SMALL MESH FISHERY BYCATCH REDUCTION IN THE SOUTHERN NEW - - PowerPoint PPT Presentation

SMALL MESH FISHERY BYCATCH REDUCTION IN THE SOUTHERN NEW ENGLAND/MID-ATLANTIC WINDOWPANE STOCK AREA

Cornell University Cooperative Extension Marine Program Emerson Hasbrouck John Scotti, Scott Curatolo-Wagemann, Tara Froehlich, Kristin Gerbino Jacqueline Wilson, Joseph Costanzo, Chris Mazzeo, Dan Kuehn Cornell University

• Dept. of Natural Resources – Ithaca, NY
• Dr. Patrick Sullivan

Superior Trawl Inc. – Narragansett, RI Jonathan Knight Funded By The New England Fishery Management Council Groundfish Research Program Through the Northeast Consortium

The goal was to test the hypothesis that windowpane flounder bycatch levels can be significantly reduced in the inshore scup fishery when a trawl net is outfitted with a LMBP without significantly reducing the catch of scup. Project objectives included:



Determine if a LMBP effectively reduces the catch of windowpane flounder in the SNE/MA small mesh scup fishery with existing gear and fishing practices in

• rder to help avoid or reduce the impact of triggering AMs



Determine the statistical level of difference (if any) between the control and experimental nets for the targeted scup catch and the windowpane flounder catch



Complete an applied experiment across a range of strata and conditions including: areas, depths, bottom type, and times reflective of the small mesh scup fishery



Validate these results for fishery managers and fishermen

Goals and Objectives

• The F/V Sea Breeze Too and F/V

Elizabeth Katherine were chartered to conduct at-sea research trips

• The vessels used identical nets and

made adjustments to uncover the panel to switch from the control design to the experimental design

• The two vessels towed side by side

through the study area while targeting scup and windowpane

• Comparisons of the control and

experimental net were based on paired differences in catch by species

Project Summary

 At-sea research was conducted in October 2015 when there

was the highest likelihood for co-occurrences of scup and windowpane flounder.

Project Summary

• 4 trips (7 days) were

conducted in SNE using an ABBA protocol

• 84 total tows were

conducted (42 tows each for the control and experimental nets)

Project Summary

 CCE tested and evaluated a large mesh belly panel (LMBP) to

reduce windowpane flounder bycatch in the inshore small mesh scup fishery in SNE/MA

 Exceeding the Annual Catch Limit (ACL) for windowpane triggers

Accountability Measures (AMs) that restrict groundfish and other trawl fishing activities

• The AMs are gear modification areas

that require the use of approved selective trawl gear in defined areas to minimize the catch of flatfish

• The LMBP was also evaluated for its

ability to maintain the catch efficiency

• f the target species (scup)

Northern & Southern Windowpane Flounder AM Areas

Southern New England Project Area

Sketch of Large Mesh Belly Panel Configuration

The LMBP was made from 80cm (~32”) knot-center to knot-center diamond mesh. The panel was 2 meshes deep and was sewn into the standard 12cm (5”) mesh of the 1st bottom belly resulting in an effective area for fish escapement of 3 full 32” meshes, or an opening in the net belly that was ~8’ deep from front to back. The LMBP attached ~1 foot (2.5 meshes/12cm) behind the footrope and extended widthwise across the belly of the net (from gore to gore) for 30 meshes.

Project Results

Boxplot Distribution of Windowpane Flounder Catch Weight in the Control and Experimental Net

Control Experimental 10 20 30 40 50 Pounds

Project Results Windowpane Flounder (by Weight)

Total Catch Weight of Windowpane Flounder (lbs) in the Experimental and Control Nets for All Trips Combined

Project Results Windowpane Flounder (by Weight)

 The reduction in windowpane flounder catch in the

experimental net was 48.04% compared to the control net (52.5% based on median)

 T- test results showed a highly significant difference in

the catch weight between the control and experimental nets (p-value <0.0001). The Wilcoxon test yielded similar results (p-value<0.0001)

Project Results – Windowpane Flounder (by Weight)

Boxplot Distribution of Windowpane Flounder Catch By Number of Fish in the Control and Experimental Net

Control Experimental 50 100 150 Count

Project Results Windowpane Flounder (by Count)

Total Catch in Numbers of Windowpane Flounder in the Experimental and Control Nets for All Trips Combined

500 1000 1500 2000 2500 Control Experimental

Project Results Windowpane Flounder (by Count)

 The reduction in windowpane flounder catch in

numbers of fish in the experimental net was 46.69% compared to the control net.

 T- test results showed a highly significant difference in

the catch numbers between the control and experimental net (p-value = 0.00015) The Wilcoxon test yielded similar results (p-value <0.0001).

