Captures of protected species in New Zealand recreational fisheries Edward Abraham 25 June 2020 Department of Conservation Project BCBC2019-07a This presentation is of provisional work, final results may differ.
Introduction This presentation is of provisional work, final results may differ.
Protected species Introduction This presentation is of provisional work, final results may differ. • All seabirds (apart from black-backed gull) • All marine mammals • All marine reptiles • Some sharks (including great white shark) • Some fish (spotted black grouper, giant grouper) • Some corals (including black corals)
How we know about recreational fishing Introduction Fishers are asked about their catch as they return to the ramps fishing throughout the year This presentation is of provisional work, final results may differ. • Boat ramp surveys have been conducted by NIWA for MPI. • Aerial surveys allow total fishing effort to be estimated • The National Panel Survey (NPS) asks fishers about their • Charter fishers provide statutory returns to MPI
Available data on protected species Boat-based line fishing NPS NPS Other fishing NPS NPS Set net fishing NPS NPS Shore fishing Boat ramp NPS/Aerial NPS Charter Introduction Charter MPI MPI Charter fishing Corals Other fish Sharks & rays Reptiles Mammals Seabird species Seabird groups Spatial effort FMA effort This presentation is of provisional work, final results may differ.
Sources of unstructured data Introduction This presentation is of provisional work, final results may differ. • Bird banding database • Marine mammal stranding database • Birds New Zealand beach patrol database • DOC hotline • Shark sightings
Previous boat ramp study of seabird captures Introduction stage in the past interview (0.22 captures per 100 hours of fishing) 6600 to 17 200) bird captures per year in FMA 1 This presentation is of provisional work, final results may differ. • 763 boatramp interviews carried out during 2007–08 • 47% of fishers recalled witnessing a bird being caught at some • There were 21 seabirds reported caught on the day of the • From this rate, there were estimated to be 11 500 (95% c.i.: • Three of the 21 captured birds were reported to have died
Seabird captures on charter vessels Introduction seabird captures fisher hours was recorded This presentation is of provisional work, final results may differ. • Observers on 57 charter trips during 2007–08 recorded • A capture rate of 0.36 (95% c.i.: 0.09 to 0.66) birds per 100
Boat ramp survey This presentation is of provisional work, final results may differ.
“Did you catch any birds with your fishing gear today?” Boat ramp survey NIWA, for MPI boat ramps take of key fish species This presentation is of provisional work, final results may differ. • Carried out between October 2017 and September 2018 by • A total of 51 295 fishers were interviewed as they returned to • Primary goal in FMA 1 was the estimation of the recreational • Conducted along with an aerial survey • For the first time, fishers were asked about seabird captures
Fishers asked about seabird captures, by FMA 0.23 7 2 789 8 502 5 0.06 8 1 509 5 190 12 9 3 1 420 4 728 0 0.00 All 43 646 155 130 455 0.29 The capture rate is the number of seabirds caught per 100 hours of fishing 0.24 1 227 Boat ramp survey 0.35 FMA Fishers Fishing hours Captures Capture rate 1 33 537 120 566 420 2 574 1 818 8 085 8 0.10 3 1 999 6 830 7 0.10 5 This presentation is of provisional work, final results may differ.
Largely rod and line fishing 0.00 Net 186 524 0 0.00 Bottom line 29 124 0 0.00 Gathering 103 102 0 Mixed 0 10 36 0 0.00 Shore fishing 13 22 0 0.00 All 43 646 155 130 455 0.29 0.00 3 838 Boat ramp survey 0.32 Method Fishers Fishing hours Captures Capture rate Rod and bait 33 536 122 041 390 0.32 Rod and lure 3 937 12 946 41 Trolling 684 0.05 Bottom gear 0.00 0 4 156 2 225 Diving 1 2 121 2 000 802 Longline 0.25 23 9 340 This presentation is of provisional work, final results may differ.
This presentation is of provisional work, final results may differ. 34 ° S 1 36 ° S 9 Captures per 100 hours 38 ° S Less than 0.1 8 0.1 to 0.2 0.2 to 0.5 0.5 to 1.0 40 ° S 2 Latitude More than 1.0 Number of interviews 10 7 30 42 ° S 100 300 1000 3000 44 ° S 3 46 ° S 5 166 ° E 168 ° E 170 ° E 172 ° E 174 ° E 176 ° E 178 ° E 180 ° Longitude
Largely snapper fishing 0.03 Shellfish and kina 0.00 0 4 492 1 026 Rock lobster 1 1 843 3 090 744 Gurnard 0.06 4 6 995 1 406 0 Gamefish 0 0.29 455 155 130 43 646 All 0.00 1 032 0.00 175 Bluenose 0.00 0 1 444 303 Hāpuku 1 166 0.15 Boat ramp survey 97 891 47 18 861 5 440 General 0.34 328 27 380 Kingfish Snapper Capture rate Captures Fishing hours Fishers Method 0.25 2 042 10 729 6 593 2 330 Blue cod 0.43 13 2 989 Tarakihi 7 716 0.87 19 2 183 905 Kahawai 0.43 33 This presentation is of provisional work, final results may differ.
