin remain below the lakewide average.
Smallmouth bass in 2003, the 5th highest estimate for bass
anglers, but a 0.9% decrease compared to the 1998-2002 average bass effort.
·
Data on smallmouth bass
fishing in Lake Ontario collected from the 1985-2003 censuses were analyzed
in more detail as part of the evaluation of the impacts of double-crested
cormorant predation on fisheries. From 1985-90, harvest rates at Henderson
Harbor were nearly equal to or greater than the lakewide average harvest
rates and averaged 1.16 smallmouth bass harvested/ angler hour. From
1991-2003, smallmouth bass harvest rates at Henderson Harbor, adjacent to
the Little Gallo Island cormorant colony, were all below the lakewide
average. The Henderson Harbor site continues to be the only localized bass
fishery that has experienced a decline in harvest rate.
·
A creel census directed at
characterizing steelhead angler effort and success in the Salmon River
estimated 6,183 angler days in 2003, the lowest level of effort recorded
since the survey began in 1997. High water conditions during the survey
period likely contributed to the reduced effort.
·
A creel census was conducted
in 1998 in the Eastern Basin of Lake Ontario as part of an overall study to
assess impacts of double-crested cormorants on sportfish populations. This
census was repeated in 2003, and indicated a 40.1% reduction in angler
effort relative to 1998. While the targeted smallmouth bass harvest rate in
2003 was unchanged from 1998, the 2003 catch rate was substantially lower.
Diets of Double-crested Cormorants and Impacts on
Sportfish Populations
·
For the fifth consecutive
year, cormorant population control was continued through oiling of eggs with
food grade vegetable oil at the Little Galloo Island colony.
·
Round gobies were first
documented in the diets of cormorants from Snake and Pigeon Islands in 2002,
and gobies dominated the diets of Snake Island cormorants in 2003.
·
Estimated consumption of
smallmouth bass by cormorant colony (Lake Ontario only) in 2003 was: Little
Galloo Island – 500,000, Pigeon Island – 10,000, and Snake Island – 110,000.
·
Estimated consumption of
yellow perch by colony (Lake Ontario only) in 2003 was: Little Galloo Island
– 4.25 million, Pigeon Island – 160,000, and Snake Island – 2.34 million.
·
Egg oiling on Little Galloo
Island reduced cormorant chick production by approximately 98%, thereby
reducing the number of cormorant feeding days by 690,000. The resulting
reduction in fish consumption was estimated at 340,000 smallmouth bass and
1.19 million yellow perch.
·
Smallmouth bass abundance in
the Eastern Basin as measured in index gill nets remains low. In addition,
harvest rates of smallmouth bass in the Eastern Basin remain below the
lakewide average.
·
Modeling suggests that an
overall reduction in cormorant numbers within the eastern basin can be
expected as a result of egg oiling on Little Galloo Island. To reach the
objective of 15,00 nesting pairs of cormorants, oiling of all nests on
Little Galloo island would need to occur through 2008. A less intensive
maintenance program would begin in 2009. Residual effects would carry into
the year 2010, at which time the target population of 1,500 pairs would be
achieved. From 2010 on, the eastern basin cormorant population would be
predicted to again increase slowly if Canadian colonies continued to grow.
Cormorant populations have continued to grow on Lake Ontario over the past
several years with the exception of 2003, but less predictably than in the
1980s and early 1990s.
·
Estimated fish consumption by
cormorants from three upper St. Lawrence River colonies (Ontario waters) in
2003 (6.35 million fish) was within the range (4.79 to 6.64 million)
reported for the four previous years. Average annual fish consumption by
cormorants from Griswold, McNair, and Strachan Islands since 1999 is 5.97
million fish. Total, combined cyprinids, 520,000 pumpkinseeds, and 40,000
smallmouth bass.
Highlights of the 2003 Lake Ontario Fishing Boat
Census
Fishing Boat Effort
·
Total fishing boat trips, and
trips targeted at trout and salmon, have declined significantly since the
1990 peak. Largest declines in effort occurred between the 1990-91 seasons
and the 1991-92 seasons, before reductions in the Lake Ontario stocking
program were even discussed.
·
In 2003, total effort was
estimated at 79,958 fishing boat trips, a record low among the 19 years
surveyed. Total fishing boat effort in 2003 was down 15,8% compared to the
1998-2002 boat trip average, and down 63.3% compared to the 1990 peak. The
largest reductions in yearly percent contributions have occurred in the
months of April and May, and in the west and west/central areas.
·
An estimated 47,873 boat trips
targeted trout and salmon in 2003 (59.9% of total trips), a record low
effort estimate for trout and salmon anglers among the years censused. Trout
and salmon fishing effort in 2003 was down 22.6% compared to its 1998-2002
average, and down 74.0% compared to the 1990 peak year. The largest
reductions in yearly percent contribution among trout and salmon anglers
have occurred in the month of April and in the west/central area.
·
Trips targeted at smallmouth
bass during the open season show a variable but statistically significant
upward trend over the years censused, averaging 3.4% per year. An estimated
27,754 boat trips targeted at smallmouth bass in 2003 (34.7% of total
trips), the 5th highest estimate for bass anglers, but a 0.9%
decrease compared to the 1998-2002 average bass effort. Effort targeted at
smallmouth bass has always been highest in the east/central and east areas,
averaging 46.0% and 26.2%, respectively, over the years censused.
Non-Fishing Boats
·
Excursions by non-fishing
power boats were estimated at just 87,783 in 2003, the third lowest estimate
among the years censused, and down 53.9% from the peak observed in 1988.
Excursions by sail boats were estimated at just 17,872 in 2003, the lowest
among the years censused, and down 63.0% from the peak observed in 1987.
Charter Boat Trips
·
The number of charter fishing
boat trips peaked between 1988 and 1991, and then declined to a low of just
8,790 boat trips in 2003, similar to the pattern described for total fishing
boat trips and trips targeting trout and salmon.
