Download Whitefish – Great Lakes – Full Species Report

WHITEFISH – GREAT LAKES
Coregonus clupeaformis
Sometimes known as Common Whitefish, Eastern Whitefish, Gizzard Fish, Great Lakes
Whitefish, Humpback Whitefish, Inland Whitefish, and Lake Whitefish
SUMMARY
Whitefish is a fast growing freshwater fish that can reach a length of three feet, a weight of
roughly 42 pounds, and live for 50 years. Whitefish are found throughout the Great Lakes and
are the main commercial fish species there. The abundance of Whitefish has varied over time,
and is currently at a medium level across the Great Lakes. Several factors are impacting
Whitefish populations in the Great Lakes, particularly competition and predation from invasive
species, loss of their primary food source, and habitat degradation. Whitefish are caught by trap
nets and gillnets, which results in minimal damage to the sea floor and medium levels of bycatch.
Criterion
Points
Final Score
Life History
3.00
2.40 - 4.00
Abundance
2.00
1.60 - 2.39
Habitat Quality and Fishing Gear Impacts
1.50
0.00 - 1.59
Management
2.50
Bycatch
2.00
Final Score
2.20
Color
Color
LIFE HISTORY
Core Points (only one selection allowed)
If a value for intrinsic rate of increase („r‟) is known, assign the score below based on this value.
If no r-value is available, assign the score below for the correct age at 50% maturity for females
if specified, or for the correct value of growth rate ('k'). If no estimates of r, age at 50% maturity,
or k are available, assign the score below based on maximum age.
1.00
Intrinsic rate of increase <0.05; OR age at 50% maturity >10 years; OR growth rate
<0.15; OR maximum age >30 years.
2.00
Intrinsic rate of increase = 0.05-0.15; OR age at 50% maturity = 5-10 years; OR a growth
rate = 0.16–0.30; OR maximum age = 11-30 years.
3.00
Intrinsic rate of increase >0.16; OR age at 50% maturity = 1-5 years; OR growth
rate >0.30; OR maximum age <11 years.
Whitefish can reach a maximum size of 1 m (Frimodt 1995), maximum weight of 19 kg
(van Oosten 1946) and can live for 50 years (Power 1978), although few fish grow to
these sizes today.
Whitefish are found throughout the Great Lakes but their age and size of maturity varies
slightly between and within lakes. In Lake Hurons‟ St. Ignace, Alpena and Hammond
Bay regions, sexually maturity occurs around 4 years and 0.41 lb in weight (Woldt et al.
2007). In the Detour region, maturity is reached around 0.71 lbs and 4 years of age, while
in Alpena maturity occurs around 0.4 lbs and 3 years of age (Woldt et al. 2007). In Lake
Superior, the size and age at sexual maturity occurs between 1.10 to 1.9 lbs and 4 years
(Woldt et al.2007). In lake Michigan, most Whitefish become sexually mature at 4 years
of age, but size at maturity can vary greatly from 0.33 lbs in Manistique to 2 lbs in Grand
Traverse Bay (Woldt et al. 2007).
In Lake Erie, growth rates ranged from 0.318 to 0.401 for males and 0.280 to 0.310 for
females between 1989 and 2001 (Cook et al. 2005), which is high. In Lake Ontario,
growth rates were highest (~0.30) in the mid 1990‟s and have since declined to around
0.20 (Hoyle 2005). The average age at maturity in this lake has increased from 4 years in
1992 to 7 years in 2002 and the mean fork length of Whitefish in Lake Ontario declined
from around 500 mm fork length (FL) in 1992 to just over 350 mm FL in 2002 (Hoyle
2005).
Because Whitefish generally mature and grow quickly, a score of 3 was awarded.
Points of Adjustment (multiple selections allowed)
-0.25 Species has special behaviors that make it especially vulnerable to fishing pressure (e.g.,
spawning aggregations; site fidelity; segregation by sex; migratory bottlenecks; unusual
attraction to gear; etc.).
-0.25 Species has a strategy for sexual development that makes it especially vulnerable to
fishing pressure (e.g., age at 50% maturity >20 years; sequential hermaphrodites;
extremely low fecundity).
-0.25 Species has a small or restricted range (e.g., endemism; numerous evolutionarily
significant units; restricted to one coastline; e.g., American lobster; striped bass; endemic
reef fishes).
-0.25 Species exhibits high natural population variability driven by broad-scale environmental
change (e.g. El Nino; decadal oscillations).
