[PPT] - or fishing round gobies with pots Lauri Saks, Kristi Kllo, Redik PowerPoint Presentation

SLIDE 1

Analysis of methodology for catching alien species and low-valued fish

r

fishing round gobies with pots

Tartu Ülikool, Eesti Mereinstituut

U N I V E R S I T A S T A R T U E N S I S T A R T U Ü L I K O O L

1 6 3 2

Lauri Saks, Kristi Källo, Redik Eschbaum, Kristiina Jürgens, Imre Taal, Viktor Kajalainen, Martin Kesler, Eerik Kurs, Virko Sirkel, Elor Sepp, Elmar Talbonen, Aare Verliin.

SLIDE 2

Why?

2012. MSFD assessment showed that fish communities

in Estonian coastal sea are not in GES.

One possible measure - increased effort in fishing for

low-valued and invasive species.

How to do that without increasing fishing pressure to
ther species?

SLIDE 3

What?

Test the effectiveness of seineing for catching of

Prussian carp.

SLIDE 4

How?

Test the effectiveness of seineing for catching of Prussian carp.

Mesh of the wings: 30 mm (knot to knot), wing length 15 m, wing height - 1,5 m, codend height at the mouth - 2 m, codend width at the mouth - 3 m, codend length – 3 m, mesh at the codend: 15 mm (knot to knot).

SLIDE 5

How?

40 80 20 Km

A

Test the effectiveness of seineing for catching of Prussian carp.

SLIDE 6

What?

First haul - 222 Prussian carps with sum. mass 195,9 kg.
Next three hauls total - three Prussian carps with sum.

mass 2,6 kg.

Next 11 hauls total - pike 1 (1 kg), roach 1 (0.05 kg),

rudd 1 (0.1 kg), perch 2 (sum. Mass 0.25 kg), Prussian carp - 0.

Test the effectiveness of seineing for catching of Prussian carp.

SLIDE 7

So.

Seems that seineing is not the most effective measure for

Prussian carp fishing.

Test the effectiveness of seineing for catching of Prussian carp.

SLIDE 8

How?

Test the effectiveness of commercially available pots for

round goby fishing.

2017 2018 2018

SLIDE 9

How?

Test the effectiveness of pots for round goby fishing.

VM R U T

Pots modified (1 kg weight added)
10 pots in line.
Tested for difference between baited

(cut up herring and roung gobies) and unbaited pods.

SLIDE 10

How?

Test the effectiveness of pots for round goby fishing.

SLIDE 11

What?

Test the effectiveness of pots for round goby fishing.

P. fluviatilis

Z. viviparus

G. cernua
S. lucioperca
R. harrisii
S. entomon
B. bjoerkna
G. aculeatus
L. fluviatilis
R. rutilus
V. vimba
N. melanostomus

Pärnu May-August 2018

2922 individuals
2074 fish
852 invertebrates

SLIDE 12

What?

Test the effectiveness of pots for round goby fishing.

Pärnu May-August 2018

2922 individuals
2074 fish
852 invertebrates
Total catch 117.5 kg
97.4 % (114.4 kg) fish
2,6 % (1.96 kg) invertebrates
9.3 % (10.97 kg) round goby
P. fluviatilis
Z. viviparus
G. cernua
S. lucioperca
R. harrisii
S. entomon
B. bjoerkna
G. aculeatus
L. fluviatilis
R. rutilus
V. vimba
N. melanostomus

SLIDE 13

What?

Test the effectiveness of pots for round goby fishing.

Käsmu April-August 2018

17895 individuals
17893 fish
2 frogs (Rana arvalis)
N. melanostomus
Z. viviparus
G. aculeatus
P. fluviatilis
G. niger
A. alburnus
G. cernua
P. pugnitius
C. harengus
H. lanceolatus

SLIDE 14

What?

Test the effectiveness of pots for round goby fishing.

