Tidal James & Chickahominy Largemouth

by Bob Greenlee - District Fisheries Biologist, VDGIF
rgreenlee@dgif.state.va.us

The tidal Chickahominy River and to some extent the tidal James River have traditionally supported and outstanding recreational largemouth bass fishery.  This fishery continued to provide excellent angler satisfaction until the summer of 2000, at which time calls started coming in to the Virginia Department of Game and Inland Fisheries (VDGIF) reporting the fishery “had really dropped off the board”.  In the fall of 2000, VDGIF biologists conducted an extensive electrofishing survey of the tidal Chickahominy system, as well as two tributaries of the tidal James River, Grays Creek and Powell Creek.  The results of these surveys indicated angler concerns were valid.  Almost no young-of-year (YOY) largemouth were collected during the survey and catch rates (number of bass per hour) of all size-classes were much lower than those from electrofishing surveys conducted in 1994 on the Chickahominy, and in 1998 on the James and its tributaries.

Through the winter of 2000-2001, VDGIF biologists examined the situation, discussed possible causes with anglers, and planned research efforts for 2001.  Unfortunately there were more questions than answers:

• Was the largemouth fishery in decline, or was 2000 a low point in a naturally occurring cyclic process of ups and downs for the largemouth population?
• Bass living in the tidal Chickahominy and James experience a complex set of environmental conditions, coexist with many other predator species, and are exposed to substantial fishing pressure.  Any of the following complex variables may be of concern:
  • Competition and/or Predation from
    • Striped bass, blue catfish, crappie, long-nose gar, …
  • Fishing pressure
    • The Chickahominy has experienced heavy fishing pressure
  • Prey availability/abundance
    • Including sunfish, shad, and plankton
  • Environmental Factor(s)
    • Salinity
    • Precipitation patterns / Climactic shifts
    • Shifts in vegetation
    • Tide cycles
    • Turbidity
  • Other factors?

• At which life stage is the critical impact occurring?  Are bass spawning successfully?  Are juvenile bass exposed to critical levels of predation and/or competition?  Are adverse shifts in nursery habitat quality or availability occurring?  Are adult largemouth exposed to excessive mortality rates? 

• And, is there a fisheries management solution to the situation?

VDGIF Research Activities – 2001

In 2001, VDGIF conducted the following activities to begin addressing the situation:

• Seasonal (spring, summer, and fall) electrofishing surveys were conducted on the tidal Chickahominy and James.  Information from this study allowed comparison of population age structure, growth rates, size distribution, condition of bass, catch rates, and other fisheries statistics with previous survey years.

• Note: Fall electrofishing will be repeated annually as part of the adult largemouth monitoring program, recently developed for the Chickahominy and James by VDGIF biologists.

• Tissue samples were collected for largemouth bass virus (LMBV) testing in the Chickahominy-James as part of a statewide effort to determine the presence or absence of LMBV in Virginia’s waters.

• A creel survey was conducted from May - September on the tidal Chickahominy in an attempt to assess the status of the largemouth fishery.  A previous angler survey was conducted in 1994, and would serve as a basis for comparison of angler success and angling pressure.

• Tournament data forms were distributed to club presidents and tournament directors in an attempt to monitor “major” tournaments on the tidal Chickhominy in 2001.  The information generated will allow comparison of tournament statistics in 2001 with other tournament years.

• To gain additional information about blue catfish population trends and distribution, we expanded our catfish monitoring efforts beyond the mainstem James, to include the mainstem Chickahominy, as well as a number of tributaries of the James and Chickahominy.

 Findings – 2001

 Age Structure & Growth Rates

VDGIF biologists collected the ear bones (otoliths) from adult largemouth throughout the tidal Chickahominy-James system in 2001.  Analysis of otoliths allows biologists to determine the age and growth rate of individual fish. The age distribution of the Chickahominy largemouth population mirrors that of the James, though bass from the Chickahominy are slower growing than those from the James.

Growth rates of largemouth in these tidal rivers are relatively high (Table 1), and rank near the top of values reported for brackish and/or tidal waters of the Mid-Atlantic and Southeastern U.S. 

Table 1.  Average length at age of largemouth bass in the James River - May 2001.
 

Two factors, good growth rates and body condition (weight relative to length), are an indication that adult largemouth in the Chickahominy and James do not experience excessive competition for food resources. 