+0.25 Species does not have special behaviors that increase ease or population consequences of
capture OR has special behaviors that make it less vulnerable to fishing pressure (e.g.,
species is widely dispersed during spawning).
+0.25 Species has a strategy for sexual development that makes it especially resilient to
fishing pressure (e.g., age at 50% maturity <1 year; extremely high fecundity).
Whitefish return to where they were born to spawn (Walker et al. 1993) and females can
produce between 8,000 to 40,000 eggs per spawning event, with fecundity dependent on
the age and size of the individual fish (Jensen 1981). Several spawning stocks have been
identified in Lake Huron (Casselman et al. 1980). There are two Whitefish spawning
populations in Lake Ontario (Hoyle 2005). The population that inhabits the southern
shore of Prince Edward County and Amherst Island spawns in November and the
population in the Bay of Quinte spawns from late October through early November
(Hoyle 2005). In Lake Erie, Whitefish spawn from late November until early December
on limestone, gravel, sand and rocky substrates in the western basin of the lake
(Goodyear et al. 1982a; Lumb et al. 2007). In Lake Superior, spawning occurs in early
November throughout the lake in shallow waters, such as embayments and near-shore
areas over coarse sand or rubble (LSC 2001). In Lake Michigan, Whitefish spawn on
nearshore reefs less than 30 m deep (Goodyear et al. 1982b). Whitefish are considered to
have a moderate fecundity so no points were added.
+0.25 Species is distributed over a very wide range (e.g., throughout an entire hemisphere
or ocean basin; e.g., swordfish; tuna; Patagonian toothfish).
Whitefish are found in North America throughout the Great Lakes and central Minnesota,
Alaska, New England and a large part of Canada (Fishbase 2010).
There are many different populations of Whitefish in the Great Lakes, which differ in
their growth rates, reproduction, movement and diet (Ihssen et al. 1981). For example, in
Lake Michigan there are at least ten different populations of Whitefish (Ebener 1997).
We consider this a medium range and have therefore not added any points.
+0.25 Species does not exhibit high natural population variability driven by broad-scale
environmental change (e.g., El Nino; decadal oscillations).
3.00 Points for Life History
ABUNDANCE
Core Points (only one selection allowed)
Compared to natural or un-fished level, the species population is:
1.00
Low: Abundance or biomass is <75% of BMSY or similar proxy (e.g., spawning
potential ratio).
2.00
Medium: Abundance or biomass is 75-125% of BMSY or similar proxy; OR
population is approaching or recovering from an overfished condition; OR
adequate information on abundance or biomass is not available.
Whitefish is the main commercial fish caught from the Great Lakes, from both US and
Canadian waters (Kinnunen 2003). Most Whitefish are caught in Lake Huron, where the
commercial catch represents about 60% of the total Whitefish catch from the Great Lakes
(Kinnunen 2003). The next most important lake for Whitefish fishing is Lake Michigan,
where catches make up around 24% of the total catch (Kinnunen 2003). Catches of
Whitefish in Lake Superior have increased over time and as of 2000 were the most
commonly captured commercial species in that lake (Ebener 2000). Historically,
abundances of Whitefish have remained stable in Lake Superior but have fluctuated to a
great degree in the other Great Lakes (Dermott and Kerec 1997; Nalepa et al. 1998;
Lozano et al. 2001).
In Lake Ontario, Whitefish landings dropped to almost nothing in the mid 1960‟s (Owens
et al. 2005). By the mid to late 1990‟s the population appeared to be recovering but by
1997, Whitefish abundance again seemed to be declining (Owens et al. 2005). For
example, in Lake Ontario' Henderson Harbor, Whitefish catches declined by 95%
between 1995 and 2001 and the abundance of Whitefish near Oswego also declined
dramatically after 1997 (Owens et al. 2005). Populations appear to be to now be
recovering (Owens et al. 2005).
In Lake Superior, the biomass of Whitefish available for fishing in the Marquette and Big
Bay areas of increased through 2004 (last year of data) and in the Munising area, biomass
has increased since 2002 (Woldt et al. 2007). In Tahquamenon Bay, biomass has declined
since its peak in 1989 and in Brimley, biomass has declined since the late 1990‟s (Woldt
et al. 2007). Overall biomass in the US and Canadian waters of Lake Superior have
declined but remained fairly stable through 2006, (Stockwell et al. 2007) and overall
abundance of Whitefish in Lake Superior is considered high (Stein et al. 2003).