·
The relative importance of
charter boats to the fishery has shown a pattern of increase over the years
censused, and in 2003 charter boats contributed 11.0% of the total fishing
boat trips. Since charter boats typically carry more anglers, fish for a
longer period of time, have higher harvest rates, and harvest a higher
percent of the fish caught, their significance is even greater when using
other statistics. In 2003, charter fishing boats contributed 20.6% of the
total boat angler trips, 29.9% of the total boat angler hours, and harvested
55.5% of all trout and salmon kept within the area censused. By species,
charter boats harvested 67.3% of the lake trout kept in 2003, 60.3% of coho
salmon, 59.0% of rainbow trout, 58.6% of brown trout, and 50.0% of Chinook
salmon.
2003 Harvest and Catch Summary:
Chinook Salmon
– Chinook salmon was the most commonly
harvested salmonine in 2003 (43.9% of total) with an estimate of 31,525
fish, a 72.2% increase compared to the 2002 Chinook harvest, and a 24.2%
increase compared to the 1998-2002 average harvest.
Brown Trout
– Brown trout was the 2nd most commonly harvested salmonine in
2003 (31.0% of total) with an estimate of 22,277 fish, a 32.5% increase
compared to the 2002 brown trout harvest, but a 6.8% decrease compared to
the 1998-2002 average harvest.
The 2003 seasonal harvest
rate among boats seeking trout and salmon was 0.457 brown trout per boat
trip, the 3rd highest seasonal harvest rate among the years
censused, and a 20.1% increase compared to the 1998-2002 average rate. Brown
trout harvest rates in 2003 were above their respective 1998-2002 averages
for the months of April and July-September, and in the west and east/central
areas.
Rainbow Trout –
Rainbow trout was the 3rd most commonly harvested salmonine in
2003 (11.5% of total) with an estimate of 8,245 fish. This represents a
20.1% increase compared to 2002, but still the 2nd lowest harvest
estimate among the years censused.
Coho Salmon
– Following a record low in 2002, coho salmon harvest rebounded in 2003,
with a modest estimate of 5,079 fish. The 2003 seasonal harvest rate among
boats seeking trout and salmon was 0.106 fish per boat trip, similar to the
average harvest rates of previous years. Compared to their respective
1998-2002 averages, 2003 harvest rates were substantially lower in the
months of April and August, but substantially higher in the month of
September. Coho salmon was the 4th most commonly harvested
salmonine in 2003 (7.1% of total) with an estimate of 5,079 fish. As in all
previous years, the 2003 coho salmon harvest was dominated by age-2 fish.
Lake Trout
– Lake trout was the 5th most commonly harvested salmonine in
2003 (6.6% of total) with a record low estimate of just 4,711 fish (58.7%
decrease compared to the 1998-2002 average harvest). The 2003 seasonal
harvest rate among boats seeking trout and salmon was 0.098 lake trout per
boat trip, the lowest seasonal harvest rate among the years censused, and a
47.8% decrease compared to the 1998-2002 average harvest rate. Harvest rates
in 2003 were below their respective 1998-2002 averages.
Total Trout & Salmon
– A total of 71,854 trout and salmon were harvested in 2003 within the area
censused. This is a 20.3% increase compared to the record low recorded in
2002, but a 14.7% decrease compared to the 1998-2002 average harvest. The
2003 seasonal harvest rate among boats seeking trout and salmon was 1.491
trout and salmon per boat trip, up 32.1% compared to the 2002 harvest rate,
and up 10.5% compared to the 1998-2002 average harvest rate. Since poor
harvest in one species is often offset by higher harvest in another, the
total trout and salmon harvest rates were more consistent between months and
areas.
Among charter boats, the
2003 harvest rate was 4.813 trout and salmon per boat trip, up 13.3%
compared to the 1998-2002 average. Aggregate 3-fish limits of
coho-chinook-rainbow-brown for the party were harvested on 16.5% of the
charter boats in 2003. Lake trout 3-fish limits for the party were harvested
on only 0.6% of the charter boats.
Among noncharter boats, the
2003 harvest rate was 0.795 per boat trip, up just 5.6% compared to the
1998-2002 average. Aggregate 3-fish limits of coho-chinook-rainbow-brown for
each angler were harvested on only 1.7% of the noncharter boats in 2003,
while lake trout 3-fish limits were harvested on only 0.1% of the noncharter
boats.
Smallmouth Bass
– Smallmouth bass has been the most commonly harvested species in recent
years (42.9% of the total in 2003). An estimated 65,633 were harvested in
2003, only 1.7% higher than the 1998-2002 average harvest.
Smallmouth bass catch and
catch rates are very impressive, and both have increased in recent years. An
estimated 405-723 smallmouth bass were caught within the area censused in
2003, the 4th highest catch among the years censused, and 2.0%
higher than the 1998-2002 average. The smallmouth bass catch rate among boat
anglers targeting smallmouth bass in 2003 was 13.7 fish per boat trip. This
was the 2nd highest seasonal catch rate among the years censused,
and 7.5% above the 1998-2002 average.
The Henderson site (Stony
Creek and Association Island Cut) was the only localized smallmouth bass
fishery along New York’s Lake Ontario shoreline, which shows a downward
trend in harvest rate ratios in recent years. Since 1991, Henderson harvest
rates have been consistently lower than the lakewide rates (13-year average
ratio 0.72). The timing corresponds with the period when relative mortality
of young smallmouth bass increased significantly in the eastern basin of
Lake Ontario, presumably in response to predation by double-crested
cormorant.
Yellow Perch and Walleye
– An estimated 8,171 yellow perch were
harvested in 2003; a 77.8% increase compared to 2002, but a 2.5% decrease
compared to the 1998-2002 average harvest. Walleye harvest in 2003 was
estimated at 560 fish; a 28.6% decrease compared to the 1998-2002 average
harvest.
