Low Frequency Electroshock Fishing Invasive Catfish in Chesapeake Bay Tributaries

Bob FisherVirginia Sea Grant, Marine Advisory Program

Virginia Sea Grant ProgramVirginia Institute of Marine Science

College Of William & Mary

East Coast Commercial Fisherman’s & Aquaculture Trade ExpositionEducation Outreach Seminar Session

January 18, 2020

Introduced Catfish Blue Catfish (Ictalurus furcatus) Flathead Catfish (Pylodictis olivaris)

Introduced into the Chesapeake Bay to establish a recreational fishery -FC 1960’s in the James River, VA-BC 1970/80’s) in the James, Rappahannock, and York Rivers in VA

Both non-native species are now well established and considered invasive: potential to negatively impact native species and ecology of the Bay

Invasive Catfish Task Force (ICTF) was established in 2012 by the Chesapeake Bay Program’s Sustainable Fisheries Goal Implementation Team (SF-GIT)

-Identify Bay-wide management options to control the spread of BC and FC -address concerns of ecological and economical impact to the Ches Bay

Recommendations were provided by ICTF to help establish coordinated management strategies for invasive catfish….but…..upon review from a panel of professionals, a comprehensive management plan was recommended that would detail specific actions, roles/responsibilities across jurisdictions, control techniques, research needs

Estimates of ~70% of biomass in river systems are non-native catfish

Reviewers and Ches Bay Program’s Scientific and Technical Advisory Committee (STAC):

Scientific gaps exist: -need a better understanding of pop size/distribution, removal rates to elicit

response from system, harvesting gear effectiveness, fish contamination levels, impact to native species (trophic ecology)

FGR Funding support.... Virginia Fishery Resource Grant ProgramGear testing for catfish harvest/removal efficiency:

Electroshock Fishing.... Low Frequency Electrofishing (LFE)Electroshock fishing is widely used by fishery managers to sample fish populations, mainly in fresh low salinity waters.

Fish become stunned when subjected to an electric current generated between a positive (anode) and negative (cathode) submerged in the water

Conductivity, Temperature, fish size, Substrate ALL affect E-fishing

Commercial-scale Low Frequency Electroshock Fishing (2014, 2015, 2016, 2017)

1979 “...these devices have been reported to affect only catfish of the family Ictaluridae....the physiological basis for selective stunning appears to be related to the ability to sense weak electrical fields (for prey location) by some ictalurids...”

2013 ...Review of the peer-reviewed literature regarding sampling gear for the most common managed ictalurids: Channeled Catfish, Blue Catfish, Flathead Catfish

2.5 GPP 5.0 GPP 7.5 GPP 9.0 GPP

Conductivity 10 to 1,750 µS/cm

10 to 5,500 µS/cm

10 to 11,000 µS/cm

100 to 25,000 µS/cm

Rated Output Power 2,500W 5,000W 7,500W 9,000W

Rated Output Max. Current 8A 16A 62A 150A

Output Pulse Modes AC & Pulsed DC AC & Pulsed DC AC & Pulsed DC Pulsed DC

Technical Specifications

Smith-Root Generator Powered Pulsator (GPP) electrofishers

For the FRG studies evaluating the use of LFE for commercial harvesting catfish, the 7.5kw unit was chosen using Pulsed DC.....this unit was modified by Smith-Root so as to not allow frequencies (pulses/sec) to exceed 15Hz, the recommended frequency for targeting catfish.

Grounded to aluminum boat (Negative electrode, Cathode)

9m long 9.5mm diameter stainless steel cable lead into water (Positive electrode, Anode)

Gas powered generator

Foot pedal operated

Electronic pulsatorpowered by generator(60Hz AC to DC waveforms, for ictalurids, pulsed DC low frequency waveform)

Training commercial fisher to e-fishing gear for commercial harvest of blue catfish

Drift FisheryUsing river current or tidal flowDrift over habitat during electrofishing

Pulsed DC (15hz): 0.3-0.7 amps, 40-60 V(based on SR and scientific literature specific for catfish )

Current flows from Cathode (boat) to Anode (end of ss cable)

Fish drawn to anode, then stunned when reach electrical field and become part of the closed electrical circuit

Involuntary swimming-GalvanotaxisStunned- Galvanonarcosis, electronarcosis

Gear highly selective to species, not size selective (smallest to largest fish effected)

Fish size selectivity controlled by netter during 60-90 sec period of galvanonarcosis . Estimated only 10-15% of stunned fish are captured.