In Lake Huron, the biomass of Whitefish in St. Ignace declined to the lowest levels since
the late 1990‟s in 2004 (Woldt et al. 2007). In the Detour region, Whitefish biomass
reached its maximum in the mid 1990‟s and has since declined (Woldt et al. 2007).
Whitefish biomass in Hammond Bay has decreased dramatically since its peak in the mid
to late 1990‟s (Woldt et al. 2007) and biomass of Whitefish has been declining since the
mid 1990‟s in Alpena (Woldt et al. 2007). However, the amount of Whitefish available to
fishermen in Lake Huron is still considered “substantial” and higher than the past two
centuries (LHBP 2008). In Canadian waters of Lake Huron, whitefish stocks peaked in
the late 1990‟s, declined since and appear to have stabilized in recent years (Cottrill et al.
2009). Overall biomass in the lake has declined since the late 1990‟s but still is
considered to be greater than it was historically (pre 1940‟s) (Ebener et al. 2008)
In Lake Michigan, Whitefish biomass in the Bay de Noc region of declined in 2001 after
the highest levels in the late 1990‟s, but has since increased (Woldt et al. 2007). Biomass
of Whitefish in Manistique peaked in the late 1990‟s, declined slightly into 2001 but has
since increased dramatically (Woldt et al. 2007). Biomass of Whitefish in Naubinway has
been increasing since 2001 (Woldt et al. 2007) and biomass of Whitefish in Beaver Island
has increased since lows in 2001 (Woldt et al. 2007). Biomass has been declining since a
peak in 1981 in Grand Traverse Bay (Woldt et al. 2007) and in Leland-Frankfurt,
biomass remained fairly high in the late 1990‟s, declined into 2001 and has since
increased dramatically (Woldt et al. 2007). Biomass has increased over time in the
Mukegon region (Woldt et al. 2007). Since 2002, overall catches of Whitefish in Lake
Michigan appear to have stabilized and between 2003 and 2008, catches fell within the
sustainable harvest range (Eshenroder et al. 1995; Breidert 2008) and as of 2009,
Whitefish captures in Lake Michigan were considered to be at high levels (Hansen 2008).
We have given a middle score to account for variability in abundances over time, while
accounting for the recovery in most of the lakes.
3.00
High: Abundance or biomass is >125% of BMSY or similar proxy.
Points of Adjustment (multiple selections allowed)
-0.25 The population is declining over a generational time scale (as indicated by biomass
estimates or standardized CPUE).
Abundances of Whitefish caught by trap nets in Lake Michigan increased through 1999
but have decreased through 2009 (Hansen 2010). Abundances of pound net caught
Whitefish in Lake Michigan have been variable over the years and the abundance of
Whitefish caught in gillnets has remained relatively stable (Hansen 2010). Decreases in
abundance of Whitefish in Lake Michigan from 1996-2002 were likely due to the
invasion of Dreissenid mussels that caused a redistribution of Whitefish (Peeters 2003).
In Lake Erie, abundances of Whitefish in the western-central basin have increased over
time (1993-2001) but have been variable in other areas of the lake (Cook et al. 2005).
Abundances of Whitefish in Lake Huron increased into the 1990‟s but decreased in the
early 2000‟s in the Canadian main basin (Mohr and Ebener 2005). While in Lake
Superior, catch rates of Whitefish by both gears (trap nets and gillnets) increased from
the mid 1990‟s through 2000 (Ebener 2000). Abundances in Lake Ontario have declined
by 66% since a peak in the mid 1990‟s (Nalepa et al. 2005). Abundances increased from
the late 1970‟s through the late 1990‟s in some areas (main basin, North Channel and
Georgian Bay) of Lake Huron (Mohr and Ebener 2005). However, abundances have since
declined in the main basin (Mohr and Ebener 2005).
Although some catch rate series show declines over time, populations appear to be
recovering in most of the Great Lakes, so we have not subtracted any points.
-0.25 Age, size or sex distribution is skewed relative to the natural condition (e.g.,
truncated size/age structure or anomalous sex distribution).