Lake Sturgeon Stocking Summary, 2001-2003
No sturgeon were stocked in 2001 or 2002.
Egg mortality claimed the entire 2001 year class, possibly due to bacterial
contamination. Egg collection protocol now includes prophylactic
decontamination on site with Erythromycin Phosphate prior to transport to
the hatchery.
In 2002, mechanical failures
in the adult lake sturgeon holding system resulted in termination of adult
collection. In 2003, adult sturgeon were captured over a three day period
from 28-30 May, with 45 sturgeon captured.
Three of 7 fish identified
as females were kept for egg take. All females retained were relatively
large from the perspective of this project history (24-28 kg). A total of 9
males, ranging from 12-20 kg, were kept as sperm donors.
Two females contributed
approximately 33,000 eggs, which were fertilized and distributed between the
NYSDEC Oneida Fish Culture Station, the USFWS Pittsford National Fish
Hatchery (Vermont), and three research facilities. One hundred percent
mortality was reported for eggs and larvae from female #13 during the first
7 days post fertilization.
Total fingerling production
for 2003 was 2,572. A single female (#18) was the sole provider of progeny
despite efforts to increase genetic variability of stocked fish.
²
2003 Ontario Fisheries of Lake Ontario
Status of Major
Species
Chinook salmon
Catch rates in the boat angling fishery
indicated that Chinook salmon abundance in Lake Ontario has been relatively
stable from 1988 to 2003, despite stocking reductions in 1993. Natural
reproduction after 1995 and density dependent survival of young Chinook
salmon may have contributed to these steady catch rates. Growth (in length)
remains good, but observed drastic declines in the weight of spawning
females in the Credit River run are cause for concern.
Rainbow Trout
Counts of rainbow trout at the Ganaraska
River fishway remain low. This may indicate that adult returns to other
Ontario tributaries are low, too. The long-term harvest rates of rainbow
trout from the boat fishery in Lake Ontario reflect the counts at the
Ganaraska Fishway, since wild rainbow trout are a significant component of
the population. Recent year-to-year variation in rainbow trout harvest rates
appears to be related to spring temperature. The low rainbow trout harvest
rate in 2003 was consistent with the average air temperature in April 2003,
which was the lowest in at least 20 years. Condition of rainbow trout in the
Ganaraska River in 2003 was similar to the long-term average. These fish
were sampled during spring, and their condition reflected growth in Lake
Ontario in 2002.
Lake Trout
The decline in abundance of mature lake
trout appeared to continue in 2003, although past changes in strains and
geographical patterns of stocking make unbiased assessment of the status of
the lake trout population difficult. Survival of young stocked fish has
stabilized in the recent past after a period of decrease, and this should
lead to a stable albeit low adult population. The condition of large lake
trout continued to decline, and lamprey wounding remained at low levels.
Lake Whitefish
Adult lake whitefish abundance remains low
with little new recruitment. Summer distribution of adult fish, as indicated
by assessment gillnets, appears to have contracted to a relatively small
area in the vicinity of Point Traverse. Reproduction was successful in 2003
after five consecutive very poor year-classes; this 2003 year-class will be
monitored closely in the years ahead in terms of distribution, growth and
survival. The commercial harvest of lake whitefish has declined
significantly in recent years.
American Eel
The numbers of eel migrating upstream at the
ladder, located at the R.H. Saunders Hydroelectric Dam on the St. Lawrence
River, remain at a very low level. Commercial harvest of eel below the dam
(Quota Zone 1-7) remains relatively stable; however, harvest above the dam
(all other quota zones) has declined in an unprecedented fashion. The low
upstream migration suggests that the commercial harvest of eel in the upper
St. Lawrence River and Lake Ontario will remain low for at least the next
decade. Ontario is continuing to work with the local commercial fishery and
with management agencies from other jurisdictions to address the decline in
eel abundance. Sustainable management practices throughout the range of
this species (Labrador to the Caribbean) will be required to restore eel
abundance.
Smallmouth Bass
The eastern Lake Ontario smallmouth bass
population remains at low but stable abundance. In the Bay of Quinte the
abundance is low, declining further in 2003. The current low abundance
levels in eastern Lake Ontario and the Bay of Quinte are not consistent with
recent mid-summer water temperatures; mid-summer water temperatures had been
driving smallmouth bass abundance prior to the mid-1990s. In the St.
Lawrence River (Thousand Islands), smallmouth bass abundance increased in
2003 and approached levels observed in the early-1990s.
Largemouth Bass
Largemouth bass have increased in recent
years in the Bay of Quinte; their abundance now rivals that of walleye in
littoral zone areas during summer. A recreational fishery (including
increased tournament angling) targeting largemouth bass has developed over
the last several years.
Yellow Perch
Yellow perch abundance in eastern Lake
Ontario and in the Thousand Island area of the St. Lawrence River remains
low but stable. In the Bay of Quinte, abundance remains high but is in
decline. The commercial harvest of yellow perch has declined since the
late-1990s.
Walleye
Walleye remain the most important species
for recreational fisheries and are valued by the First Nation's fishery and
non-native commercial fishery in eastern Lake Ontario. Currently, the
population comprised of fish age-3 and older appears to be in a relatively
steady state, with numbers hovering around 400,000 fish. Reproduction
appears to have improved slightly—the strongest two year-classes since 1995
occurred in the last three years. Age-2 fish represented the bulk of the
recreational fishery in 2003. This 2001 year-class should cause the age-3
and older population to increase in 2004. Simulations suggest that given the
most recent reproduction observations and the current level of mortality
from all sources, the age-3 and older walleye population will remain at
about 400,000 fish until 2006.