Our analysis indicates that year-class strength has been variable in this population, with relatively few largemouth spawned in 2000 and 1999 recruited to the adult population.  In contrast, the 1998 year-class was outstanding (Figure 1).   Comparison with a survey of largemouth conducted on the tidal James in 1998 indicates age-1 and age-2 largemouth are well represented in our electrofishing samples when recruitment of year-classes is strong (Figure 2). Thus, the lack of age-1 and age-2 bass in our 2001 samples was not a result of gear bias, but was in fact reflective of poor year-class strength.

Figure 1.   Age structure of James River largemouth collected in spring 2001.  Bass up to age-13 occurred in our samples, and age-3 fish accounted for 45% of the bass collected.

Figure 2.  Age structure of James River largemouth collected in spring 1998.

Size Structure & Electrofishing Catch Rates

It's no surprise that the size distribution of bass collected in 2001 reflects the poor year-class strength of 1999-2000, with extremely low numbers of fish under 10 inches in our samples (Figure 3).

Figure 3.  Size distribution (inch groups) of largemouth collected from the tidal Chickahominy River in the spring of 2001.

Electrofishing catch rates (bass/hour) can be highly variable, however comparisons are possible when extensive sampling effort across a number of sites has been expended.  In 2001, catch rates for fingerling and intermediate size bass (bass < 15 inches) were significantly lower than previous survey years for both the Chickahominy and tidal James Rivers (Table 2).  Interestingly, in the James and its tributaries catch rates for bass over 15 inches was higher than 1998 (Table 2).

Table 2.  Fall 2001electrofishng catch rates of fingerling (< 12 inches), intermediate (12-15 inches), and harvestable (> 15 inches) largemouth bass compared to 1994 (Chickahominy), or to 1998 (James).

POSITIVE NOTE: Young-of-year largemouth were fairly well represented in samples collected in the fall of 2001.  This was not the case in fall of 2000.

Creel Survey – 2001

The perception has been that angling pressure on the Chickahominy has increased dramatically in recent years.  To obtain the data to evaluate this a creel survey was conducted from May – September on the tidal Chickahominy. The results can be compared to those of a similar survey conducted in 1994.  Some aspects of this comparison are quite interesting.

Estimated angler pressure on largemouth was half what it was in 1994 for the same time period.  Differences in creel design may account for some of this difference.  But, we can safely say that fishing pressure on the Chickahominy was not greater in 2001 than 1994, and was actually significantly lower. Expansion of the 2001 seasonal pressure estimate to an annual fishing pressure estimate indicates the pressure on the Chickahominy in 2001 was not unusually high compared to other heavily utilized largemouth fisheries.

The catch rate for anglers targeting largemouth bass was 0.33 bass/hour, essentially the same as it was in 1994 (0.29 bass/hr).  Again, this value is in line with those reported from creel surveys conducted on other largemouth bass waters.  One explanation for an apparently steady catch rate combined with increased angler dissatisfaction is that percentage of tournament participants and club members doubled between 1994 and 2001 (Figure 4).  In other words, the leisure-time or occasional weekend angler was a much smaller component of the largemouth bass fishery in 2001.  So, the expert angler was likely catching fewer bass/hour in 2001 than in 1994.

Figure 4. Percentage of tournament participants and club members fishing for largemouth in the Chickahominy in 1994 and 2001.

In 2001, 100% of anglers targeting largemouth on the tidal Chickahominy were practicing catch and release.  Of 25,413 largemouth caught by all anglers during the survey, 212 were harvested.

VDGIF will be following this survey up in 2002 by including the tidal Chickahominy in an all-inclusive creel survey of the tidal James freshwater fishery.

Tournaments – 2001

VDGIF documented 18 “major” tournaments in 2001, compared to 25 such tournaments in 1994.  To date we have received data from 9 of the 18 tournaments, a 50% response rate to our request for tournament information.  Results of the 2001 tournaments can be compared with previous years to track tournament success rates and shifts in tournament pressure over time.