In Lakes Michigan (Pothoven et al. 2001), Superior (Schneeberger et al. 2005), Huron
(Mohr and Ebener 2005) and Ontario (Hoyle 1999), some research has shown a decrease
in Whitefish growth rates over time. In addition, in Lake Ontario, reproductive “success”
has declined since the mid 1990‟s (Hoyle et al. 1999; Hoyle 2005). For example, in Lake
Ontario, growth rates were highest (~0.30) in the mid 1990‟s and have since declined to
around 0.20 (Hoyle 2005). The average age at maturity in this lake has increased from 4
years in 1992 to 7 years in 2002 and the mean fork length of Whitefish in Lake Ontario
declined from around 500 mm fork length (FL) in 1992 to just over 350 mm FL in 2002
(Hoyle 2005). These changes are most likely linked to the loss of their primary food,
Diporeia spp., which is discussed below (Hoyle 2005).
In Lake Michigan, length at age decreased by 4-7% during the 1990‟s, and weight at age
decreased by 36-47% (Schneeberger et al. 2005).
In Lake Superior, length at age declined by 4-7% between the early to late 1990‟s and
weight declined by 36-47% (Schneeberger et al. 2005). The number of age 4 Whitefish
(age at which they start being caught) remained stable from 1994 to 2001 in the
Marquette and Big Bay areas of Lake Superior but decreased in the Munising area (Woldt
et al. 2007).
A decrease in growth has also been seen in some parts, particularly in the main basin, of
Lake Huron, while size at age is decreasing in the southern basin (Mohr and Ebener
2005). Age at maturity in the southern main basin increased from 3.7 years in 1989
(females) to 5.9 years in 1998 (Mohr and Ebener 2005). In Lake Hurons‟ southern main
basin, the mean age of Whitefish in the catch has increased from 2.6 in 1983 to 7.6 in
2000 and it has remained stable since (Mohr and Ebener 2005). In the northern basin of
this lake, the mean age increased from 4 to 5 during the 1970‟s to 7 since 1997 (Mohr
and Ebener 2005). In the southern Georgian Bay of Lake Huron, mean age of harvested
Whitefish decreased to around 3 years from 1975 to 1985 and then increased to 6 years
by 2000 (Mohr and Ebener 2005). It is thought the loss of food exacerbated these
declines, which may have been more closely related to high Whitefish densities (evener
et al. 2010). The effect of food on Whitefish abundance is discussed in more detail below.
-0.25 Species is listed as "overfished" OR species is listed as "depleted", "endangered", or
"threatened" by recognized national or international bodies.
-0.25 Current levels of abundance are likely to jeopardize the availability of food for other
species or cause substantial change in the structure of the associated food web.
+0.25 The population is increasing over a generational time scale (as indicated by biomass
estimates or standardized CPUE).
+0.25 Age, size or sex distribution is functionally normal.
+0.25 Species is close to virgin biomass.
+0.25 Current levels of abundance provide adequate food for other predators or are not
known to affect the structure of the associated food web.
Competition and predation by invasive species have been implicated in Whitefish
declines in abundance throughout the Great Lakes (Nalepa et al. 2005). Specifically, in
Lake Ontario invasions by sea lamprey during the 1960‟s (Christie 1973; Loftus and
Hulsman 1986), rainbow smelt, alewife and white perch during the 1960‟s and 70‟s
(Casselman et al. 1996) and Dreissinid mussels from the 1990‟s onward (Dermott 2001;
Hoyle et al. 2003) have been implicated in these declines. In Lake Michigan, sea
lampreys and rainbow smelt, which eat Whitefish fry, were introduced into the lake
during 1930‟s (Shetter 1949; Wells and McLain 1972). Rainbow smelt also entered Lake
Erie in the 1930‟s and negatively impacted Whitefish recruitment (Van Oosten and Hile
1937; Hardy 1994; Ryan et al. 1999). In Lake Ontario, Dreissenid mussels invaded
during the 1990‟s and have been indirectly linked to the collapse of the Whitefish
population in this lake (Dermott 2001; Lozano 2001). Evidence from Lake Huron
suggests the weight of Whitefish in Lake Huron and southern Lake Michigan were 38%
lower after the Dreissenid mussel invasion (Pothoven and Madenjian 2008). However,
the recovery of predatory species such as walleye have aided in the recovery of Whitefish
in the Great Lakes (Nalepa et al. 2005).
The loss of the amphipod Diporeia, which is Whitefish‟s main prey item, in some of the
Great Lakes, specifically Lake Ontario (1993-1995), is considered to have decreased fish
numbers (Hoyle 2005; Nalepa et al. 2005). After the loss of Diporeia, Whitefish began
eating quagga mussels, clams, and opossum shrimp in Lake Ontario (Owens et al. 2005).