Prey Fish
Whole-lake hydroacoustic assessment of the
two principal prey fish species in Lake Ontario, alewife and smelt,
suggested record low population levels in 2003. The abundance estimates of
yearling-and older fish of both species were approximately one-fifth of the
average levels observed in recent years. Furthermore, the body condition of
alewives was also the lowest observed in the recent years.
Invasive Species
Data from index bottom trawling program
suggests that in 2003 the round goby has completed its spread throughout the
Bay of Quinte, and may be reaching abundances that are comparable to those
of all other species combined at some locations in the lower bay. Gobies
have also been reported in western Lake Ontario since the late-1990s. Their
presence in other areas is poorly documented, but absence of reports from
the Canadian side of central Lake Ontario suggests that this area remained
free of gobies in 2003.
Hydroacoustic
Assessment of Prey Fish
Alewife
The 2003 survey consisted of five
shore-to-shore north-south transects in the main lake, and one U-shaped
transect in the Kingston basin. The 2003 population estimate of
yearling-and-older (YAO) alewife was 123 million fish or 2360 metric tons.
This is the lowest abundance since the start of the current data series in
1997, and the biomass only 14% of the 1997-2002 average level. The condition
of the alewife was significantly poorer than in any year since 1997.
Smelt
The 2003 population estimate of YAO rainbow
smelt was 90 million fish or 602 metric tons. This is also the lowest
abundance observed since 1997, and represents approximately 23% of the
average biomass observed during the recent low abundance period starting in
1999. The condition of smelt was not assessed in 2003 due to insufficient
sample size.
Threespine sticklebacks
Threespine sticklebacks are not currently
assessed from the acoustic data, but midwater trawls conducted during the
hydroacoustic surveys provide some information on their population trends.
In 2003 the catches of threespine sticklebacks were among the lowest since
the mid 1990s when this species came into prominence.
St. Lawrence River Fish Community
Surveys – Thousand Islands
The overall catch from 48 gillnet sets in
the 2003 Thousand Islands project was 1,574 fish comprising 20 species. The
average number of fish captured per net set during 2003 (39.9 fish per net,
both netting types combined) was higher than was observed in the 2001
survey, however the numbers of fish remain lower than those observed during
the late 1980s. As was the case in 2001, average catches were higher in
mono-filament nets than in multi-filament nets. For this reason, a
correction factor of 1.58 was applied. See the 2001 annual report for
discussion of the statistical treatment of the two net types.
Yellow Perch –
Yellow perch continue to be the most
abundant fish captured in the Thousand Islands gillnet program. The total
catch in 2003 increased from 2001 levels. Age analysis of fish sampled
during the 2003 netting program estimated the average age of the yellow
perch community to be 3.5 years.
Centrarchids
– Six centrarchid species were captured in the netting program: rock bass,
pumpkinseed, bluegill, smallmouth bass, largemouth bass and black crappie.
Rock bass catches were lower in 2003 than 2001, yet still very high relative
to other species. Pumpkinseed and smallmouth bass populations appear to have
followed similar trends until 2003, where smallmouth numbers increased and
pumpkinseed declined slightly. Smallmouth bass catches increased in 2003 to
levels previously seen in the early-1990s. Strong age-1 and age-4 age groups
were likely responsible for the upward smallmouth bass abundance trend
observed in 2003. Although catches of pumpkinseed increased during 1999,
they resumed their overall declining trend in 2001 and 2003.
Northern Pike
– For the first time since 1989, the catch of northern pike increased. A
decline in northern pike catches through the 1990s has also been reported
over the same time period in the New York waters of the Thousand Islands,
with weak fluctuations since 1997.
Sea Lamprey Management in Lake Ontario
Lampreys Observed
– 3,370 lam-preys were estimated attached to angler caught trout and salmon
within the area censused in 2003, up 100.4% compared to the 1998-2002
average, and the highest yearly number estimated since 1990. Wounding rates
in Lake Ontario have been remarkably stable during 1985-2003, ranging from
1-3 marks per 100 fish.
During 1983-2003, the USFWS
(Service) and Dept. of Fisheries and Oceans (Department) annually have
trapped spawning-phase sea lampreys in an average of 15 tributaries, and
have estimated lakewide abundance of spawning. Estimated lakewide abundance
averaged 72,000 during 1981-1990, and was reduced to an average of 33,000
during 1991-2000. During 1984-2003, abundance of spawners has shown a
significant negative linear trend.
Tributary Information
·
Lake
Ontario has 659 tributaries (405 Canada, 254 U.S.).
·
59 tributaries (30 Canada, 29
U.S.) have historical records of production of sea lamprey larvae.
·
43 tributaries (22 Canada, 21
U.S.) have been treated with lampricide at least once during 1994-2003.
·
Of these, 29 tributaries (13
Canada, 16 U.S.) are treated on a regular cycle.
Lampricide Control
·
Treatments were completed in
13 tributaries (7 Canada, 6 U.S.) scheduled for treatment.
·
South
Sandy Creek, treated in 2002, was
added to the stream treatment list after a quantitative assessment was
conducted in 2003.
·
The treatment of Duffins Creek
was conducted from above the sea lamprey barrier due to the presence of
larvae in this portion of the stream. Adult sea lampreys were observed above
the barrier during the treatment.
Barriers
·
A new seasonal stop log sea
lamprey barrier was constructed in Wesleyville Creek during 2003 under a
partnership agree-ment between Ontario power Generation, Ganaraska
Conserva-tion Authority and the Great Lakes Fishery Commission.
·
Feasibility studies, detailed
design, and tendering for remedial works on an existing dam on the Credit
River were completed. Negotiations regarding property agreements with the
dam owner delayed construction, which is now scheduled for summer 2004.
·
A new construction project is
being developed for Bronte Creek.
·
Presently, 13 streams have sea
lamprey barriers or components of barriers that are operated and maintained
by agent staff.
