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

Analysis of methodology for catching alien species and low-valued fish or fishing round gobies with pots Lauri Saks, Kristi Källo, Redik Eschbaum, Kristiina Jürgens, Imre Taal, Viktor Kajalainen, Martin Kesler, Eerik Kurs, Virko Sirkel, Elor Sepp, Elmar Talbonen, Aare Verliin. Tartu Ülikool, Eesti Mereinstituut Ü L U I K T O R O A L T S U I N S I N V E E U R 1 6 3 2 T S R I T A A T S

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 other species?

What? • Test the effectiveness of seineing for catching of Prussian carp.

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).

How? Test the effectiveness of seineing for catching of Prussian carp. A 0 20 40 80 Km

What? Test the effectiveness of seineing for catching of Prussian carp. • 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.

So. Test the effectiveness of seineing for catching of Prussian carp. • Seems that seineing is not the most effective measure for Prussian carp fishing.

How? • Test the effectiveness of commercially available pots for round goby fishing. 2018 2018 2017

How? Test the effectiveness of pots for round goby fishing. VM R 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. U

How? Test the effectiveness of pots for round goby fishing.

What? Test the effectiveness of pots for round goby fishing. Pärnu May-August 2018 G. aculeatus V. vimba R. rutilus • 2922 individuals L. fluviatilis B. bjoerkna • 2074 fish S. entomon N. melanostomus • 852 invertebrates P. fluviatilis R. harrisii Z. viviparus S. lucioperca G. cernua

What? Test the effectiveness of pots for round goby fishing. L. fluviatilis Pärnu May-August 2018 V. vimba R. rutilus G. aculeatus • 2922 individuals B. bjoerkna S. entomon N. melanostomus • 2074 fish R. harrisii • 852 invertebrates S. lucioperca • Total catch 117.5 kg • 97.4 % (114.4 kg) fish • 2,6 % (1.96 kg) invertebrates G. cernua • 9.3 % (10.97 kg) round goby P. fluviatilis Z. viviparus

What? Test the effectiveness of pots for round goby fishing. Käsmu April-August 2018 P. fluviatilis G. cernua P. pugnitius G. niger C. harengus A. alburnus • 17895 individuals H. lanceolatus G. aculeatus • 17893 fish Z. viviparus • 2 frogs ( Rana arvalis ) N. melanostomus

What? Test the effectiveness of pots for round goby fishing. Käsmu April-August 2018 Other species Z. viviparus • 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

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.

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

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.

What? Test the effectiveness of pots for round goby fishing. • Pot type and month had a significant effect: Pärnu: CPUE WPUE df Pseudo-F p df Pseudo-F P 3 6.418 0.001 Pot type 3 15.2 0.001 Pot type 3 24.165 0.001 Month 3 5.0 0.001 Month Pot type x Pot type x 9 2.0212 0.003 9 1.8 0.006 Month Month 200 11000 U T 180 10000 R R T U 9000 Kõigi liikide summaarne arvukus 160 VM VM Kõigi liikide summeeritud mass (g) 8000 140 7000 120 6000 100 5000 80 4000 60 3000 40 2000 20 1000 0 0 mai juuni juuli august mai juuni juuli august Püügikuu Püügikuu

What? Test the effectiveness of pots for round goby fishing. • Pot type and month had a significant effect: Pärnu: round gobies 2.4 120 mai 2.2 juuni mai juuli juuni 2.0 100 august juuli 1.8 august 1.6 Ümarmudil WPUE 80 Ümarmudil CPUE 1.4 1.2 60 1.0 0.8 40 0.6 0.4 20 0.2 0.0 0 VM U T R VM U T R Kadiskatüüp Kadiskatüüp

What? Test the effectiveness of pots for round goby fishing. • Pot type and month had a significant effect: Käsmu: CPUE WPUE df Pseudo-F p df Pseudo-F p 4 5.39 0.011 Pot type 4 52.06 0.001 Pot type 4 65.51 0.001 Month 3 8.78 0.001 Month 12 3.19 0.001 12 5.06 0.001 Pot type x Month Pot type x Month 700 26000 aprill aprill 24000 mai mai 600 22000 juuni juuni Kõigi liikide summarne isendite arv juuli juuli 20000 Kõigi liikide summaarne mass (g) august 500 august 18000 16000 400 14000 12000 300 10000 8000 200 6000 100 4000 2000 0 0 VM T R U VM U T R Kadiskatüüp Kadiskatüüp

What? Test the effectiveness of pots for round goby fishing. • Pot type and month had a significant effect: Käsmu: round gobies 90 3500 aprill aprill 80 mai mai 3000 juuni juuni 70 juuli juuli august 2500 august 60 Ümarmudil CPUE Ümarmudil WPUE 2000 50 40 1500 30 1000 20 500 10 0 0 VM U T R VM U R T Kadiskatüüp Kadiskatüüp

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.

What? Test the effectiveness of pots for round goby fishing. State of fish in the pots: Pärnu: 97.8 % survived Käsmu: 87.2 % survived Pot # dead individuals type 1200 perch eelpout ruffe white round bream goby juuni juuli 1000 T 4 May august U 10 2 2 May VM May 800 Surnud ümarmudil WPUE R 3 May 10 0 9 0 2 total May 600 T 2 1 1 6 June U 1 7 June VM 400 June R 2 6 June 5 0 14 0 6 total total 200 T 4 1 1 July U 3 July 0 VM 3 July VM U T R R 4 July total 0 0 14 1 1 Kadiskatüüp July

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.

What? Test the effectiveness of pots for round goby fishing. • Comparing pot catches with other gear Pärnu Käsmu 600 280 round goby 260 ruffe eelpout perch 240 500 other species eelpout 220 round goby 200 Prussian carp 400 other species 180 160 CPUE CPUE 300 140 120 100 200 80 60 100 40 20 0 0 T U VM R Net series T U VM R Net series Gear Gear

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