In Lake Michigan, snails, fly larvae and pupae, Dreissenid mussels and shrimp became
important prey items for Whitefish after the loss of Diporeia in the southern areas, while
fly larvae and pupae, other small bottom invertebrates and fish became important in the
northern areas (Pothoven 2005).
In Lake Huron, age-0 Whitefish consume mostly large zooplankton, medium sized
Whitefish eat zooplankton, fly larvae and pupae and quagga mussels and large Whitefish
eat mostly quagga mussels, and snails (Pothoven and Nalepa 2006). For medium sized
Whitefish, fly larvae and pupae are the predominate prey items in the west-central and
northwestern sections of Lake Huron during the spring, while consumption of quagga
mussels increases in the summer months (Pothoven and Nalepa 2006). Research
conducted in Lake Huron, suggests that Whitefish diet will only be 57 to 84% of their
energy content before the zebra mussel invasion, unless they switch their diet to Mysis, a
type of shrimp (McNickle et al. 2006).
Although abundances of species such as Diporeia have influenced Whitefish abundances,
Whitefish are not a major component of any other species diet and therefore their
abundance level do not affect associated food webs. We have therefore added points.
2.00 Points for Abundance
HABITAT QUALITY AND FISHING GEAR IMPACTS
Core Points (only one selection allowed)
Select the option that most accurately describes the effect of the fishing method upon the habitat
that it affects
1.00
The fishing method causes great damage to physical and biogenic habitats (e.g., cyanide;
blasting; bottom trawling; dredging).
2.00
The fishing method does moderate damage to physical and biogenic habitats (e.g.,
bottom gillnets; traps and pots; bottom longlines).
Whitefish in the Great Lakes are caught using gillnets and trap nets, but their use varies
between and within lakes. Gillnets are vertical nets that can be placed on the bottom or in
the middle or upper water layers and work by entangling fish in the netting. Trap nets
consist of a long net that diverts fish into a separate enclosure through a tunnel or pot. In
Lake Erie, commercial fishing mostly takes place in the central and western basins
(Nalepa et al. 2005) and gillnets are primarily used to capture Whitefish in this lake
(Cook et al. 2005).
In Lake Superior, trap nets caught around 73% of all Whitefish in Marquette and Big Bay
between 1986 and 2004, although the use of gillnets increased from 2000 onward (Woldt
et al. 2007). In the Munising area of this lake, trap net and gill nets catch a similar
proportion of Whitefish and in the Grand Marais region, gillnets have caught 93% of
Whitefish since 1976 (Woldt et al. 2007). In Tahquamenon Bay the large mesh gillnet
fishery caught around three quarters of all Whitefish from 1976 to 2004 but the
percentage of gillnet usage has increased since the late 1990‟s (Woldt et al. 2005). In
Brimley, the use of trap nets has been increasing over time, now representing around 75%
of the catch, while the use of gillnets has been declining (Woldt et al. 2007).
In the St. Ignace region of Lake Huron, gillnets have accounted for 37-81% of the
Whitefish catch since 1985 (Woldt et al. 2007). Trap nets have become increasingly
popular in the Detour region of Lake Huron and became the most commonly used gear
by 1999, although its use has decreased since then (Woldt et al. 2007). Trap net usage has
increased in the Drummonds region and now this gear type catches around 50% of
Whitefish (Woldt et al. 2007). In Hammond Bay, both trap nets and gillnets are used to
catch Whitefish at similar levels and all of the Whitefish caught in Alpena since 2000
have been caught with trap nets (Woldt et al. 2007). In Ontario waters of Lake Huron,
where the majority of the whitefish are caught, less than 10% of the total harvest was
taken by trap nets. The remainder was taken by gill nets. The only trap net fisheries in the
whole lake are in the main basin. The North Channel and Georgian Bay fisheries are both
gill net fisheries.
Currently about half of Whitefish caught throughout Lake Michigan are caught with trap
nets and the other half with gillnets (Hansen 2010). Specifically, in Bay de Noc, trap nets
have historically caught the majority of Whitefish and since 2001 have been the only gear
used (Woldt et al. 2007). In Manistique, trap nets and gillnets were used in similar
proportions until 2004, when trap net usage declined drastically (Woldt et al. 2007). In
Naubinway, trap nets have become increasingly popular since the late 1990‟s and as of
2000 caught the majority of Whitefish in this region (Woldt et al. 2007). Gillnet fishing
in Beaver Island has declined as a result of regulations in 2000 requiring fisherman to
switch from gillnets to trap nets (Wodlt et al. 2004). The proportion of Whitefish caught
by gillnets in Grand Traverse Bay has remained fairly steady since the early 1990‟s while
the use of trap nets has declined dramatically since the late 1990‟s (Woldt et al. 2007). In
the Leland-Frankfurt region, trap net usage has been declining since 2001, while gillnet
usage has increase (Woldt et al. 2007). Trap nets are the only fishing technique used in
the Ludington and Muskegon region (Woldt et al. 2007).