²
MNR Recreational
Fishery Surveys
W. Lake
Ontario Boat Fishery
During 2003, Chinook salmon dominated the
catch and harvest in the boat angler fishery in Ontario's waters of Lake
Ontario, followed by rainbow trout. Together they represented over 90% of
the catch and harvest. Declines in catch over the past decade have
paralleled a decline in effort. The effort of launch daily anglers and all
boat anglers was estimated at 190,015 and 346,766 angler-hours,
respectively. This is the lowest effort in all of the years surveyed since
1977, and continues a long-term gradual decline.
Catch rates for the time
series from 1977 to 2003 show major shifts in the salmon and trout
population in Lake Ontario. Coho salmon was the dominant salmonid in Lake
Ontario during the 1970s. Catch rates of rainbow trout and Chinook salmon
increased as more were stocked in the 1980s.
Growth of Chinook salmon
declined slightly however, 2 year-olds and 3 year-olds were just 10 mm and
16 mm smaller, respectively, than the long-term average length at age.
Commercial Fishery
Quota and
Harvest Summary
The commercial harvest comes primarily from
the Canadian waters of Lake Ontario east of Brighton (including the Bay of
Quinte) and the St. Lawrence River. Commercial harvest statistics for 2003
were compiled from daily catch report (DCR) records managed by the Ministry
of Natural Resources in partnership with the Ontario Commercial Fisheries
Association (OCFA).
Lake
Ontario
The total harvest of all species was 447,643
lb. ($324,320) in 2003, and has declined 65% since 1996. The majority of
this decline can be accounted for by a decline in whitefish harvest (see
below). The top five species in terms of landed value in 2003 were yellow
perch, whitefish, brown bullhead, sunfish and eel; compared to lake
whitefish, yellow perch, eel, brown bullhead and walleye in 1994.
Lake whitefish
– Lake whitefish harvest was 124,748 lb., 61% of the quota. The annual lake
whitefish harvest has declined over 80% since 1996.
Eel
–Eel harvest was 7,452 lb., 8% of the quota. Eel harvest has declined
dramatically in the last decade, while the value (price per lb.) has
increased.
Yellow perch
– Yellow perch harvest was 99,919 lb., 22% of the quota. Yellow perch
harvest had increased significantly from 1996 to 1999 but declined by over
60% between 1999 and 2003.
Walleye
– Walleye harvest was 6,063 lb., 12% of the
quota. The walleye harvest was the lowest it has been since commercial
fishing for this species was reestablished in 1989.
Other species
– Commercial harvest of brown bullhead, sunfish, black crappie, freshwater
drum and suckers declined in 2003, while that of white perch and rock bass
increased.
St. Lawrence River
The total harvest of all species was 211,255
lb. ($203,710), and has declined 44% since 1998. The top three species in
terms of landed value were yellow perch, eel, and brown bullhead compared to
eel, yellow perch, and brown bullhead in 1994.
Eel
– Eel harvest was 21,693 lb., 47% of the quota. Of note, 58% of the total
eel harvest from Lake Ontario and the St. Lawrence River was taken in Quota
Zone 1-7. This quota zone has only 23% of the total quota.
Yellow perch
– Yellow perch harvest was 54,148 lb., 35% of the quota.
Other species
– Commercial harvest of black crappie,
sunfish and brown bullhead declined in 2003.
Lake
Whitefish Commercial Catch
Sampling of commercially harvested lake
whitefish for biological attribute information occurs annually. In 2003,
biological sampling took place to obtain samples for a lake whitefish
bioenergetics study. In total, fork length was measured for 5,134 fish and
age was interpreted (otoliths) for 414 fish.
Lake Ontario
– Mean fork length and age were 490 mm and
10.8 years, respectively. Fish ranged from age-7 to age-17 years. Age-11
(1992 year-class) fish were the most abundant. Fish age-8 to 12 comprised
over 90% of the harvest. Mean age of the commercial lake whitefish harvest
increased steadily after 1995 as the strong 1991 and 1992 year-classes
“moved through” the fishery, and as age-at-first recruitment to the fishery
increased over the same time-period.
Bay of Quinte
– Mean fork length and age were 488 mm and 10.6 years, respectively. Fish
ranged from age-4 to age-20 years. Age-12 fish were the most abundant. This
represents the 10th consecutive year that the 1991 year-class was the most
numerous year class in Quota Zone 1-3 commercial harvest. Age-8 and age-9
fish also figured prominently in the harvest. As for Lake Ontario, mean age
of the commercial lake whitefish harvest in the Bay of Quinte increased
steadily after 1995 as the 1991 year-class “moved through” the fishery, and
as age at first recruitment to the fishery increased over the same
time-period.
Enforcement Update
This is the first time an enforcement update
has been included in the Lake Ontario Management Unit Annual Report. The
enforcement program consists of six full-time staff positions, with an
Enforcement Supervisor and three Conservation Officers (COs) based out of
Glenora. Two other Conservation Officers are based out of Darlington
Provincial Park in Bowmanville.
The Glenora COs are primarily responsible
for commercial fish management and enforcement, sport fish enforcement, and
other enforcement duties as required. Commercial fish management involves
the issuance and maintenance of approximately 175 commercial fishing
licences for Eastern Lake Ontario, Western Lake Ontario, the Bay of Quinte
and some Inland Lakes and waters. Commercial fish duties also include
inspecting commercial fish documents from both fishers and local wholesalers
to ensure compliance with seasons, quotas, size limits and compliance with
legislation governing the purchase and sale of commercial fish.
Darlington COs are primarily responsible for
the management and enforcement of commercial fish wholesale and retail
outlets in the Greater Toronto Area. The Officers inspect documents from
both retail and wholesale outlets to ensure compliance with the Fish and
Wildlife Conservation Act and O. Reg 664 as they relate to the purchase and
sale of fish.
All Lake COs are responsible for Sport Fish
Enforcement on Lake Ontario from Cornwall to the Niagara River. The Lake
Ontario Management Unit Enforcement Section usually enters into an agreement
with Kemptville District to cover the sport fish enforcement on the St.