Käsmu April-August 2018

17895 individuals
17893 fish
2 frogs (Rana arvalis)
Total catch 528.3 kg
93.7 % (494.9 kg) round goby
6.0 % (31.7 kg) eelpout
0.3 % (1.6 kg) ohter species
N. melanostomus
Z. viviparus

Other species

SLIDE 15

So?

Test the effectiveness of pots for round goby fishing.

Seems that pots can be applied for increasing selective

fishing for round gobies. However! Bycatch of other species may be rather large.

SLIDE 16

What?

Test the effectiveness of pots for round goby fishing.

Baiting the pots had no effect:

Pärnu:

Two way ANOSIM : CPUE bait - R = 0.02; p = 0.1, pot type - R = 0.12; p = 0.01; WPUE bait - R = 0.01; p = 0.21, pot type - R = 0.12; p = 0.01).

Käsmu:

Two way ANOSIM : CPUE bait - R = 0.03; p = 0.89, pot type - R = 0. 20; p = 0.01; WPUE bait - R = 0.02; p = 0.85, pot type - R = 0.25; p = 0.01). Mann-Whitney U-tests – Z=0.33-1.8; p=0.07-0.59

SLIDE 17

So?

Test the effectiveness of pots for round goby fishing.

Seems that pots can be applied for increasing selective

fishing for round gobies.

Bycatch of other species may be rather large.
Baiting the pots had no effect on catches.

SLIDE 18

What?

Test the effectiveness of pots for round goby fishing.

Pot type and month had a significant effect: Pärnu:

CPUE df Pseudo-F p Pot type 3 6.418 0.001 Month 3 24.165 0.001 Pot type x Month 9 2.0212 0.003 WPUE df Pseudo-F P Pot type 3 15.2 0.001 Month 3 5.0 0.001 Pot type x Month 9 1.8 0.006

T R U VM mai juuni juuli august

Püügikuu

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000

Kõigi liikide summeeritud mass (g) U R T VM

mai juuni juuli august

Püügikuu

20 40 60 80 100 120 140 160 180 200

Kõigi liikide summaarne arvukus

SLIDE 19

What?

Test the effectiveness of pots for round goby fishing.

Pot type and month had a significant effect: Pärnu:

round gobies

mai juuni juuli august

R T U VM

Kadiskatüüp

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4

Ümarmudil CPUE mai juuni juuli august R T U VM Kadiskatüüp 20 40 60 80 100 120 Ümarmudil WPUE

SLIDE 20

aprill mai juuni juuli august VM U T R Kadiskatüüp 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 26000 Kõigi liikide summaarne mass (g) aprill mai juuni juuli august VM U T R Kadiskatüüp 100 200 300 400 500 600 700 Kõigi liikide summarne isendite arv

What?

Test the effectiveness of pots for round goby fishing.

Pot type and month had a significant effect: Käsmu:

CPUE df Pseudo-F p Pot type 4 5.39 0.011 Month 4 65.51 0.001 Pot type x Month 12 3.19 0.001 WPUE df Pseudo-F p Pot type 4 52.06 0.001 Month 3 8.78 0.001 Pot type x Month 12 5.06 0.001

SLIDE 21

What?

Test the effectiveness of pots for round goby fishing.

Pot type and month had a significant effect: Käsmu:

round gobies

aprill mai juuni juuli august VM U T R Kadiskatüüp 10 20 30 40 50 60 70 80 90 Ümarmudil CPUE aprill mai juuni juuli august VM U T R Kadiskatüüp 500 1000 1500 2000 2500 3000 3500 Ümarmudil WPUE

SLIDE 22

So?

Test the effectiveness of pots for round goby fishing.

Seems that pots can be applied for increasing selective

fishing for round gobies.

Bycatch of other species may be rather large.
Baiting the pots had no effect on catches.
Pot type and month had a significant effect on total catch

and landed amount of round gobies.

Larger pots with larger mesh caught more round gobies.

SLIDE 23

What?