Gillnets have a very low to medium impact on bottom habitat depending on where they
are placed in the water column, while trap nets have a medium impact (Morgan and
Chuenpagdee 2003).
3.00
The fishing method does little damage to physical or biogenic habitats (e.g., hand
picking; hand raking; hook and line; pelagic long lines; mid-water trawl or gillnet; purse
seines).
Points of Adjustment (multiple selections allowed)
-0.25 Habitat for this species is so compromised from non-fishery impacts that the ability
of the habitat to support this species is substantially reduced (e.g., dams; pollution;
coastal development).
Habitat degradation and a decline in water quality have been implicated in the declines of
Whitefish abundance in the Great Lakes (Nalepa et al. 2005). Specifically, eutrophication
of Whitefish spawning habitat in Lake Ontario negatively affected Whitefish abundance
during the 1960‟s and 1970‟s (Hurley and Christie 1977). In Lake Erie, spawning
populations have been lost due to shoals and dams (LaMP 2008a) and dams in Lake
Michigan can negatively affect the movement of Whitefish (LMFT 2004).
Some research shows that Whitefish now reside in deeper waters in Lakes Michigan,
Ontario and Huron during the summer and that this could be due to overall increases in
surface water temperatures or because more light now gets through the surface because of
increased filtering by Dreissenid mussels and/or because of the loss of Diporeia (Nalepa
et al. 2005). In Lake Ontario, the mean depth of capture for Whitefish has increased from
30 to 80 m over time and this is likely a factor of Whitefish having to search for different
prey after the loss of Diporeia (Owens et al. 2005). In Lake Ontario‟s Kingston Basin,
Whitefish are commonly found in the summer at depths of 20 to 35 m (Hoyle 2005).
Nursery habitat for Whitefish in the Great Lakes includes shallow waters over rubble,
gravel and sand substrate during the spring and summer, and deeper waters over the
winter (Faber 1970; Reckahn 1970; Lawrie and Raher 1973; Berst and Spangler 1980;
Ihssen et al. 1981; Goodyear et al. 1982a and b; Lane et al. 1996).
-0.25 Critical habitat areas (e.g., spawning areas) for this species are not protected by
management using time/area closures, marine reserves, etc.
Spawning Whitefish are protected by a commercial fishing closure during November in
Michigan waters (Anonymous 2010). However, critical habitat areas are not protected
throughout their range so we have subtracted points.
-0.25 No efforts are being made to minimize damage from existing gear types OR new or
modified gear is increasing habitat damage (e.g., fitting trawls with roller rigs or
rockhopping gear; more robust gear for deep-sea fisheries).
-0.25 If gear impacts are substantial, resilience of affected habitats is very slow (e.g., deep
water corals; rocky bottoms).
+0.25 Habitat for this species remains robust and viable and is capable of supporting this
species.
+0.25 Critical habitat areas (e.g., spawning areas) for this species are protected by management
using time/area closures, marine reserves, etc.
+0.25 Gear innovations are being implemented over a majority of the fishing area to minimize
damage from gear types OR no innovations necessary because gear effects are minimal.
+0.25 If gear impacts are substantial, resilience of affected habitats is fast (e.g., mud or sandy
bottoms) OR gear effects are minimal.
1.50 Points for Habitat Quality and Fishing Gear Impacts
MANAGEMENT
Core Points (only one selection allowed)
Select the option that most accurately describes the current management of the fisheries of this
species.
1.00
Regulations are ineffective (e.g., illegal fishing or overfishing is occurring) OR the
fishery is unregulated (i.e., no control rules are in effect).
2.00
Management measures are in place over a major portion over the species' range but
implementation has not met conservation goals OR management measures are in
place but have not been in place long enough to determine if they are likely to
achieve conservation and sustainability goals.