Summary of Tournament Results – 2001

• Average number of anglers = 99
• Average of 66 anglers weighing in
• Bass/angler = 3.2 (for anglers weighing in)
• Catch Rate = 0.31 bass/angler-hr, or 3 hr = 1 bass (Constrained by tournament limits)
• Average wt/bass = 1.6 lbs
• Big Fish
  • Range (3.9 -7.1 lbs)
  • Average = 5.2 lb
• Mortality at weigh-in (0 - 2.7%); avg. = 1.3%

Comparison of Tournament Results 2001 – 1994

 VDGIF Research Plans – 2002

The results of work to date indicate the fishery has experienced two consecutive years of poor recruitment, preceded by a relatively strong 1998 year-class.  Year-class strength appears to be set prior to the first winter of life, as evidenced by the lack of young-of-year bass in fall 2000 electrofishing samples.  While this understanding helps narrow the focus of inquiry, there remain several questions which must be addressed:

• Are adult bass spawning successfully, and
  • Where does spawning occur (in which tributaries or sections of river)?
  • What habitat characterizes these spawning areas?
• If adults are spawning successfully, what factors are causing the variability in YOY survival?
  • Reduced or poor quality nursery habitat
    • Shifts in vegetation, salinity, …
  • Competition and/or Predation
  • A combination of environmental and biotic factors

To better understand these issues the following studies will be undertaken:

• Assuming current drought conditions do not persist VDGIF will track male largemouth to their spawning areas and nests using radio tags.  This study will allow biologists to identify spawning areas and to classify critical habitat features.  Adults will also be tracked in the months following the spawn to further determine movement patterns of largemouth in this diverse system.  However, radio signals can’t be detected in saline (brackish) water.  Therefore, we will be unable to conduct the study unless we get much needed significant rainfall during March.
   
• The diets of potential predators on largemouth bass, including blue catfish and striped bass will be studied.  This analysis will focus on habitats where these species co-occur with largemouth.  Though it seems unlikely that predation is the key factor at work here.  Fish predators typically target the most abundant prey item, and we have no evidence of a lack of forage in the Chickahominy and James.
   
• A creel survey will be conducted from March 1 – November 30, 2002 on the tidal James River from the fall line at Richmond to the freshwater license line below Hog Island.  The survey will include the tidal Appomattox and tidal Chickahominy.  This will be the first freshwater angler survey on the tidal James River and will allow biologists to characterize this diverse recreational fishery.  The survey will also provide a second consecutive year of creel data on the tidal Chickahominy, and will be used to verify the results of the 2001 seasonal survey.
   

• In addition to continued fall monitoring of adult largemouth, summer electrofishing surveys will be conducted to identify distribution patterns of young-of-year largemouth, determine nursery reaches, and classify critical habitat for young bass.

The Future

There is no doubt the fishery is not as good as it has been in recent years.  However, while largemouth numbers are down, our research, results of the 2001 seasonal creel survey and analysis of information from organized tournaments indicate the fishery has not  “crashed”.   That is not to say there are not reasons for concern, or that VDGIF will not be focusing continued efforts on the problem.

All information to date indicates the current state of the population is related to variability in year-class strength, and that year-class strength is likely set prior to the first winter of life.  Whether this variability s related to adult spawning success, or juvenile bass survival after the spawn must be addressed, and will be one focus of our efforts over the next year.

Should issues with recruitment persist in this system, there are fisheries management options available to us which may alleviate the situation.  VDGIF is examining the feasibility of stocking as an option in this system.  If there are consecutive years of poor recruitment, then stocking may be used to supplement weak year-classes.  However, even if stocking is determined to be feasible in this system, we must have an understanding of the reasons behind year-class failure or we may cause more harm than good by stocking. 

It is possible that disturbance during the spawn may reduce spawning success.  Efforts to protect the spawn by restricting fishing pressure may be beneficial. This could be accomplished either by protecting spawning reaches or restricting angling pressure during the spawn.  This would not necessarily need to be mandated by VDGIF through regulation, it could likely be accomplished through voluntary efforts coordinated by angling clubs.  Results of the 2001 creel survey indicate that half the anglers targeting largemouth in the Chickahominy are club members.

VDGIF plans to continue to focus intensive research efforts to develop a better understanding of the factors influencing largemouth population dynamics in these tidal rivers with the goal of implementing an effective management plan for this important fishery.

I appreciate the opportunity to communicate with you through the B.A.S.S. web site, and look forward to receiving feedback from interested anglers.

You can contact Robert by e-mailing him at rgreenlee@dgif.state.va.us

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