Test the effectiveness of pots for round goby fishing. State of fish in the pots:

Pot type # dead individuals perch eelpout ruffe white bream round goby May T 4 May U 10 2 2 May VM May R 3 May total 10 9 2 June T 2 1 1 6 June U 1 7 June VM June R 2 6 total total 5 14 6 July T 4 1 1 July U 3 July VM 3 July R 4 July total 14 1 1

Pärnu: 97.8 % survived Käsmu: 87.2 % survived

juuni juuli august VM U T R Kadiskatüüp 200 400 600 800 1000 1200 Surnud ümarmudil WPUE

SLIDE 24

So?

Test the effectiveness of pots for round goby fishing.

Seems that pots can be applied for increasing selective

fishing for round gobies.

Bycatch of other species may be rather large.
Baiting the pots had no effect on catches.
Pot type and month had a significant effect on total catch

and landed amount of round gobies.

Larger pots with larger mesh caught more round gobies.
While bycatch of other species may be rather large then

the survival of fish in the pods is usually good. Unwanted catch can be released with low mortality.

SLIDE 25

What?

Test the effectiveness of pots for round goby fishing.

Comparing pot catches with other gear

T U VM R Net series Gear 100 200 300 400 500 600 CPUE ruffe perch eelpout round goby Prussian carp

ther species

Net series Gear 20 40 60 80 100 120 140 160 180 200 220 240 260 280 CPUE VM R T U

ther species

round goby eelpout

Pärnu Käsmu

SLIDE 26

What?

Test the effectiveness of pots for round goby fishing.

Comparing pot catches with other gear

Käsmu

Gear average CPUE (±SD) average WPUE (±SD) round goby eelpout

ther

round goby eelpout

ther

T 0,5 (±0,4) 0,1 (±0,1) 0,01 (±0,03) 16,5 (±13,8) 2,2 (±2,9) 0,02 (±0,1) R 0,2 (±0,1) 0,02 (±0,04) 0,02 (±0,05) 12,0 (±6,6) 1,1 (±2,5) 3,3 (±7,4) U 0,5 (±0,4) 0,1 (±0,2) 0,01 (±0,04 15,4 (±14,4) 2,6 (±3,6) 0,03 (±0,1) VM 0,1 (±0,1) 0,00 0,00 3,5 (±4,9) 0,00 0,00 Pots total 0,4 (±0,4) 0,1 (±0,1) 0,01 (±0,03) 13,9 (±13,0) 2,0 (±3,1) 0,4 (±2,6) fykenet 2,6 1,5 19,4 16,9

SLIDE 27

What?

Test the effectiveness of pots for round goby fishing.

Comparing pot catches with other gear

Gear round goby Prussian carp

ther

Round goby Prussian carp

ther

Pärnu 2017 summed May 2017 fykenet (large) 77,99 28,91 167,85 53,55 19,47 8743,93 gillnet 10,13 25,07 7158,03 104,00 69,37 Poundnet 6557,43 6677,14 fykenet (eel trap) 40,00 80,00 seine fykenet 1-3 m 62,51 46,88 104,70 7,88 14,33 103,14 Fykenet < 1 m 57,23 53,98 48,23 50,67 103,67 92,15 total 64,92 32,46 9,08 45,04 35,72 1941,46 Käsmu 2017 summed August 2017 fykenet (large) 7,77 2,29 3,13 2,71 gillnet 8,71 11,00 3,85 9,04 20,73 3,12 Poundnet fykenet (eel trap) seine fykenet 1-3 m 3,33 2,00 3,33 2,00 Fykenet < 1 m total 8,45 10,50 3,78 8,51 20,73 3,85

SLIDE 28

So?

Test the effectiveness of pots for round goby fishing.

Seems that pots can be applied for increasing selective

fishing for round gobies.

Bycatch of other species may be rather large.
Baiting the pots had no effect on catches.
Pot type and month had a significant effect on total catch

and landed amount of round gobies.

Larger pots with larger mesh caught more round gobies.
While bycatch of other species may be rather large then

the survival of fish in the pods is usually good. Unwanted catch can be released with low mortality.

While catches are bigger with most of other gear types,

pot catches are still in comparable range with some other gear types. Cost much less though.

SLIDE 29

Marcus Porcius Cato