Largely “petrel & shearwater” 20 4 2 231 Shag 38 2 2 3 45 Tern 19 1 Unidentified Petrel 65 1 1 67 All 420 8 7 3 5 12 455 225 3 Boat ramp survey 1 Taxon FMA 1 2 3 5 7 8 All Albatross 7 5 2 3 15 Gannet 32 32 Gull 31 1 2 1 1 6 42 Penguin This presentation is of provisional work, final results may differ.
Largely released alive Alive Alive 74 Removed Dead 1 Tangled 261 11 Dead 6 Unknown 24 All 455 Removed Alive Boat ramp survey Hooked, externally Capture Hook Outcome Caught in net Alive 2 Not removed Not removed Alive 4 Removed Alive 72 Hooked, beak/gizzard This presentation is of provisional work, final results may differ.
Data issues Boat ramp survey fisher, interviewers were instructed to assign other captures to other fishers in the group same number of captures as the number of fishers, with all the details being the same (unkown species, tangled) in a single group This presentation is of provisional work, final results may differ. • The form only allowed for a single incident to be recorded per • In 46 cases, multiple captures were reported that had the • Of the 7 seabirds reported as dead, 6 were repeated captures
Estimated seabird captures This presentation is of provisional work, final results may differ.
Method Estimated seabird captures The boat ramp survey can be used to estimate seabird captures from boat-based recreational line-fishing, by FMA and method (“Line” or “Longline”), from the product of the following terms: hours fishing) This presentation is of provisional work, final results may differ. • An estimated seabird capture rate (seabirds caught per 100 • Number of hours of fishing per trip • Total fishing effort during 2017–18
Seabird capture rate Estimated seabird captures time fishing varies with FMA and with method with Normal(0, 1) priors, and 4000 samples taken from the posterior distribution of the capture rate by FMA and method This presentation is of provisional work, final results may differ. • Use a generalised linear model • Assume that seabird captures are proportional to length of • Draw the captures from a Poisson distribution, with a rate that • The model was fitted using Bayesian methods, using BRMS, capture ~ offset(log(hours)) + method + fma
Seabird capture rate, model summary Estimated seabird captures This presentation is of provisional work, final results may differ. −0.9 −1.0 −1.1 b_Intercept −1.2 0 200 400 600 800 1000 1 0 −1 −2 b_methodLongline −3 −4 0 200 400 600 800 1000 0.0 −0.5 −1.0 −1.5 b_fma2 −2.0 0 200 400 600 800 1000 0 Chain b_fma3 −1 −2 1 0 200 400 600 800 1000 2 3 1 b_fma5 0 4 −1 −2 0 200 400 600 800 1000 −1 b_fma7 −2 −3 0 200 400 600 800 1000 0.5 b_fma8 0.0 −0.5 −1.0 −1.5 0 200 400 600 800 1000 b_fma9 −1 −2 −3 −4 −5 −3 −2 −1 0 1 0 200 400 600 800 1000
Seabird capture rate Estimated seabird captures This presentation is of provisional work, final results may differ. 0.6 Rate (captures per 100 hours) Method 0.4 Line Longline 0.2 0.0 1 2 3 5 7 8 9 FMA
Recreating the boat ramp data Estimated seabird captures This presentation is of provisional work, final results may differ. 1000 300 FMA Estimated seabird captures 1 100 2 3 5 7 30 8 9 10 Method Line Longline 3 1 0 0 1 3 10 30 100 300 1000 Observed seabird captures
Fishing hours per trip Estimated seabird captures From the boat ramp data, take 4000 bootstrap samples of the mean number of hours spent fishing, using each method, during each trip. The mean hours per trip were: This presentation is of provisional work, final results may differ. • 3.79 (CV:0.008) for line fishing • 2.53 (CV: 0.01) for longline fishing
Number of trips during 2017–18 same mean and CV. Estimated seabird captures This presentation is of provisional work, final results may differ. Samples weer generated from log-normal distributions with the Estimated trips by method and FMA were provided by NRB. 900 800 700 600 Trips (x 1000) Method 500 Line 400 Longline 300 200 100 1 2 3 5 7 8 9 FMA
Recommend
More recommend