-Provide size-specific samples to address research and management needs, and

-ability to target preferred market size

-ability to not impact native white catfish

16 lbs/min

46 lbs/min

Total weight harvested by electrofishing by category and river. (2014 FRG project)Note fish size structure for each river.

70,380kg (155,161lbs) of catfish were harvested electrofishing for 5430 minutes resulting in a CPUE of 13kg (28.6lbs) per minute in James River, and 15kg (33 lbs) per minute in Pamunkey River

71% of fish in the Pamunkey River were between 1.5 and 3.6kg (3.3-8lbs)

What we learned from first attempt to apply commercial practice for LFE catfish

No species other than catfish appeared to be effected by the equipment. ....Sturgeon???.....Gar observed swimming within current field

Blue catfish was the main species harvested (areas targeted) compromising approximately 90% of weight harvested, followed by Flathead catfish. The native white catfish (Ameiurus catus) were effected but not landed. These comprised a very small amount (est~<0.5%)

Highly effective/efficient fishery that can be used to help control invasive catfish populations, especially in high density areas like in the Chesapeake Bay watershed

Highly selective gear for catfish harvest....but not size selective...Diversity in fish size = expansion of catfish markets

Temperature is a big factor in regards to low-frequency electrofishing……gear is effective when water temperatures are between 23-30 degree C (73-86 degree F). Mid-May through Sept

Fresh water influx result in inefficient LFE

“effectiveness" of the gear for commercial application as to CPUE needs further testing

Stunned fish at the surface rarely exceeded 90 seconds, leaving a brief period for capture.

sometimes an estimated 15% was netted while other times less than 5% was netted from an area.

blue catfish become desensitized to low-frequency electrofishing and do not surface after being shocked multiple times within a certain timeframe.

This fishery could be greatly improved by increasing catch efficiency…….

Reduce Gear Conflict Issues with traditional catfish fisheries

Improved catch efficiency

What we learned from first attempt to apply commercial practice for LFE catfish..Cont...

FRG 2015: Testing experimental collection gears to increase harvest efficiency of the electrofishing fishery targeting introduced blue catfish in VA waters.

Industry-driven ideas to improve catch efficiency

Gear modifications made during study to improve CPU....but

Butterfly rig, towed surface trawl, side-mounted hoop-nets

Weight breakdown of fish harvested during the 2015 FRG commercial low-frequency electrofishing season. Note fish size structure for each river.

The James River is inundated with small BCF

Large amount of BCF in PamunkeyRiver between 1.5 and 3.6kg (3.3-8lbs)

334,680lbs of catfish were harvested electrofishing for 12,850 minutes resulting in a CPUE of 26lbs per minute in James River, and 15kg (33 lbs) per minute in PamunkeyRiver

Started to address the marketing side of increased harvesting of non-native catfish

LFE providing larger amounts of catfish to market on a consistent basis during the summer when catch from traditional fisheries slows

Highly marketed size 3-8 lb fish

Small fish <1lb gaining markets

Prey items as removed from blue catfish stomachs from James River at dock.August 12, 2015

Stomach content of blue catfish from James River 8-12-2015Fish 26”: bones of relatively large fish (A) not yet identifiedFish 24”: 1 Spot (B)Fish 25”: 2 menhaden (D) and snail (E)Fish 23”: 1 eel (F)Fish 30”: 1 spot (C) and 2 blue crabs (F)Fish 28”: 6 small (~50-60mm) croakers (not shown)

A

B

C

D

F

F

E

17” bcf inside a 32” bcf

2016

Gear Conflict Question: E-fishing v hoop-net

“e-fishing causes catfish to not go to bait.... and they shock over our nets and take all the fish”

Worked with the processing sector: fish went to processor for weigh out to size categories..... BUT ALSO FOR FILLET PROCCESSING...first attempt to increase the value of BCF through processing it here in the Commonwealth.