Whitefish management is a cooperative effort between individual State Departments of
Natural Resources, the Ontario Ministry of Natural Resources and the Chippewa-Ottawa
Resource Authority. Each Lake has prepared a set of fish-community objectives through
respective Lake Committees that work under the Great Lakes Fishery Commission (Ryan
et al. 2003). These goals have helped guide the development of management actions
(Ryan et al. 2003).
In US waters of Lakes Huron, Superior and Michigan, Whitefish are regulated with yield
limits in areas were both state and tribal commercial fisheries operate (Woldt et al. 2007).
The yield and effort limits are developed by the Modeling Subcommittee of the Technical
Fisheries Committee (Woldt et al. 2007). In Canadian waters, individual transferable
quotas limit total harvest along with gear restrictions (number/length of net and minimum
mesh size), season/area closures, limited entry, species limitations and limits on the
number and size of vessels. This is similar to the measured used in the Lake Superior
fishery.
In Lake Michigan, the Whitefish commercial fishery is managed through limited entry,
annual harvest limits, and individual transferable quotas (LMFT 2004). The Lake
Michigan Integrated Fisheries Management Plan, has four goals, to have a balanced,
diverse and healthy ecosystem, a diverse multi-species sport fishery, a stable commercial
fishery, (through regulation of harvest, and putting an emphasis on improved population
assessment models, and automated setting of harvest limits through linkage with
population abundance), and science based management (LMFT 2004). The Lake Ontario
Lakewide Management Plan, focuses on improving the integrity of the physical and
biological waters of the lake, eliminating pollutants and restoring beneficial use (LaMP
2008b). In Lake Erie, the Lake Erie Committee has the goal of having a secure fish
community with sustainable harvest of species like Whitefish (Ryan et al. 2003).
Canadian vessels fishing in Lake Ontario must provide daily catch reports that indicate
the species captured, size, gear type, effort, location and weight (Belore et al. 2006).
Monitoring agencies also take biological samples and collect fishery specific information
from the commercial fisheries (Belore et al. 2006).
Although Whitefish management actions have been very effective in the upper Great
Lakes, the presence of invasive species has been large enough to disrupt the food web
sufficiently to affect overall production and we have therefore awarded a middle score.
3.00
Substantial management measures are in place over a large portion of the species range
and have demonstrated success in achieving conservation and sustainability goals.
Points of Adjustment (multiple selections allowed)
-0.25 There is inadequate scientific monitoring of stock status, catch or fishing effort.
-0.25 Management does not explicitly address fishery effects on habitat, food webs, and
ecosystems.
-0.25 This species is overfished and no recovery plan or an ineffective recovery plan is in
place.
-0.25 Management has failed to reduce excess capacity in this fishery or implements subsidies
that result in excess capacity in this fishery.
+0.25 There is adequate scientific monitoring, analysis and interpretation of stock status,
catch and fishing effort.
There are a number of programs implemented by individual Great Lakes management
units that are used to assess the status of Whitefish (and other species) populations
(Belore et al. 2006). Examples include trawling surveys to determine the status of young
Whitefish, and gillnet sampling for ages 1 and older (Belore et al. 2006). In Lake Ontario,
mark-recapture tagging programs are used to determine migratory habits of Whitefish
and population assessments, at some level, are performed on Whitefish in all of the Great
Lakes (Belore et al. 2006). For example, Catch Per Unit Effort is plotted over time in
Lake Superior (Ontario waters), while in Lake Huron and Lake Erie, data from fishing
independent and dependent monitoring programs, among others, are used in statistical
models (Belore et al. 2006). In general, trends related to the age at maturity, ages
represented in the current population, survival estimates and mean weight at age are
available for Whitefish in the Great Lakes (Belore et al. 2006).
+0.25 Management explicitly and effectively addresses fishery effects on habitat, food webs,
and ecosystems.
+0.25 This species is overfished and there is a recovery plan (including benchmarks, timetables
and methods to evaluate success) in place that is showing signs of success OR recovery
plan is not needed.
+0.25 Management has taken action to control excess capacity or reduce subsidies that
result in excess capacity OR no measures are necessary because fishery is not
overcapitalized.
The size and number of vessels are limited in the Lake Superior commercial Whitefish
fishery (Ebener 2000) and Lake Michigan‟s commercial Whitefish fishery operates under
a limited entry system (LMFT 2004). Ontario‟s commercial fishery is also a limited entry
fishery with no new licenses available.