Lawrence River.
In 2003, the Lake Ontario Enforcement
Program entered into joint forces work with Fisheries Officers from the
Federal Department of Fisheries and Oceans (DFO). The joint forces work
included vessel patrols, market inspections, and intelligence and
investigative work. The joint forces work provides a training opportunity to
DFO Fisheries Officers and provides additional manpower to MNR. The joint
forces work will continue into 2004.
Other enforcement duties for Lake Unit COs
involve supporting Provincial enforcement initiatives, assisting other
Districts / Lake Units and enforcement of ancillary legislation such as the
Off Road Vehicles Act, the Motorized Snow Vehicle Act, etc. In future years
this update will include enforcement statistics.
MNR Stocking Lake
Ontario
In 2003, OMNR stocked about 1.8 million
salmon and trout into Lake Ontario. Just over 500,000 Chinook salmon spring
fingerlings were stocked at various locations to provide put-grow-and take
fishing opportunities.
About 20,000 Chinook
salmon were held in pens at two embayment sites in eastern Lake Ontario
for a short period of time prior to stocking. This project was done in
partnership with a local community group to determine whether these fish
would successfully imprint on the embayments. It is hoped that
pen-imprinting will help improve returns of mature adults to this area in
the fall, thereby enhancing local nearshore fishing opportunities. Follow-up
monitoring is planned.
About 95,000 coho salmon
yearlings were stocked into the Credit River. A poor run of coho in the fall
of 2002 resulted in a shortfall of 55,000 fish this year.
OMNR stocked about 112,000
Atlantic salmon spring fingerlings and 84,000 fall fingerlings, in
support of an ongoing program to restore self sustaining populations of this
native species to the Lake Ontario watershed. Partners stocked out about
39,000 Atlantic salmon eggs in incubation boxes, as well as about 15,000
fry.
About 410,000 lake trout
yearlings were also stocked. Lake trout stocking is focused in eastern
Lake Ontario where most of the historic spawning shoals are found.
About 146,000 rainbow
trout yearlings were stocked by OMNR. In addition, local community
groups reared about 186,000 rainbow trout fry and 31,000 fall fingerlings.
About 181,000 brown trout yearlings were stocked at various locations to
provide shore and boat fishing opportunities.
New York State DEC also
stocked 3.6 million salmon and trout into Lake Ontario in 2003.
American Eel
The numbers of eel migrating upstream at the
ladder, located at the R.H. Saunders Hydroelectric Dam, remain at a very low
level. Commercial harvest of eel below the dam remains relatively stable;
however harvests above the dam (upper St. Lawrence River and Lake Ontario)
have declined in an unprecedented fashion. The low levels of upstream eel
migration suggest that the commercial harvest of eel in the upper St.
Lawrence River and Lake Ontario will remain low for at least the next
decade.
Actions taken by the Lake Ontario Management
Unit to address the declining abundance of eel include:
1) no new commercial licenses issued;
2) commercial quotas for eel reduced by 50%
in 2001 and 50% more in 2002;
3) continued operation of the eel ladder at
the Saunders Hydroelectric Dam;
4) development of a management plan for
American eel in Canadian waters in cooperation with DFO and the Province of
Quebec;
5) contributed to the American Fisheries
Society eel symposium held during August 2003.²
Status and Trends – Lk
Superior
continued from page 1
There continues to be sharp
differences in biomass of prey fish populations among jurisdictions. The
greatest concentrations of biomass of herring, bloater, smelt and lake
whitefish were observed in Wisconsin waters. Prior to 2001, the greatest
biomass of bloater was taken in Michigan waters, however, sharp declines in
Michigan bloater populations coupled with increases in Wisconsin waters has
shifted the area of concentration.
Biomass of prey fishes in
Minnesota waters continues to be the lowest among U.S. jurisdictions. Trends
in prey fish biomass in Canadian waters followed patterns and levels for
U.S. waters and biomass for herring, bloater, whitefish, smelt was
substantially greater in western Ontario waters. However, biomass in
Canadian waters continues to remain at near record low levels in 2003.
Overall, trends in Lake Superior prey fish populations are of continuing
decline since the mid-1990s. The 1998 cohorts of herring and bloater
produced moderate year classes in 2002, and if another is produced in 2003,
prey fish biomass may increase in subsequent years over the present
relatively low levels.
Lake herring
During the 26 years of monitoring, strong
year-classes occurred during only three intervals, 1984, 1988-1990, and
1998. Most of the adult herring population present in the lake is the result
of growth and recruitment of the 1998 year-class. The new, moderate 2002
year class was produced by the 1998 cohort. Lake herring mean biomass in
U.S. waters during 1978-2002 was higher than any other species captured,
accounting for 22% of the total community biomass. Trends in biomass of lake
herring appear to be linked to recruitment of strong year classes and
reproductive failures.
Rainbow smelt
Rainbow smelt biomass in U.S. waters during
1978-2003 was ranked second behind lake herring and accounted for 20% of the
total biomass. In 1978-1979 smelt was the dominant prey fish, representing
40-50 % of the total biomass. Prior to the monitoring period, smelt
populations were at record levels in Lake Superior. In 1978-1979, the
beginning of the monitoring period, smelt biomass in U.S. waters peaked but
subsequently dropped by more than 85% by 1981.
Between 1986 - 1995, biomass
fluctuated and then declined steadily after 1995, reaching record low levels
in 2002 and 2003. Unlike lake herring, strong year classes of smelt did not
fluctuate so widely. Estimates of total mortality show that loss of adult
fish >3 years of age increased sharply after 1978 and mortality rates have
remained high ever since, such that fish 4 years and older have represented
less than 1.3% of the total population since 1981. Trends in smelt biomass
were similar among jurisdictions in U.S. waters.