Project Results Windowpane Flounder (by Count)

Boxplot Distribution of Scup Catch Weight in the Control and Experimental Net

Control Experimental 200 400 600 800

Scup Pounds

Pounds

Project Results - Scup(by Weight)

Total Catch Weight of Scup (lbs) in the Experimental and Control Nets for All Trips Combined

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Control Experimental Pounds

Project Results - Scup(by Weight)

Results – Scup (by Weight)

 The overall reduction in scup catch weight in the

experimental net due to the large mesh belly panel treatment was 26.14% compared to the control net.

 T- test results showed a marginally significant

difference in the catch weight between the control and experimental net (p-value = 0.01341). The Wilcoxon test returned a similar result (p=0.001521).

 The significant difference in scup catch weight was

attributed to the reduction in sub-legal sized fish.

Boxplot Distribution of Scup Catch By Number in the Control and Experimental Nets

Control Experimental 500 1000 1500 2000 2500

Scup Count

Count

Project Results - Scup(by Count)

Total Catch in Numbers of Scup (lbs) in the Experimental and Control Nets for All Trips Combined

5000 10000 15000 20000 25000 30000 35000 40000 Control Experimental

Project Results - Scup(by Count)

Results (Scup by Count)

 The overall reduction in scup catch in numbers of fish in

the experimental net due to the large mesh belly panel treatment was 47.60% compared to the control net.

 T- test results showed a highly significant difference in

the catch numbers between the control and experimental net (p-value <0.0001). The Wilcoxon test yielded similar results (p-value <0.0001).

 The experimental net significantly reduced the catch of

scup in numbers of fish compared to the control net. However, this significant difference can be attributed to the reduction in sub-legal sized fish.

Windowpane Flounder Length Frequency Distributions

50 100 150 200 250 300 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839 Number at Length Length (cm)

Control

50 100 150 200 250 300 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 Number at Length Length (cm)

Experimental

Length Frequency Distribution Results - Windowpane

 The peak of the windowpane flounder length distribution occurs in

both nets at 27 cm. There was a 49.3% reduction in fish of this size as a result of the large mesh belly panel. A large reduction

• ccurs at nearly all of the size intervals.

 The mean length of windowpane flounder in the control net was

• nly 0.12 cm larger than the mean length in the experimental net.

The large mesh belly panel is reducing the catch of all sizes of windowpane flounder.

Length Frequency Distribution - Scup

 The scup lengths that were collected were fork

• lengths. The commercial legal minimum size for

scup is 9” (22.9 cm) measured in total length.

 We used a standard ASMFC conversion formula to

determine that 22.9 cm (9”) total length equates to a 20.2 cm fork length.

Scup Length Frequency (Fork Length) Distributions

1000 2000 3000 4000 5000 6000 7000 8000 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839 Number at Length Length (cm)

Control

1000 2000 3000 4000 5000 6000 7000 8000 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839 Number at Length Length (cm)

Experimental

Minimum legal size Minimum legal size

Length Frequency Results - Scup



Peaks in the length frequency distribution occur in both nets at 9, 16 and 26

• cm. The highest peak is at 9 cm in the control net. There was a 75% reduction

in fish of this size in the experimental net.



The experimental net reduced the catch of undersized, sublegal scup (20.2cm fork length) by 68%.



The mean length of scup in the experimental net was 1.75 cm larger than the mean length in the control net indicating that the large mesh belly panel is allowing for escapement of smaller fish while retaining larger fish.



The escapement of small scup may be attributed to scup stratifying by size within a school, with small fish at the bottom and larger fish at the top. Also smaller scup likely tire quicker than larger scup and may fall back into the net sooner while also being close to the bottom of the net.



The reduction in undersized, sublegal scup observed in the experimental net is beneficial to the industry and to the scup resource.

Management

 In Fishing Year 2015, Northern and Southern windowpane flounder

ACLs were exceeded by >20%. This overage triggered the implementation of AMs which go into effect on May 1, 2017. Use of selective gear types designed to avoid flounder must be used in the large and small AM areas.

 Based on project results, CCE recommends that the large mesh

belly panel be considered in management as an approved selective gear type utilized to reduce windowpane bycatch in designated areas when AMs are triggered. 

More tows may need to be conducted to further verify the effectiveness of the large mesh belly panel in additional areas and during other times of the year. www.squidtrawlnetwork.com www.ccesuffolk.org/marine/fisheries

Acknowledgements

 Northeast Consortium and NEFMC

Groundfish Research Program

 F/V Sea Breeze Too – Owner Phil Ruhle

Jr., Captain Jason Sawyer and Crew

 F/V Elizabeth Katherine –

Owner/Captain Steve Arnold and Crew

 Jonathan Knight - Superior Trawl Inc.