2.50 Points for Management
BYCATCH
Core Points (only one selection allowed)
Select the option that most accurately describes the current level of bycatch and the
consequences that result from fishing this species. The term, "bycatch" used in this document
excludes incidental catch of a species for which an adequate management framework exists. The
terms, "endangered, threatened, or protected," used in this document refer to species status that is
determined by national legislation such as the U.S. Endangered Species Act, the U.S. Marine
Mammal Protection Act (or another nation's equivalent), the IUCN Red List, or a credible
scientific body such as the American Fisheries Society.
1.00
Bycatch in this fishery is high (>100% of targeted landings), OR regularly includes a
"threatened, endangered or protected species."
2.00
Bycatch in this fishery is moderate (10-99% of targeted landings) AND does not
regularly include "threatened, endangered or protected species" OR level of
bycatch is unknown.
Apart from bycatch of lake trout, there is little information about what additional species
are caught in Whitefish fisheries. Bycatch of lake trout is considerably higher in gillnets
than in trap nets (Schorfhaar and Peck 1993), which agrees with the findings of Morgan
and Chuenpagdee (2003) who compared bycatch levels among fishing gear. It is likely
that the Whitefish fishery does not regularly capture threatened, endangered or protected
species.
3.00
Bycatch in this fishery is low (<10% of targeted landings) and does not regularly include
"threatened, endangered or protected species."
Points of Adjustment (multiple selections allowed)
-0.25 Bycatch in this fishery is a contributing factor to the decline of "threatened, endangered,
or protected species" and no effective measures are being taken to reduce it.
-0.25 Bycatch of targeted or non-targeted species (e.g., undersize individuals) in this
fishery is high and no measures are being taken to reduce it.
Lake trout bycatch in Whitefish gillnet fisheries has exceeded trout harvest quotas in
some management locations (Johnson et al. 2004a). Research suggests that lake trout
mortality is considerably higher in gill nets (McNeil et al. 1988; McNeil and deLaplante
1989; Gallinat 1997; Johnson et al. 2004a and b) than in trap nets (Van Oosten et al.
1946; Smith 1988; Schorfhaar and Peck 1993; Toneys 2000; Peeters 2001; Johnson et al.
2004a and b). For example, 300,000 lbs of lake trout caught in gill nets were dead
between 1983 and 1989, but only 1,300 lbs of lake trout caught in trap nets during the
same time period (Schorfhaar and Peck 1993). In Wisconsin, gill nets were responsible
for 96% of lake trout incidental mortality (Peters 2001).
In addition, in Lake Michigan, significant amounts of lake trout and chubs are also
incidentally caught in gillnets targeting Whitefish (LMFT 2004). The Lake Michigan
Management Committee is investigating alternative gears types, such as trap or pound
nets (LMFT 2004). There may also be some walleye bycatch in areas where Whitefish
and walleye populations overlap, such as Saginaw Bay in Lake Huron (Anonymous
2010).
Management efforts to reduce bycatch such as, converting a large portion of the
commercial US fishery from gillnets to trapnets in the mid 1980‟s (Ebener et al. 2008),
mesh size restrictions on gillnets and quotas on lake trout, have been put into place but
bycatch still remains at moderate levels (Anonymous 2010). Because bycatch is not high,
no points were subtracted.
-0.25 Bycatch of this species (e.g., undersize individuals) in other fisheries is high OR bycatch
of this species in other fisheries inhibits its recovery, and no measures are being taken to
reduce it.
-0.25 The continued removal of the bycatch species contributes to its decline.
+0.25 Measures taken over a major portion of the species range have been shown to reduce
bycatch of "threatened, endangered, or protected species" or bycatch rates are no longer
deemed to affect the abundance of the "protected" bycatch species OR no measures
needed because fishery is highly selective (e.g., harpoon; spear).
+0.25 There is bycatch of targeted (e.g., undersize individuals) or non-targeted species in this
fishery and measures (e.g., gear modifications) have been implemented that have been
shown to reduce bycatch over a large portion of the species range OR no measures are
needed because fishery is highly selective (e.g., harpoon; spear).
+0.25 Bycatch of this species in other fisheries is low OR bycatch of this species in other
fisheries inhibits its recovery, but effective measures are being taken to reduce it over a
large portion of the range.
+0.25 The continued removal of the bycatch species in the targeted fishery has had or will
likely have little or no impact on populations of the bycatch species OR there are no
significant bycatch concerns because the fishery is highly selective (e.g., harpoon; spear).
2.00 Points for Bycatch
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