Both linear and log-linear models were estimated to determine if LFE harvest gear had an impact on hoop net harvest levels. Six sites were compared with harvest from three sites utilizing hoop-net and LFE gears. A comparison of hoop-net harvest levels with and without LFE indicated no statistically significant difference in hoop-net harvest levels.

Low-Frequency Electrofishing Affect on the Catch of Blue Catfish Hoop-Net Fishery; Gear conflict study. NOAA Sustainable Fisheries Goal Implementation Team (GIT) semi-annual meeting, Annapolis, MD., December 6, 2016. 30 attendees representing state and regional management agencies.

Currently (2019) – Fillets, Heads

2020 – Bellies, roe

2015 project first steps with Catfish processing to retain resource value in the Commonwealth...filleting

2017

Blue Catfish Range Extension into waters of higher conductivity

Comparing functionality and area over-lap of 7.5kw and 9.0kw GPP’s in higher saline habitat

Focus for comparison was given within the lower James River where salt-wedge shifts

2.5 GPP 5.0 GPP 7.5 GPP 9.0 GPP

Conductivity 10 to 1,750 µS/cm

10 to 5,500 µS/cm

10 to 11,000 µS/cm

100 to 25,000 µS/cm

Rated Output Power 2,500W 5,000W 7,500W 9,000W

Rated Output Max. Current 8A 16A 62A 150A

Output Pulse Modes AC & Pulsed DC AC & Pulsed DC AC & Pulsed DC Pulsed DC

Technical Specifications

Smith-Root Generator Powered Pulsator (GPP) electrofishers

9.0 provided better efficiency in fringe temperature and conductivity ranges: extend fishing season

9.0...Larger effected field range=more power into water and fish become de-sensitized quicker

Pilot cooperative fishery project managed by VIMS MAP FRGP coordinator

It is proposed to solicit collaborating VA fishers from traditional catfish fisheries to partner in a pilot program to enhance the landings of invasive catfish from the James and PamunkeyRivers within the commercial LFE catfish fishery. This proposed work will expand the number of stakeholders, primarily traditional catfish fishers who can supplement their current fishing activity, as well as provide fishery catch data for fishery management and economic analyses. With increased capture efficiency in the commercial LFE fishery, the reduction of invasive catfish biomass will help obtain goals set by the Invasive Catfish Task Force designed to restore an ecological balance in VA tributaries and relieve pressure on native populations. A key component in the design of this work is to provide a transparent and equal opportunity program foundation supported by VIMS and VMRC.

Timeline of Commercial Electrofishing in Virginia 2014: Invasive Catfish Working Group of the Chesapeake Bay Program calls for states to increase invasive catfish removals and to consider the promotion of commercial electrofishing.

2014-2017: Experimental electrofishing program in James and Pamunkey Rivers.

April 2019: VMRC begins developing a commercial electrofishing regulation.

August 1, 2019: VMRC attends a public meeting at DGIF with recreational catfish anglers and charter captains.

October 22, 2019: VMRC requests a December 17, 2019, public hearing on commercial electrofishing at their monthly Commission meeting.

November 14, 2019: VMRC holds an informational session for watermen eligible under the current draft regulation to ask questions about electrofishing.

November 14, 2019: VMRC presents the plan for a commercial electrofishing fishery to the Finfish Management Advisory Committee at their publicly advertised meeting.

November 25, 2019: VMRC reviews the draft language for a commercial electrofishing regulation with the Finfish Management Advisory Committee at their publicly advertised meeting.

December 2, 2019: The full draft regulation is publicly posted in the VMRC Main Office. The Public Notice advertising the Public Hearing is published on the VMRC website and in the Daily Press, the Richmond Times Dispatch, the Virginian Pilot, and the Eastern Shore News.

December 12, 2019; Meeting with Delegate Ransone and 14 catfish fishermen from Rappahannock River

December 17, 2019: The Commission hears public comments and votes 9-0 to approve the commercial electrofishing fishery and regulation at their monthly Commission meeting.