Download STUDY PERFORMANCE REPORT

STUDY PERFORMANCE REPORT
State: Michigan
Project No.:
Study No.: 230695
Title: Northern Lake Huron coolwater fish
community assessment
Period Covered:
F-81-R-11
October 1, 2009 to September 30, 2010
Study Objective: To collect relative abundance, growth rate, and other biological data with which to
assess responses of the Les Cheneaux Islands region and the St. Marys River coolwater fish
communities to exploitation, management initiatives, and changing environmental and biological
conditions.
Summary: Yellow perch abundance increased in the Les Cheneaux Islands in 2009 and was the third
greatest value since the early 1980s. Despite this, it appears that the recovery of that population
may have pleateaued and is now recruitment limited. Total annual mortality rate continues to
decline in the presence of lower cormorant abundance. Other species also continue to show
greater abundance in the absence of cormorants. Sampling in 2010 was conducted as scheduled
for both the Les Cheneaux Islands and the St. Marys River.
Findings: Jobs 1 through 5 were scheduled for 2009–10, and progress is reported below.
Job 1. Title: Survey design and coordination.–There were no changes to, or deviations from, the
study design in 2009.
Job 2. Title: Conduct surveys and process samples.–A total of 6 gillnet lifts spanning three
stations in the Les Cheneaux Islands were conducted in 2009. The 2010 survey was conducted
during the first week of October and will be reported on in next years reporting cycle. The 2009
survey in the Les Cheneaux Islands marked the 40th anniversary of this time series. While only
funded by Sport Fish Restoration since 2001, this time series has informed fisheries management
since 1969 and has been the centerpiece of much of the knowledge base over cormorant impacts
on fisheries in the Great Lakes. The data base that stems from this survey series has become
something of an information heritage for the State of Michigan.
The St. Marys River was not slated for sampling in this current reporting cycle.
Job 3. Title: Maintain data – maintain databases.–Databases for the Les Cheneaux survey were
updated with the 2009 collections. Some data encoding for the 2009 St. Marys survey is
complete.
Job 4. Title: Analyze data, modeling.–Yellow perch abundance in 2009, as indicated by gillnet
CPUE, increased in the Les Cheneaux Islands to 48.2 per net lift. This is the third highest CPUE
value since 1985. Mean age of yellow perch declined slightly in 2009 to 3.3 years but still
reflects a considerable improvement over the period of high cormorant predation. The total
annual mortality rate for yellow perch from 2007–09 was 55% which is a small increase but still
an improvement over the period of high cormorant abundance, when rates were as great as 87%.
Northern pike continue to increase in the Les Cheneaux Islands, reaching a mean CPUE value of
14.7 in 2009. On the whole, the Les Cheneaux Islands fish community continues to show
1
F-81-R-11, Study 230695
improvement in 2009 over the period of high cormorant abundance. Cormorant control began in
2004 and related research and analysis documented the strong correlation between cormorant
predation and declines in yellow perch, northern pike, and other fish species. The sport fishery
for yellow perch in 2009, however, declined and was trending differently than the abundance of
perch in the fish community survey.
Analysis of the 2009 St. Marys River fish community survey has begun. A total of 3,862
specimens were collected by the various agencies contributing data as part of this
multijurisdictional effort. Walleye gillnet CPUE was 5.0 which was a decline from the last
survey in 2006 but well within the usual range over the history of this survey series, which dates
to 1975. Yellow perch abundance as indicated by gillnet CPUE was largely unchanged from the
2006 survey at 40.0 perch per lift. Similarly northern pike were virtually unchanged at 2.0 per lift
although that still represents a substantial decline from the abundances between 1975 and 1987.
It’s unclear why northern pike are less abundant in the St. Marys River, while they are
flourishing in the neighboring Les Cheneaux Islands. Ciscos exhibited a slight improvement in
abundance in 2009 with a CPUE of 7.1 but, like pike, are trending lower since 1987. Analysis of
the St. Marys River data continues with expectations of a full written report by 2011.
Job 5. Title: Write annual performance report.–The performance report has been written. The
2009 survey in the Les Cheneaux Islands marked the 40th anniversary of this time series. While
only funded by Sport Fish Restoration since 2001, this time series has informed fisheries
management since 1969 and has been the centerpiece of much of the knowledge base over
cormorant impacts on fisheries in the Great Lakes. The data base that stems from this survey
series has become something of an information heritage for the State of Michigan.
Prepared by: David Fielder
Date: September 30, 2010
2