During the 1989-2003
monitoring period, trends in smelt biomass in Canadian waters shared
features with those in U.S. waters, but biomass levels were consistently
much higher in Canadian waters until 2001. In 2002, smelt biomass in
Canadian waters plummeted similar to the low levels observed in U.S. waters.
Bloater
Bloater
mean biomass in U.S. waters during 1978-2003 ranked fourth behind lake
herring, rainbow smelt, and lake whitefish, and accounted for 11.9% of the
total community biomass. In U.S. waters, bloater biomass was low during
1978-1983, then more than doubled in 1984-1986 and remained relatively high
through 1993. After the peak in 1992, biomass declined to low levels in
1994-1995, but recovered partially by 1998. Trends in biomass in U.S. and
Canadian jurisdictions between 1989-2001 were very similar.
Lake
whitefish
Whitefish biomass in U.S. waters during
1978-2003 was second only to lake herring and accounted for 19% of the total
community biomass. During 1978-1983, biomass of whitefish was low in U.S.
waters, then increased during 1984-1986 and then fluctuated to the present
time. Year class strength in U.S. waters varied by a factor of 9 over the 25
year monitoring period, which was much less than that for other coregonids.
As a result, there were numerous moderate to strong year classes, especially
after 1987 when population levels and biomass had fully recovered. Trends in
whitefish biomass in Canadian waters were similar during 1989-2003, but
dropped to record lows in 1999-2003.
Ninespine
stickleback
Ninespine stickleback was a relatively minor
species in U.S. and Canadian waters during 1978-2003, and accounted for 2%
of the total community biomass.
Trout-perch
Trout-perch was another relatively minor
species in U.S. and Canadian waters during 1978-2003; mean biomass accounted
for 1.4% of the total community biomass.
Slimy sculpin
Slimy sculpin, another minor species, was
the most abundant sculpin species in U.S. waters during 1978-2003. In
Canadian waters, slimy sculpin biomass has tended to be higher than in U.S.
waters, but the trends for the 1989-2003 period were similar. Like that in
U.S. waters, slimy sculpin biomass in Canadian waters declined to the lowest
levels in the time series during the 2000-2002 interval.
Summary
Lakewide trawl assessments indicate that
total community biomass, including lake trout, has been in decline since the
mid-1990s, which has occurred despite what appears to be an ample food base.
Further increases in lake trout biomass in Lake Superior depend heavily on
increasing stocks of lake herring. The key, then to further restoration of
the Lake Superior fish community is to fully recover lake herring, the
principal prey species
Sea Lampreys in Lake Superior 2003
Tributary Information
·
Lake Superior has 1,566 (833
Canada, 733 U.S.) tributaries.
·
139 (47 Canada, 92 U.S.)
tributaries have historical records of production of sea lamprey larvae.
·
68 (29 Canada, 39 U.S.)
tributaries have been treated with lampricides at least once during
1993-2003.
·
Of these, 51 (19 Canada, 32
U.S.) tributaries are treated on a regular cycle.
Lampricide Control
Lampricide treatments are system-atically
scheduled for tributaries harboring larval sea lampreys to eliminate or
reduce the populations of larvae before they recruit to the lake as
parasitic adults. USFWS (Service) and Department of Fisheries and Oceans
Canada (Department) treatment units apply formulations of the lampricides
TFM and Bayluscide to scheduled tributaries and lentic areas. Specialized
equipment and techniques are employed to provide concentrations of
lampricides that eliminate about 95% of the lamprey larvae and minimize the
risk to non-target species. Service and Department treatment units
administer and monitor doses of the lampricide TFM, sometimes augmented with
Bayluscide 70% Wettable Powder, to scheduled tributaries.
Treatments with TFM
were completed in 12 tributaries (6 Canada, 6 U.S.).
·
Treatments of all Canadian
tributaries were considered successful with the exception of the Batchawana
River. Low discharge conditions may have compromised treatment effectiveness
in the lower 10% of the watershed.
·
Bayluscide granules were
applied to lentic areas of Lake Helen. One area, located off the mouth of
the upper Nipigon River, was treated in conjunction with the TFM application
of the upper Nipigon River to take advantage of the reduced flows required
for the river treatment.
·
The Dead River was eliminated
from the lampricide treatment schedule when an extensive flood destroyed all
infested habitat.
·
The Marengo River (Bad River)
was treated further upstream than ever previously treated to eliminate a
source of residual larvae.
Sterile Male Release Technique
Male sea lampreys are captured during their
spawning migrations in 20 tributaries to lakes Superior, Michigan, Huron,
and Ontario, and the St. Marys River and transported to the sterilization
facility at the Hammond Bay Biological Station. At the facility sea lampreys
are sterilized with the chemosterilant bisazir. They are then delivered and
released into the St. Marys River. Laboratory and field studies have shown
that treated male sea lampreys are sterile, sexually competitive, and
numbers of eggs that hatch in sterile male nests are reduced. A total of 666
spawning-phase male sea lampreys were transported to the facility from the
Brule River.
Barriers
·
A new seasonal stop log
barrier was constructed in Furnace Creek during 2003.
·
New construction projects are
in various stages of development on the Sucker and Bad Rivers and Harlow
Creek.
Assessment
·
Assessments of populations of
sea lamprey larvae were conducted in 81 tributaries (38 Canada, 43 U.S.) and
offshore of 6 tributaries (1 Canada, 5 U.S.).
·
4,838 sea lampreys were
trapped in 24 tributaries during 2003.
·
The estimated population of
spawning-phase sea lampreys for 2003 was 86,778 (western U.S. 30,107,
eastern U.S. 56,671 and Canada).
²
Wisconsin Lake Superior Fishery
Lake Trout
Assessment
Mean catch-per-unit-effort (CPUE) of lake
trout in WI-1 and WI-2 decreased in 2003. Although hatchery fish have been
decreasing gradually, the decrease in native fish CPUE was inconsistent with
recent trends. Lake trout stocking is no longer necessary in WI-2 and the
1994 year class was the last to be stocked. Lake trout will continue to be
stocked in WI-1 until the stocking protocol established by the Lake Superior
Technical indicates otherwise.
Spawning assessments were
conducted on two reefs in October to monitor trends in abundance. The
population at Gull Island Shoal declined in the 1950s and by 1961, no
females were sampled during annual assessments. Spawning lake trout
abundance has continually increased due to sea lamprey control, sport and
commercial harvest restrictions and the creation of the Gull Island Refuge
in 1976. The Gull Island Shoal stock-recruitment relationship is linear,
indicating the population still has the capacity to increase. Spawning lake
trout abundance has remained stable at Sand Cut Reef.
Lake Herring Assessment
–
Lake herring abundance increased dramatically during the late 1980s due to
the exceptional year class in 1984 and several in the late 1980s. Those
strong year classes are now declining in abundance and are being replaced
with the 1998 year class, which accounted for 64% of the spawners in 2003.
Spawner abundance declined in 2003 despite the strong 1998 year class.
Sport Harvest
An annual creel survey was conducted at all
major ports along the Wisconsin shoreline. In 2003, an estimated 42,597
individual angler trips were made on Lake Superior, resulting in 201,132
angling hours. The harvest was estimated at 23,058 salmonids. 26 charter
fishing operations were active in 2003, down from a peak of 50 licenses in
1990.
Commercial
Production
Wisconsin
has 10 State licensed commercial fishers operating in Lake Superior.
Whitefish and lake trout are primary targets. Other commercial species
harvested include lake herring, siscowet lake trout, deep-water chubs
(cisco) and smelt.
Sea Lamprey
Barriers
Wisconsin DNR operates three sea lamprey
barriers on Lake Superior. The Middle River barrier has been in operation
since 1984, the Iron River barrier since 2002 and the Brule River
barrier/fishway since 1985. In 2003, 1,975 sea lamprey were captured at the
Brule River barrier.
2003 Salmonid Stocking
Lake Trout
45,154
Splake
70,891
Brown Trout
98,452
Chinook
293,816
2004 Proposed Salmonid
Stocking
Lake Trout
89,400
Splake
80,000
Brown Trout
80,000
Chinook
200,000 ²
Minnesota Lake Superior Fishery 2003
Sea Lamprey
The Minnesota waters of Lake Superior
encompass three statistical districts. In 2003 marking rates in MN-1
decreased, while in MN-2 and MN-3 they increased when compared to 2002.
Total marks per 100 lake trout in 2003 were highest in MN-3. Compared to
2002, lamprey marks per 100 lake trout in 2003 increased for the two larger
size groups and decreased slightly for the two smaller size groups. Total
marking rate increased slightly from 6.2 to 6.6 marks per 100 lake trout.
Status of Lake Trout Stocks
Lake Trout
– The catch per unit effort (CPUE) of stocked lake trout decreased from 2002
to 2003. The total CPUE of stocked lake trout in the May assessment
generally increased from 1976-1982, then stabilized at about 50 lake
trout/1,000 m of net through 1991, and has since generally declined to a low
of 7.8 lake trout/1,000 m in 2003. The average total CPUE of stocked lake
trout during the 1992-2003 period was well below the 1976-1991 average.
There has also been a lakewide decline in survival of stocked lake trout.
Total CPUE of wild lake
trout declined in 2003 to 21.1 lake trout/1,000 m, but is still about three
times the catch rate for stocked lake trout. The rate of decline was not as
large as that reported in 2002 when the CPUE decreased by about half.
Unusually high numbers of wild fish were captured in 2000 and 2001.
Commercial/Forage Species
Lake herring
– Lake herring abundance has increased substantially in the commercial catch
since 1985. In 2003, harvest of herring in the gill net fishery was 292,966
lbs., down from 375,946 lbs. in 2002. The adult lake herring stock
vulnerable to the commercial fishery appears to be decreasing in Minnesota
waters, as indicated by the commercial catch statistics from 1995-2003.
However, a very strong 1998 year class which was well represented in the
USGS 1999 spring forage survey has started recruiting to the fishery as
indicated by the occurrence of many younger, smaller fish in the 2003
harvest. The 1998 year class of lake herring was the strongest
recorded in Minnesota waters since 1990 and now accounts for much of the
harvest.
Rainbow smelt
– In 2003, the spring rainbow smelt spawning run along the Minnesota shore
of Lake Superior remained at a very low level, and few fish were captured in
the dip net fishery, compared to the pre-1980 period. From 1980-1990,
commercial harvest had stabilized at approximately 15% of the average
harvest during the 1970s. Commercial harvest in the 2002 pound net fishery
was 18,180 lb. and decreased to 2,037 lb. in 2003. In 2003 there was only
one smelt fisherman in the pound net fishery. No commercial trawling for
smelt occurred in 2003.
Fish Production/Stocking for ‘04
In 2004, Minnesota plans to produce and
stock three species of trout and salmon. Two strains of rainbow trout will
be produced: steelhead and Kamloops. All steelhead will originate from
Minnesota stocks. The Chinook salmon program was revised in 1998. Because of
extremely low Chinook salmon returns to the French River Trap, not enough
gametes could be collected to sustain a program. The decision was made to
obtain gametes from the Swan River, Lake Huron. The new quota for Chinook
salmon is 355,000 fingerlings. From 1998-2001 Minnesota secured eggs from
Lake Huron. Starting in 2002, gametes were again collected at the French
River Trap and used to produce Chinook salmon fingerlings for the stocking
program. In 2004, Minnesota plans to stock approximately 270,000 lake trout.
In 2003, lake trout stocking was discontinued in statistical district MN-3
because the criteria to discontinue stocking was met.
²
Inland Seas Angler
